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Bulletin of the Global Volcanism Network

All reports of volcanic activity published by the Smithsonian since 1968 are available through a monthly table of contents or by searching for a specific volcano. Until 1975, reports were issued for individual volcanoes as information became available; these have been organized by month for convenience. Later publications were done in a monthly newsletter format. Links go to the profile page for each volcano with the Bulletin tab open.

Information is preliminary at time of publication and subject to change.


Recently Published Bulletin Reports

Erta Ale (Ethiopia) Continued summit activity and lava flow to the E during April 2018-March 2019

Etna (Italy) Lava flows from NSEC scoria cone and SE flank fissure in December 2018; ash emissions through March 2019

Manam (Papua New Guinea) Ash plumes reaching 15 km altitude in August and December 2018

Merapi (Indonesia) Dome appears at summit on 12 August 2018; grows to 447,000 m3 by late March 2019

Bagana (Papua New Guinea) Intermittent ash plumes; thermal anomalies continue through January 2019

Fuego (Guatemala) Frequent explosive activity with ash plumes, avalanches, lava flows, and lahars from July 2018 through March 2019

Stromboli (Italy) Constant explosions from both crater areas during November 2018-February 2019

Krakatau (Indonesia) Ash plumes, ballistic ejecta, and lava extrusion during October-December; partial collapse and tsunami in late December; Surtseyan activity in December-January 2019

Santa Maria (Guatemala) Daily explosions cause steam-and-ash plumes and block avalanches, November 2018-February 2019

Masaya (Nicaragua) Lava lake persists with decreased thermal output, November 2018-February 2019

Reventador (Ecuador) Multiple daily explosions with ash plumes and incandescent blocks rolling down the flanks, October 2018-January 2019

Kuchinoerabujima (Japan) Weak explosions and ash plumes beginning 21 October 2018



Erta Ale (Ethiopia) — April 2019 Citation iconCite this Report

Erta Ale

Ethiopia

13.6°N, 40.67°E; summit elev. 613 m

All times are local (unless otherwise noted)


Continued summit activity and lava flow to the E during April 2018-March 2019

Erta Ale is the most active volcano in Ethiopia, containing multiple active pit craters within both the summit and southeast calderas. Multiple recent lava flows are visible as darker-colored areas on the broad flanks. A new fissure eruption began in January 2017, forming a lava lake and multiple large lava flow fields during January 2017-March 2018. This report summarizes activity during April 2018 through March 2019 and is based on satellite data.

During April 2018 through March 2019 minor activity continued in the calderas and along the active lava flow to the E. Several persistent thermal anomalies were present in both the summit and southeast calderas (figure 88). A small lava outbreak was detected in Sentinel-2 thermal data on 25 December 2018 located approximately 6 km from the vent. Numerous small outbreak flows at the distal end of the lava flow located around 10-15 km away from the vent (figure 89).

Figure (see Caption) Figure 88. Sentinel-2 thermal satellite images showing Erta Ale activity in November and December 2018 with persistent thermal anomalies (bright orange-yellow) in the summit and southeast calderas (circled) and an active lava flow to the E. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 89. Sentinel-2 thermal images showing small lava flow outbreaks (bright orange) in the distal part of the latest Erta Ale flow. Courtesy of Sentinel Hub Playground.

Thermal activity using MODIS detected by the MIROVA system has been stable with a slight decrease in energy since January 2019 (figure 90). The number of thermal alerts identified by the MODVOLC system was typically below 20/month (figure 91), but with notably lower numbers in April, August, September, and November 2018, and February-March 2019. There were 30 alerts noted in December 2018.

Figure (see Caption) Figure 90. Plot showing log radiative power of MODIS infrared data at Erta Ale using the MIROVA algorithm for the year ending 9 April 2019. Black lines indicate that the location of the thermal anomaly is over 5 km from the vent while blue lines indicate that the thermal anomaly is within 5 km of the vent. Courtesy of MIROVA.
Figure (see Caption) Figure 91. Graph showing the number of MODIS thermal alerts in the MODVOLC system for Erta Ale during April 2018-March 2019 (top) and the locations of the thermal alerts (bottom). Data courtesy of HIGP - MODVOLC Thermal Alerts System.

Sentinel-1 imagery analyzed by Christopher Moore, University of Leeds (Moore et al., in prep, 2019), show a lowering of the lava lake level down to 70-90 m below the rim in October 2018, consistent with broader recent trends. Lava lake activity since late 2014 can be broken down into four stages: the pre-eruption stage during October 2014-January 2017 when the level was stable at less than 20 m below the rim; the initial fissure eruption during 11-28 January 2017 when there was a rapid drop from a state of overflowing down to 80-100 m below the rim; the early stage of the eruption period during January 2017 through mid-2017 when there was a gradual rise up to 50-70 m below the rim; and the late eruption stage during mid-2017 through October 2018 when there was a gradual drop down to 70-90 m below the rim.

Reference: Moore, C., Wright, T., Hooper, A., and Biggs, J., In Prep. Insights into the Shallow Plumbing System of Erta 'Ale Volcano, Ethiopia, from the Long-Lived 2017 Eruption.

Geologic Background. Erta Ale is an isolated basaltic shield that is the most active volcano in Ethiopia. The broad, 50-km-wide edifice rises more than 600 m from below sea level in the barren Danakil depression. Erta Ale is the namesake and most prominent feature of the Erta Ale Range. The volcano contains a 0.7 x 1.6 km, elliptical summit crater housing steep-sided pit craters. Another larger 1.8 x 3.1 km wide depression elongated parallel to the trend of the Erta Ale range is located SE of the summit and is bounded by curvilinear fault scarps on the SE side. Fresh-looking basaltic lava flows from these fissures have poured into the caldera and locally overflowed its rim. The summit caldera is renowned for one, or sometimes two long-term lava lakes that have been active since at least 1967, or possibly since 1906. Recent fissure eruptions have occurred on the N flank.

Information Contacts: MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Christopher Moore, Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom (URL: https://environment.leeds.ac.uk/see/pgr/2207/chris-moore).


Etna (Italy) — April 2019 Citation iconCite this Report

Etna

Italy

37.748°N, 14.999°E; summit elev. 3295 m

All times are local (unless otherwise noted)


Lava flows from NSEC scoria cone and SE flank fissure in December 2018; ash emissions through March 2019

Italy's Mount Etna on the island of Sicily has had historically recorded eruptions for the past 3,500 years and has been erupting continuously since September 2013 through at least March 2019. Lava flows, explosive eruptions with ash plumes, and Strombolian lava fountains commonly occur from its summit areas that include the Northeast Crater (NEC), the Voragine-Bocca Nuova (or Central) complex (VOR-BN), the Southeast Crater (SEC, formed in 1978), and the New Southeast Crater (NSEC, formed in 2011). A new crater, referred to as the "cono della sella" (saddle cone), emerged during early 2017 in the area between SEC and NSEC and has become the highest part of the SEC-NSEC complex. After several months of low-level activity in early 2018, increases in Strombolian activity at several vents began in mid-July (BGVN 43:08). This was followed by new lava flows emerging from the saddle cone and the E vent of the NSEC complex in late August and discontinuous Strombolian activity and intermittent ash emissions through November 2018 (BGVN 43:12). An eruption from a new fissure produced a lava flow into the Valle del Bove in late December 2018 and is covered in this report along with activity through March 2019 that included frequent ash emissions. Information is provided primarily by the Osservatorio Etneo (OE), part of the Catania Branch of Italy's Istituo Nazionale di Geofisica e Vulcanologica (INGV).

For the first three weeks of December 2018, Strombolian activity and ash emissions continued from the summit vents. A series of small flows from multiple vents near the scoria cone inside NSEC formed a small flow field on the E flank mid-month. A lateral eruption from a fissure on the SE flank of NSEC opened on 24 December and produced a series of flows that traveled E into the Valle del Bove for three days. Sporadic ash emissions, some with dense plumes and significant SO2 emissions, were typical throughout January and February 2019. Activity declined significantly during March 2019 to minor ash emissions and ongoing outgassing from the summit vents. The MIROVA plot of thermal energy recorded the increased heat from the lava flows during December 2018, along with minor pulses from the ash emissions and Strombolian activity in January and February (figure 240).

Figure (see Caption) Figure 240. The Etna MIROVA thermal anomaly data for 5 July 2018 through March 2019 showed a spike in thermal activity from lava flows and increased Strombolian activity in late August and during December 2018. Courtesy of MIROVA.

Activity during December 2018. Strombolian activity, with modest ash emissions, continued from the Bocca Nuova, NSEC, and NEC during the first three weeks of December. Lava flowed from the scoria cone located within the E vent of NSEC and was associated with incandescent blocks rolling down the E flank of NSEC. Variable Strombolian activity at the scoria cone beginning on 4 December produced continuous overlapping small flows from several vents near the scoria cone for two weeks (figure 241). Intermittent explosions lasted 5-10 minutes with similar length pauses; activity increased on 16 December with near-continuous lava effusion. Several small flows traveled NE, E, and SE down the E flank of NSEC during the second and third weeks of the month (figure 242). A few flows reached the base of the cone at 2,900 m elevation and were almost a kilometer in length. Small collapses of portions of the lava field also produced minor plumes of ash.

Figure (see Caption) Figure 241. Map of the summit crater area at Etna (DEM 2014). Black hatch lines outline the edge of the summit craters: BN = Bocca Nuova, with the north-western depression (BN-1) and the south-eastern depression (BN-2); VOR = Voragine; NEC = Northeast Crater; SEC = Southeast Crater; NSEC = New Southeast Crater. Yellow circles are degassing vents, and red circles are vents with Strombolian activity and/or ash emissions. The cooling lava field from the E vent scoria cone at NSEC is shown in yellow; the red flows were active on 17 December 2018. Courtesy of INGV (Report 51/2018, ETNA, Bollettino Settimanale, 10/12/2018 - 16/12/2018, data emissione 18/12/2018).
Figure (see Caption) Figure 242. The scoria cone inside the E vent of NSEC at Etna produced multiple small lava flows and Strombolian explosions for most of the first half of December 2018. (a) Strombolian activity at the scoria cone inside the E vent of the New Southeast Crater, seen from Milo (on Etna's eastern slope) on 11 December 2018. (b) Summit area of Etna seen from the south on 11 December 2018. (c) Eastern flank of the New South-East Crater seen from Fornazzo (eastern slope of Etna), with Strombolian activity and lava flows on 16 December 2018. (d) Active lava flows seen from Zafferana (eastern slope of Etna) on 16 December 2018. Courtesy of INGV (Report 51/2018, ETNA, Bollettino Settimanale, 10/12/2018 - 16/12/2018, data emissione 18/12/2018).

A lateral eruption and intense seismic swarm began on 24 December 2018 from a nearly 2-km-long fissure trending NNW-SSE on the SE flank of NSEC; it produced a flow into the Valle del Bove and covered about 1 km2 (figures 243). The other summit craters produced intense Strombolian activity and abundant ash emissions during 24-27 December. Beginning around 0800 local time on 24 December, degassing intensity from the summit craters increased significantly. In the following hours, intermittent reddish-gray ash emissions rose from Bocca Nuova and NEC becoming continuous by late morning. Shortly after noon, an eruptive fissure opened up at the southeastern base of NSEC, releasing intense Strombolian activity which rapidly formed a dense plume of dark ash. A second smaller fissure located between NSEC and NEC also opened at the same time and produced weaker Strombolian activity that lasted a few tens of minutes. Over the following two hours, the main fissure spread SE, crossing over the western edge of the Valle del Bove and reaching down to 2,400 m elevation. Continuous Strombolian activity of variable intensity occurred at NEC and Bocca Nuova. The ash cloud created by the multiple eruptive vents generated a dense plume that drifted SE, producing ashfall mainly in the area around Zafferana Etnea and Santa Venerina (figure 244).

Figure (see Caption) Figure 243. Preliminary map of the lava flows and scoria cones at Etna active during the eruption of 24-27 December 2018. The topographic base used was provided by TECNOLAB of the INGV Catania Section Observatory Etneo, Laboratory for Technological Advances in Volcano Geophysics. The abbreviations at the top left identify the various summit craters (NEC = North-East Crater, VOR = Voragine, BN = Bocca Nuova, SEC = South-East Crater, NSEC = New South-East Crater). Courtesy of INGV (Report 01/2019, ETNA, Bollettino Settimanale, 24/12/2018 - 30/12/2018, data emissione 01/01/2019).
Figure (see Caption) Figure 244. Eruptive activity from the fissure at Etna that opened on 24 December 2018 included multiple flows, Strombolian explosions, and a significant ash plume that caused ashfall in nearby communities. Top left: The eruptive fissure opened near the edge of the western wall of the Valle del Bove. Top right: An ash and steam plume produced by the opening of the fissure, taken from the south. Bottom left: Ash fall on a sidewalk in Zafferana Etnea. Bottom right: Multiple lava flows were fed by an eruptive fissure that opened along the western wall of the Valle del Bove. Images taken on 24 December by B. Behncke. Courtesy of INGV (25 dicembre 2018, Redazione INGV Vulcani, L'eruzione laterale etnea iniziata il 24 dicembre 2018).

As the fissure opened it fed several flows that descended the W face of the Valle del Bove (figure 245), past Serra Giannicola Grande, merged into a single flow at the base of the wall, and continued E across the valley floor. Ash emissions decreased significantly from Bocca Nuova and NEC after 1430 on 24 December. By 1800 the fissure was active mainly at the lower end where it continued to feed the flow in the Valle del Bove with strong Strombolian activity and abundant ash emissions. Around 1830 intense Strombolian activity resumed at Bocca Nuova along with abundant ash emissions which gradually decreased overnight. Effusive activity from the fissure continued through 26 December when it decreased significantly; new lava feeding the flow ended on 27 December, but the flow front continued to move slowly (figure 246). Degassing continued at Bocca Nuova, forming a dilute ash plume that drifted hundreds of km S before dissipating. A persistent SO2 plume was measured with satellite instruments drifting SSE during 25-30 December while the eruptive fissure was active (figure 247).

Figure (see Caption) Figure 245. Visual and thermal images of the 24-27 December 2018 fissure vent at Etna taken on 26 December 2018. (a) The eruptive fissure (yellow arrows) opened on 24 December 2018 along the W wall of the Valle del Bove and sent fresh lava down the wall (black areas), the yellow dashed rectangles indicate the areas shown with thermal images in c and d. (b) The crew that carried out the overflight on 26 December, using the helicopter of the 2nd Coast Guard Air Force in Catania. (c) and (d) are thermal camera images of the eruptive fissure that highlight the flows moving down the W wall of Valle del Bove. Visible image photo by Marco Neri. Thermal images by Stefano Branca. Courtesy of INGV (Report 01/2019, ETNA, Bollettino Settimanale, 24/12/2018 - 30/12/2018, data emissione 01/01/2019).
Figure (see Caption) Figure 246. The flow from the fissure eruption at Etna traveled past Serra Giannicola Grande and E into the Valle del Bove during 24-27 December 2018. By the time of this image at 1600 on 27 December, the lava flows were no longer being fed with new material and were almost stationary within the Valle del Bove. Photo by Marco Neri, courtesy of INGV (Report 01/2019, ETNA, Bollettino Settimanale, 24/12/2018 - 30/12/2018, data emissione 01/01/2019).
Figure (see Caption) Figure 247. The OMPS instrument on the Suomi NPP satellite measured significant SO2 plumes from Etna during the December eruptive episode, shown here by data on (clockwise from top left) 25, 27, 29, and 30 December 2018. The SO2 plumes on these days all drifted SSE from Etna. Courtesy of NASA Goddard Space Flight Center.

A significant increase in the release of seismic strain and frequency of earthquakes began around 0830 on 24 December 2018. Around 300 events occurred during the first three hours of increased seismicity which continued throughout the week, with over 2,000 events recorded in different areas around Etna. The initial swarm was located in the summit area near the fissure with events located 0-3 km below sea level; subsequent seismicity was located in the Valle del Bove and included multiple earthquakes with magnitudes greater than M 4.0. The E and SW slopes of the volcano were also affected by seismic events. The largest earthquake (M 4.8) was recorded on 26 December at 0319 local time, located about 1 km below sea level between the towns of Fleri and Pennisi on the Faglia Fiandaca fault. It was widely felt in many urban centers and caused damage in some areas. INGV noted that it was likely not generated by movement of magmatic material in the epicentral area.

Activity during January 2019. No lava flow activity was reported in January, but sporadic ash emissions and weak Strombolian activity persisted at NEC and Bocca Nuova (figure 248); occasional nighttime incandescent bursts were seen from Voragine. During one of these ash-emission episodes, on the evening of 18 January, fine ashfall was reported on the SE flank in the towns of Zafferana Etnea and Santa Venerina. Slight increases in volcanic tremor amplitude accompanied incandescent flashes from Voragine crater on the evenings of 16 and 18 January and in the early morning of 21 January (figure 249). On 19 January gas emissions and explosions were reported from a new vent near the NE edge of VOR, about 40 m NW from the 7 August 2016 vent (figure 250).

Figure (see Caption) Figure 248. Strong degassing from the summit craters at Etna was accompanied by ash emissions from NEC on 16 (a) and 19 January 2019 (b). The images were taken with the high-resolution webcam at Monte Cagliato (located E of Etna). Courtesy of INGV (Report 04/2019, ETNA, Bollettino Settimanale, 14/01/2019 - 20/01/2019, data emissione 22/01/2019).
Figure (see Caption) Figure 249. Episodes of strong incandescence appeared at Etna's Voragine crater at 1710 UTC on 16 January (a), at 1143 UTC on 18 January (b), and at 0307 on 21 January (c). Photo (a) was taken from Tremestieri Etneo (south side of Etna), (b) and (c) were recorded by the high resolution camera in Monte Cagliato (eastern slope of Etna). Courtesy of INGV (Report 04/2019, ETNA, Bollettino Settimanale, 14/01/2019 - 20/01/2019, data emissione 22/01/2019).
Figure (see Caption) Figure 250. A newly opened vent under the NE rim of the Voragine crater at Etna was observed on 19 January 2019. Behind it on the right, about 40 m SE, is the 7 August 2016 vent. Video taken by Prof. Carmelo Ferlito, Department of Biological, Geological and Environmental Sciences of the University of Catania. Courtesy of INGV (Report 04/2019, ETNA, Bollettino Settimanale, 14/01/2019 - 20/01/2019, data emissione 22/01/2019).

Newly available higher resolution SO2 data from the TROPOMI Tropospheric Monitoring Instrument on board the Copernicus Sentinel-5 Precursor (S5P) satellite showed persistent SO2 plumes from Etna that drifted significant distances in multiple directions before dissipating for much of the month. The strongest plumes were recorded during 16-22 January 2019 (figure 251).

Figure (see Caption) Figure 251. Sulfur dioxide plumes were recorded from Etna during most days in January 2019 from the TROPOMI Tropospheric Monitoring Instrument on the Copernicus S5P satellite. The densest plumes were recorded during 16-22 January; plumes from 18, 19, 20 and 21 January 2019 are shown here. Courtesy of NASA Goddard Space Flight Center.

Ash emissions intensified during the last week of January. During the morning of 23 January 2019 a dense ash plume drifted ENE from NEC, producing ashfall on the E flank of the volcano as far as the coast, including in Giarre (figure 252). Discontinuous ash emissions were reported from Bocca Nuova on 25 January; the following morning ash emissions intensified again from NEC and drifted S, producing ashfall in the S flank as far as Catania (figure 253). Emissions persisted until sometime during the night of 26-27 January. The ashfall from 22-23 and 26 January were analyzed by INGV personnel; the components were 95-97% lithic fragments and crystals with only 3-5% juvenile material. An ash plume from Bocca Nuova on 28 January drifted E and produced ashfall in the Valle del Bove. Ash emission decreased from Bocca Nuova on 29-30 January; only dilute ash was observed from NEC during the last few days of the month.

Figure (see Caption) Figure 252. Dense ash emissions during the morning of 23 January 2019 at Etna were observed (a) from the Catania camera CUAD (ECV), (b) from the Catania CUAD high resolution camera (ECVH), (c) from the area stop at Linera on the A18 Messina-Catania motorway (photo B. Behncke), and (d) from the hamlet of Pisano, near Zafferana Etnea, on the SE slope of the volcano (photo B. Behncke). Courtesy of INGV (Report 05/2019; ETNA, Bollettino Settimanale, 21/01/2019 - 27/01/2019, data emissione 29/01/2019).
Figure (see Caption) Figure 253. Ash emissions covered the snow on the S flank of Etna on 26 January 2019. Photo was taken from the SS 121 at the Adrano junction, on the SW flank of the volcano. Photo by R. Corsaro, courtesy of INGV (Report 05/2019; ETNA, Bollettino Settimanale, 21/01/2019 - 27/01/2019 ,data emissione 29/01/2019).

Activity during February 2019. Typical degassing and discontinuous explosive activity from the summit characterized Etna during February. An explosion was observed at NEC at 0230 UTC on 2 February which initially produced a dense ash plume that drifted NE, producing ashfall in the summit area and the Piano Provenzana. Ash emission decreased throughout the day. Repeated ash emissions were visible beginning in the afternoon of 6 February from NEC after several days of cloudy weather. Continuous ash emissions were observed overnight on 7-8 February, producing a dilute plume that drifted S then SE. A similar dilute ash emission was observed on 9 February; the plume drifted SW. Analysis of the ash by INGV indicated a similar composition to the samples measured two weeks prior. Webcams captured numerous pulsating ash emissions from NEC in mid-February, many of which produced substantial SO2 plumes (figure 254). Emissions increased in intensity and frequency and were nearly continuous during most of the third week, with plumes drifting W, S, and SE resulting in ashfall in those directions, and also led to temporary air space closures in Catania and Comiso (figures 255 and 256). Also during the third week, Strombolian activity took place at BN-1, while pulsating degassing was observed at BN-2. Incandescent degassing continued at the vent located on the N edge of Voragine. Irregular ash emissions that rapidly dispersed near the summit were produced by BN on 26 and 27 February.

Figure (see Caption) Figure 254. Substantial SO2 plumes accompanied ash emissions from Etna during many days in February 2019. The largest plumes were captured with the TROPOMI instrument on the Sentinel-5P satellite on 19, 20, 21, and 22 February. Courtesy of NASA Goddard Space Flight Center.
Figure (see Caption) Figure 255. Ash emission from Etna's North-East Crater (NEC) on the morning of 18 February 2019 was captured by the INGV-OE webcam in Milo. The different colored lines roughly indicate the topographic profiles observable from that position of the various summit craters of Etna: NSEC = New South-East Crater; BN = Bocca Nuova; VOR = Voragine. Courtesy of INGV (Report 09/2019, ETNA, Bollettino Settimanale, 18/02/2019 - 24/02/2019, data emissione 26/02/2019).
Figure (see Caption) Figure 256. An ash emission drifted W from Etna's NEC on 19 February 2019 as viewed from Tremestieri Etneo, located 20 km S of the volcano. Photo by Boris Behncke, courtesy of INGV-OE (Report 09/2019, ETNA, Bollettino Settimanale, 18/02/2019 - 24/02/2019, data emissione 26/02/2019).

Activity during March 2019. Discontinuous and moderate outgassing characterized activity at all the summit vents of Etna throughout March 2018 after an ash plume from Bocca Nuova on 2 March reached 4 km above the crater. The ash plume was accompanied by seismic activity that INGV concluded was likely related to an intra-crater collapse. The discontinuous degassing was interrupted on 16 March by a single small emission of brown ash from Bocca Nuova which rapidly dissipated (figure 257). During a site visit on 30 March, INGV personnel noted pulsating degassing with apparent temperatures above 250°C from the new vent formed in mid-January at the E rim of Voragine (figure 258). At NEC, low-temperature pulsating degassing was occurring at the vent at the bottom of the crater and from fumaroles along the inner walls (figure 259).

Figure (see Caption) Figure 257. A small ash emission from the BN crater on 16 March 2019 was recorded by the high-resolution webcams in Monte Cagliato, on the eastern slope of Etna (a) and in Bronte, on the west side (b). Courtesy of INGV (Report 12/2019, ETNA, Bollettino Settimanale, 11/03/2019 - 17/03/2019, data emissione 19/03/2019).
Figure (see Caption) Figure 258. Degassing continued at the vents along the E edge of Voragine crater at Etna on 30 March 2019, producing temperatures in excess of 250°C. In the background is the NE Crater (NEC) whose southern edge was affected by modest collapses in March 2019. Courtesy of INGV (Report 14/2019, ETNA, Bollettino Settimanale, 25/03/2019 - 31/03/2019, data emissione 02/04/2019).
Figure (see Caption) Figure 259. Degassing continued from the vents located on the bottom of the NE Crater at Etna on 30 March 2019 as seen from the eastern edge with visual and thermal images. Courtesy of INGV (Report 14/2019, ETNA, Bollettino Settimanale, 25/03/2019 - 31/03/2019, (data emissione 02/04/2019).

Geologic Background. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Information Contacts: Sezione di Catania - Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/it/ ); Blog INGVvulcani, Istituto Nazionale di Geofisica e Vulcanologia (INGV); (URL: http://ingvvulcani.wordpress.com); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).


Manam (Papua New Guinea) — February 2019 Citation iconCite this Report

Manam

Papua New Guinea

4.08°S, 145.037°E; summit elev. 1807 m

All times are local (unless otherwise noted)


Ash plumes reaching 15 km altitude in August and December 2018

Manam is a basaltic-andesitic stratovolcano that lies 13 km off the northern coast of mainland Papua New Guinea; it has a 400-year history of recorded evidence for recurring low-level ash plumes, occasional Strombolian activity, lava flows, pyroclastic avalanches, and large ash plumes. Activity during 2017 included a strong surge in thermal anomalies beginning in mid-February that lasted through mid-June; low levels of intermittent thermal activity continued for the rest of the year (BGVN 43:03). Activity during 2018, discussed below, included two ash explosions that rose higher than 15 km altitude, in August and December, resulting in significant ashfall and evacuations of several villages. Information about Manam is primarily provided by Papua New Guinea's Rabaul Volcano Observatory (RVO), part of the Department of Mineral Policy and Geohazards Management (DMPGM). This information is supplemented with aviation alerts from the Darwin Volcanic Ash Advisory Center (VAAC). MODIS thermal anomaly satellite data is recorded by the University of Hawai'i's MODVOLC thermal alert recording system, and the Italian MIROVA project; sulfur dioxide monitoring is done by instruments on satellites managed by NASA's Goddard Space Flight Center. Satellite imagery provided by the Sentinel Hub Playground is also a valuable resource for information about this remote location.

Satellite imagery confirmed thermal activity in December 2017, February-April 2018, and June-December 2018. Explosive activity with ash plumes was reported in June, August-October, and December 2018. Ash plumes from explosions in late August and early December rose to over 15 km altitude and caused heavy ashfall on the island. Lava flows were reported in late August, late September to early October, and December; a pyroclastic flow on the NE flank occurred during the late August explosive episode. MODVOLC thermal alerts were issued during the same periods when lava flows were reported on the NE flank. The MIROVA Log Radiative Power graph for 2018 showed intermittent pulses of thermal activity throughout the year; levels of increased activity were apparent in late December 2017-early January 2018, mid-May, August, late September-early October, and early December 2018 (figure 42). Many of these thermal events could be confirmed with either satellite or ground-based information.

Figure (see Caption) Figure 42. The MIROVA Log Radiative Power graph for Manam during 2018 showed intermittent pulses of thermal activity throughout the year, many of which could be confirmed with satellite imagery or ground observations. Levels of increased activity were apparent in late December 2017-early January 2018, mid-May, August, late September to early October, and the first half of December 2018. Courtesy of MIROVA.

Activity during December 2017-July 2018. Both Sentinel-2 satellite imagery, and MIROVA data thermal evidence, indicated continued thermal activity at both of Manam's summit craters (Main and Southern) during December 2017-April 2018. Satellite imagery on 11, 26, and 31 December showed two thermal hotspots on each date, with a gas plume drifting E on 26 December 2017. One strong thermal anomaly was visible in satellite imagery on 19 February 2018 along with a SE-drifting gas plume (figure 43). A single anomaly was visible through atmospheric clouds on 1 March 2017 with a thin gas plume drifting NNE. On 10 April two hotspots were clearly visible, the one at Southern Crater was larger than the one at Main Crater, both with ESE drifting gas plumes. Though there was diffuse atmospheric cloud cover on 15 April, both anomalies were visible with SW-drifting gas plumes. On 25 April clouds covered the likely thermal anomalies, but a dense gas plume drifted N from the summit (figure 44).

Figure (see Caption) Figure 43. Sentinel-2 images (bands 12, 14, 2) of Manam on 11, 26, and 31 December 2017 and 19 February 2018 all showed evidence of either one or two thermal anomalies at the summit craters and gas plumes drifting in multiple directions. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 44. Thermal anomalies and/or gas plumes were visible at Manam's Main and Southern Craters on 1 March and 10, 15, and 25 April 2018 in Sentinel-2 imagery (bands 12, 14, 2), confirming continued activity at the volcano. Courtesy of Sentinel Hub Playground.

Although no satellite images confirmed thermal activity in May 2018, several anomalies were recorded by the MIROVA project (figure 42). Sentinel-2 imagery on 9 June confirmed two hotspots at the summit with Southern Crater's signal larger than the weak Main Crater signal; the first VAAC report of 2018 was issued on 10 June based on a pilot report of ash at 1.8 km altitude, but it did not appear in satellite imagery. Two thermal anomalies were both more clearly visible on 29 July, with NNE drifting gas plumes (figure 45).

Figure (see Caption) Figure 45. Two thermal anomalies with steam and gas plumes were visible in Sentinel-2 imagery (bands 12,4, 2) at the summit of Manam on 9 June and 29 July 2018. Courtesy of Sentinel Hub Playground.

Activity during August 2018.Thermal activity began increasing in early August 2018, as seen in the MIROVA data, but satellite imagery also indicated a growing hotspot at Main Crater on 13 August. The thermal source appeared to be some type of incandescent flow on the upper NE flank that was visible in 23 August imagery along with the second anomaly at Southern Crater (figure 46).

Figure (see Caption) Figure 46. Growing hotspots were visible at the summit of Manam in Sentinel-2 imagery (bands 12,4, 2) on 13 August 2018 compared with the June and July imagery (figure 45). By 23 August a much larger thermal anomaly was visible beneath cloud cover originating from Main Crater. Courtesy of Sentinel Hub Playground.

The Rabaul Volcano Observatory (RVO) issued an information bulletin early on 25 August indicating a new eruption from Main Crater (figure 47). Residents on the island reported increased activity around 0500 local time. The Darwin VAAC also issued a report a few hours later (24 August 2019 UTC) where they increased the Aviation Color code to Red, and indicated a high-impact eruption with an ash plume visible in satellite imagery that rose to 15.2 km altitude and drifted WSW after initially moving N (figure 48). Reports received at RVO indicated that ash, scoria, and mud fell in areas between the communities of Dangale on the NNE and Jogari on the SW part of the island. They also indicated that the most affected areas were Baliau and Kuluguma where wet, heavy, ashfall broke tree branches and reduced visibility (figure 49). A lava flow was observed in the NE valley slowly moving downhill, and there was evidence of a pyroclastic flow that reached the ocean in the same valley (figure 50).

Figure (see Caption) Figure 47. A large explosion at Manam on 25 August 2018 (local time) produced an ash plume that rose to over 15 km altitude. Islanders reported that ash and other debris from the eruption was so thick that sunlight was totally blocked for hours. Photo taken from the New Guinea mainland by members of the Police force. Courtesy of Scott Waide.
Figure (see Caption) Figure 48. A substantial ash plume from an explosion at Manam on 25 August 2018 (local time) rose to 15.2 km altitude and drifted WSW for about five hours. Photo by Sean Richards, courtesy of Scott Waide.
Figure (see Caption) Figure 49. Vegetation on Manam was covered and damaged by heavy, wet, ash after an explosion on 25 August 2018. Photo by Anisah Isimel, courtesy of Scott Waide.
Figure (see Caption) Figure 50. A fresh lava flow was visible in the major drainage on the NE flank at Manam a few days after a large explosion on 25 August 2018. Pyroclastic flows scorched trees and left behind debris. Posted online on 28 August 2018 by journalist Scott Waide from an article by journalist Martha Louis, EMTV.

The eruption ceased around 1030 local time and was followed by dense steam plumes rising from the summit. RVO reported the following day that six houses in Boakure village on the NE side of the island were buried by debris from the pyroclastic flow. The occupants of the houses had escaped earlier to nearby Abaria village and no casualties were reported. The OMI instrument on NASA's Aura satellite captured a significant SO2 plume drifting WSW a few hours after reports of the 25 August eruption (figure 51). The Darwin VAAC reported a possible ash eruption on 28 August that was drifting WNW at 3.4 km altitude for a brief period before dissipating. According to RVO, several mudflows were reported in areas between the NW and SW parts of the island after the 25 August 2018 eruption, triggered by the heavy rainfall that followed.

Figure (see Caption) Figure 51. The OMI instrument on NASA's Aura satellite captured a significant SO2 plume drifting WSW from Manam a few hours after reports of the 25 August 2018 eruption. Courtesy of NASA Goddard Space Flight Center.

Activity during September-November 2018. Satellite evidence during September 2018 confirmed the ongoing activity at the summit where a thermal anomaly was visible at Southern Crater on 7 September. On 12 September a gas plume drifted NW from the thermal anomaly at Southern crater while an incandescent lava flow was visible on the NE flank below Main Crater. (figure 52). RVO reported increased activity at Southern Crater during 20-24 September that included variable amounts of steam and gray to brown ash plumes. The Darwin VAAC reported a short-lived ash plume visible in satellite imagery on 23 September that rose to 8.5 km altitude and drifted NW. A small ash emission seen in visible imagery on 25 September rose to 2.4 km altitude and extended SE briefly before dissipating. Although partially obscured by clouds, the lava flow was still visible on the upper NE flank on 27 September (figure 52).

Figure (see Caption) Figure 52. Satellite evidence (Sentinel-2, bands 12, 4, 2) during September 2018 at Manam confirmed the ongoing activity at the summit where a thermal anomaly was visible at Southern Crater on 7 September. On 12 September a gas plume drifted NW from Southern Crater while an incandescent flow traveled down the NE flank from Main Crater. Although partially obscured by clouds, the flow was still visible on the upper NE flank on 27 September. A nearly clear satellite image on 2 October showed incandescent lava reaching almost to the ocean in two lobes on the NE flank of the island. Courtesy of Sentinel Hub playground.

Continuous ash emissions from a new explosion were first reported based on satellite imagery by the Darwin VAAC on 30 September (UTC) at 4.3 km altitude extending SW, and also at 3.0 km altitude drifting W. The emissions at 4.3 km altitude dissipated the following day, but lower level emissions continued at 2.1 km altitude drifting NW through 3 October. On 1 October residents reported hearing continuous loud roaring, rumbling, and banging noises, and reports from Tabele on the SW side of the island indicated very bright incandescence at the summit area. The incandescence was also visible from the Bogia Government Station on the mainland. Small amounts of fine ash and scoria were reported at Jogari and surrounding villages to the N on 1 October. Field observations on 1 October confirmed the presence of a two-lobed lava flow into the NE valley. The smaller lobe traveled towards Kolang village on the N side of the valley and the larger lobe went to the S towards Boakure village. Both flows stopped before reaching inhabited areas. A nearly clear satellite image on 2 October showed the incandescent lava reaching almost to the ocean in the two lobes on the NE flank of the island (figure 52). An SO2 plume drifting SW from Manam was captured by the OMI instrument on the Aura satellite on 1 October 2018 (figure 53).

Figure (see Caption) Figure 53. The OMI instrument on NASA's Aura satellite captured an SO2 plume drifting SW from Manam on 1 October 2018. Courtesy of NASA Goddard Space Flight Center.

RVO reported that during 2-12 October Southern Crater produced variable amounts of brown, gray-brown and dark gray ash clouds that rose between a few hundred meters and a kilometer above the summit craters before drifting NW. The Darwin VAAC reported an ash emission to 10.4 km altitude on 5 October that extended 25 km W before dissipating within a few hours. Continuous emissions to 2.4 km altitude extending WNW began a few hours later and were intermittently visible in satellite imagery through 12 October. Incandescent lava was visible in satellite imagery on the NE flank on 12 October (figure 54). Activity decreased significantly during the rest of October and most of November 2018, with no ground reports, VAAC reports, or satellite imagery indicating thermal activity; only the MIROVA data showed low-level thermal anomalies (figure 42). A satellite image on 26 November 2018 indicated that thermal activity continued at one of the summit craters (figure 54).

Figure (see Caption) Figure 54. Incandescent lava was visible on the NE flank of Manam on 12 October 2018 in this Sentinel-2 satellite image (bands 12, 4, 2). A single hotspot appeared through meteoric clouds on 26 November. Courtesy of Sentinel Hub Playground.

Activity during December 2018. The Darwin VAAC reported a minor ash emission on 6 December 2018 that rose to 5.2 km altitude and drifted SE for a few hours before dissipating. A much larger ash emission on 8 December was clearly observed in satellite imagery and reported by a pilot, as well as by ground and ocean-based observers. It was initially reported at 12.2 km altitude but rose to 15.2 km a few hours later, drifting E for about 10 hours before dissipating (figure 55). This was followed later in the day by an ongoing ash emission at 8.2 km altitude that drifted E before dissipating on 9 December. According to the UNHCR news organization Relief Web, the eruption started around 1300 local time on 8 December and lasted until about 1000 on 9 December. Based on reports from the ground, the eruption affected the NE part of the island. In particular, a lava flow affected Bokure (Bokuri) and Kolang (NE Manam). Communities in both localities were evacuated. The Loop PNG reported that RVO noted that the flow stopped before reaching Bokure. Ash and scoria fall was described as being moderate in downwind areas, including Warisi village on the SE side of the island. An SO2 plume was also identified by satellite instruments. Hotspots were visible from both craters on 11 December and from one of the craters on 16 December (figure 56).

Figure (see Caption) Figure 55. This image of an eruption at Manam on 8 December 2018 (local time) was likely taken from a Papua New Guinea government ship, and made available via Jhay Mawengu of the Royal Papua New Guinea Constabulary.
Figure (see Caption) Figure 56. Sentinel-2 satellite images indicated thermal activity continuing as hotspots at the summit of Manam on 11 and 16 December 2018. Courtesy of Sentinel Hub Playground.

Geologic Background. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys" channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Information Contacts: Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea; Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://SO2.gsfc.nasa.gov/); Scott Waide (URL: https://mylandmycountry.wordpress.com/2018/08/, Twitter: @Scott_Waide); Jhay Mawengu, Royal Papua New Guinea Constabulary (URL: https://www.facebook.com/mawengu.jeremy.7); Relief Web, United Nations Office for the Coordination of Humanitarian Affairs, Resident Coordinator's Office, 380 Madison Avenue, 7th floor, New York, NY 10017-2528, USA (URL: https://reliefweb.int/); LOOP Pacific (URL: http://www.looppng.com/).


Merapi (Indonesia) — April 2019 Citation iconCite this Report

Merapi

Indonesia

7.54°S, 110.446°E; summit elev. 2910 m

All times are local (unless otherwise noted)


Dome appears at summit on 12 August 2018; grows to 447,000 m3 by late March 2019

Merapi volcano in central Java, Indonesia (figure 69), has a lengthy history of major eruptive episodes. Activity has included lava flows, pyroclastic flows, lahars, Plinian explosions with heavy ashfall, incandescent block avalanches, and dome growth and destruction. Fatalities from these events were reported in 1994, 2006, and during a major event in 2010 (BGVN 36:01) where hundreds were killed and hundreds of thousands of people were evacuated. Renewed phreatic explosions in May 2018 cancelled airline fights and generated significant SO2 plumes in the atmosphere. The volcano then remained quiet until an explosion on 11 August 2018 marked the beginning of the growth of a new lava dome. The period June 2018 through March 2019 is covered in this report with information provided primarily by Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), the Center for Research and Development of Geological Disaster Technology, a branch of PVMBG, which monitors activity specifically at Merapi.

Figure (see Caption) Figure 69. A drone aerial photo of Merapi taken on 11 November 2018 shows the Gendol river drainage in the foreground and the upper part that is often referred to as Bebeng. Pyroclastic flows descended through this drainage in both 2006 and 2010. Courtesy of Øystein Lund Andersen.

The first sign of renewed activity at Merapi came with an explosion and the appearance of a lava dome at the summit on 12 August 2018. The growth rate of the dome fluctuated between August 2018 and January 2019, with a low rate of 1,000 m3/day in late September to a high of 6,200 m3/day in mid-October. By mid-December the dome was large enough to send block avalanches down the Kali Gendol ravine on the SSE flank. The rate of dome growth declined rapidly during January 2019, when most of the new lava moved down the ravine in numerous block avalanches. By late March 2019 the dome had reached 472,000 m3 in volume and block avalanches were occurring every few days.

After the eruptive events between 11 May and 1 June 2018, seismicity fluctuated at levels slightly above normal during June and July, with the highest levels recorded on 18 and 29 July. A VONA on 3 June reported a plume of steam that rose 800 m above the summit; for the rest of June the plume heights gradually decreased to a maximum of 400 m by the third week. During July steam plume heights varied from 30 to 350 m above the summit.

On 1 August 2018 an explosion was heard at the Babadan Post. An explosion on 11 August was heard by residents of Deles on the SE flank. Photos taken in a survey by drone the following day indicated the presence of new material in the middle of the 2010 dome fracture (figure 70). The presence of a new lava dome was confirmed with a site visit on 18 August 2018. The dome was 55 m long and 25 m wide, and about 5 m below the 2010 dome surface (figure 71). As of 23 August, the volume of the dome was 23,000 m3, growing at an average rate of 2,700 m3/day. By the end of the month the volume was estimated to be 54,000 m3 with a growth rate of 4,000 m3/day (figure 72). Throughout the month, persistent steam plumes rose 50-200 m above the summit.

Figure (see Caption) Figure 70. The first sign of new dome growth at Merapi appeared in this drone photo taken on 12 August 2018. Courtesy of BPPTKG (Siaran Pers 18 Agustus 2018 Pukul 17:00 WIB, Press Release 18 August 2018, 1700 local time).
Figure (see Caption) Figure 71. The new dome at the summit of Merapi on 18 August 2018. Courtesy of BPPTKG (Siaran Pers 18 Agustus 2018 Pukul 17:00 WIB, Press Release 18 August 2018, 1700 local time).
Figure (see Caption) Figure 72. A comparison of the dome on 18 (top) and 28 (bottom) August 2018 at Merapi taken from the Puncak webcam on the N flank. By the end of August 2018, the dome size was about 54,000 m3. Courtesy of BPPTKG (posted via Twitter on 27 August 2018).

During September-November 2018 the summit dome grew at varying rates from 1,000 to 6,200 m3/day (table 22). At the beginning of September its volume was 54,000 m3; it had reached 329,000 m3 by the end of November (figure 73). Steam plumes in September rose from 100 to 450 m above the summit. They were lower in October, rising only 50-100 m high. During November they rose 100 to400 m above the summit. Intermittent seismic activity remained above background levels. By mid-November, the growth of the dome was clearly visible from the ground 4.5 km S of the summit (figure 74).

Table 22. The volume and growth rate of the lava dome at Merapi was measured weekly from late August 2018 through January 2019. Data courtesy of BPPTKG Merapi weekly reports.

Date Size (m3) Rate (m3 / day)
23 Aug 2018 23,000 2,700
30 Aug 2018 54,000 4,000
06 Sep 2018 82,000 3,900
13 Sep 2018 103,000 3,000
20 Sep 2018 122,000 3,000
27 Sep 2018 129,000 1,000
04 Oct 2018 135,000 1,000
11 Oct 2018 160,000 3,100
18 Oct 2018 201,000 6,200
21 Oct 2018 219,000 6,100
31 Oct 2018 248,000 2,900
07 Nov 2018 273,000 3,500
14 Nov 2018 290,000 2,400
21 Nov 2018 308,000 2,600
29 Nov 2018 329,000 2,500
06 Dec 2018 344,000 2,200
13 Dec 2018 359,000 2,200
19 Dec 2018 370,000 2,000
27 Dec 2018 389,000 2,300
03 Jan 2019 415,000 3,800
10 Jan 2019 439,000 3,400
16 Jan 2019 453,000 2,300
22 Jan 2019 461,000 1,300
29 Jan 2019 461,000 --
07 Feb 2019 461,000 --
14 Feb 2019 461,000 --
21 Feb 2019 466,000 --
05 Mar 2019 470,000 --
21 Mar 2019 472,000 --
Figure (see Caption) Figure 73. Images from September-November 2018 show the growth of the lava dome at the summit of Merapi. In each pair the left image is from the Deles webcam, and the right image is from the Puncak webcam on the same date. Top: 26 September 2018, left growth lines show change from 8 to 27 September, from 18 to 26 September on right; Middle: 22 October 2018, both sets of growth lines are from 13 September to 22 October; Bottom: 22 November 2018, left growth lines are from mid-September to 21 November and right growth lines are 15 and 22 November. In each Puncak image the red outline at the center is the dome outline on 18 August 2018. Courtesy of BPPTKG, from weekly reports of Merapi activity, 21-27 September, 19-25 October, and 16-22 November 2018.
Figure (see Caption) Figure 74. A comparison of the crater area of Merapi on 2 June 2018 (left) and 11 November 2018 (right). The new dome is clearly visible in the later photo. The images were taken about 4.5 km S of the summit. Persistent gas emissions rose from both the new dome and around the summit crater. Courtesy of Øystein Lund Andersen.

The lava dome continued to grow during December 2018, producing steam plumes that rose 50-200 m. As the height of the dome increased, block avalanches began descending into the upper reaches of Kali Gendol ravine on the SSE flank. Avalanches on 16 and 19 December reached 300 m down the drainage; on 21 December a larger avalanche lasted for 129 seconds and traveled 1 km based on the duration of the seismic data (figure 75). By the end of December BPPTKG measured the volume of the dome as 389,000 m3.

Figure (see Caption) Figure 75. Steam and gas from a recent block avalanche rose from the edge of the new dome at Merapi on 21 December 2018 (top). By the end of December BPPTKG measured the volume of the dome as 389,000 m3. Top image from BPPTKG press release of 21 December 2018; bottom images from the weekly Merapi Mountain activities report of 21-27 December. Courtesy of BPPTKG.

The rate of dome growth declined steadily during January 2019, and by the third week most of the lava extrusion was collapsing as block avalanches into the upper part of Kali Gendol, and dome growth had slowed. Steam plumes rose 50-450 m during the month. In spite of slowing growth, a comparison of the dome size between 11 November 2018 and 13 January 2019 indicated an increase in volume of over 150,000 m3 of material (figure 76). Incandescence at the dome and in the block avalanches was visible at night when the summit was clear (figures 77 and 78). Three block avalanches occurred during the evening of 29 January; the first traveled 1.4 km, the second 1.35 km, and the third 1.1 km down the ravine; each one lasted for about two minutes. By the end of January the size of the dome was reported by BPPTKG to be about 461,000 m3.

Figure (see Caption) Figure 76. A comparison of the dome growth at Merapi from 11 November 2018 to 13 January 2019 showed an increase in volume of over 150,000 m3 according to Indonesian authorities (BPPTKG), as well as the accumulation of debris as material fell down the ravine. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 77. Incandescence appeared at the growing dome at the summit of Merapi late on 13 January 2019. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 78. Incandescent blocks from the growing dome at Merapi traveled several hundred meters down Kali Gendol on 14 January 2019. Courtesy of Øystein Lund Andersen.

Numerous block avalanches were observed during February 2019 as almost all of the lava extrusion was moving down the slope. Multiple avalanches were reported on 7, 11, 18, 25, and 27 February, with traveling distances ranging from 200 to 2,000 m. Steam plumes did not rise more than 375 m during the month. By the end of February, the dome had only grown slightly to 466,000 m3. Seventeen block avalanches were reported during March 2019; they traveled distances ranging from 500 to 1,900 m down the Kali Gendol ravine. A drone measurement on 5 March determined the volume of the dome to be 470,000 m3; it was only 2,000 m3 larger when measured again on 21 March.

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities during historical time.

Information Contacts: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Center for Research and Development of Geological Disaster Technology (URL: http://merapi.bgl.esdm.go.id/, Twitter: @BPPTKG); Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Øystein Lund Andersen (Twitter: @OysteinLAnderse, https://twitter.com/OysteinLAnderse, URL: https://www.oysteinlundandersen.com/).


Bagana (Papua New Guinea) — February 2019 Citation iconCite this Report

Bagana

Papua New Guinea

6.137°S, 155.196°E; summit elev. 1855 m

All times are local (unless otherwise noted)


Intermittent ash plumes; thermal anomalies continue through January 2019

The relatively remote Bagana volcano, located on Bougainville Island, Papua New Guinea, is poorly monitored and most of the available data is obtained by satellites (figure 30). The most recent eruptive phase began on or before early 2000 with intermittent ash plumes and detected thermal anomalies (BGVN 41:04, 41:07, 42:08, 43:05). The Darwin Volcanic Ash Advisory Centre (VAAC) monitors satellite imagery for ash plumes that could impact aviation.

Figure (see Caption) Figure 30. Sentinel-2 satellite image (natural color, bands 4, 3, 2) of Bagana on 28 May 2018. Courtesy of Sentinel Hub Playground.

Cloud cover obscured the volcano during much of the reporting period, but significant ash plumes were identified five times by the Darwin Volcanic Ash Advisory Centre (VAAC), in May, July, and December 2018 (table 6). Infrared satellite imagery from Sentinel-2 frequently showed thermal anomalies, both at the summit and caused by hot material moving down the flanks (figure 31).

Table 6. Summary of ash plumes from Bagana reported during May 2018 through January 2019. Courtesy of the Darwin Volcanic Ash Advisory Centre (VAAC).

Date Max Plume Altitude (km) Plume Drift
08 May 2018 2.1 W
11 May 2018 2.1 SW
22 Jul 2018 2.4 W
29-30 Jul 2018 1.8-2.1 SW
01 Dec 2018 3-6.1 SE
Figure (see Caption) Figure 31. Infrared satellite images from Sentinel-2 (atmospheric penetration, bands 12, 11, 8A) showing hot areas at the summit and on the flanks on 7 July (top left), 31 August (top right), 14 November (bottom left) and 14 December (bottom right) 2018. Courtesy of Sentinel Hub Playground.

The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, recorded a large number of thermal alerts within 5 km of the summit throughout this reporting period (figure 32). Thermal alerts increased in number and intensity beginning mid-July 2018. This pattern is also consistent with the MODVOLC data (also based on MODIS satellite data). A total of 76 thermal anomaly pixels were recorded during the reporting period; of these, greater than 40 pixels were observed during July 2018 alone with 13 pixels reported in December 2018 (figure 33).

Figure (see Caption) Figure 32. Thermal anomalies identified at Bagana by the MIROVA system (log radiative power) for the year ending 8 February 2019. Courtesy of MIROVA.

Small sulfur dioxide (SO2) anomalies were detected by the AuraOMI instrument during this period, the highest being in the range of 1.5-1.8 Dobson Units (DU). Emissions in this range occurred during July 7, 21, and 28 July, and 3-5 and 19 December 2018.

Geologic Background. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA, a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) – MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).


Fuego (Guatemala) — April 2019 Citation iconCite this Report

Fuego

Guatemala

14.473°N, 90.88°W; summit elev. 3763 m

All times are local (unless otherwise noted)


Frequent explosive activity with ash plumes, avalanches, lava flows, and lahars from July 2018 through March 2019

Fuego is one of Guatemala's most active volcanoes, regularly producing ash plumes and incandescent ballistic ejecta, along with lava flows, avalanches, pyroclastic flows, and lahars down the ravines (barrancas) and rivers (figure 104). Frequent ash plumes have been recorded in recent years (figure 105). A major eruptive event occurred on 3-5 June that resulted in fatalities. Thermal data show an increase in activity from November 2018, that continued through the reporting period (figure 106). This report summarizes activity from July 2018 through March 2019 based on reports by Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH) and the National Office of Disaster Management (CONRED), Washington Volcanic Ash Advisory Center (VAAC), satellite data.

Figure (see Caption) Figure 104. Map of Fuego showing the ravines, rivers, and communities. Map created in 2005 (see BGVN 30:08).
Figure (see Caption) Figure 105. Ash plume altitudes from 1999 through 2019 for Fuego as reported by the Washington VAAC. The gray vertical lines represent paroxysmal eruptions. Courtesy of Rudiger Escobar Wolf, Michigan Technological University.
Figure (see Caption) Figure 106. Log radiative power MIROVA plot of MODIS infrared data at Fuego for the year ending April 2019 showing increased activity since November 2018. Courtesy of MIROVA.

Gas emissions and avalanches characterized activity in early July 2018; an increase was reported on the 4th. Avalanches descended through the Cenizas, Las Lajas, and Santa Teresa ravines on the 6th. One explosion every two hours on 8 July produced ash plumes up to 4.3 km altitude (500 m above the crater) that dispersed towards the SW. Avalanches down the flanks accompanied this activity. On 10 July ash plumes rose to 4.2 and 5 km altitude dispersing to the SW, and ashfall was reported in Morelia and Panimache (figure 107). Avalanches continued on the 19-20 and 23-24 July and weak explosions on the 23-24 produced low ash plumes that dispersed to the N. Hot lahars containing blocks 2-3 m in diameter and tree trunks and branches were generated in the Taniluyá, Ceniza, El Jute, and Las Lajas ravines on 30 and 31 July, and 2 and 9 August.

Figure (see Caption) Figure 107. A moderate explosion produced an ash plume at Fuego on 10 July 2018. Photo courtesy of CONRED.

During August and September, weak to moderate explosions produced ash plumes that rose to 4.7 km altitude and incandescent material was ejected to 150 m above the crater, producing avalanches down the ravines. Additional hot lahars carrying boulders and tree branches occurred on 29 August-2 September and 21-27 September down the Honda (E), El Jute (SE), Las Lajas (SE), Cenizas (SSW), Taniluyá (SW), Seca (W), Santa Teresa (W), Niagara (W), Mineral, and Pantaleón (W) drainages.

An increase in activity occurred on 29 September with degassing pulses lasting 3-4 hours recorded and heard. Avalanches occurred on the flanks and weak-moderate explosions occurred at a rate of 10-15 per hour with ash plumes rising up to 4.7 km. Hot lahars traveled down the Seca, Santa Teresa, and Mineral ravines, transporting blocks up to 3 m in diameter along with tree trunks and branches. Similar lahars were generated in the Las Lajas ravine on 5, 8, and 9 October (figure 108). The lahars were hot and smelled of sulfur, and they carried blocks 1-3 m in diameter.

On 12 October activity increased and produced incandescent ejecta up to 100-200 m above the crater and out to 300 m away from the crater, avalanches in the ravines, and a lava flow with a length of 800-1,000 m, that had reached 1,500 m by the 13th. Ash plumes reached 4.8 km altitude and dispersed up to 12 km towards the S and SE. Explosions occurred at a rate of 8-10 per hour with shockwaves that were reported near the volcano. At 1640 a pyroclastic flow was generated down the Seca ravine (figure 109). Similar activity continued through the 13th, with ash plumes reaching 5 km and ashfall reported in communities including Panimache I, Morelia, Santa Sofia, Sangre de Cristo, El Porvenir, and Palo Verde Estate. This episode of increased activity continued for 32 hours. Lahars traveled down the Ceniza and Seca ravines, the Achiguate River, and the Mineral and Taniluyá ravines (both tributaries of the Pantaleón river). A 30-m-wide lahar with a depth of 2 m was reported on 16 October that carried blocks up to 2 m in diameter, tree trunks, and branches. More lahars descended the Las Lajas ravine on the 17-18, and 20 October. Explosions continued through to the end of October, with increased activity on 31 October.

Figure (see Caption) Figure 108. Seismograms and RSAM (Real-time Seismic Amplitude Measurement) graphs of activity at Fuego showing a change in signal indicative of lahars in the Las Lajas ravine on 8 and 9 October 2018 (red boxes and arrows). The change in seismic signal correlates with an increase in RSAM values. Courtesy of INSIVUMEH.
Figure (see Caption) Figure 109. A pyroclastic flow at Fuego traveling down the Seca ravine on 12 October 2018. Courtesy of CONRED.

Frequent activity continued into November with elevated activity reported on the 2 and 4-6 November. On 6 November ash plumes rose to 4.8 km altitude and traveled 20 km W and SW resulted in ashfall on communities including Panimache, El Porvenir, Morelia, Santa Sofia, Sangre de Cristo, Palo Verde Estate, and San Pedro Yepocapa. Constant explosions ejected incandescent material to 300 m above the crater. A lava flow 1-1.2 km long observed in the Ceniza ravine generated avalanches from the front of the flow, which continued through the 9th.

Activity increased again on 17 November, initiating the fifth eruptive phase of 2018. There were 10-15 explosions recorded per hour along with ash plumes up to 4.7 km that dispersed 10-15 km to the W and SW. Incandescent material was ejected up to 200-300 m above the crater, and avalanches were generated. A new lava flow reached 800 m down the Ceniza ravine. Ashfall was reported in Panimaché I, Morelia, Santa Sofia, El Porvenir, Sangre de Cristo, Palo Verde Estate, Yepocapa, and other communities.

The elevated activity continued through 18 November with 12-17 explosions per hour and a constant ash plume to 5 km altitude, dispersing to the W and SW for 20-25 km. Moderate avalanches traveled down the Ceniza, Taniluyá, and Seca ravines out to the vegetation line. Incandescent blocks were ejected up to 400 m above the crater. Ashfall was reported in communities including Panimaché I, Morelia, Santa Sofia, Sangre de Cristo, and Palo Verde Estate. Avalanches from the front of the lava flow traveled down the Taniluyá and Seca ravines.

Ash plumes rose to 7 km altitude on the 19th and dispersed 50-60 km towards the W, SW, and NE (figure 110). Incandescent ballistic ejecta reached 1 km above the crater and scattered to over 1 km from the crater (figure 111), with the explosions shaking houses over 15 km away to the W and SW, and avalanches moved down the Seca, Ceniza, Taniluyá, Las Lajas, and Honda ravines reaching the vegetation. Two new lava flows formed, extending to 300 m down the Seca and Santa Teresa ravines. Pyroclastic flows traveled down the Seca, Las Lajas, and Honda ravines. Ashfall due to the generation of pyroclastic flows was reported in Panimaché I and II, Santa Sofía, Sangre de Cristo, Palo Verde Estate, and in Alotenango and Antigua, Guatemala, to the NE. CONRED reported the evacuation of 3,925 people. INSIVUMEH reported that the eruption phase was over at 1800 on 19 November after 32 hours of increased activity.

Figure (see Caption) Figure 110. Eruption at Fuego on 19 November 2018 producing ash plumes and incandescent ejecta. Courtesy of European Pressphoto Agency via BBC News.
Figure (see Caption) Figure 111. Explosions at Fuego on 19 November 2018 generated ash plumes to 5.2 km altitude, incandescent blocks up to 1 km above the crater, and avalanches. Courtesy of CONRED.

Explosions continued through 20 November at a rate of 8-13 per hour, ejecting incandescent material up to 200 m above the crater and ash plumes to at least 4.6 km that drifted 20-25 km NW, W, and SW. Avalanches continued with some reaching the vegetation. Ashfall was reported in communities including Panimaché, El Porvenir, Morelia, Santa Sofia, Sangre de Cristo, Palo Verde Estate, and San Pedro Yepocapa.

Similar activity continued through to the end of November with explosions producing shockwaves felt out to 25 km; some explosions were heard in Guatemala City, 40 km ENE. Ash plumes rose to 5 km (figures 112 and 113) and dispersed 20 km W, S, and SW, and ash fell in communities including Panimaché, El Porvenir, Morelia, Santa Sofia, Sangre de Cristo, Palo Verde Estate, San Pedro Yepocapa, Alotenango, and San Miguel Dueñas. Explosions were recorded 10 to 18 per hour. Incandescent ejecta rose to 200 m above the crater and resulted in avalanches in the Las Lajas, Ceniza, El jute, Honda, Taniluyá, Trinidad, and Seca ravines with some reaching the vegetation line. Some avalanches entrained large blocks up to 3 m in diameter that produced ash plumes as they traveled down the ravines. Hot lahars were generated in the Seca, Santa Maria, and Mineral ravines, carrying blocks up to 3 m in diameter (figure 114).

Figure (see Caption) Figure 112. Explosions at Fuego generated ash plumes and caused avalanches in the Las Lajas, Trinidad, and Ceniza ravines on 22 November 2018. Courtesy of CONRED.
Figure (see Caption) Figure 113. Ash plume up to 5.5 km altitude at Fuego on 28 November 2018. Courtesy of CONRED.
Figure (see Caption) Figure 114. A lahar from Fuego traveling down the Mineral River in November 2018. Courtesy of CONRED.

During December white to light gray fumarolic plumes rose to a maximum height of 4.5 km. Ash plumes reached up to 5.2 km and dispersed to a maximum of 25 km S, SW, and W. There were 3-15 explosions recorded per hour with shockwaves, incandescent ejecta reaching 300 m above the crater, and avalanches down the Seca, Taniluyá, Ceniza, Trinidad, Las Lajas, and Honda ravines. Ashfall was reported in communities including Panimaché I and II, Morelia, Santa Sofia, El Porvenir, Palo Verde Estate, Sangre de Cristo, Yepocapa, La Rochela, San Andrés Osuna, Ceylon, Alotenango, and San Pedro.

Similar activity continued through January 2019 with fumarolic plumes rising to a maximum of 4.4 km altitude, ash plumes reaching 4.8 km and dispersing over 15 km to the NE, WSW, and NW; 3-25 explosions per hour sent shockwaves and avalanches in multiple directions. Ashfall was reported in Panimaché, Morelia, Santa Sofia, Sangre de Cristo, Palo Verde Estate, and San Pedro Yepocapa. Also in Alotenango, La Reunion, and El Porvenir, Alotenango.

An increase in activity began on 21 January with moderate to strong explosions producing ash plumes up to 5 km altitude that dispersed 12 km W and SW. The explosions were heard over 15 km away and shook windows and roofs out to 12 km away. Avalanches were triggered in multiple ravines. On 22 January there were 15-25 recorded explosions per hour, each lasting 2-3 minutes and producing ash plumes to 4.8 km and incandescent ejecta up to 300 m above the crater (figure 115).

Figure (see Caption) Figure 115. An ash plume rising during an explosive event at Fuego on 22 January 2019. Courtesy of CONRED.

Frequent explosions continued during February through to late-March, with a range of 8-18 per hour, producing ash plumes rising to 4.8 km (figure 116), and dispersing out to 15 km in multiple directions. Incandescent ejecta rose to 350 m above the crater and resulted in avalanches down multiple ravines. Ashfall was reported in communities including El Rodeo, El Zapote, Ceylon, La Roche-la, Panimache, Morelia, Santa Sofia, Sangre de Cristo, San Miguel Dueñas, Ciudad Vieja, and Alotenango, Verde Estate, San Pedro Yepocapa, La Rochelle, and San Andrés Osuna.

On 22 March there was an increase in the number and energy of explosions with 15-20 per hour. Accompanying ash plumes rose to 5 km altitude and dispersed 25-30 km S, W, SW, E, and SE, depositing ash in La Rochela, Ceylon, Osuna, Las Palmas, Siquinalá, and Santa Lucia Cotzumalguapa. Explosions were heard over 20 km from the volcano. Incandescent ejecta rose to 300 m above the crater and moderate to strong avalanches flowed down the Seca, Taniluyá, Ceniza, Trinidad, Las Lajas and Honda ravines. Explosions increased to 14-32 events per hour by 31 March, continuing to produce ash plumes up to 5 km and depositing ash on nearby communities and causing avalanches down the flanks. A new lava flow reached 800 m down the Seca ravine.

Figure (see Caption) Figure 116. Examples of small ash plumes at Fuego on 21 February and 12 March 2019. Courtesy of William Chigna, CONRED (top) and CONRED (bottom).

Geologic Background. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango. In contrast to the mostly andesitic Acatenango, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); Coordinadora Nacional para la Reducción de Desastres (CONRED), Av. Hincapié 21-72, Zona 13, Guatemala City, Guatemala (URL: http://conred.gob.gt/www/index.php); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Rudiger Escobar Wolf, Michigan Technologicla University, 630 Dow Environmental Sciences, 1400 Townsend Drive, Houghton, MI 49931, USA (URL: https://www.mtu.edu/geo/department/staff/wolf.html); William Chigna, CONRED (URL: https://twitter.com/william_chigna); BBC News (URL: https://www.bbc.com; https://www.bbc.com/news/world-latin-america-46261168?intlink_from_url=https://www.bbc.com/news/topics/c4n0j0d82l0t/guatemala-volcano&link_location=live-reporting-story); European Pressphoto Agency (URL: http://www.epa.eu/); Agence France-Presse (URL: http://www.afp.com/).


Stromboli (Italy) — March 2019 Citation iconCite this Report

Stromboli

Italy

38.789°N, 15.213°E; summit elev. 924 m

All times are local (unless otherwise noted)


Constant explosions from both crater areas during November 2018-February 2019

Nearly constant fountains of lava at Stromboli have served as a natural beacon in the Tyrrhenian Sea for at least 2,000 years. Eruptive activity at the summit consistently occurs from multiple vents at both a north crater area (N Area) and a southern crater group (CS Area) on the Terrazza Craterica at the head of the Sciara del Fuoco, a large scarp that runs from the summit down the NW side of the island. Thermal and visual cameras that monitor activity at the vents are located on the nearby Pizzo Sopra La Fossa, above the Terrazza Craterica, and at a location closer to the summit craters.

Eruptive activity from November 2018 to February 2019 was consistent in terms of explosion intensities and rates from both crater areas at the summit, and similar to activity of the past few years (table 5). In the North Crater area, both vents N1 and N2 emitted a mixture of coarse (lapilli and bombs) and fine (ash) ejecta; most explosions rose less than 80 m above the vents, some reached 150 m. Average explosion rates ranged from 4 to 21 per hour. In the CS crater area continuous degassing and occasional intense spattering were typical at vent C, vent S1 was a low-intensity incandescent jet throughout the period. Explosions from vent S2 produced 80-150 m high ejecta of ash, lapilli and bombs at average rates of 3-16 per hour. Thermal activity at Stromboli was actually higher during November 2018-February 2019 than it had been in previous months as recorded in the MIROVA Log Radiative Power data from MODIS infrared satellite information (figure 139).

Table 5. Summary of activity levels at Stromboli, November 2018-February 2019. Low intensity activity indicates ejecta rising less than 80 m and medium intensity is ejecta rising less than 150 m. Data courtesy of INGV.

Month N Area Activity CS Area Activity
Nov 2018 Low- to medium-intensity explosions at both N1 and N2, lapilli and bombs mixed with ash, explosion rates of 6-16 per hour. Continuous degassing at C; intense spattering on 26 Nov. Low- to medium-intensity incandescent jetting at S1. Low- to medium-intensity explosions at S2 with a mix of coarse and fine ejecta and explosion rates of 3-18 per hour.
Dec 2018 Low- to medium-intensity explosions at both N1 and N2, coarse and fine ejecta, explosion rates of 4-21 per hour. Three days of intense spattering at N2. Continuous degassing at C; intense spattering 1-2 Dec. Low- to medium-intensity incandescent jets at S1, low and medium-intensity explosions of coarse and fine material at S2. Average explosion raters were 10-18 per hour at the beginning of the month, 3-4 per hour during last week.
Jan 2019 Low- to medium-intensity explosions at N1, coarse ejecta. Low- to medium-intensity and spattering at N2, coarse and fine ejecta. Explosion rates of 9-16 per hour. Continuous degassing and low-intensity explosions of coarse ejecta at C. Low-intensity incandescent jets at S1. Low- and medium-intensity explosions of coarse and fine ejecta at S2.
Feb 2019 Medium-intensity explosions with coarse ejecta at N1. Low-intensity explosions with fine ash at N2. Explosion rates of 4-11 per hour. Continuous degassing and low-intensity explosions with coarse and fine ejecta at C and S2. Low intensity incandescent jets at S1. Explosion rates of 2-13 per hour.
Figure (see Caption) Figure 139.Thermal activity at Stromboli increased during November 2018-February 2019 compared with the preceding several months as recorded in the MIROVA project log radiative power data taken from MODIS thermal satellite information. Courtesy of MIROVA.

Activity at the N area was very consistent during November 2018 (figure 140). Explosions of low-intensity (less than 80 m high) to medium-intensity (less than 150 m high) occurred at both the N1 and N2 vents and produced coarse material (lapilli and bombs) mixed with ash, at rates averaging 6-16 explosions per hour. In the SC area continuous degassing was reported from vent C with a brief period of intense spattering on 26 November. At vent S1 low- to medium-intensity incandescent jetting was reported. At vent S2, low- and medium-intensity explosive activity produced a mixture of coarse and fine (ash) material at a frequency of 3-18 events per hour.

Figure (see Caption) Figure 140. The Terrazza Craterica at Stromboli on 12 November 2018 as viewed by the thermal camera placed on the Pizzo sopra la Fossa, showing the two main crater areas and the active vents within each area that are discussed in the text. Heights above the crater terrace, as indicators of intensity of the explosions, are shown divided into three intervals of low (basso), medium (media), and high (alta). Courtesy of INGV (Report 46/2018, Stromboli, Bollettino Settimanale 05/11/2018 - 11/11/2018, data emissione 13/11/2018).

Similar activity continued during December at both crater areas, although there were brief periods of more intense activity. Low- to medium-intensity explosions at both N area vents produced a mixture of coarse and fine-grained material at rates averaging 4-21 per hour. During 6-7 December ejecta from the N vents fell onto the upper part of the Sciara del Fuoco and rolled down the gullies to the coast, producing tongues of debris (figure 141). An explosion at N1 on 12 December produced a change in the structure of the crater area. During 10-16 December the ejecta from the N area landed outside the crater on the Sciara del Fuoco. Intense spattering was observed from N2 on 18, 22, and 31 December. In the CS area, continuous degassing took place at vent C, along with a brief period of intense spattering on 1-2 December. Low to medium intensity incandescent jets persisted at S1 along with low-and medium-intensity explosions of coarse and fine-grained material at vent S2. Rates of explosion at the CS area were higher at the beginning of December (10-18 per hour) and lower during the last week of the month (3-4 per hour).

Figure (see Caption) Figure 141. Images from the Q 400 thermal camera at Stromboli taken on 6 December 2018 showed the accumulation of pyroclastic material in several gullies on the upper part of the Sciara del Fuoco following an explosion at vent N2 at 1520 UTC. The images illustrate the rapid cooling of the pyroclastic material in the subsequent two hours. Courtesy of INGV (Report 50/2018, Stromboli, Bollettino Settimanale, 03/12/2018 - 09/12/2018, data emissione 11/12/2018).

Explosive intensity was low (ejecta less than 80 m high) at vent N1 at the beginning of January 2019 and increased to medium (ejecta less than 150 m high) during the second half of the month, producing coarse ejecta of lapilli and bombs. Intensity at vent N2 was low to medium throughout the month with both coarse- and fine-grained material ejected. Explosions from N2 sent large blocks onto the Sciara del Fuoco several times throughout the month and usually was accompanied by intense spattering. Explosion rates varied, with averages of 9 to 16 per hour, throughout the month in the N area. In the CS area continuous degassing occurred at vent C, and low-intensity explosions of coarse-grained material were reported during the second half of the month. Low-intensity incandescent jets at S1 along with low- and medium-intensity explosions of coarse and fine-grained material at S2 persisted throughout the month.

A helicopter overflight of Stromboli on 8 January 2019 allowed for detailed visual and thermal observations of activity and of the morphology of the vents at the summit (figure 142). Vent C had two small hornitos, and a small scoria cone was present in vent S1, while a larger crater was apparent at S2. In the N crater area vent N2 had a large scoria cone that faced the Sciara del Fuoco to the north; three narrow gullies were visible at the base of the cone (figure 143). Vent S1 was a large crater containing three small vents aligned in a NW-SE trend; INGV scientists concluded the vents formed as a result of the 12 December 2018 explosion. Thermal images showed relatively low temperatures at all fumaroles compared with earlier visits.

Figure (see Caption) Figure 142. Thermal images from Stromboli taken during the overflight of 8 January 2019 showed the morphological structure of the individual vents of the N and CS crater areas. Courtesy of INGV (Report 03/2019, Stromboli, Bollettino Settimanale, 07/01/2019 - 13/01/2019, (data emissione 15/01/2019).
Figure (see Caption) Figure 143. An image taken at Stromboli during the overflight of 8 January 2019 shows the morphological structure of the summit Terrazza Craterica with three gullies at the base of the scoria cone of vent N2. The top thermal image (inset a) shows that the fumaroles in the upper part of the Sciara del Fuoco have low temperatures. Courtesy of INGV (Report 03/2019, Stromboli, Bollettino Settimanale, 07/01/2019 - 13/01/2019, data emissione 15/01/2019).

Activity during February 2019 declined slightly from the previous few months. Explosions at vent N1 were of medium-intensity and produced coarse material (lapilli and bombs). At N2, low-intensity explosions produced fine ash. Average explosion rates in the N area ranged from 4-11 per hour. At the CS area, continuous degassing and low-intensity explosions produced coarse and fine-grained material from vents C and S2 while low-intensity incandescent jets were active at S1. The explosion rates at the CS area averaged 2-13 per hour.

Geologic Background. Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5,000 years ago due to a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

Information Contacts: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy, (URL: http://www.ct.ingv.it/en/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).


Krakatau (Indonesia) — March 2019 Citation iconCite this Report

Krakatau

Indonesia

6.102°S, 105.423°E; summit elev. 813 m

All times are local (unless otherwise noted)


Ash plumes, ballistic ejecta, and lava extrusion during October-December; partial collapse and tsunami in late December; Surtseyan activity in December-January 2019

Krakatau volcano, between Java in Sumatra in the Sunda Straight of Indonesia, is known for its catastrophic collapse in 1883 that produce far-reaching pyroclastic flows, ashfall, and tsunami. The pre-1883 edifice had grown within an even older collapse caldera that formed around 535 CE, resulting in a 7-km-wide caldera and the three surrounding islands of Verlaten, Lang, and Rakata (figure 55). Eruptions that began in late December 1927 (figures 56 and 57) built the Anak Krakatau cone above sea level (Sudradjat, 1982; Simkin and Fiske, 1983). Frequent smaller eruptions since that time, over 40 short episodes consisting of ash plumes, incandescent blocks and bombs, and lava flows, constructed an island reaching 338 m elevation.

Figure (see Caption) Figure 55. The three islands of Verlaten, Lang, and Rakata formed during a collapse event around 535 CE. Another collapse event occurred in 1883, producing widespread ashfall, pyroclastic flows, and triggering a tsunami. Through many smaller eruptions since then, Anak Krakatau has since grown in the center of the caldera. Sentinel-2 natural color (bands 4, 3, 2) satellite image acquired on 16 November 2018, courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 56. Photo sequence (made from a film) at 6-second intervals from the early phase of activity on 24 January 1928 that built the active Anak Krakatau cone above the ocean surface. Plume height reached about 1 km. View is from about 4.5 km away at a beach on Verlaten Island looking SE towards Rakata Island in the right background. Photos by Charles E. Stehn (Netherlands Indies Volcanological Survey) from the E.G. Zies Collection, Smithsonian Institution.
Figure (see Caption) Figure 57. Submarine explosions in January 1928 built the active Anak Krakatau cone above the ocean surface. View is from about 600 m away looking E towards Lang Island in the background. Photos by Charles E. Stehn (Netherlands Indies Volcanological Survey) from the E.G. Zies Collection, Smithsonian Institution.

Historically there has been a lot of confusion about the name and preferred spelling of this volcano. Some have incorrectly made a distinction between the pre-1883 edifice being called "Krakatoa" and then using "Krakatau" for the current volcano. Anak Krakatau is the name of the active cone, but the overall volcano name is simply Krakatau. Simkin and Fiske (1983) explained as follows: "Krakatau was the accepted spelling for the volcano in 1883 and remains the accepted spelling in modern Indonesia. In the original manuscript copy submitted to the printers of the 1888 Royal Society Report, now in the archives of the Royal Society, this spelling has been systematically changed by a neat red line through the final 'au' and the replacement 'oa' entered above; a late policy change that, from some of the archived correspondence, saddened several contributors to the volume."

After 15 months of quiescence Krakatau began a new eruption phase on 21 June 2018, characterized by ash plumes, ballistic ejecta, Strombolian activity, and lava flows. Ash plumes reached 4.9 km and a lava flow traveled down the SE flank and entered the ocean. This report summarizes the activity from October 2018 to January 2019 based on reports by Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), also known as the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM), MAGMA Indonesia, the National Board for Disaster Management - Badan Nasional Penanggulangan Bencana (BNPB), the Darwin Volcanic Ash Advisory Center (VAAC), satellite data, and eye witness accounts.

Activity during October-21 December 2018. The eruption continued to eject incandescent ballistic ejecta, ash plumes, and lava flows in October through December 2018. On 22 December a partial collapse of Anak Krakatau began, dramatically changing the morphology of the island and triggering a deadly tsunami that impacted coastlines around the Sunda Straight. Following the collapse the vent was located below sea level and Surtseyan activity produced steam plumes, ash plumes, and volcanic lightning.

Sentinel-2 satellite images acquired through October show incandescence in the crater, lava flows on the SW flank, and incandescent material to the S to SE of the crater (figure 58). This correlates with eyewitness accounts of explosions ejecting incandescent ballistic ejecta, and Volcano Observatory Notice for Aviation (VONA) ash plume reports. The Darwin VAAC reported ash plumes to 1.5-2.4 km altitude that drifted in multiple directions during 17-19 October, but throughout most of October visual observations were limited due to fog. A video shared by Sutopo on 24 October shows ash emission and lava fountaining producing a lava flow that entered the ocean, resulting in a white plume. Video by Richard Roscoe of Photovolcanica shows explosions ejecting incandescent blocks onto the flanks and ash plumes accompanied by volcanic lightning on 25 October.

Figure (see Caption) Figure 58. Sentinel-2 thermal satellite images showing lava flows, incandescent avalanche deposits, and incandescence in the crater of Anak Krakatau during October 2018. Courtesy of Sentinel-2 hub playground.

Throughout November frequent ash plumes rose to 0.3-1.3 km altitude, with explosion durations spanning 29-212 seconds (figure 59). Observations by Øystein Lund Andersen describe explosions ejecting incandescent material with ash plumes and some associated lightning on 17 November (figure 60).

Figure (see Caption) Figure 59. Sentinel-2 satellite images showing ash plumes at Krakatau during 6-16 November 2018. Natural color (Bands 4, 3, 2) Sentinel-2 images courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 60. Krakatau erupting an ash plume and incandescent material on 17 November 2018. Courtesy of Øystein Lund Andersen.

During 1-21 December intermittent explosions lasting 46-776 seconds produced ash plumes that rose up to 1 km altitude. Thermal signatures were sporadically detected by various satellite thermal infrared sensors during this time. On 22 December ash plumes reached 0.3-1.5 km through the day and continuous tremor was recorded.

Activity and events during 22-28 December 2018. The following events during the evening of the 22nd were recorded by Øystein Lund Andersen, who was photographing the eruption from the Anyer-Carita area in Java, approximately 47 km from Anak Krakatau. Starting at 1429 local time, incandescence and ash plumes were observed and the eruption could be heard as intermittent 'cannon-fire' sounds, sometimes shaking walls and windows. An increase in intensity was noted at around 1700, when the ash column increased in height and was accompanied by volcanic lightning, and eruption sounds became more frequent (figure 61). A white steam plume began to rise from the shore of the southern flank. After sunset incandescent ballistic blocks were observed impacting the flanks, with activity intensity peaking around 1830 with louder eruption sounds and a higher steam plume from the ocean (figure 62).

Figure (see Caption) Figure 61. Ash plumes at Krakatau from 1429 to 1739 on 22 December 2018. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 62. Krakatau ejecting incandescent blocks and ash during 1823-1859 on 22 December 2018. The top and middle images show the steam plume at the shore of the southern flank. Courtesy of Øystein Lund Andersen.

PVMBG recorded an eruption at 2103. When viewed at 2105 by Øystein Lund Andersen, a dark plume across the area blocked observations of Anak Krakatau and any incandescence (figure 63). At 2127-2128 the first tsunami wave hit the shore and traveled approximately 15 m inland (matching the BNPB determined time of 2127). At approximately 2131 the sound of the ocean ceased and was soon replaced by a rumbling sound and the second, larger tsunami wave impacted the area and traveled further inland, where it reached significant depths and caused extensive damage (figures 64 and 65). After the tsunami, eruption activity remained high and the eruption was heard again during intervals from 0300 through to early afternoon.

Figure (see Caption) Figure 63. Krakatau is no longer visible at 2116 on 22 December 2018, minutes before the first tsunami wave arrived at west Java. A dark ash plume takes up much of the view. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 64. The second tsunami wave arriving at Anyer-Carita area of Java after the Krakatau collapse. This photo was taken at 2133 on 22 December 2018, courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 65. Photographs showing damage caused in the Anyer-Carita area of Java by the tsunami that was triggered by the partial collapse of Krakatau. From top to bottom, these images were taken approximately 40 m, 20 m, and 20 m from the shore on 23 December 2018. Courtesy of Øystein Lund Andersen.

Observations on 23 December reveal steam-rich ash plumes and base surge traveling along the water, indicative of the shallow-water Surtseyan eruption (figure 66). Ashfall was reported on the 26th in several regions including Cilegon, Anyer, and Serang. The first radar observations of Krakatau were on 24 December and showed a significant removal of material from the island (figure 67). At 0600 on the 27th the volcanic alert level was increased from II to III (on a scale of I-IV) and a VONA with Aviation Color Code Red reported an ash plume to approximately 7 km altitude that dispersed to the NE. When Anak Krakatau was visible, Surtseyan activity and plumes were observed through the end of December. On 28 December, plumes reached 200-3000 m. At 0418 the eruption paused and the first observation of the post-collapse edifice was made. The estimated removed volume (above sea level) was 150-180 million m3, leaving a remaining volume of 40-70 million m3. The summit of the pre-collapse cone was 338 m, while the highest point post-collapse was reduced to 110 m. Hundreds of thousands of lightning strokes were detected during 22-28 December with varying intensity (figure 68).

Figure (see Caption) Figure 66. Steam-rich plumes and underlying dark ash plumes from Surtseyan activity at Krakatau on 23 December 2018. Photos by Instagram user @didikh017 at Grand Cava Susi Air, via Sutopo.
Figure (see Caption) Figure 67. ALOS-2 satellite radar images showing Krakatau on 20 August 2018 and 24 December 2018. The later image shows that a large part of the cone of Anak Krakatau had collapsed. Courtesy of Geospatial Information Authority of Japan (GSI) via Sutopo.
Figure (see Caption) Figure 68. Lightning strokes during the eruption of Krakatau within a 20 km radius of the volcano for 30 minute intervals on 23, 25, 26, and 28 December 2018. Courtesy of Chris Vagasky.

Damage resulting from the 22 December tsunami. On the 29 December the damage reported by BNPB was 1,527 heavily damaged housing units, 70 with moderate damage, 181 with light damage, 78 damaged lodging and warung units, 434 damaged boats and ships and some damage to public facilities. Damage was recorded in the five regencies of Pandenglang, Serang, South Lampung, Pesawaran and Tanggamus. A BNPB report on 14 January gave the following figures: 437 fatalities, 10 people missing, 31,943 people injured, and 16,198 people evacuated (figure 69). The eruption and tsunami resulted in damage to the surrounding islands, with scouring on the Anak-Krakatau-facing slope of Rakata and damage to vegetation on Kecil island (figure 70 and 71).

Figure (see Caption) Figure 69. The impacts of the tsunami that was triggered by a partial collapse of Anak Krakatau from an update given on 14 January 2019. Translations are as follows. Korban Meninggal: victims; Korban hilang: missing; Korban luka-luka: injured; Mengungsi: evacuated. The color scale from green to red along the coastline indicates the breakdown of the human impacts by area. Courtesy of BNPB.
Figure (see Caption) Figure 70. Damage on Rakata Island from the Krakatau tsunami. This part of the island is facing Anak Krakatau and the scoured area was estimated to be 25 m high. Photographs taken on 10 January 2019 by James Reynolds.
Figure (see Caption) Figure 71. Damage to vegetation on Kecil island to the East of Krakatau, from the Krakatau December 2018 eruption. Photographs taken on 10 January 2019 by James Reynolds.

Activity during January 2019. Surtseyan activity continued into January 2019. Øystein Lund Andersen observed the eruption on 4-5 January. Activity on 4 January was near-continuous. The photographs show black cock's-tail jets that rose a few hundred meters before collapsing (figure 72), accompanied by white lateral base surge that spread from the vent across the ocean (figure 73), and white steam plumes that were visible from Anyer-Carita, West Java. In the evening the ash-and-steam plume was much higher (figure 74). It was also noted that older pumice had washed ashore at this location and a coating of sulfur was present along the beach and some of the water surface. Activity decreased again on the 5th (figure 75) with a VONA reporting an ash plume to 1.5 km towards the WSW. SO2 plumes were dispersed to the NE, E, and S during this time (figure 76).

Figure (see Caption) Figure 72. Black ash plumes and white steam plumes from the Surtseyan eruption at Krakatau on 4 January 2019. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 73. An expanding base surge at Krakatau on 4 January 2019 at 0911. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 74. Ash-and-steam plumes at Krakatau at 1702-2250 on 4 January 2018. Lightning is illuminating the plume in the bottom image. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 75. Ash plumes at Krakatau on 5 January 2019 at 0935. Courtesy of Øystein Lund Andersen.
Figure (see Caption) Figure 76. Sulfur dioxide (SO2) emissions produced by Krakatau and drifting to the NE, E, and SE on 3-6 January 2018. Dates and times of the periods represented are listed at the top of each image. Courtesy of the NASA Space Goddard Flight Center.

During 5-9 January intermittent explosions lasting 20 seconds to 13 minutes produced ash plumes rising up to 1.2 km and dispersing E. From 11 to 19 January white plumes were observed up to 500 m. Observations were prevented due to fog during 20-31 January. MIROVA thermal data show elevated thermal anomalies from July through January, with a decrease in energy in November through January (figure 77). The radiative power detected in December-January was the lowest since June 2018.

Figure (see Caption) Figure 77. Log radiative power MIROVA plot of MODIS thermal infrared data for June 2018-January 2019. The peaks in energy correlate with observed lava flows. Courtesy of MIROVA.

Morphological changes to Anak Krakatau. Images taken before and after the collapse event show changes in the shoreline, destruction of vegetation, and removal of the cone (figure 78). A TerraSAR-X image acquired on 29 January shows that in the location where the cone and active vent was, a bay had formed, opening to the W (figure 79). These changes are also visible in Sentinel-2 satellite images, with the open bay visible through light cloud cover on 29 December (figure 80).

By 9 January a rim had formed, closing off the bay to the ocean and forming a circular crater lake. Photos by James Reynolds on 11 January show a new crater rim to the W of the vent, which was filled with water (figure 81). Steam and/or gas emissions were emanating from the surface in that area. The southern lava delta surface was covered with tephra, and part of the lava delta had been removed, leaving a smooth coastline. By the time these images were taken there was already extensive erosion of the fresh deposits around the island. Fresh material extended the coast in places and filled in bays to produce a more even shoreline.

Figure (see Caption) Figure 78. Krakatau on 5 August 2018 (top) and on 11 January 2019 showing the edifice after the collapse event. The two drone photographs show approximately the same area. Courtesy of Øystein Lund Andersen (top) and James Reynolds (bottom).
Figure (see Caption) Figure 79. TerraSAR-X radar images showing the morphological changes to Krakatau with the changes outlined in the bottom right image as follows. Red: 30 August 2018 (upper left image); blue: 29 December 2018 (upper right image); yellow: 9 January 2019 (lower left image). Part of the southern lava delta was removed and material was added to the SE and NE to N shoreline. In the 29 December image the cone has collapsed and in its place is an open bay, which had been closed by a new rim by the 9 January. Courtesy of BNPB, JAXA Japan Aerospace Exploration Agency, and Badan Informasi Geospasial (BIG).
Figure (see Caption) Figure 80. Sentinel-2 satellite images showing the changing morphology of Krakatau. The SW section is where the cone previously sat and collapsed in December 2018. In the upper right image the cone and southern lava delta are gone and there are changes to the coastline of the entire island. Natural color (bands 4, 3, 2) Sentinel-2 satellite images courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 81. Drone footage of the Krakatau crater and new crater rim taken on 11 January 2019. The island is coated in fresh tephra from the eruption and the orange is discolored water due to the eruption. The land between the crater lake and the ocean built up since the collapse and the hot deposits are still producing steam/gas. Courtesy of James Reynolds.
Figure (see Caption) Figure 82. An aerial view of Krakatau with the new crater on 13 January 2019. Courtesy of BNPB.

References. Simkin, T., and Fiske, R.S., 1983, Krakatau 1883: the volcanic eruption and its effects: Smithsonian Institution Press, Washington DC, 464 p. ISBN 0-87474-841-0.

Sudradjat (Sumartadipura), A., 1982. The morphological development of Anak Krakatau Volcano, Sunda Straight. Geologi Indonesia, 9(1):1-11.

Geologic Background. The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.

Information Contacts: Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); Sutopo Purwo Nugroho, BNPB (Twitter: @Sutopo_PN, URL: https://twitter.com/Sutopo_PN ); Geospatial Information Authority of Japan (GSI), 1 Kitasato, Tsukuba, Ibaraki 305-0811, Japan. (URL: http://www.gsi.go.jp/ENGLISH/index.html); Badan Informasi Geospasial (BIG), Jl. Raya Jakarta - Bogor KM. 46 Cibinong 16911, Indonesia. (URL: http://www.big.go.id/atlas-administrasi/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); JAXA | Japan Aerospace Exploration Agency, 7-44-1 Jindaiji Higashi-machi, Chofu-shi, Tokyo 182-8522 (URL: https://global.jaxa.jp/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Øystein Lund Andersen (Twitter: @OysteinLAnderse, https://twitter.com/OysteinLAnderse, URL: https://www.oysteinlundandersen.com/krakatau-volcano-witnessing-the-eruption-tsunami-22december2018/); James Reynolds, Earth Uncut TV (Twitter: @EarthUncutTV, URL: https://www.earthuncut.tv/, YouTube: https://www.youtube.com/channel/UCLKYsEXfI0PGXeKYL1KV7qA); Chris Vagasky, Vaisala Inc., Louisville, Colorado (URL: https://www.vaisala.com/en?type=1, Twitter: @COweatherman, URL: https://twitter.com/COweatherman).


Santa Maria (Guatemala) — March 2019 Citation iconCite this Report

Santa Maria

Guatemala

14.757°N, 91.552°W; summit elev. 3745 m

All times are local (unless otherwise noted)


Daily explosions cause steam-and-ash plumes and block avalanches, November 2018-February 2019

The dacitic Santiaguito lava-dome complex on the W flank of Guatemala's Santa María volcano has been growing and actively erupting since 1922. The youngest of the four vents in the complex, Caliente, has been erupting with ash explosions, pyroclastic, and lava flows for more than 40 years. A lava dome that appeared within the summit crater of Caliente in October 2016 has continued to grow, producing frequent block avalanches down the flanks. Daily explosions of steam and ash also continued during November 2018-February 2019, the period covered in this report, with information primarily from Guatemala's INSIVUMEH (Instituto Nacional de Sismologia, Vulcanologia, Meterologia e Hidrologia) and the Washington VAAC (Volcanic Ash Advisory Center).

Activity at Santa Maria continued with little variation from previous months during November 2018-February 2019. Plumes of steam with minor magmatic gases rose continuously from the Caliente crater 100-500 m above the summit, generally drifting SW or SE before dissipating. In addition, daily explosions with varying amounts of ash rose to altitudes of around 2.8-3.5 km and usually extended 20-30 km before dissipating. Most of the plumes drifted SW or SE; minor ashfall occurred in the adjacent hills almost daily and was reported at the fincas located within 15 km in those directions several times each month. Continued growth of the Caliente lava dome resulted in daily block avalanches descending its flanks. The MIROVA plot of thermal energy during this time shows a consistent level of heat flow with minor variations throughout the period (figure 89).

Figure (see Caption) Figure 89. Persistent thermal activity was recorded at Santa Maria from 6 June 2018 through February 2019 as seen in the MIROVA plot of thermal energy derived from satellite thermal data. Daily explosions produced ash plumes and block avalanches that were responsible for the continued heat flow at the volcano. Courtesy of MIROVA.

During November 2018 steam plumes rose to altitudes of 2.8-3.2 km from Caliente summit, usually drifting SW, sometimes SE. Several ash-bearing explosions were reported daily, rising to 3-3.2 km altitude and also drifting SW or SE. The highest plume reported by INSIVUMEH rose to 3.4 km on 25 November and drifted SW. The Washington VAAC reported an ash emission on 9 November that rose to 4.3 km altitude and drifted W; it dissipated within a few hours about 35 km from the summit. On 11 November another plume rose to 4.9 km altitude and drifted NW. INSIVUMEH issued a special report on 2 November noting an increase in block avalanches on the S and SE flanks, many of which traveled from the crater dome to the base of the volcano. Nearly constant avalanche blocks descended the SE flank of the dome and occasionally traveled down the other flanks as well throughout the month. They reached the bottom of the cone again on 29 November. Ashfall was reported around the flanks more than once every week and at Finca Florida on 12 November. Finca San Jose reported ashfall on 11, 13, and 23 November, and Parcelamiento Monte Claro reported ashfall on 15, 24, 25, and 27 November.

Constant degassing from the Caliente dome during December 2018 formed white plumes of mostly steam that rose to 2.6-3.0 km altitude during the month. Weak explosions averaging 9-13 per day produced gray ash plumes that rose to 2.8-3.4 km altitude. The Washington VAAC reported an ash emission on 4 December that extended 25 km SW of the summit at 3.0 km altitude and dissipated quickly. Small ash plumes were visible in satellite imagery a few kilometers WNW on 8, 12, 30, and 31 December at 4.3 km altitude; they each dissipated within a few hours. Ashfall was reported in Finca Monte Claro on 1 and 4 December, and in San Marcos Palajunoj on 26 and 30 December along with Loma Linda. On 28 December ashfall on the E flank affected the communities of Las Marías, Calahuache, and El Nuevo Palmar. Block avalanches occurred daily, sending large blocks to the base of the volcano that often stirred up small plumes of ash in the vicinity (figure 90).

Figure (see Caption) Figure 90. Activity during December 2018 at Santa Maria included constant degassing of steam plumes, weak explosions with ash plumes, and block avalanches rolling down the flanks to the base of the cone. Courtesy of INSIVUMEH (Reporte Semanal de Monitoreo: Volcán Santiaguito (1402-03), Diciembre 2018).

Multiple explosions daily during January 2019 produced steam-and-ash plumes (figure 91). Constant degassing rising 10-500 m emerged from the SSE part of the Caliente dome, and ashfall, mainly on the W and SW rim of the cone, was a daily feature. Seismic station STG-3 detected 10-18 explosions per day that produced ash plumes, which rose to between 2.7 and 3.5 km altitude. The Washington VAAC noted a faint ash emission in satellite imagery on 1 January that was about 25 km W of the summit at 4.3 km altitude. A new emission appeared at the same altitude on 4 January about 15 km NW of the summit. A low-density emission around midday on 5 January produced an ash plume that drifted NNE at 4.6 km altitude. Ash plumes drifted W at 4.3 km altitude on 11 and 14 January for short periods of time before dissipating.

Figure (see Caption) Figure 91. Explosions during January produced numerous steam-and-ash plumes at the Santiaguito complex of Santa Maria. A moderate explosion on 31 January 2019 produced an ash plume that rose to about 3.1 km altitude (top). A thermal image and seismograph show another moderate explosion on 18 January 2019 that also rose nearly vertically from the summit of Caliente. Courtesy of INSIVUMEH (Informe mensual de actividad Volcanica enero 2019, Volcan Santiaguito).

Ash drifted mainly towards the W, SW, and S, causing ashfall in the villages of San Marcos Palajunoj, Loma Linda, Monte Bello, El Patrocinio, La Florida, El Faro, Patzulín and a few others several times during the month. The main places where daily ashfall was reported were near the complex, in the hilly crop areas of the El Faro and San José Patzulín farms (figure 92). Blocks up to 3 m in diameter reached the base of the complex, stirring up ash plumes that settled on the immediate flanks. Juvenile material continued to appear at the summit of the dome during January; the dome had risen above the edge of the crater created by the explosions of 2016. Changes in the size and shape of the dome between 23 November 2018 and 13 January 2019 showed the addition of material on the E and SE side of the dome, as well as a new effusive flow that travelled 200-300 m down the E flank (figure 93).

Figure (see Caption) Figure 92. Near-daily ashfall affected the coffee plants at the El Faro and San José Patzulín farms (left) at Santiaguito during January 2019. Large avalanche blocks descending the flanks, seen here on 23 January 2018, often stirred up smaller ash plumes that settled out next to the cone. Courtesy of INSIVUMEH (Informe mensual de actividad Volcanica enero 2019, Volcan Santiaguito).
Figure (see Caption) Figure 93. A comparison of the growth at the Caliente dome of the Santiaguito complex at Santa Maria between 23 November 2018 (top) and 13 January 2019 (bottom) shows the emergence of juvenile material and a 200-300 m long effusive flow that has moved slowly down the E flank. Courtesy of INSIVUMEH (Informe mensual de actividad Volcanica enero 2019, Volcan Santiaguito).

Persistent steam rising 50-150 m above the crater was typical during February 2019 and accompanied weak and moderate explosions that averaged 12 per day throughout the month. White and gray ash plumes from the explosions rose to 2.8-3.3 km altitude; daily block avalanches usually reached the base of the dome (figure 94). Ashfall occurred around the complex, mainly on the W, SW, and NE flanks on a daily basis, but communities farther away were affected as well. The Washington VAAC reported an ash plume on 7 February in visible satellite imagery moving SW from the summit at 4.9 km altitude. The next day a new ash plume was located about 20 km W of the summit, dissipating rapidly, at 4.3 km altitude. Ashfall drifting SW affected Palajuno Monte Claro on 5, 9, 15, and 16 February. Ash drifting E and SE affected Calaguache, Las Marías and surrounding farms on 14 and 17 February, and fine-grained ash drifting SE was reported at finca San José on 21 February.

Figure (see Caption) Figure 94. Activity at the Caliente dome of the Santiaguito complex at Santa Maria included daily ash-and-steam explosions and block avalanches descending the sides of the dome in February 2019. A typical explosion on 2 February 2019 produced an ash plume that rose to about 3 km altitude and drifted SW (left). A block avalanche on 14 February descended the SE flank and stirred up small plumes of ash in the vicinity (right, top); the avalanche lasted for 88 seconds and registered with seismic frequencies between 3.46 and 7.64 Hz (right bottom). Courtesy of INSIVUMEH (Reporte Semanal de Monitoreo: Volcán Santiaguito (1402-03), Semana del 01 al 08 de febrero de 2019).

Geologic Background. Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing W towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).


Masaya (Nicaragua) — March 2019 Citation iconCite this Report

Masaya

Nicaragua

11.984°N, 86.161°W; summit elev. 635 m

All times are local (unless otherwise noted)


Lava lake persists with decreased thermal output, November 2018-February 2019

Nicaragua's Volcan Masaya has an intermittent lava lake that has attracted visitors since the time of the Spanish Conquistadores; tephrochronology has dated eruptions back several thousand years. The unusual basaltic caldera has had historical explosive eruptions in addition to lava flows and an actively circulating lava lake. An explosion in 2012 ejected ash to several hundred meters above the volcano, bombs as large as 60 cm fell around the crater, and ash fell to a thickness of 2 mm in some areas of the park. The reemergence of the lava lake inside Santiago crater was reported in December 2015. By late March 2016 the lava lake had grown and intensified enough to generate a significant thermal anomaly signature which has varied in strength but continued at a moderate level into early 2019. Information for this report, which covers the period from November 2018 through February 2019, is provided by the Instituto Nicareguense de Estudios Territoriales (INETER) and satellite -based imagery and thermal data.

The lava lake in Santiago Crater remained visible and active throughout November 2018 to February 2019 with little change from the previous few months (figure 70). Seismic amplitude RSAM values remained steady, oscillating between 10 and 40 RSAM units during the period.

Figure (see Caption) Figure 70. A small area of the lava lake inside Santiago Crater at Masaya was visible from the rim on 25 November 2018 (left) and 17 January 2019 (right). Left image courtesy of INETER webcam; right image courtesy of Alun Ebenezer.

Every few months INETER carries out SO2 measurements by making a transect using a mobile DOAS spectrometer that samples for gases downwind of the volcano. Transects were done on 9-10 October 2018, 21-24 January 2019, and 18-21 February 2019 (figure 71). Average values during the October transect were 1,454 tons per day, in January they were 1,007 tons per day, and in February they averaged 1,318 tons per day, all within a typical range of values for the last several months.

Figure (see Caption) Figure 71. INETER carries out periodic transects to measure SO2 from Masaya with a mobile DOAS spectrometer. Transects taken along the Ticuantepe-La Concepcion highway on 9-10 October 2018 (left) and 21-24 January 2019 (right) showed modest levels of SO2 emissions downwind of the summit. Courtesy of INETER (Boletín Sismos y Volcanes de Nicaragua. Octubre 2018 and Enero 2019).

During a visit by INETER technicians in early November 2018, the lens of the Mirador 1 webcam, that had water inside it and had been damaged by gases, was cleaned and repaired. During 21-24 January 2019 INETER made a site visit with scientists from the University of Johannes Gutenberg in Mainz, Germany, to measure halogen species in gas plumes, and to test different sampling techniques for volcanic gases, including through spectroscopic observations with DOAS equipment, in-situ gas sampling (MultiGAS, denuders, alkaline traps), and using a Quadcopter UAV (drone) sampling system.

Periodic measurements of CO2 from the El Comalito crater have been taken by INETER for many years. The most recent observations on 19 February 2019 indicated an emission rate of 46 +/- 3 tons per day of CO2, only slightly higher than the average value over 16 measurements between 2008 and 2019 (figure 72).

Figure (see Caption) Figure 72. CO2 measurements taken at Masaya on 19 February 2019 were very close to the average value measured during 2008-2019. Courtesy of INETER (Boletín Sismos y Volcanes de Nicaragua, Febrero 2019).

Satellite imagery (figure 73) and in-situ thermal measurements during November 2018-February 2019 indicated constant activity at the lava lake and no significant changes during the period. On 14 January 2019 temperatures were measured with the FLIR SC620 thermal camera, along with visual observations of the crater; abundant gas was noted, and no explosions from the lake were heard. The temperature at the lava lake was measured at 107°C, much cooler than the 340°C measured in September 2018 (figure 74).

Figure (see Caption) Figure 73. Sentinel-2 satellite imagery (geology, bands 12, 4, and 2) clearly indicated the presence of the active lava lake inside Santiago crater at Masaya during November 2018-February 2019. North is to the top, and the Santigo crater is just under 1 km in diameter for scale. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 74. Thermal measurements were made at Masaya on 14 January 2019 with a FLIR SC620 thermal camera that indicated temperatures over 200°C cooler than similar measurements made in September 2018.

Thermal anomaly data from satellite instruments also confirmed moderate levels of ongoing thermal activity. The MIROVA project plot indicated activity throughout the period (figure 75), and a plot of the number of MODVOLC thermal alerts by month since the lava lake first appeared in December 2015 suggests constant activity at a reduced thermal output level from the higher values in early 2017 (figure 76).

Figure (see Caption) Figure 75. Thermal anomalies remained constant at Masaya during November 2018-February 2019 as recorded by the MIROVA project. Courtesy of MIROVA.
Figure (see Caption) Figure 76. The number of MODVOLC thermal alerts each month at Masaya since the lava lake first reappeared in late 2015 reached its peak in early 2017 and declined to low but persistent levels by early 2018 where they have remained for a year. Data courtesy of MODVOLC.

Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras pyroclastic shield volcano and is a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The twin volcanoes of Nindirí and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals cause health hazards and crop damage.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Alun Ebenezer (Twitter: @AlunEbenezer, URL: https://twitter.com/AlunEbenezer).


Reventador (Ecuador) — March 2019 Citation iconCite this Report

Reventador

Ecuador

0.077°S, 77.656°W; summit elev. 3562 m

All times are local (unless otherwise noted)


Multiple daily explosions with ash plumes and incandescent blocks rolling down the flanks, October 2018-January 2019

The andesitic Volcán El Reventador lies well east of the main volcanic axis of the Cordillera Real in Ecuador and has historical eruptions with numerous lava flows and explosive events going back to the 16th century. The eruption in November 2002 generated a 17-km-high eruption cloud, pyroclastic flows that traveled 8 km, and several lava flows. Eruptive activity has been continuous since 2008. Daily explosions with ash emissions and ejecta of incandescent blocks rolling hundreds of meters down the flanks have been typical for many years. Activity continued during October 2018-January 2019, the period covered in this report, with information provided by Ecuador's Instituto Geofisico (IG-EPN), the Washington Volcano Ash Advisory Center (VAAC), and infrared satellite data.

Multiple daily reports were issued from the Washington VAAC throughout the entire October 2018-January 2019 period. Plumes of ash and gas usually rose to altitudes of 4.3-6.1 km and drifted about 20 km in prevailing wind directions before either dissipating or being obscured by meteoric clouds. The average number of daily explosions reported by IG-EPN for the second half of 2018 was more than 20 per day (figure 104). The many explosions during the period originated from multiple vents within a large scarp that formed on the W flank in mid-April (BGVN 43:11, figure 95) (figure 105). Incandescent blocks were observed often in the IG webcams; they traveled 400-1,000 m down the flanks.

Figure (see Caption) Figure 104. The number of daily seismic events at El Reventador for 2018 indicated high activity during the first and last thirds of the year; more than 20 explosions per day were recorded many times during October-December 2018, the period covered in this report. LP seismic events are shown in orange, seismic tremor in pink, and seismic explosions with ash are shown in green. Courtesy of IG-EPN (Informe Anual del Volcán El Reventador – 2018, Quito, 29 de marzo del 2019).
Figure (see Caption) Figure 105. Images from IG's REBECA thermal camera showed the thermal activity from multiple different vents at different times during the year (see BGVN 43:11, figure 95 for vent locations). Courtesy if IG (Informe Anual del Volcán El Reventador – 2018, Quito, 29 de marzo del 2019).

Activity during October 2018-January 2019. During most days of October 2018 plumes of gas, steam, and ash rose over 1,000 m above the summit of Reventador, and most commonly drifted W or NW. Incandescence was observed on all nights that were not cloudy; incandescent blocks rolled 400-800 m down the flanks during half of the nights. During episodes of increased activity, ash plumes rose over 1,200 m (8, 10-11, 18-19 October) and incandescent blocks rolled down multiple flanks (figure 106).

Figure (see Caption) Figure 106. Ash emissions rose over 1,000 m above the summit of Reventador numerous times during October 2018, and large incandescent blocks traveled hundreds of meters down multiple flanks. The IG-EPN COPETE webcam that captured these images is located on the S caldera rim. Courtesy of IG Daily Reports (Informe diario del estado del Volcan Reventador, numbers 2018-282, 292, 295, 297).

Similar activity continued during November. IG reported 17 days of the month with steam, gas, and ash emissions rising more than 1,000 m above the summit. The other days were either cloudy or had emissions rising between 500 and 1,000 m. Incandescent blocks were usually observed on the S or SE flanks, generally travelling 400-600 m down the flanks. The Washington VAAC reported a discrete ash plume at 6.1 km altitude drifting WNW about 35 km from the summit on 15 November. The next day, intermittent puffs were noted moving W, and a bright hotspot at the summit was visible in satellite imagery. During the most intense activity of the month, incandescent blocks traveled 800 m down all the flanks (17-19 November) and ash plumes rose over 1,200 m (23 November) (figure 107).

Figure (see Caption) Figure 107. Ash plumes rose over 1,000 m above the summit on 17 days during November 2018 at Reventador, and incandescent blocks traveled 400-800 m down the flanks on many nights. Courtesy of IG Daily Reports (Informe diario del estado del Volcan Reventador, numbers 2018-306, 314, 318, 324).

Steam, gas, and ash plumes rose over 1,200 m above the summit on 1 December. The next day, there were reports of ashfall in San Rafael and Hosteria El Hotelito, where they reported an ash layer about 1 mm thick was deposited on vehicles during the night. Ash emissions exceeded 1,200 m above the summit on 5 and 6 December as well. Incandescent blocks traveled 800 m down all the flanks on 11, 22, 24, and 26 December, and reached 900 m on 21 December. Ash emissions rising 500 to over 1,000 m above the summit were a daily occurrence, and incandescent blocks descended 500 m or more down the flanks most days during the second half of the month (figure 108).

Figure (see Caption) Figure 108. Ash plumes that rose 500 to over 1,000 m were a daily occurrence at Reventador during December 2018. Incandescent blocks traveled as far as 900 m down the flanks as well. Courtesy of IG Daily Reports (Informe diario del estado del Volcan Reventador, numbers 2018-340, 351, 353, 354, 358, 359).

During the first few days of January 2019 the ash and steam plumes did not rise over 800 m, and incandescent blocks were noted 300-500 m down the S flank. An increase in activity on 6 January sent ash-and-gas plumes over 1,000 m, drifting W, and incandescent blocks 1,000 m down many flanks. For multiple days in the middle of the month the volcano was completely obscured by clouds; only occasional observations of plumes of ash and steam were made, incandescence seen at night through the clouds confirmed ongoing activity. The Washington VAAC reported continuous ash emissions moving SE extending more than 100 km on 12 January. A significant explosion late on 20 January sent incandescent blocks 800 m down the S flank; although it was mostly cloudy for much of the second half of January, brief glimpses of ash plumes rising over 1,000 m and incandescent blocks traveling up to 800 m down numerous flanks were made almost daily (figure 109).

Figure (see Caption) Figure 109. Even during the numerous cloudy days of January 2019, evidence of ash emissions and significant explosions at Reventador was captured in the Copete webcam located on the S rim of the caldera. Courtesy of IG Daily Reports (Informe diario del estado del Volcan Reventador, number 2019-6, 21, 26, 27).

Visual evidence from the webcams supports significant thermal activity at Reventador. Atmospheric conditions are often cloudy and thus the thermal signature recorded by satellite instruments is frequently diminished. In spite of this, the MODVOLC thermal alert system recorded seven thermal alerts on three days in October, four alerts on two days in November, six alerts on two days in December and three alerts on three days in January 2019. In addition, the MIROVA system measured moderate levels of radiative power intermittently throughout the period; the most intense anomalies of 2018 were recorded on 15 October and 6 December (figure 110).

Figure (see Caption) Figure 110. Persistent thermal activity at Reventador was recorded by satellite instruments for the MIROVA system from 5 April 2018 through January 2019 in spite of frequent cloud cover over the volcano. The most intense anomalies of 2018 were recorded on 15 October and 6 December. Courtesy of MIROVA.

Geologic Background. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Information Contacts: Instituto Geofísico (IG-EPN), Escuela Politécnica Nacional, Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Kuchinoerabujima (Japan) — March 2019 Citation iconCite this Report

Kuchinoerabujima

Japan

30.443°N, 130.217°E; summit elev. 657 m

All times are local (unless otherwise noted)


Weak explosions and ash plumes beginning 21 October 2018

Activity at Kuchinoerabujima is exemplified by interim explosions and periods of high seismicity. A weak explosion occurred on 3 August 2014, the first since 1980, and was followed by several others during 29 May-19 June 2015 (BGVN 42:03). This report describes events through February 2019. Information is based on monthly and annual reports from the Japan Meteorological Agency (JMA) and advisories from the Tokyo Volcanic Ash Advisory Center (VAAC). Activity has been limited to Kuchinoerabujima's Shindake Crater.

Activity during 2016-2018. According to JMA, between July 2016 and August 2018, the volcano was relatively quiet. Deflation had occurred since January 2016. On 18 April 2018 the Alert Level was lowered from 3 to 2 (on a scale of 1-5). A low-temperature thermal anomaly persisted near the W fracture in Shindake crater. During January-March 2018, both the number of volcanic earthquakes (generally numerous and typically shallow) and sulfur dioxide flux remained slightly above baselines levels in August 2014 (60-500 tons/day compared tp generally less than 100 tons/day in August 2014).

JMA reported that on 15 August 2018 a swarm of deep volcanic earthquakes was recorded, prompting an increase in the Alert Level to 4. The earthquake hypocenters were about 5 km deep, below the SW flanks of Shindake, and the maximum magnitude was 1.9. They occurred at about the same place as the swarm that occurred just before the May 2015 eruption. Sulfur dioxide emissions had increased since the beginning of August; they were 1,600, 1,000, and 1,200 tons/day on 11, 13, and 17 August, respectively. No surficial changes in gas emissions or thermal areas were observed during 16-20 August. On 29 August, JMA downgraded the Alert Level to 3, after no further SO2 flux increase had occurred in recent days and GNSS measurements had not changed.

A very weak explosion was recorded at 1831 on 21 October, with additional activity between 2110 on 21 October and 1350 on 22 October; plumes rose 200 m above the crater rim. During an overflight on 22 October, observers noted ash in the emissions, though no morphological changes to the crater nor ash deposits were seen. Based on satellite images and information from JMA, the Tokyo VAAC reported that during 24-28 October ash plumes rose to altitudes of 0.9-1.5 km and drifted in multiple directions. During a field observation on 28 October, JMA scientists did not observe any changes in the thermal anomalies at the crater.

JMA reported that during 31 October-5 November 2018, very small events released plumes that rose 500-1,200 m above the crater rim. On 6 November, crater incandescence began to be periodically visible. During 12-19 November, ash plumes rose as high as 1.2 km above the crater rim and, according to the Tokyo VAAC, drifted in multiple directions. Observers doing fieldwork on 14 and 15 November noted that thermal measurements in the crater had not changed. Intermittent explosions during 22-26 November generated plumes that rose as high as 2.1 km above the crater rim. During 28 November-3 December the plumes rose as high as 1.5 km above the rim.

JMA reported that at 1637 on 18 December an explosion produced an ash plume that rose 2 km and then disappeared into a weather cloud. The event ejected material that fell in the crater area, and generated a pyroclastic flow that traveled 1 km W and 500 m E of the crater. Another weak explosion occurred on 28 December, scattering large cinders up to 500 m from the crater.

The Tokyo VAAC did not issue any ash advisories for aviation until 21 October 2018, when it issued at least one report every day through 13 December. It also issued advisories on 18-20 and 28 December.

Activity during January-early February 2019. JMA reported that at 0919 local time on 17 January 2019 an explosion generated a pyroclastic flow that reached about 1.9 km NW and 1 km E of the crater. It was the strongest explosion since October 2018. In addition, "large cinders" fell about 1-1.8 km from the crater.

Tokyo VAAC ash advisories were issued on 1, 17, 20, and 29 January 2018. An explosion at 1713-1915 on 29 January produced an ash plume that rose 4 km above the crater rim and drifted E, along with a pyroclastic flow. Ash fell in parts of Yakushima. During 30 January-1 February and 3-5 February, white plumes rose as high as 600 m. On 2 February, an explosion at 1141-1300 generated a plume that rose 600 m. No additional activity during February was reported by JMA. The Alert Level remained at 3.

Geologic Background. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. The youngest cone, centrally-located Shindake, formed after the NW side of Furudake was breached by an explosion. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

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Bulletin of the Global Volcanism Network - Volume 44, Number 01 (January 2019)

Managing Editor: Edward Venzke

Aira (Japan)

Ash plumes continue at the Minamidake crater from July through December 2018

Ambrym (Vanuatu)

Fissure eruption in mid-December 2018 produces fountaining and lava flows; no activity evident in caldera after 17 December

Copahue (Chile-Argentina)

Frequent emissions and small ash plumes continue from July through 7 December 2018

Erebus (Antarctica)

Lava lakes persist through 2017 and 2018

Kilauea (United States)

Fissure 8 lava flow continues vigorously until 4 August, ocean entry ends in late August, last activity at fissure 8 cone on 5 September 2018

Planchon-Peteroa (Chile)

New eruption begins in September 2018; continuous ash emissions and intermittent explosions December 2018-February 2019

Poas (Costa Rica)

Frequent changes at the crater lake throughout 2018

Sangay (Ecuador)

Eruption produced ash plumes, lava flows, and rockfalls during August-December 2018

Soputan (Indonesia)

Ash explosions on 3-4 October and 16 December 2018

Suwanosejima (Japan)

Multiple explosive events with incandescence and ash plumes during November 2018

Veniaminof (United States)

Eruption with lava flows and ash plumes during September-December 2018



Aira (Japan) — January 2019 Citation iconCite this Report

Aira

Japan

31.593°N, 130.657°E; summit elev. 1117 m

All times are local (unless otherwise noted)


Ash plumes continue at the Minamidake crater from July through December 2018

Sakurajima is one of the most active volcanoes in Japan and is situated in the Aira caldera in southern Kyushu. It regularly produces ash plumes and scatters blocks onto the flanks during explosions. This report covers July through December 2018 and describes activity at the Minamidake crater, which has continued with the activity typically observed at Sakurajima volcano. In late 2017 the eruptive activity has migrated from being centered at the Showa crater, to being focused at the Minamidake crater. This change has continued into the later half of 2018. The following activity summarizes information issued by the Japan Meteorological Agency (JMA), the Japan Volcanic Ash Advisory Center (VAAC), and satellite data.

Activity from July through December 2018 was focused at the summit Minamidake crater with 8 to 64 ash emission events per month, with 50-60% being explosive in nature during four of the six months reported (table 20, figure 67). The maximum explosions per day was 64 on 31 August (figure 68). No pyroclastic flows were recorded during this time. Recent activity at the Showa crater has been declining and no activity was observed during the reporting period. Sakurajima has remained on Alert Level 3 on a 5-level scale during this time, reflecting the regular ash plumes and volcanic blocks that erupt out onto the slopes of the volcano during explosive events.

Table 20. Monthly summary of eruptive events recorded at Sakurajima's Minamidake crater in Aira caldera, July-December 2018. The number of events that were explosive in nature are in parentheses. No events were recorded at the Showa crater during this time. Data courtesy of JMA (July to December 2018 monthly reports).

Month Ash emissions (explosive) Max. plume height above the crater Max. ejecta distance from crater
Jul 2018 29 (16) 4.6 km 1.7 km
Aug 2018 64 (37) 2.8 km 1.3 km
Sep 2018 44 (22) 2.3 km 1.1 km
Oct 2018 8 (0) 1.6 km --
Nov 2018 14 (2) 4 km 1.7 km
Dec 2018 56 (34) 3 km 1.3 km
Figure (see Caption) Figure 67. Satellite images showing ash plumes from Sakurajima's Minamidake summit crater (Aira caldera) in August, September, and November 2018. Natural color satellite images (bands 4, 3, 2) courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 68. Explosions per day at Sakurajima's Minamidake summit crater (Aira caldera) for July through December 2018. Data courtesy of JMA.

Activity through July consisted of 29 ash emission events (16 of which were explosive) producing ash plumes up to a maximum height of 4.6 km above the crater and ballistic ejecta (blocks) out to 1.7 km from the crater, but ash plumes were more commonly 1.2 to 2.5 km high. The largest explosive event occurred on 16 July, producing an ash plume up to 4.6 km from the vent and ejecting ballistic rocks out to 1.3-1.7 km from the crater (figure 69). On 17 July, sulfur dioxide emissions were measured at 1,300 tons per day, and on 26 July emissions were measured to be 2,100 tons per day.

Figure (see Caption) Figure 69. Ash plumes erupting from the Sakurajima Minamidake crater (Aira caldera) on 16 July 2018 at 1538 (upper) and 1500 (lower) local time. The ash plumes reached 4.6 km above the crater rim and ejected rocks out to 1.3-1.7 km from the crater. Higashikorimoto webcam images courtesy of JMA (July 2018 monthly report).

During August the Minamidake crater produced 64 ash emission events (37 explosive in nature) with a maximum ash plume height of 2.8 km above the crater, and a maximum ballistic ejecta distance of 1.3 km from the crater on 31 August (figure 70). Ash plumes were more commonly up to 1 to 2.1 km above the crater. Sulfur dioxide emissions were very high on 2 August, measured as high as 3,200 tons per day, and was measured at 1,500 tons per day on 27 August.

Figure (see Caption) Figure 70. Activity at Sakurajima volcano (Aira Caldera) in August 2018. Top: A gas-and-ash plume that reached 2.8 km above the crater at 1409 on 29 August. Bottom: Scattered incandescent blocks out to 1-1.3 km from the crater on the flanks of Sakurajima after an explosion on 31 August. Higashikorimoto and Kaigata webcam images courtesy of JMA (August 2018 monthly report).

Throughout September 44 ash emission events occurred, with 22 of those being explosive in nature. The Maximum ash plume height reached 2.3 km above the crater, and the maximum ejecta landed out to 1.1 km from the crater. An explosive event on 9 September ejected material out to 700 m away from the crater and on 22 September an event scattered blocks out to 1.1 km from the crater (figure 71).

Figure (see Caption) Figure 71. Incandescent blocks on the flanks of Sakurajima volcano (Aira caldera) after an explosion on 22 September 2018 at 2025. The event scattered blocks out to 1.1 km from the Minamidake crater. Kaigata webcam image courtesy of JMA (September 2018 monthly report).

October and November were relatively quiet with regards to the number of ash emission events with only 22 events over the two months. The maximum ash plume heights reached 1.6 and 4 km, respectively. An observation flight on 22 October showed the currently inactive Showa crater restricted to minor fumarolic degassing, and steam-and-gas and dilute ash plume activity in the Minamidake crater (figure 72). An eruption on 14 November at 0043 local time produced an ash plume to over 4 km above the crater and scattered incandescent blocks out to over 1 km from the crater (figure 73). This was the first ash plume to exceed a height of 4 km since 16 July 2018. Two events occurred during 16-19 November that produced ash plumes up to 1.6 km. Sulfur dioxide measurements were 3,400 tons on 4 October, 400 tons on 17 October, 1,000 tons on 23 October, 1,100 tons on 6 November, and 1,400 tons on 20 November.

Figure (see Caption) Figure 72. Minor fumarolic degassing has occurred in Sakurajima's Showa crater (Aira caldera) and the vent has been blocked by ash and rock. The active Minamidake crater is producing a blue-white plume to 400 m above the crater and a dilute brown plume that remained within the crater. Images taken by the Japan Maritime Self-Defense Force 1st Air Group P-3C on 22 October 2018, courtesy of JMA (October 2018 monthly report).
Figure (see Caption) Figure 73. Eruption of Sakurajima (Aira caldera) on 14 November at 0043 local time ejecting incandescent blocks more than 1 km from the crater and an ash plume up to 4 km above the crater. Photos courtesy of The Asahi Shimbun.

Small ash plumes continued through December with 56 ash emission events, 34 of which were explosive in nature. The maximum ash plume height above the crater reached 3 km, and the maximum distance that ejecta traveled from the vent was 1.3 km, both during an event on 24 December (figure 74). An explosive event produced an ash plume that reached a height of 2.5 km above the crater and scattered ejecta out to 1.1 km from the crater.

Figure (see Caption) Figure 74. An explosive event at 1127 on 24 December 2018 at Sakurajima's Minamidake crater (Aira caldera). The ash plume reached 3 km above the crater rim. Higashikorimoto webcam image courtesy of JMA (December 2018 monthly report).

Intermittent incandescence was observed at the summit at nighttime throughout the entire reporting period. Areas of elevated thermal energy within the Minamidake crater were visible in cloud-free Sentinel-2 satellite images (figure 75) and elevated temperatures were detected in MIROVA on a few days.

Figure (see Caption) Figure 75. Sentinel-2 thermal satellite images showing the summit area of Sakurajima volcano, Aira caldera, in October 2018. The areas of elevated thermal activity (bright orange-red) are visible within the Minamidake crater. No thermal anomalies are visible within the Showa crater. Thermal (Urban) satellite images (bands 12, 11, 4) courtesy of Sentinel Hub Playground.

Geologic Background. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); The Asahi Shimbun (URL: http://www.asahi.com/ajw/articles/AJ201811140035.html accessed on 12 March 2018).


Ambrym (Vanuatu) — January 2019 Citation iconCite this Report

Ambrym

Vanuatu

16.25°S, 168.12°E; summit elev. 1334 m

All times are local (unless otherwise noted)


Fissure eruption in mid-December 2018 produces fountaining and lava flows; no activity evident in caldera after 17 December

Ambrym is a shield volcano in the Vanuatu archipelago with a 12-km-wide summit caldera containing the persistently active Benbow and Marum craters. These craters are home to multiple active vents that produce episodic lava lakes, explosions, lava flows, ash, and gas emissions. Occasional fissure eruptions occur outside of these main craters. This report covers July to December 2018 and summarizes reports by the Vanuatu Meteorology and Geohazards Department (VMGD), the Wellington Volcanic Ash Advisory Center (VAAC), and multiple sources of satellite data.

As of the beginning of the reporting period, the hazard status at Ambrym had remained at Volcanic Alert Level 2 ("Major unrest") since 7 December 2017. Monthly VMGD activity reports describe the continued activity within the two main craters, consisting of multiple lava lakes, sustained substantial degassing and steam emission, and seismic unrest. Frequent thermal anomalies were detected throughout the reporting period (figure 42). The danger areas were confined to the Permanent Exclusion Zone within a 1 km radius of Benbow crater, and the Permanent Exclusion Zone and Danger Zone A within about a 2.7 km radius of Marum crater (including Maben-Mbwelesu, Niri-Mbwelesu and Mbwelesu, see BGVN 43:07, figure 38).

Figure (see Caption) Figure 42. Plot of MODIS thermal infrared data analyzed by MIROVA showing the log radiative power of thermal anomalies at Ambrym for the year ending on 1 February 2019. After the December 2018 eruption no further thermal anomalies were noted for the reporting period. Courtesy of MIROVA.

Observations and seismic data analysis by VMGD confirmed the onset of a small-scale intra-caldera fissure eruption at 0600 local time on 15 December. This new fissure produced lava fountains and lava flows with ash and gas plumes (figure 43). Footage of the eruption by John Tasso shows the fissure eruption to the SE of Marum crater producing lava fountaining. A Sentinel-2 satellite image shows a white eruption plume and two new lava flow lobes (figure 44); the actual fissure vent was hidden by the plume. The northernmost lava flow filled in the 500 x 900 m Lewolembwi crater and a smaller lobe continued to flow towards the E (figure 44). Due to this elevated activity, the Volcanic Alert Level was raised to 3 ("Minor eruption"), with the danger zones increased to a 2 km radius around Benbow crater and a 4 km radius around Marum crater. VMGD warned of additional risk within 3 km of eruptive fissures in the SE caldera area.

Figure (see Caption) Figure 43. Image of the fissure eruption producing lava fountaining at Ambrym volcano, taken from a video recorded by John Tasso on 16 December 2018.
Figure (see Caption) Figure 44. Satellite imagery showing the Ambrym caldera area in November-December 2018. Top: True color Landsat-8 satellite image acquired on 13 December 2018 showing the area prior to the fissure eruption. Bottom: False-color infrared Sentinel-2 composite image (bands 12, 11, and 4) showing the multiple active vents and lava lakes within Marum and Benbow craters (top third of the image, acquired on 25 November 2018), and the eruption plume and the bright orange/red lava flow fronts in the bottom of the image (acquired on 15 December 2018); the fissure is obscured by the plume. Courtesy of Sentinel-Hub Playground.

Through 16-17 December, ash and gas emission continued from Benbow and Marum craters (figures 45 and 46), accompanied by ongoing localized seismicity; earthquakes with a magnitude greater than five were felt on neighboring islands. The Wellington VAAC issued ash advisories on 16 and 17 December noting maximum cloud altitudes of approximately 8 km.

Figure (see Caption) Figure 45. Ash emission from Ambrym volcano at 1600 on 16 December 2018. Webcam image courtesy of, and annotated by, VMGD.
Figure (see Caption) Figure 46. Elevated atmospheric SO2 emissions from Ambrym on 17 December 2018 with a total measured mass of 23.383 kt in this scene. The units on the scale bar reflect SO2 in terms of Dobson Units (DU). Courtesy of the NASA Goddard Flight Center Atmospheric Chemistry and Dynamics Laboratory.

From 14 to 26 December, the National Volcano Monitoring Network detected over 4,500 earthquakes related to the eruptive activity, but locally felt seismicity decreased. Analysis of satellite imagery confirmed surface deformation associated with the increase in activity. Media reports from Radio New Zealand indicated that seismic activity during December resulted in ground rupture and damage to homes on the island and residents were moved to evacuation centers.

During the reporting period, thermal anomalies were frequently detected by the MODIS satellite instruments and subsequently analyzed using the MODVOLC algorithm, reflecting the lava lake activity in Benbow and Marum craters, as well additional thermal anomalies during the December 2018 fissure eruption and subsequent lava flows to the SE of the main crater area (figures 47 and 48).

Figure (see Caption) Figure 47. MODVOLC Thermal Alert System from July through December 2018 showing the two active craters of Ambrym, Benbow and Marum, and the December 2018 fissure eruption. Red areas indicate approximate locations of Thermal Anomaly detections along with the number of detections. Courtesy of HIGP - MODVOLC Thermal Alerts System.
Figure (see Caption) Figure 48. MODVOLC thermal alerts detected over Ambrym volcano during July 2018 through December 2018 showing hot spots located at Benbow and Marum craters and the December 2018 fissure eruption. Courtesy of HIGP - MODVOLC Thermal Alerts System.

As of 7 January 2019, Ambrym remains on Alert Level 3 with continued seismic activity. The MIROVA (Middle InfraRed Observation of Volcanic Activity) system has not detected any recent thermal anomalies, indicating the end of the fissure eruption and a reduction in activity at the main craters.

Geologic Background. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. A thick, almost exclusively pyroclastic sequence, initially dacitic, then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major plinian eruption with dacitic pyroclastic flows about 1900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the caldera floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.

Information Contacts: Geo-Hazards Division, Vanuatu Meteorology and Geo-Hazards Department (VMGD), Ministry of Climate Change Adaptation, Meteorology, Geo-Hazards, Energy, Environment and Disaster Management, Private Mail Bag 9054, Lini Highway, Port Vila, Vanuatu (URL: http://www.vmgd.gov.vu/, https://www.facebook.com/VanuatuGeohazardsObservatory/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Radio New Zealand, 155 The Terrace, Wellington 6011, New Zealand (URL: https://www.radionz.co.nz/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); John Tasso, Vanuatu Island Experience, Port Vatu, West Ambrym, Vanuatu (URL: http://vanuatuislandexperience.com/).


Copahue (Chile-Argentina) — January 2019 Citation iconCite this Report

Copahue

Chile-Argentina

37.856°S, 71.183°W; summit elev. 2953 m

All times are local (unless otherwise noted)


Frequent emissions and small ash plumes continue from July through 7 December 2018

Copahue, on the border of Chile and Argentina, has frequent small ash eruptions and gas-and-steam plumes. The volcano alert was raised from Green to Yellow (on a scale going from green, yellow, orange, to red) on 24 March 2018 due to an increase in seismic activity and a phreatic explosion. Copahue has a dozen craters with recent activity focused at the Agrio crater, which contains a persistent fumarole field and a crater lake. This report summarizes activity from July through December 2018 and is based on reports issued by Servicio Nacional de Geología y Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur, (OVDAS), Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI), Buenos Aires Volcanic Ash Advisory Center (VAAC), and satellite data.

Throughout July, Copahue produced gas-and-steam and ash plumes that deposited ash on and away from the slopes of the volcano (figure 19). From 1 to 15 July degassing was continuous with a maximum plume height of 300 m above the crater. A more energetic gas-and-steam plume was produced on 18 July (figure 20). Persistent gas and ash plumes during 16-31 July rose up to 1,500 m above the crater. Nighttime incandescence was present throughout the month.

Figure (see Caption) Figure 19. Sentinel-2 natural color satellite images of Copahue that show plumes and dark ash deposition throughout July 2018. The location of the active Agrio crater is indicated by the black arrow in the upper left image. Sentinel-2 Natural Color images (bands 12, 11, 14) courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 20. Energetic degassing at Copahue related to hydrothermal activity on 18 July 2018. Webcam image courtesy of SERNAGEOMIN-OVDAS.

Throughout August intermittent gas-and-steam and ash plumes continued due to the interaction of the hydrothermal and magmatic system within the volcano (figure 21). Notices were issued by the Buenos Aires VAAC on 14 and 15 August for diffuse steam plumes possibly containing ash up to an altitude on 3.6 km. Constant degassing, intermittent ash plumes, and nighttime incandescence continued through September (figure 22).

Figure (see Caption) Figure 21. Low-level ash-and-gas emission at Copahue on 11, 24, and 28 of August 2018, and a plume and incandescence on 15 August. Webcam images courtesy of SERNAGEOMIN-OVDAS via CultureVolcan and Roberto Impaglione.
Figure (see Caption) Figure 22. A plume from Copahue on 1 September 2018. Webcam image courtesy of SERNAGEOMIN-OVDAS via Roberto Impaglione.

During September, October, and November, variable gas-and-steam and ash plumes were accompanied by visible incandescence at night. Continuous ash emission was observed from 16 to 30 November (figure 23); similar activity with plume heights up to 800 m from 1 to 6 December. On 2 December a Buenos Aires VAAC notice was issued for a narrow ash plume that drifted ESE. During 6-7 December an ash plume that rose up to 3 km altitude and drifted towards the SW was accompanied by a seismic swarm. No further ash emissions were noted through the end of the year.

Figure (see Caption) Figure 23. A low-lying plume at Copahue on the morning of 23 November 2018. Courtesy of Valentina.

MIROVA (Middle InfraRed Observation of Volcanic Activity) data showed intermittent minor thermal activity at the summit from July through December. There were no thermal anomalies detected by the MODVOLC algorithm for this time period. Twenty cloud-free Sentinel-2 satellite images revealed elevated thermal activity (hotspots) within Agrio crater throughout the reporting period (figure 24).

Figure (see Caption) Figure 24. Thermal activity in the Copahue crater during 2018 seen in Sentinel-2 infrared images. The orange-yellow areas indicate high temperatures within the active Agrio crater. Courtesy of Sentinel Hub Playground.

Geologic Background. Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.

Information Contacts: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI), Beaucheff 1637/1671, Santiago, Chile (URL: http://www.onemi.cl/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Valentina (URL: https://twitter.com/valecaviahue, Twitter: @valecaviahue); Roberto Impaglione (URL: https://twitter.com/robimpaglione, Twitter: @robimpaglione); CultureVolcan (URL: https://twitter.com/CultureVolcan, Twitter: @CultureVolcan).


Erebus (Antarctica) — January 2019 Citation iconCite this Report

Erebus

Antarctica

77.53°S, 167.17°E; summit elev. 3794 m

All times are local (unless otherwise noted)


Lava lakes persist through 2017 and 2018

Between the early 1980's through 2016, activity at Erebus was monitored by the Mount Erebus Volcano Observatory (MEVO), using seismometers, infrasonic recordings to measure eruption frequency, and annual scientific site visits. MEVO recorded occasional explosions propelling ash up to 2 km above the summit of this Antarctic volcano and the presence of two, sometimes three, lava lakes (figure 26). However, MEVO closed in 2016 (BGVN 42:06).

Activity at the lava lakes in the summit crater can be detected using MODIS infrared detectors aboard the Aqua and Terra satellites and analyzed using the MODVOLC algorithm. A compilation of thermal alert pixels during 2017-2018 (table 4, a continuation of data in the previous report) shows a wide range of detected activity, with a high of 182 alert pixels in April 2018. Although no MODVOLC anomalies were recorded in January 2017, detectors on the Sentinel-2 satellite imaged two active lava lakes on 25 January.

Table 4. Number of MODVOLC thermal alert pixels recorded per month from 1 January 2017 to 31 December 2018 for Erebus by the University of Hawaii's thermal alert system. Table compiled by GVP from data provided by MODVOLC.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec SUM
2017 0 21 9 0 0 1 11 61 76 52 0 3 234
2018 0 21 58 182 55 17 137 172 103 29 0 0 774
SUM 0 42 67 182 55 18 148 233 179 81 0 3 1008
Figure (see Caption) Figure 26. Sentinel-2 images of the summit crater area of Erebus on 25 January 2017. Top: Natural color filter (bands 4, 3, 2). Bottom: Atmospheric penetration filter (bands 12, 11, 8A) in which two distinct lava lakes can be observed. The main crater is 500 x 600 m wide. Courtesy of Sentinel Hub Playground.

Geologic Background. Mount Erebus, the world's southernmost historically active volcano, overlooks the McMurdo research station on Ross Island. It is the largest of three major volcanoes forming the crudely triangular Ross Island. The summit of the dominantly phonolitic volcano has been modified by one or two generations of caldera formation. A summit plateau at about 3,200 m elevation marks the rim of the youngest caldera, which formed during the late-Pleistocene and within which the modern cone was constructed. An elliptical 500 x 600 m wide, 110-m-deep crater truncates the summit and contains an active lava lake within a 250-m-wide, 100-m-deep inner crater; other lava lakes are sometimes present. The glacier-covered volcano was erupting when first sighted by Captain James Ross in 1841. Continuous lava-lake activity with minor explosions, punctuated by occasional larger Strombolian explosions that eject bombs onto the crater rim, has been documented since 1972, but has probably been occurring for much of the volcano's recent history.

Information Contacts: Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Kilauea (United States) — January 2019 Citation iconCite this Report

Kilauea

United States

19.421°N, 155.287°W; summit elev. 1222 m

All times are local (unless otherwise noted)


Fissure 8 lava flow continues vigorously until 4 August, ocean entry ends in late August, last activity at fissure 8 cone on 5 September 2018

Kilauea's East Rift Zone (ERZ) has been intermittently active for at least two thousand years. Since the current eruptive period began in 1983 there have been open lava lakes and flows from the summit caldera and the East Rift Zone. A marked increase in seismicity and ground deformation at Pu'u 'O'o Cone on the upper East Rift Zone on 30 April 2018, and the subsequent collapse of its crater floor, marked the beginning of the largest lower East Rift Zone eruptive episode in at least 200 years; the ending of this episode in early September 2018 marked the end of 36 years of continuous activity.

During May 2018, lava moving into the Lower East Rift Zone opened 24 fissures along a 6-km-long NE-trending fracture zone, sending lava flows in multiple directions. As lava emerged from the fissures, the lava lake at Halema'uma'u drained and explosions sent ash plumes to several kilometer's altitude (BGVN 43:10). At the end of May, eruptive activity focused on 60-m-high fountains of lava from fissure 8 that created a rapidly moving flow that progressed 13 km in just five days, entering the ocean at Kapoho Bay and destroying over 500 homes. Throughout June vigorous effusion from fissure 8 created a 50-m-tall cone and a massive lava channel that carried lava to a growing 3-km-wide delta area which spread out into the ocean along the coast (BGVN 43:12). At Halema'uma'u crater, regular collapse explosion events were the response of the crater to the subsidence caused by the magma withdrawal on the lower East Rift Zone. The deepest part of the crater had reached 400 m below the caldera floor by late June. The eruptive events of July-September 2018 (figure 424), the last three months of this episode, are described in this report with information provided primarily from the US Geological Survey's (USGS) Hawaii Volcano Observatory (HVO) in the form of daily reports, volcanic activity notices, and abundant photo, map, and video data.

Figure (see Caption) Figure 424. Timeline of Activity at Kilauea, 1 July through 14 September 2018. Blue shaded region denotes activity at Halema'uma'u crater at the summit. Green shaded area describes activity on the lower East Rift Zone (LERZ). HST is Hawaii Standard Time. Black summit symbols indicate earthquakes; red LERZ symbols indicate lava fountains (stars), lava flows (triangles) and lava ocean entry.

Summary of activity, July-September 2018. The lava flow emerging from the fissure 8 cone on the Lower East Rift Zone continued unabated throughout July 2018. Overflows from the open channel were common, and often occurred a few hours after summit collapse events. There were multiple active ocean entry areas along the north, central, and southern portions of the coastal flow front of the fissure 8 flow at various times throughout the month. As the flow approached the delta area, lava spread out over the flow field and was no longer flowing on the surface but continued on the interior of the delta; numerous ocean entry points spanned the growing delta. In mid-July, an overflow diverted the channel W of Kapoho Crater, causing a new channel to the S of the delta that destroyed a park and a school, and increased the width of the delta to 6 km. The near-daily collapse events at Halema'uma'u crater continued until 2 August, transforming the geomorphology of the summit caldera.

Lower lava levels at the fissure 8 channel flow were first reported in early August; a reduced output from the cone was reported on 4 August and the lava level in the cone fell below the spillway the next day, shutting off the lava supply to the channel. The lava channel drained and crusted over during the next few days, but lava continued to enter the ocean at a decreasing rate for the rest of the month; the last ocean entry point had ceased by 29 August. A minor burst of spatter from gas jets inside the cone was noted on 20 August. The last activity was a small flow that covered the floor of the fissure 8 cone and created a small spatter cone during 1-5 September. Incandescence at the crater subsided during the next week until only steam activity was reported on the Lower East Rift Zone by the second half of September 2018.

Activity on the Lower East Rift Zone during 1-12 July 2018. The lava flow emerging from the fissure 8 cone on the Lower East Rift Zone continued unabated during July 2018 (figure 425). Overflows from the open channel were common, sending multiple short streams of lava down the built-up flanks of the channel (figure 426). The fissure 8 lava flow was the most significant activity at the Lower East Rift Zone during July 2018, but it was not the only activity observed by HVO scientists. Fissure 22 was also spattering tephra 50-80 m above a small spatter cone and feeding a short lava flow that was moving slowly NE along the edge of earlier flows during 1-11 July (figures 427 and 428). There were multiple active ocean entry areas along the north, central, and southern portions of the coastal flow front of the fissure 8 flow at various times throughout the month.

Figure (see Caption) Figure 425. The lava flow emerging from the fissure 8 cone on Kilauea's Lower East Rift Zone continued unabated on 3 July 2018, as viewed from the early morning HVO helicopter overflight. Recent heavy rains had soaked into the still-warm tephra causing the moisture to rise as steam around the channel. Note house and road in lower right for scale. Courtesy of HVO.
Figure (see Caption) Figure 426. Numerous overflows were visible from Kilauea's LERZ fissure 8 lava channel during the HVO morning overflight on 2 July 2018. They appear as lighter gray to silver areas on the margins of the channel. Note road and Puna Geothermal Venture (PGV) for scale on top. Courtesy of HVO.
Figure (see Caption) Figure 427. Ocean entries were active on the northern and central parts of the ocean entry delta of Kilauea's LERZ fissure 8 flow on 2 July 2018. Flows and overflows were also active along the W side of the delta area. Dark red areas are active flow zones, shaded purple areas indicate lava flows erupted in 1840, 1955, 1960, and 2014-2015. Courtesy of HVO.
Figure (see Caption) Figure 428. This thermal map shows the fissure system and lava flows as of 0600 HST on 2 July 2018. The fountain at fissure 8 remained active, with the lava flow entering the ocean at Kapoho, although the active channel on the surface ended about 0.8 km from the coast. Fissure 22 was also spattering tephra 50-80 m above a small spatter cone and feeding a short lava flow that was moving slowly NE along the edge of earlier flows. The black and white area is the extent of the thermal map. Temperature in the image is displayed as gray-scale values, with the brightest pixels indicating the hottest areas. The map was constructed by stitching many overlapping oblique images collected by a handheld thermal camera during a helicopter overflight of the flow field. The base is a copyrighted color satellite image (used with permission) provided by Digital Globe. Courtesy of HVO.

The lava channel had begun crusting over near the coast late in June, and the lava was streaming from the flow's molten interior into the ocean at many points along its broad front during the first half of July. The crusted-over area was 0.8 km from the coast on 2 July and had increased to 2 km from the coast on 6 July (figure 429). Temporary channel blockages of the flow caused minor overflows north of Kapoho Crater during 4-6 July. Multiple breakouts fed flows on the N and the SW edge of the main `a`a flow. HVO captured images during an overflight on 8 July of the area where the open channel ended and turned into the broad flow area of the delta (figure 430).

Figure (see Caption) Figure 429. This thermal map shows the fissure system and lava flows as of 0600 on 6 July 2018. The fountain at fissure 8 remained active, with the lava flow entering the ocean in several places at Kapoho; the northern delta area was especially active. The crusted over area had increased to 2 km from the coast (compare with figure 428). Small flows were still observed near fissure 22. The black and white area is the extent of the thermal map. Temperature in the image is displayed as gray-scale values, with the brightest pixels indicating the hottest areas. The map was constructed by stitching many overlapping oblique images collected by a handheld thermal camera during a helicopter overflight of the flow field. The base is a copyrighted color satellite image (used with permission) provided by Digital Globe. Courtesy of HVO.
Figure (see Caption) Figure 430. The end of the surface channel in Kilauea's LERZ fissure 8 was near Kapoho Crater on 8 July 2018. Top: The partially filled Kapoho Crater (center) is next to the open lava channel where it makes a 90-degree turn around the crater. Lava flows freely through the channel only to the southern edge of the crater (left side of image). Lava then moves into and through the molten core of the thick 'a'a flow across a broad area. Bottom: Close up view of the "end" of the open lava channel where lava moves beneath the crusted 'a'a flow. Courtesy of HVO.

By 9 July the main lava channel had reorganized and was nearly continuous to the ocean on the S side of the flow, expanding the south margin by several hundred meters (figure 431). Lava was also entering the ocean along a 4-km-long line of small entry points across the delta. Early that afternoon observers reported multiple overflows along both sides of the main lava channel in an area just W of Kapoho Crater; small brushfires were reported along the margins. Another flow lobe farther down the channel was moving NE from the main channel. The channel near Four Corners was mostly crusted over, and plumes from the ocean entry were significantly reduced. The dramatic difference in landscapes on the northern and southern sides of the fissure 8 lava channel was readily apparent during a 10 July overflight (figure 432). With dominant trade winds blowing heat and volcanic gases to the SW, the N side of the lava channel remained verdant, while vegetation on the S side was severely impacted and appeared brown and yellow.

Figure (see Caption) Figure 431. By 9 July 2018 the lower part of Kilauea's LERZ fissure 8 flow had reorganized and was nearly continuous to the ocean on the south side of the flow, expanding the south margin by several hundred meters. Dark red areas denote active flow expansion and shaded purple areas indicate lava flows erupted in 1840, 1955, 1960, and 2014-2015. Courtesy of HVO.
Figure (see Caption) Figure 432. During HVO's morning overflight on 10 July 2018, the dramatic difference in landscapes on the northern and southern sides of Kilauea's LERZ fissure 8 lava channel was readily apparent. With dominant trade winds blowing heat and volcanic gases to the SW, the N side of the lava channel remains verdant, while vegetation on the S side has been severely impacted and appears brown and yellow. The fissure 8 cone is obscured by a cloud of steam (top center), but a small speck of incandescence rises at the center. The width of the channel and levee in the narrowest place at lower left is about 500 m. Note houses and trees for scale. Courtesy of HVO.

A channel blockage just W of Kapoho Crater overnight on 10-11 July sent most of the channel S along the W edge of previous flows on the W side of the crater. By mid-morning this channelized ?a?a flow had advanced to within 0.5 km of the coast at Ahalanui Beach Park. A few houses were also threatened by overflows along the upper channel on 11 July (figure 433). The broad ocean entry area widened as a result and covered nearly 6 km by 12 July (figure 434).

Figure (see Caption) Figure 433. A pahoehoe flow fed by overflows from Kilauea's LERZ fissure 8 lava channel was active and threatening homes along Nohea Street in the Leilani Estates subdivision on 11 July 2018. Courtesy of HVO.
Figure (see Caption) Figure 434. An aerial view to the SW of the ocean entry at Kapoho from Kilauea's LERZ fissure 8 on 11 July 2018 shows Cape Kumukahi (with lighthouse) in the foreground surrounded by lava flows that formed in 1960. The northern edge of the new fissure 8 flow is close to the steam plume closest to the lighthouse. Kapoho Crater in the upper right is surrounded by new lava from fissure 8. See figure 431 for additional location details. Courtesy of HVO.

HVO first mentioned a connection between the lava levels in the upper channel of the fissure 8 flow and the collapse-explosion events at the summit on 12 July. They observed a rise in the lava level shortly after each collapse event at the summit for most of the rest of July. Overnight into 12 July, the diverted channelized ?a?a flow W of Kapoho Crater advanced to the ocean destroying the Kua O Ka La Charter School and Ahalanui Count Beach Park and established a robust ocean entry area (figure 435). Despite no visible surface connection to the fissure 8 channel, lava continued to stream out at several points on the 6-km-wide flow front into the ocean. A small island of lava also appeared offshore of the northernmost part of the ocean entry on 12 July (figure 436).

Figure (see Caption) Figure 435. The channel overflow during 9-10 July from Kilauea's LERZ fissure 8 flow created a new lobe that reached the ocean on 12 July 2018 destroying Ahalanui Park and the nearby charter school. The lava flow was also still entering the ocean at numerous points along the coast. The black and white area is the extent of the thermal map. Temperature in the image is displayed as gray-scale values, with the brightest pixels indicating the hottest areas. The map was constructed by stitching many overlapping oblique thermal images collected by a handheld camera during a helicopter overflight of the flow field. The base is a copyrighted color satellite image (used with permission) provided by Digital Globe. Courtesy of HVO.
Figure (see Caption) Figure 436. A small new island of lava from Kilauea's LERZ fissure 8 flow formed on the northernmost part of the ocean entry; it was visible during the morning overflight on 13 July 2018. HVO's field crew noticed the island was effusing lava similar to the lava streaming from the broad flow front along the coastline. The freshest lava in the delta has a silvery sheen and is adjacent to older flows. Courtesy of HVO.

Activity on the LERZ during 13-31 July 2018. As the southern margin of the flow continued to advance slowly south, it reached to within 1 km of the Isaac Hale Park on 14 July and within 750 m on 17 July. An increase in lava supply overnight into 18 July produced several channel overflows threatening homes on Nohea street and also additional overflows downstream on both sides of the channel. The overflows had stalled by mid-morning. South of Kapoho Crater, the surge produced an ?a?a flow that rode over the active southern flow that was still entering the ocean. The southern margin was 500 m from the boat ramp at Isaac Hale Park on 19 July (figure 437).

Figure (see Caption) Figure 437. The southern margin of Kilauea's LERZ fissure 8 flow was 500 m N of Isaac Hale Park on 19 July 2018. Active flow expansion is shown in dark red, shaded purple areas indicate lava flows erupted in 1840, 1955, 1960, and 2014-2015. Courtesy of HVO.

During the HVO morning overflight on 20 July scientists noted that the channel was incandescent along its entire length from the vent to the ocean entry (figure 438, top). The most vigorous ocean entry was located a few hundred meters NE of the southern flow boundary; a few small pahoehoe flows were also entering the ocean on either side of the channel's main entry point (figure 438, bottom). On 23 July there were overflows just NW of Kapoho Crater following a collapse event at the summit the previous evening. During the day, small breakouts along the edge of the lava flow in the Ahalanui area caused the flow to expand westward. The flow margin was about 175 m from the Pohoiki boat ramp in Isaac Hale Park by the end of 24 July, and the active ocean entry was still a few hundred meters to the E of the lava flow margin. The numerous ocean entry points were concentrated along the southern half of the 6-km-long delta (figure 439).

Figure (see Caption) Figure 438. HVO scientists noted that Kilauea's LERZ fissure 8 flow was incandescent all the way from the vent to the ocean the day before these 21 July 2018 images of the flow. Top: Fissure 8, source of the white gas plume in the distance, continued to erupt lava into the channel heading NE from the vent. Near Kapoho Crater (lower left), the channel turned S on the W side of the crater, sending lava toward the coast, where it entered the ocean in the Ahalanui area (bottom image). Channel overflows are visible in the lower right. Bottom: The most vigorous ocean entry of the fissure 8 flow was located a few hundred meters NE of the southern flow margin in the Ahalanui area. Courtesy of HVO.
Figure (see Caption) Figure 439. Kilauea's LERZ fissure 8 flow at 0600 on 24 July 2018. The dominant ocean entry points were on the section of coastline near Ahalanui and Pohoiki. The flow margin was about 175 m from the Pohoiki boat ramp in Isaac Hale Park by the end of 24 July. The black and white area is the extent of the thermal map. Temperature in the image is displayed as gray-scale values, with the brightest pixels indicating the hottest areas. The map was constructed by stitching many overlapping oblique images collected by a handheld thermal camera during a helicopter overflight of the flow field. The base is a copyrighted color satellite image (used with permission) provided by Digital Globe. Courtesy of HVO.

On 26 July, lava movement in the channel appeared sluggish and levels had dropped in the lower part of the channel compared to previous days. Pulses of lava were recorded every few minutes at the fissure 8 vent (figure 440). HVO suggested that overflows on 28 July may have resulted from a channel surge following a summit collapse event in the morning (figures 441 and 442). Lava was actively entering the ocean along a broad 2 km flow front centered near the former Ahalanui Beach Park, but the edge of the flow remained about 175 m from the Pohoiki boat ramp at Isaac Hale park for the rest of the month. There were a few breakouts to the W that were distant from the coast and not directly threatening Pohoiki. A more minor entry was building a pointed delta near the south edge of the flow. At 2202 on 29 July an earthquake on Kilauea's south flank was felt as far north as Hilo by a few people. The M 4.1 (NEIC) earthquake was weaker than recent summit earthquakes but it was felt more widely, possibly due to its greater depth of 7 km (compared with 2 km for summit earthquakes).

Figure (see Caption) Figure 440. Pulses of lava from Kilauea's LERZ fissure 8 vent occurred intermittently every few minutes on 26 July 2018. These photographs, taken over a period of about 4 minutes, showed the changes that occurred during these pulses. Initially, lava within the channel was almost out of sight. A pulse in the system then created a banked lava flow that threw spatter (fragments of molten lava) onto the channel margin. After the bottom photo was taken, the lava level again dropped nearly out of sight. Courtesy of HVO.
Figure (see Caption) Figure 441. Incandescent lava covering the 'a'a flow between Kilauea's LERZ fissure 8 lava channel and Kapoho Crater (lower left) is from an overflow that may have resulted from a channel surge following the morning summit collapse event on 28 July 2018. The active ocean entry can be seen in the far distance (upper left). Courtesy of HVO.
Figure (see Caption) Figure 442. Overflows from Kilauea's LERZ fissure 8 lava channel on 28 July 2018 may have ignited this fire (producing dark brown smoke) on Halekamahina, an older cinder-and-spatter cone to the west of Kapoho Crater. Courtesy of HVO.

Activity at Halema'uma'u during July and August 2018. Periodic collapse explosion events with energy equivalents to a M 5.2 or 5.3 earthquake continued on a near daily basis throughout July at Halema'uma'u, enlarging the crater floor inside the Kilauea caldera and creating large down-dropped blocks and fractures across the caldera (figure 443). Ash-poor plumes occasionally rose a few hundred meters above the caldera floor. Summit seismicity would drop dramatically after each explosion and then gradually increase to 25-35 earthquakes (mostly in the M 2-3 range) prior to the next collapse explosion. The periodicity of the explosion events was consistent until 24 July when a gap of 53 hours occurred until the next event on 26 July, the longest break since early June.

Figure (see Caption) Figure 443. The WorldView-3 satellite acquired this view of Kilauea's summit on 3 July 2018. Despite a few clouds, the area of heaviest fractures in the caldera is clear. Views into the expanding Halema'uma'u crater revealed a pit floored by rubble. The now-evacuated Jaggar Museum and Hawaii Volcano Observatory (HVO) is labelled on the NW caldera rim. Remains of the Crater Rim Drive are visible along the bottom of the image; the overlook parking lot was completely removed by the growing S rim of the crater. Courtesy of HVO.

Images of the caldera on 13 July and 1 August demonstrated the unprecedented magnitude of change that affected Kilauea during the month (figures 444 and 445). The last collapse explosion event, at 1155 HST on 2 August, was reported as a M 5.4 seismic event (figure 446). Seismicity increased after the event as it had after previous events, but after reaching about 30 earthquakes per hour on 4 August, seismicity decreased without a collapse-explosion event occurring. The rate of deformation at the summit as measured by tiltmeter and GPS was also much reduced after 4 August.

Figure (see Caption) Figure 444. USGS scientists acquired this aerial photo of Halema'uma'u and part of the Kilauea caldera floor during a helicopter overflight of the summit on 13 July 2018. In the lower third of the image are the buildings that housed the USGS Hawaiian Volcano Observatory and Hawai'i Volcanoes National Park's Jaggar Museum, the museum parking area, and a section of the Park's Crater Rim Drive. Although recent summit explosions had produced little ash, the gray landscape was a result of multiple thin layers of ash that blanketed the summit area during the ongoing explosions. Courtesy of HVO.
Figure (see Caption) Figure 445. This aerial view of Kilauea's summit taken on 1 August 2018 shows the continued growth of the crater. Compare with the previous image (figure 444) taken a few weeks earlier; a section of Hawai'i Volcanoes National Park's Crater Rim Drive and the road leading to the Kilauea Overlook parking area are visible at lower right. HVO, Jaggar Museum, and the museum parking area are visible at far middle right. On the far rim of the caldera, layers that are downdropped significantly more than on 13 July are clearly exposed. On the caldera rim (upper right) light-colored ash deposits from explosions in May were stirred up by brisk winds, creating a dust cloud dispersing downwind. Courtesy of HVO.
Figure (see Caption) Figure 446. Rockfalls along Kilauea's caldera walls were common during summit collapse events. This image, taken just after the 1155 HST collapse on 2 August 2018, shows dust rising from rockfalls along Uekahuna Bluff. This was the last collapse explosion event at Halema'uma'u during the current eruption.

Activity on the Lower East Rift Zone during August 2018. Activity continued essentially unchanged on the fissure 8 flow during 1-4 August, although there were reports of somewhat lower lava levels in the channel. Multiple overflows were reported late on 2 August, one of which started a small fire near Noni Farms Road. Other overflows were concentrated in the wide lava field W and SSW of Kapoho Crater, also igniting small fires in adjacent vegetation (figure 447). The south edge of the flow did not advance any closer to the boat ramp in Isaac Hale Park (figure 448). The channel was incandescent at its surface to approximately 4.5 km from the vent (figure 449); lava was still flowing farther beneath the crust to the vicinity of Kapoho Crater where it was seeping out of both sides of the channel. The lower lava channel adjacent to Kapoho Crater shifted W about 0.25 km early on 4 August and was feeding lava into the SW sector of the lower flow field.

Figure (see Caption) Figure 447. Overflows formed a pool of lava at the channel bend just west of Kapoho Crater (vegetated cone at left) on 1 and 2 August 2018 as seen in this view toward the SE on 1 August 2018 at Kilauea's LERZ fissure 8 flow. Courtesy of HVO.
Figure (see Caption) Figure 448. During the morning overflight on 2 August 2018, HVO geologists observed the ocean entry laze plume was being blown offshore, allowing this fairly clear view (looking NE) of the Pohoiki boat ramp at Isaac Hale Beach Park (structure, lower left). Incandescent spots of lava can be seen within the flow field beyond the boat ramp. HVO geologists also observed some lava escaping on or near the western flow margin. The southern margin of the flow front was still more than 100 m from the boat ramp. Courtesy of HVO.
Figure (see Caption) Figure 449. Kilauea's LERZ fissure 8 channel was incandescent for about 4.5 km from the vent in the early morning on 2 August 2018. Downstream of the vent, the channel split to form a "braided" section in the lava channel, and the north (right) arm of the braided section appeared to be partially abandoned. Lava was still visible in part of the northern braid, but the lower section was only weakly incandescent. The lava within the channel generally appeared to be at a lower level than in previous days. Courtesy of HVO.

The NE half of the flow's ocean-front was inactive with no evidence of effusion into the ocean by 4 August. Field observations and UAS overflight images indicated a reduced output of lava from fissure 8 during the day on 4 August. During the morning helicopter overflight on 5 August geologists confirmed a significant reduction in lava output from fissure 8 that began the previous day. HVO field geologists observed low levels of fountaining within the fissure 8 spatter cone and largely crusted lava in the spillway and channel system downstream (figure 450). The lava level in the channel near Kapoho Crater had dropped substantially on 5 August. (figure 451).

Figure (see Caption) Figure 450. HVO field geologists observed low levels of fountaining within Kilauea's LERZ fissure 8 spatter cone and largely crusted lava in the spillway and channel system downstream (left) during the morning overflight on 5 August 2018. The inner walls of the cone and lava surface were exposed and a dark crust had formed on the lava with the spillway. Courtesy of HVO.
Figure (see Caption) Figure 451. Incandescent lava remained visible in a section of Kilauea's LERZ fissure 8 channel W of Kapoho Crater (just visible at far left) on 5 August 2018 after a large drop in the flow rate during the previous day. This view is looking S toward the ocean; the laze plume rising from the ocean entry can be seen in the far distance. Courtesy of HVO.

Lava continued to slowly enter the ocean along a broad flow front generally near Pohoiki, but remained about 70 m SE of the boat ramp on 5 August. The next morning's overflight crew saw a weak to moderately active bubbling lava lake within the fissure 8 cone, a weak gas plume, and a completely crusted lava channel. Later in the morning ground crews found the upper channel largely devoid of lava, confirming that the channel was empty to at least the vicinity of Kapoho Crater where a short section of spiny active lava in a channel was present. There were small active breakouts near the coast on the Kapoho Bay and Ahalanui lobes, but the laze plume was greatly diminished. Active lava was close to the Pohoiki boat ramp but had not advanced significantly toward it. A major change in the heat flow recorded by satellite instruments was apparent by the end of the first week in August (figure 452). The MIROVA signal, which had shown a persistent high-intensity thermal signal for several years, recorded an abrupt drop in activity early in May that coincided with the opening of the fissures on the LERZ, and the dropping of the lava lake at Halema'uma'u. The lower levels of heat flow fluctuated from May through early August, and then ended abruptly after the first week of August.

Figure (see Caption) Figure 452. The MIROVA plot of thermal activity at Kilauea changed abruptly after the first week of August 2018 after many years of registering high heat flow from numerous sources at Kilauea. Compare with figure 310 (BGVN 43:03) and figure 290 (BGVN 42:11). Courtesy of MIROVA.

On 7 August the surface of the lava lake was about 5-10 m below the spillway entrance (figure 453) and the upper part of the channel was crusted over (figure 454). There were a diminishing number of small active flow points near the coast on the Kapoho Bay and Ahalanui lobes. By 9 August the overflight crew observed a crusted lava pond deep inside the steaming cone at a level significantly below that seen on 7 August. Up-rift of fissure 8, fissures 9, 10, and 24, and down-rift fissures 13, 23, 3, 21 and 7, continued to steam, but no new activity was observed. Lava was streaming at several points along the Kapoho Bay and Ahalanui coastline, causing wispy laze plumes on 10 August, and only minor areas of incandescence were visible in the lava pond inside the fissure 8 cone (figure 455). The next day the overflight crew noted two small ponds of lava inside the cone; one was crusted over and stagnant, and the other was incandescent and sluggishly convecting. A gas plumed billowed up from fissure 8 and low-level steaming was intermittent from a few of the otherwise inactive fissures.

Figure (see Caption) Figure 453. On 7 August 2018 Hawaii County's Civil Air Patrol got a closer view of Kilauea's LERZ fissure 8 cone and the small pond of lava within the vent. The lava was below the level of the spillway that fed the fissure 8 channel from May 27 to August 4, 2018. Courtesy of HVO.
Figure (see Caption) Figure 454. Lava in Kilauea's LERZ fissure 8 channel near the vent was crusted over by 7 August 2018. Fissure 8 and other inactive fissures were steaming in the background. Courtesy of HVO.
Figure (see Caption) Figure 455. The Unmanned Aircraft Systems (UAS) team flew over Kilauea's LERZ fissure 8 on 10 August 2018 and provided this aerial view into the cinder cone. The pond of lava within the vent had receded significantly from a few days earlier (see figure 453), and was about 40 m below the highest point on the cone's rim. Courtesy of HVO.

By 12 August the only incandescent lava visible on the flow field was that entering the ocean between Kapoho Bay and the Ahalanui area. Fresh black sand, created as molten lava is chilled and shattered by the surf, was being transported SW by longshore currents and accumulating in the Pohoiki small boat harbor (figure 456). A sandbar blocked the entrance to the harbor the following day. The westernmost ocean entry of lava was about 1 km from the harbor on 13 August.

Figure (see Caption) Figure 456. The Pohoiki boat ramp at Isaac Hale Park at Kilauea on 11 August 2018 was blocked in by a black sand bar forming from the longshore currents carrying material SW from the edge of the fissure 8 flow delta even though the southern-most flow margin had not advanced significantly toward the Pohoiki boat ramp. Geologists observed several small lava streams trickling into the sea along the southern portion of the lava delta, producing weak laze plumes. Courtesy of HVO.

By 14 August only a small, crusted over pond of lava deep inside the fissure 8 cone and a few scattered ocean entries were active; there had been no new lava actively flowing in the lower East Rift Zone since 6 August. No collapse events had occurred at the summit since 2 August. Earthquake and deformation data showed no net changes suggesting movement of subsurface magma or pressurization. Sulfur dioxide emission rates at both the summit and LERZ were drastically reduced; the combined rate was lower than at any time since late 2007. As a result of the reduced activity, HVO lowered the Alert Level for ground-based hazards from WARNING to WATCH on 17 August. By 18 August, the only incandescence visible was at the coast near Ahalanui, where there were a few ocean entries and minor laze plumes (figure 457).

Figure (see Caption) Figure 457. Lava was still entering the ocean at scattered entry points, mainly near Ahalanui (shown here), but also at Kapoho from Kilauea's LERZ fissure 8 flow on 17 August 2018 even though no new lava had entered the system since 6 August. Courtesy of HVO.

Gas jets were throwing spatter, fragments of glassy lava, from small incandescent areas deep within the fissure 8 cone on 20 August (figure 458). The last day that the small lava pond deep within the fissure 8 cone was visible during an overflight was on 25 August; a few ocean entries were still active. A single small lava stream from the Kapoho Bay lobe was the only moving lava noted during an HVO overflight on 27 August (figure 459). Two days later, on 29 August, no lava was entering the ocean.

Figure (see Caption) Figure 458. Gas jets were throwing spatter (fragments of glassy lava) from small incandescent areas deep within Kilauea's LERZ fissure 8 cone on 20 August 2018. The spatter is the light gray material around the two incandescent points at the center. Courtesy of HVO.
Figure (see Caption) Figure 459. Only one small ocean entry near Ahalanui was visible on 27 August 2018 at Kilauea's LERZ fissure 8 flow delta. Courtesy of HVO.

The fissure 8 lava flow entering the ocean had built a lava delta over 354 hectares (875 acres) in size by the end of August 2018 (figure 460). A sand bar, comprised of black sand and lava fragments carried by longshore currents from the lava delta, completely blocked the boat ramp at Isaac Hale Beach Park on 31 August 2018 (figure 461).

Figure (see Caption) Figure 460. Kilauea's LERZ fissure 8 lava flows had built a lava delta over 354 hectares (875 acres) in size, but no active ocean entries were observed by HVO geologists on 30 August 2018. View is to the SW. Courtesy of HVO.
Figure (see Caption) Figure 461. A sand bar, comprised of black sand and lava fragments carried by longshore currents from Kilauea's LERZ fissure 8 lava delta, blocked access to the boat ramp at Isaac Hale Beach Park on 31 August 2018. The white cement ramp leads down to a small pool of brackish water surrounded by black sand. The S edge of the ocean-entry delta is at lower left. Courtesy of HVO.

Activity during September 2018. A brief resurgence of minor activity during the first few days of September was the last observed from LERZ fissure 8. Incandescence was noted in the fissure 8 cone on 1 September. There was a persistent spot of spattering, and lava slowly covered the 15 x 65 m crater floor by evening (figure 462). Webcam views showed weak incandescence occasionally reflected on the eastern spillway wall from the crater overnight, suggesting that the lava in the crater remained active. A UAS oblique image the next afternoon showed that the new lava was mostly confined to the crater floor within the cone, although a small amount extended a short distance into the spillway (figure 463). Weak lava activity continued inside the fissure 8 cone for several days; lava filled the small footprint-shaped crater inside the cone as sluggish pahoehoe flows crept across the crater floor but did not flow down the spillway. A small spatter cone ejecting material every few seconds was noted on the floor of the crater on 4 September; observations the next day showed that it had reached an estimated height of around 3-4 m (figure 464). Only a small amount of incandescence was visible overnight on 5-6 September at fissure 8.

Figure (see Caption) Figure 462. An Unmanned Aircraft Systems overflight of Kilauea's LERZ fissure 8 on 1 September 2018 showed incandescence within the cinder cone, with reports that lava had covered the 15 x 65 m foot-print shaped crater floor by evening. Courtesy of HVO.
Figure (see Caption) Figure 463. This 2 September 2018 UAS oblique image of Kilauea's LERZ fissure 8 cone showed that the new lava was mostly confined to the crater floor within the cone, although a small amount extended a short distance into the spillway. HVO geologists noted that the lava activity was at a low level by the evening, with only minimal (if any) incandescence emanating from the cone. Gas emissions from the vent were nearly nonexistent. Courtesy of HVO.
Figure (see Caption) Figure 464. A close-up view of the small cone that formed on the floor of the crater within Kilauea's LERZ fissure 8 on 5 September 2018. Bits of spatter emitted from the cone every few seconds had built it up to an estimated height of around 3-4 m. See video of spatter on HVO website. Courtesy of HVO.

 Pu'u O'o crater experienced a series of small collapses on 8 September. These produced episodes of visible brown plumes throughout the day and generated small tilt offsets and seismic energy recorded by nearby geophysical instruments. The collapses had no discernable effect on other parts of the rift and continued for several days at a decreasing frequency. Minor amounts of incandescence and fuming continued to be observed on 9 September at the fissure 8 cone. A small collapse pit formed in the cone on 10 September exposing hot material underneath and producing a short-lived increase in incandescence. Minor fuming was visible the next day from the small spatter cone. Incandescence at the collapse pit decreased over the next few days, but a glowing spot just west of the pit appeared on 11 September and grew slowly for a few days before diminishing. HVO interpreted it to be a layer of incandescence exposed in the slowly subsiding lava surface within the fissure 8 cone. Minimal incandescence was visible overnight on 14-15 September. After this, only minor fuming was visible during the day; incandescence was no longer observed for the remainder of the month.

HVO determined that the 2018 Lower East Rift Zone eruptive episode ended on 5 September 2018, bringing with it an end to the lava lake at Halema'uma'u crater and the eruptive activity that had been continuous at either Pu'u O'o or Halema'uma'u since 3 January 1983; a period of more than 36 years. Satellite imagery from early September 2018 demonstrated some of the impact of this last eruptive episode on the region around Kilauea's lower East Rift Zone since the first fissure opened at the beginning of May 2018 (figures 465 and 466).

Figure (see Caption) Figure 465. This comparison shows satellite images of Leilani Estates subdivision before (2014) and after the LERZ eruptive episode of May-September 2018 at Kilauea. The image on the right, collected in early September 2018, shows that the eastern portion of the subdivision was covered by new lava. The fissure 8 lava channel runs NE from the fissure 8 cone at the start of the channel. Note also the brown areas of dead vegetation S of the lava flow. Highway 130 runs N-S along the left side of the images. Courtesy of HVO.
Figure (see Caption) Figure 466. This comparison of satellite imagery from before (2014) and after the May-September 2018 LERZ eruptive episode at Kilauea shows the area of Kapoho before and after the event. Kapoho Crater is in the left portion of the image. Lava filled much of the crater, including the small nested crater that contained Green Lake. The Kapoho Beach Lots subdivision is on the right side of the image, north of Kapoho Bay, and was completely covered by the fissure 8 lava flow. Vacationland Hawai'i, in the lower right corner of the image, was also completely covered, along with the adjacent tide pools. Kapoho Farm Lots, near the center of the image, is also beneath the flow. Courtesy of HVO.

Geologic Background. Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.

Information Contacts: Hawaiian Volcano Observatory (HVO), U.S. Geological Survey, PO Box 51, Hawai'i National Park, HI 96718, USA (URL: http://hvo.wr.usgs.gov/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).


Planchon-Peteroa (Chile) — January 2019 Citation iconCite this Report

Planchon-Peteroa

Chile

35.223°S, 70.568°W; summit elev. 3977 m

All times are local (unless otherwise noted)


New eruption begins in September 2018; continuous ash emissions and intermittent explosions December 2018-February 2019

Planchón-Peteroa, a large basaltic to dacitic volcanic complex, lies on the remote Chile-Argentina border roughly 200 km S of Santiago, Chile. Its intermittent eruptive history has been characterized by short-lived explosive events with gas and ash plumes from active craters around the Volcán Peteroa area (figure 10). The most recent eruption, from February-June 2011, was a series of sporadic ash and gas plumes which rose as high as 5.5 km altitude and produced ashfall as far as 70 km away (BGVN 38:11). After seven years of little surface activity, a new series of ash emissions and explosive activity began in September 2018; a major seismic swarm in 2016 did not result in surface activity. Information for this report, covering through February 2019, was provided primarily by Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS) and the Buenos Aires Volcanic Ash Advisory Center (VAAC).

Figure (see Caption) Figure 10. The Planchón-Peteroa volcanic complex was last active from February to June 2011, as seen in this image taken on 23 April 2011 from Santa Cruz de Colchagua, located 100 km NW. Image copyright by Andres Figueroa Z (HBOC), courtesy of Cumbres y Montañas de O'Higgins and used with permission from the photographer.

Planchón-Peteroa remained quiet during 2014 and 2015. A significant seismic swarm during 2016 led SERNAGEOMIN to raise the alert level for nearly the entire year, although no surface eruptive activity took place. A smaller seismic event in 2017 also did not include surface activity. Increased emissions that included particulate material were first reported in September 2018; the first explosions with ash took place in early November 2018. Persistent emissions with dense plumes of ash began in mid-December and continued through February 2019; intermittent pulses and explosions during that time coincided with increased seismic and thermal activity.

Activity during 2014-2015. Background levels of volcano-tectonic (VT) and long-period (LP) earthquakes were reported by SERNAGEOMIN throughout 2014 and 2015. A single seismic event greater than M 3.0 was reported on 11 May 2014, located within 1 km of the crater. Inclinometer, SO2, and thermal data all indicated no significant changes during the period. During March-July 2015 sporadic fumaroles were observed rising less than 200 m from the active crater.

Activity during 2016. An increase in LP seismic events from a few to several hundred per month was noted by SERNAGEOMIN beginning in January 2016. As a result, they increased the Alert Level of the volcano from Green to Yellow on 22 January. The webcam revealed degassing of mainly water vapor reaching close to 200 m above the active crater. During the first two weeks of February 2016 the number of LP events increased ten-fold from 328 in January to 3,634; all the events were smaller than M 1.1. The rate of LP seismicity increased further during the last two weeks of February to 7,301 events, and the steam plumes reached 400 m above the crater. LP seismicity remained high during March with 9,627 measured events; similar numbers of events were sustained through May 2016 (figure 11).

Figure (see Caption) Figure 11. Seismicity at Planchón-Peteroa from October 2015 through February 2019. Two periods of increased seismicity were detected prior to 2018, although the only observed changes in surface activity were slight increases in the height and intensity of the steam plumes. The first event, from January 2016-January 2017 included periods with very high numbers of both VT and LP events at different times during the year. The second period of increased seismicity was from July to December 2017; the numbers of VT events were elevated briefly in July, but the LP event numbers remained elevated through December. The number of LP seismic events began increasing again in July 2018; the first particulate emissions were noted in September, and significant explosions with ash began in November 2018. Note two vertical axes on graph, the left represents numbers of LP seismic events in orange, the right represents the number of VT seismic events in blue. Data courtesy of SERNAGEOMIN.

LP seismicity decreased substantially to only 470 events during the first two weeks of June 2016, leading SERNAGEOMIN to reduce the Alert Level to Green. However, during the second half of June a spike in the VT events from 8 during the first half of the month to 944 caused authorities to raise the Alert Level back to Yellow. This increase in VT seismic events was also accompanied by an increase in the number and spectral frequency of the LP events. They changed from having dominant frequencies between 1.9 and 2 Hz to 4-5 Hz, with a location that moved closer to the crater zone than before, and occurred at depths of around 1.5 km. On 28 June a M 3.4 VT event occurred 4.3 km NNE of the crater at a depth of 4.8 km. LP events numbered between 2,100 and 4,100 events monthly during June-September.

VT seismic events increased to their highest levels of 2016 during July (4,609 events) before beginning a gradual decline through the end of the year, ending with about 700 events in December (figure 11). A strong steam plume rose 550 m above the crater on 4 July 2016 and was accompanied by 400 VT events. The number of LP events increased significantly for the second time during the year beginning in October and remained over 14,000 events through January 2017. Three seismic events with local magnitude (ML) greater than M 3.0 were recorded on 7, 12, and 16 October; the locations of the events were approximately 3 km NNW at an average depth of 5 km. A M 3.4 event was recorded on 19 November. Low-level steam plumes did not rise more than 200 m above the crater for the remainder of the year. SERNAGEOMIN installed two new seismic stations, on 29 November and 15 December 2016.

Activity during 2017. Levels of both VT and LP seismic events declined during January-May 2017. A M 3.5 VT earthquake on 19 February was located 3.7 km NNW of the crater and 4.5 km deep. On 28 March, a M 3.6 event occurred in a similar location. Steam plumes occasionally rose as high as 200 m during the period. SERNAGEOMIN lowered the Alert Level to Green on 17 May 2017 based on the gradual decrease in seismicity to baseline levels accompanied by little to no surface activity.

A seismic swarm of 39 events on 15 June was located 14 km SE and 8-10 km deep. VT seismic events during the first half of July 2017 were located 4-7 km deep under the summit craters and included a M 4.0 event on 8 July. An increase in both VT and LP seismicity in early July led SERNAGEOMIN to raise the Alert Level to Yellow on 10 July (figure 11). The monthly number of VT events dropped below 100 in August and remained low for the rest of the year. A M 3.5 VT event was reported on 5 November, located 6.5 km E and 6 km deep. On 14 November seismometers recorded a 30-minute tremor event. A brief increase in degassing began on 23 November; steam plumes reached 600 m the next day but returned to less than 150 m by the end of the month. SERNAGEOMIN lowered the Alert Level to Green in mid-December 2017 as a result of decreased surface and seismic activity.

Activity during 2018. Low levels of surface and seismic activity persisted into early June 2018. Steam plumes rose no more than 500 m above the crater, numbers of VT events remained low, and the numbers of LP events decreased steadily. In mid-May the amplitude of continuous tremor events began to increase. The frequency of the tremor events had been around 1-2 Hz earlier in the year, but beginning on 21 June they increased to around 5 Hz; this was accompanied by an oscillating amplitude seismic signal referred to as "banded tremor." SERNAGEOMIN interpreted the increase in amplitude and the banded tremor as an indication of increased heat in the system, and as a result raised the Alert Level to Yellow on 6 July 2018. The number of LP seismic events increased steadily beginning in June, along with the amplitude of the seismic events, although there were no apparent changes in surface activity (figure 12). Weak thermal anomalies were first detected in satellite data in mid-August. SERNAGEOMIN noted that the locations of the seismic events were migrating closer to the crater, and the depths were shallowing from June to August 2018.

Figure (see Caption) Figure 12. No surface activity was seen at Planchón-Peteroa on 11 July 2018; SERNAGEOMIN had raised the Alert Level to Yellow from Green a few days earlier due to increased seismicity. Photo from SERNAGEOMIN webcam located about 10 km W. Courtesy of SERNAGEOMIN.

SERNAGEOMIN first reported the presence of particulate material in the persistent degassing from the active crater on 21 September 2018, noting that the degassing steam turned "slightly gray" but plumes did not rise more than 600 m above the crater. Mostly-white emissions continued during October, although they specifically mentioned emissions of low-intensity particulate material observed during 13-15 October, rising 600 m above the crater. Three MIROVA thermal alerts appeared on 14 October, the first over 1 MW to be recorded (figure 13). During the second half of October, SERNAGEOMIN noted persistent mostly-white degassing in the webcam that rose up to 700 m above the crater. They also reported webcam images in the second half of October that showed ash emissions rising a short distance above the crater, generally drifting SE, although they did not specify certain dates

Figure (see Caption) Figure 13. A graph of satellite thermal data by the MIROVA project from 8 April 2018 through February 2019 indicates that thermal anomalies were first reported in mid-October 2018; this corresponds with SERNAGEOMIN's observations of emissions containing significant quantities of particular material. Increased thermal activity during December 2018 and February 2019 corresponded with reports of increased explosive activity and ash emissions. Courtesy of MIROVA.

SERNAGEOMIN reported an explosion with an ash emission visible in the webcam on 7 November 2018; they reported the plume height at about 1,000 m above the crater (figure 14). The Buenos Aires VAAC reported the ash plume drifting SE visible in satellite imagery at 4.3 km altitude. Low-altitude ash emissions were observed in the webcam multiple additional times during November. In a special report issued on 7 December, SERNAGEOMIN reported a 1,300-m-high ash emission that dispersed ESE. The Buenos Aires VAAC reported continuous ash emissions beginning on 14 December that lasted through the rest of the month (figure 15).

Figure (see Caption) Figure 14. A webcam located a few kilometers W of Peteroa captured these images of the ash plume released on 7 November 2018. Courtesy of SERNAGEOMIN.
Figure (see Caption) Figure 15. An ash cloud from Planchón-Peteroa was photographed from Paso Vergara on the Chile/Argentina border 5 km NE on 14 December 2018; the ash dispersed to the SE. Courtesy of Volcanes de Chile and SEGEMAR (Servicio Geológico Minero Argentino), copyright by Gendarmeria Nacional Argentina.

Plumes generally drifted SE at 4.6-4.9 km altitude during December, with occasional stronger puffs that were reported as high as 5.8 km altitude (figure 16). On 16 December the webcam recorded high-intensity pulsating ash emissions that drifted 20 km SE. Incandescence was visible around the crater that night. Webcam images showed dark gray plumes during the second half of December, suggesting a high concentration of ash; the pulsating nature of the emissions was observed in the webcam again during 24-27 December, reaching 1,600 m above the crater. Multiple thermal alerts were reported during the second half of the month.

Figure (see Caption) Figure 16. Volcanes de Chile annotated this 15 December 2018 Sentinel-2 satellite image showing the ash plume from Planchón-Peteroa drifting SE into Argentina. Courtesy of Sentinel Hub and Volcanes de Chile.

Activity during January-February 2019. Dense ash plumes were reported daily during January and February 2019 by both SERNAGEOMIN and the Buenos Aires VAAC; plumes heights were generally between 400 m and 1 km above the active crater (figure 17). Higher plumes that reached 2 km above the crater and drifted E were reported on 1 and 3 February (figure 18). SERNAGEOMIN noted that the first of these events was accompanied by an increase in very low frequency seismic activity (VLP).

Figure (see Caption) Figure 17. Dense ash plumes drifted SE from Planchón-Peteroa on 4 January 2019 as seen in this false-color Sentinel-2B satellite image. Courtesy of Sentinel Hub and Volcanes de Chile.
Figure (see Caption) Figure 18. Volcanes de Chile captured this image of a dense ash plume drifting SE over Argentina from the SERNAGEOMIN webcam located about 10 km W of Planchón-Peteroa on 3 February 2018. Courtesy of Volcanes de Chile and SERNAGEOMIN.

Satellite-based SO2 instruments also detected a significant gas plume on 3 February (figure 19). SERNAGEOMIN reported a tremor signal on 14 February 2019 associated with a dense ash plume that rose to 2 km above the summit and drifted NE. Webcam images during the second half of February showed constant degassing; gray plumes drifted mostly SE about 2 km above the summit (figure 20).

Figure (see Caption) Figure 19. The TROPOMI instrument on the Sentinel-5P satellite recorded significant SO2 plumes drifting both E and W of Planchón-Peteroa on 3 February 2019; SERNAGEOMIN reported dense ash emissions the same day. Courtesy of NASA Goddard Space Flight Center.
Figure (see Caption) Figure 20. Explosive activity at Planchón-Peteroa was recorded in Paso Vergara on the Chile/Argentina border 5 km NE on 20 February 2019 at the SEGEMAR CNEA webcam. Courtesy of SEGEMAR (Servicio Geológico Minero Argentino) and Felipe Aguilera Volcanes.

Geologic Background. Planchón-Peteroa is an elongated complex volcano along the Chile-Argentina border with several overlapping calderas. Activity began in the Pleistocene with construction of the basaltic-andesite to dacitic Volcán Azufre, followed by formation of basaltic and basaltic-andesite Volcán Planchón, 6 km to the north. About 11,500 years ago, much of Azufre and part of Planchón collapsed, forming the massive Río Teno debris avalanche, which traveled 95 km to reach Chile's Central Valley. Subsequently, Volcán Planchón II was formed. The youngest volcano, andesitic and basaltic-andesite Volcán Peteroa, consists of scattered vents between Azufre and Planchón. Peteroa has been active into historical time and contains a small steaming crater lake. Historical eruptions from the complex have been dominantly explosive, although lava flows were erupted in 1837 and 1937.

Information Contacts: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Servicio Geológico Minero Argentino (SEGEMAR), Av. General Paz 5445 (colectora), Parque Tecnológico Miguelete, Edificio 14 y Edificio 25, San Martín (B1650 WAB) (URL: http://www.segemar.gov.ar/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Cumbres y Montañas de O'Higgins (URL: https://www.facebook.com/cymohiggins/); Volcanes de Chile (URL: https://www.volcanesdechile.net/, Twitter: @volcanesdechile); Felipe Aguilera Volcanes (Twitter: @FelipeVolcanes, URL: https://twitter.com/FelipeVolcanes).


Poas (Costa Rica) — January 2019 Citation iconCite this Report

Poas

Costa Rica

10.2°N, 84.233°W; summit elev. 2708 m

All times are local (unless otherwise noted)


Frequent changes at the crater lake throughout 2018

After an eruption in April 2017, the hot acidic lake of Poás volcano has been in a state of frequent change, with a fluctuating or absent crater lake and other crater changes. During 2018 low-level activity was dominated by hydrothermal vents and degassing. The crater lake was variable, with changes in water level and complete drying of the lake several times. Seismicity was variable with some periods of increased seismicity, deformation was variable but slight, and gas levels fluctuated through the year (figure 120).

Figure (see Caption) Figure 120. Typical situation in the Poás crater and gas data from 2018. Left: The bottom of the dry crater in March 2018 (top) and hydrothermal activity at the bottom of the crater in May 2018 (bottom). Right: Time series graphs showing the maximum concentration of SO2, ratio of SO2/CO2, and the ratio of H2S/SO2 measured at the Poás volcano by the permanent MultiGAS station. The variations are associated with the presence of the lake and with seismicity. Courtesy of OVSICORI-UNA (2018 annual bulletin).

Hydrothermal activity took place during January, with associated low-level gas emissions, and seismicity that reduced later in the month. At the beginning of January the crater lake was absent. After an increase in hydrothermal activity, the lake returned between 18-20 January (figure 121). The lake was measured to be 54°C on 22 January (on the eastern edge) and had a milky blue color with abundant degassing. Temperatures at actively degassing vents reached 97°C. Fumaroles with abundant yellow sulfur deposits were measured to be 160°C (figure 122).

Figure (see Caption) Figure 121. Changes to the Poás crater lake from January through March 2018. The level of water in the crater varies through time and the lake drained in January and March. Images courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 122. Active fumaroles within the Poás crater, east of the lake. Yellow sulfur deposits and active degassing are visible. The fumaroles had a temperature of 160°C on 22 January 2018 when this photograph was taken. Courtesy of OVSICORI-UNA (22 January 2018 field report).

During February, activity remained low with fluctuating levels of CO2, SO2, and seismicity; the level of the lake also fluctuated. Activity remained shallow and related to the hydrothermal system with no magmatic activity. During March the seismicity decreased, coinciding with the disappearance of the crater lake during the March-May dry season. During April there was no change observed at the crater, and gas and seismicity continued to fluctuate within normal levels. Background activity and normal fluctuations continued through May until a phreatic (steam) eruption occurred on 25 May, producing a small gray plume and a larger white steam-and-gas plume (figure 123).

Figure (see Caption) Figure 123. A phreatic (steam) explosion on 25 May 2018 at the active Poás crater. Courtesy of OVSICORI-UNA (20 December 2018 report).

In June there was an increase in activity on the crater floor with increased submarine degassing and an increase in the lake water level. A high flow of SO2 (approximately 500 tons per day) was measured on 22 June. The measured level of SO2 was higher on 27 June, at 1,500 tons per day.

Gas emissions, deformation, and seismicity continued with fluctuations through July and August, with a decrease in SO2 around 30 July. Underwater fumaroles continued to be active. A milky-blue crater lake was present throughout this time (figure 124). During September, seismicity was described as highly variable and the crater lake was present (figure 125). Increased seismicity around 8 October coincided with slight inflation at the surface with an increase in activity through to 16 October. Gas emissions remained variable throughout September and October. A slight increase in seismicity occurred in early November and declined again by 19 November, with all other activity variable and within normal levels.

Figure (see Caption) Figure 124. The Caliente crater at Poás with a blue crater lake on 28 August 2018. Courtesy of Costa Rica Gobierno del Bicentenario.
Figure (see Caption) Figure 125. The partially-flooded Poás crater with a blue 38°C lake on 14 September 2018. The black arrow points to convection in the water from a flooded vent, with the insert photo showing a vent on the dry crater floor on 4 September 2017. Courtesy of OVSICORI-UNA (14 September 2018 report).

During December phreatic activity was observed at hydrothermal vents on the 19th (four events) and 20th (three events) that ejected water-saturated material up to 30 m above the vent accompanied by strong degassing and steam plumes. On 20 December it was observed that the lake level had dropped by 1 m and the lake was divided into two bodies of water, Boca A and Boca C. There were also changes in the crater lake color. Starting at the beginning of the month, the lake progressively changed from blue to green, especially visible on 8 December (figures 126, 127, and 128).

Figure (see Caption) Figure 126. Photos of the Poás crater lake showing the nearly-dry lakebed on 31 May, a blue lake on 7 July and 1 August, and a green lake on 6 December 2018. The change in the color of the water is due to the chemical composition of the lake including silica, iron, and sulfur, reflecting different wavelengths of light. Courtesy of OVSICORI-UNA.
Figure (see Caption) Figure 127. A view of the green crater lake with reduced water levels at Poás on 13 December 2018. Photo by Federico Chavarría-Kopper courtesy of OVSICORI-UNA.
Figure (see Caption) Figure 128. The changing crater lake of Poás volcano in December 2018. In one month the crater had a turquoise lake, a green lake, and was dry with no lake. Images courtesy of Sentinel Hub Playground.

Geologic Background. The broad, well-vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano, which is one of Costa Rica's most prominent natural landmarks, are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the 2708-m-high complex stratovolcano extends to the lower northern flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, is cold and clear and last erupted about 7500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world's most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since the first historical eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water.

Information Contacts: Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica (URL: http://www.ovsicori.una.ac.cr/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Costa Rica Gobierno del Bicentenario, Official Website - Presidency of the Republic of Costa Rica, Zapote, San José, Costa Rica (URL: https://presidencia.go.cr/comunicados/2018/08/29-de-agosto-presidente-alvarado-dara-banderazo-de-reapertura-del-volcan-poas/).


Sangay (Ecuador) — January 2019 Citation iconCite this Report

Sangay

Ecuador

2.005°S, 78.341°W; summit elev. 5286 m

All times are local (unless otherwise noted)


Eruption produced ash plumes, lava flows, and rockfalls during August-December 2018

Sangay is the southernmost active volcano in Ecuador and has displayed frequent eruptive activity since 1628, producing pyroclastic flows, lava flows, ash plumes, and lahars. An eruption from July through October 2017 produced ash plumes and lava flows on the ESE flank. After nine months of quiescence an eruption occurred from 8 August to 7 December 2018, with four months of continuous activity producing ash plumes, lava flows, and rockfalls. This report covers March through December 2018 and summarizes reports issued by the Instituto Geofisico, the Washington Volcano Ash Advisory Center (VAAC), and satellite data.

There was no reported activity from March through July. After nine months of inactivity a new eruptive phase began on 8 August 2018. On this day the Washington VAAC reported a possible ash plume that rose approximately 500 m above the vent and drifted 28 km WSW. An ash plume on 11 August reached a height of 2.3 km above the crater and moved towards the WSW. Prior to these two events, the last ash plume was detected on 13 October 2017.

The NASA Fire Information for Resource Management System (FIRMS) thermal alert and the first thermal anomaly alert issued by the MODVOLC near-real-time thermal monitoring algorithm for this eruptive episode was on 14 August. The eruption onset was confirmed visually on 14 August when an incandescent lava flow was seen on the upper SE flank on a webcam image (figure 22). Sentinel-2 detected elevated temperatures at the summit and lava effusion on the ESE flank (figure 23).

Figure (see Caption) Figure 22. Visual confirmation of eruptive activity with incandescence on the upper SE flank of Sangay volcano on 14 August. Webcam image by ECU911 from the city of Macas, courtesy of Instituto Geofisico (14 August 2018 report).
Figure (see Caption) Figure 23. Sentinel-2 thermal satellite image showing the active central crater, Ñuñurco dome, and a lava flow (bright orange/yellow) on the ESE flank of Sangay on 25 August 2018. The bright blue indicates snow on the volcano and the white/light blue areas are meteoric clouds. Sentinel-2 false color (Urban) image (bands 12, 11, 4) courtesy of Sentinel Hub Playground.

During 28 August to 3 September ash emissions reached altitudes of 5.8-6.7 km and traveled various directions out to 45 km. Ash plumes on 11, 13, 15, and 17 September reached altitudes of 5.8-6.4 km and drifted to the SW and W. Light ashfall occurred in the city of Guayaquil on 18 September, 170 km W. Ash plumes reached 5.8 to 6.1 km altitude on 19 and 20 September and drifted 37 km to the WNW and W.

Activity continued through October with lava emission. A Sentinel-2 thermal satellite image acquired on 24 October shows the lava flow on the ESE flank, with elevated thermal energy at the central crater and the Ñuñurco dome (figure 24). The final MODVOLC thermal alert was on 30 November 2018. During this time, lava flows were emitted and flowed down the ESE flank, and ash plumes were often produced and traveled to the W and NW (figure 25). From 2 December there was a substantial decrease in seismicity, ten times less than the previous months (figure 26). No further activity was noted in December.

Figure (see Caption) Figure 24. False color Sentinel-2 Satellite image of Sangay acquired on 24 October 2018 showing the active crater, the Ñuñurco dome, and a hot lava flow (bright orange/yellow) that has traveled more than 1.83 km. Sentinel-2 false color (Urban) image (bands 12, 11, 4) courtesy of Sentinel Hub Playground, figure labels and description courtesy of Instituto Geofisico (17 December 2018 report).
Figure (see Caption) Figure 25. The activity of Sangay during September, August, and November 2018. Small explosive events occurred at the main crater throughout the eruptive episode. The red outlines the active lava flow on the ESE flank and the yellow indicates the area impacted by rockfalls and possible collapse of the lava flow front. Annotated images courtesy of Instituto Geofisico (21 November 2018 report), webcam images taken by ECU-911 from the city of Macas.
Figure (see Caption) Figure 26. Chart showing the number of seismic events during the November-December 2018 activity at Sangay. The tremor was related to the lava flow activity, VT (volcano-tectonic) events are related to rock fracturing, LP (long-period) events are related to fluid movement, and explosions are the number of detected explosions. Between 25 and 88 explosions were detected per day prior to a decrease in seismicity on 2 December. Courtesy of Instituto Geofisico (17 December 2018 report).

Elevated temperatures on the volcano were detected from 14 August to 30 November (figure 27). During this period the Washington Volcanic Ash Advisory Center (VAAC) issued 164 alerts for ash plumes. The ash plumes occasionally exceeded 2 km above the crater but were typically below 1.4 km, drifting in different directions through time (figures 28 and 29). The continuous emission of lava produced flows that traveled 1-2 km from the vent. Rockfalls and possible small pyroclastic flows produced at the lava flow fronts reached a distance of 7 km from the crater. Due to a decrease in thermal activity, ash plumes, and seismicity, Instituto Geofisico declared the eruption over on 7 December, after 121 days of activity.

Figure (see Caption) Figure 27. Plot of MODIS (Moderate Resolution Imaging Spectroradiometer) thermal infrared satellite data analyzed by MIROVA from February 2018 to 2019. Top: the log radiative power of thermal anomalies showing through the eruptive episode. Bottom: The locations of the crater, dome, and lava flow as indicated by thermal anomalies, measured as the distance of the thermal anomalies from the vent in kilometers. Courtesy of MIROVA.
Figure (see Caption) Figure 28. The ash plume heights in meters above the Sangay crater during the 2018 August to December eruption period (top) with detected thermal energy (bottom). Ash plume heights were given by the Washington VAAC and thermal anomalies were calculated by the MODVOLC satellite algorithm. Courtesy of Instituto Geofisico (17 December 2018 report).
Figure (see Caption) Figure 29. A summary of ash plumes from Sangay during the August-December 2018 eruptive episode. A) The ash plume heights as reported by the Washington VAAC. The red line gives the average value for that month while the box represents the standard deviation. The maximum heights are indicated by the circles. B) The ash plume extents overlain over an image of Ecuador. Courtesy of Instituto Geofisico (21 November 2018 report).

Geologic Background. The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.

Information Contacts: Instituto Geofísico (IG-EPN), Escuela Politécnica Nacional, Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec); ECU911 - Integrated Security Service ECU 911, ulio Endara street s/n. Sector Parque Itchimbía Quito – Ecuador (URL: http://www.ecu911.gob.ec/servicio-integrado-de-seguridad-ecu-911/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Soputan (Indonesia) — January 2019 Citation iconCite this Report

Soputan

Indonesia

1.112°N, 124.737°E; summit elev. 1785 m

All times are local (unless otherwise noted)


Ash explosions on 3-4 October and 16 December 2018

Soputan typically erupts every few years with ash explosions, lava flows, and Strombolian eruptions (SEAN 07:08, BGVN 42:03). After a short eruptive period during January-February 2016, the volcano quieted, with only occasional steam plumes and low seismicity. An ash explosion on 3 October 2018 marked the beginning of a new eruption. The volcano is monitored by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG). This report discusses activity during September through December 2018.

According to PVMBG, increased seismicity at Soputan was notable on 2 October 2018, characterized by an increased number of signals indicating emissions and avalanches (which began in September and mid-July, respectively), increased Real-time Seismic-Amplitude Measurement (RSAM) values, and a higher number of volcanic earthquakes (since September). Data from a thermal camera showed increased summit temperatures, interpreted as indicating the presence of lava. The Alert Level was increased to 3 (on a scale of 1-4) on 3 October; people were advised not to approach the craters within a radius of 4 km, with an additional expansion to 6.5 km on the WSW flank due to increased risk from a breach in the crater rim.

An eruption at 0847 on 3 October produced a dense ash plume that rose 4 km above the summit and drifted W and NW (figure 16). Based on seismic data the event lasted six minutes. Events at 1044, 1112, and 1152 produced ash plumes that rose 2, 2.5, and 5 km above the crater rim, respectively. A thermal anomaly identified in satellite data significantly increased, and incandescent ejecta at the summit was clearly observed by residents. Avalanches of material traveled 2.5 km down the NE flank.

Figure (see Caption) Figure 16. An ash plume from Soputan on 3 October 2018, as seen from Tomohon (25 km NNE). Courtesy of AP Photo/Hetty Andih.

Based on satellite images, information from PVMBG, and wind model data, the Darwin Volcanic Ash Advisory Center (VAAC) reported that on 4 October ash plumes rose to an altitude of 4.6 km and drifted W. On 16 October, PVMBG issued a Volcano Observatory Notice for Aviation (VONA) that noted only white emissions; consequently, the Aviation Color Code was lowered to Yellow.

According to PVMBG, seismic activity rapidly and significantly increased at 1700 on 15 December. An eruption began at 0102 on 16 December, though dark and foggy conditions prevented views of emissions. The event lasted for almost 10 minutes, and thunderous sounds were heard at the Soputan Volcano Observation Post located in Silian Raya (about 10 km SW). The conditions improved about two hours later, and a dense ash plume was visible, rising 3 km above the summit and drifting SE. Incandescence from the summit was also visible. An event that began at 0540 produced dense gray-to-black ash plumes that rose as high as 7 km above the summit (summit elevation is 1,785 m) and drifted SE. The event lasted for 6 minutes and 10 seconds based on the seismic network. Ash plumes from events at 0743 and 0857 rose as high as 7.5 km and drifted SW.

Satellite data. Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were observed during two days in September (14 and 30 September), seven days in October, and lastly on 8 November 2018. Pixel numbers peaked during 3-7 October (six pixels on 3 October). The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, detected numerous hotspots within 5 km of the volcano during the reporting period. Significant sulfur dioxide levels near the volcano were recorded by NASA's satellite-borne ozone instruments on or just after the 3 October and 16 December explosions.

Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Associated Press (URL: http://www.ap.org/).


Suwanosejima (Japan) — January 2019 Citation iconCite this Report

Suwanosejima

Japan

29.638°N, 129.714°E; summit elev. 796 m

All times are local (unless otherwise noted)


Multiple explosive events with incandescence and ash plumes during November 2018

Suwanosejima, an andesitic stratovolcano in Japan's northern Ryukyu Islands, was intermittently active for much of the 20th century, producing ash plumes, Strombolian explosions, and ash deposits. Continuous activity since October 2004 has produced intermittent explosions, generating ash plumes in most months that rise hundreds of meters above the summit to altitudes between 1 and 3 km. Ongoing activity for the second half of 2018 is covered in this report with information provided by the Japan Meteorological Agency (JMA) and the Tokyo Volcanic Ash Advisory Center (VAAC).

Activity during July-December 2018 was intermittent with explosions reported twice in September and 21 times during November. Incandescent activity was observed a few times each month, increasing significantly during November. Thermal data support a similar pattern of activity; the MIROVA thermal anomaly graph indicated intermittent activity through the period that was most frequent during October and November (figure 33). MODVOLC thermal alerts were issued once in September (9), three times in October (7, 21), and four times on 14 and 15 November.

Figure (see Caption) Figure 33. MIROVA thermal data for Suwanosejima from 7 February through December 2018 indicated intermittent activity at the summit that increased to more significant activity during October and November before declining by the end of the year. Courtesy of MIROVA.

There were no explosions at Suwanosejima during July or August 2018; steam plumes rose 900-1,000 m above the crater rim and incandescence was intermittently observed on clear nights. During September incandescence was also observed at night; in addition, explosions were reported on 12 and 13 September, with ash plumes rising 1,100 m above the crater rim. October was again quiet with no explosions, only steam plumes rising 800 m, and occasional incandescence at night, although thermal activity increased (figure 33).

More intense activity resumed during November 2018 with 21 explosions reported. On 9 and 14 November tephra was ejected up to 700 m from the Mitake crater. The Tokyo VAAC reported an ash plume visible in satellite imagery at 2.4 km altitude moving E on 14 November. The next day, a plume was reported at 2.7 km altitude drifting NW but it was not visible in satellite imagery. JMA reported gray ash plumes that rose up to 2,000 m above the crater rim on 16 and 23 November (figure 34). The ash plume on 23 November was visible in satellite imagery drifting N at 2.7 km altitude. On 30 November the Tokyo VAAC reported an ash plume visible in satellite data drifting SE at 2.4 km altitude. Incandescence was often observed at night from the webcams throughout the month. Ashfall was confirmed in the village 4 km SSW on 14, 17, and 23 November, and sounds were reported on 20 November.

Figure (see Caption) Figure 34. Ash plumes rose 2,000 m above the crater rim at Suwanosejima on 23 November 2018 as seen with the 'campsite' webcam. Courtesy of JMA (Volcanic activity commentary (November, 2018) of Suwanose Island).

During December 2018, no explosive eruptions were reported, but an ash plume rose 1,800 m above the summit on 26 December. Incandescence was observed on clear nights in the webcam. Throughout 2018, a total of 42 explosive events were reported; 21 of them occurred during November (figure 35).

Figure (see Caption) Figure 35. Eruptive activity at Suwanosejima during 2018. Black bars represent heights of steam, gas, or ash plumes in meters above crater rim (left axis), gray volcanoes along the top represent explosions, usually accompanied by ash plumes, red volcanoes represent large explosions with ash plumes, orange diamonds indicate incandescence observed in webcams. Courtesy of JMA (Volcanic activity of Suwanose Island in 2018).

Geologic Background. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).


Veniaminof (United States) — January 2019 Citation iconCite this Report

Veniaminof

United States

56.17°N, 159.38°W; summit elev. 2507 m

All times are local (unless otherwise noted)


Eruption with lava flows and ash plumes during September-December 2018

The most recent eruptive period at Veniaminof began in September 2018 with seismic activity followed by ash emissions and lava flows continuing through mid-December 2018, the end of this reporting period (figure 25). An intracaldera cone has been the source of historic volcanic activity in the last 200 years and more recent activity last reported in June 2013 (BGVN 42:02). Veniaminof is closely monitored by the Alaska Volcanic Observatory (AVO) and the Anchorage Volcanic Ash Advisory Center (VAAC), and is also monitored by a Federal Aviation Administration (FAA) web camera in the town of Perryville, 35 km E.

Figure (see Caption) Figure 25. View of Veniaminof to the W with a diffuse ash plume at 1517 local time on 5 September 2018. Photo by Zachary Finley (color adjusted from original); courtesy of USGS/AVO.

The most recent Strombolian-type eruptive cycle commenced with increased seismic activity on 2 September 2018. Low-level ash that rose 3 km and pulsatory low-altitude ash emissions were observed in FAA webcam images on 4-6 September. Ash deposits extended onto the snowfield at and below the summit to the SSW and SE, forming a "v" shape downslope from the summit. On 7 September a thermal feature was detected, suggesting lava fountaining at the summit, which was later confirmed by satellite data showing a S-flank lava flow about 800 m long on 9-11 September (figure 26). FAA webcam images on 26 September showed lava fountains issuing from a second vent 75 m N of the first, producing additional lava flows on the S flank (figures 27 and 28). Minor ash emissions associated with lava fountaining possibly rose as high as 4.5 km and quickly dispersed.

Figure (see Caption) Figure 26. Geologic sketch map of lava flows and features on the intracaldera cone of Veniaminof as of 11 September 2018. DigitalGlobe WorldView-3 image (left) acquired with Digital Globe NextView License. Image by Chris Waythomas; courtesy of USGS/AVO.
Figure (see Caption) Figure 27. Veniaminof eruption on the evening of 18 September 2018. Photo by Pearl Gransbury; courtesy USGS/AVO.
Figure (see Caption) Figure 28. Veniaminof in eruption on 26 September 2018. A lava flow is visible on the S flank of the volcano with steaming at the base. Photo by Jesse Lopez (color adjusted from original); courtesy of USGS/AVO.

The lava flow had traveled 1 km down the S flank of the summit cone by 1 October. Satellite imagery from 6 October showed three lobes of lava flows and a plume over a thin tephra deposit. By 25 October the lava flow had traveled as far as 1.2 km (figures 29 and 30). Fractures in the ice sheet adjacent to the lava flow field continued to grow due to meltwater flowing beneath. Additionally, a persistent and robust steam plume which contained sulfur dioxide was visible from the FAA webcam on 18 October.

Figure (see Caption) Figure 29. False color ESA Sentinel-2 image of Veniaminof on 6 October 2018 showing lava effusion and a plume with a thin tephra deposit beneath to the N. The flow is ~1 km in length with the most active front on the E, which has a SWIR (short wave infrared) anomaly extending to the flow front. A branch in the channel feeding the western lobes appears to be active as well, but without any SWIR anomaly near the flow front, suggesting that this western branch is less active. The eastern flow front is producing the strongest steam plume. Prepared by Hannah Dietterich with ESA Sentinel-2 imagery; courtesy of USGS/AVO.
Figure (see Caption) Figure 30. Sentinel-2 satellite image of Veniaminof acquired 5 December 2018. Image shows three lava lobes with relative ages from oldest (1) to youngest (3). AVO became aware of flow 3 on 29 November 2018. It is uncertain when this flow first formed because the volcano had been obscured by clouds earlier. Prepared by Chris Waythomas; courtesy of USGS/AVO.

Ash emissions significantly increased overnight on 20-21 November, prompting AVO to raise the Aviation Color Code (ACC) to Red and the Alert Level to "Warning" (the highest levels on a four-level scale). The ash emissions rose to below 4.6 km and drifted more than 240 km SE. On 21 November observations and FAA webcam images indicated continuous ash emissions through most of the day as ash plumes drifted SE, extending as far as 400 km (figure 31). A short eruptive pulse was recorded during 1526-1726, and subsequent ash plumes rose to below 3 km with low-altitude ash emissions drifting 100 km S on 22 November (figure 32). Decreased ash emissions prompted AVO to lower the ACC and Alert Level to Orange and "Watch", respectively. However, lava effusion was persistent through 27 November.

Figure (see Caption) Figure 31. Plume rising from Veniaminof on 9 November 2018. View is to the west. Ash is visible at the summit and steam is rising from the S-flank lava flow. Photo by Zachary Finley (color adjusted from original); courtesy of USGS/AVO.
Figure (see Caption) Figure 32. Annotated satellite image of the Veniaminof eruption taken by Sentinel-2 on 22 November 2018. The image shows an eruptive plume above the active cone within the caldera, as well as a broad tephra deposit to the SE on snow extending to Perryville. Image courtesy of USGS/AVO (ESA/Copernicus; Sentinel-2 image visualized in EOS LandViewer).

During 27-28 November acoustic waves were recorded by regional infrasound sensors. A continuous low-amplitude tremor was recorded until the network went offline following a M 7 earthquake in Anchorage on 30 November. On 6 December seismicity changed from nearly continuous low-level volcanic tremor to intermittent small low-frequency events and short bursts of tremors, possibly indicating that lava effusion had slowed or stopped. Variable seismicity continued through 12 December, though there was no visual confirmation of lava effusion.

Minor ashfall was recorded in Perryville (35 km E) on 25 October and 22 November 2018. Elevated surface temperatures and thermal anomalies were identified in satellite data on 7, 12-26 September, 2-9 and 24-30 October, 7-22 November, and 4-5 December. Nighttime incandescence was visible from the FAA webcam at various times during this reporting period (figure 27). Following 22 November, the ACC remained at Orange and the Volcano Alert Level remained at "Watch."

The MIROVA thermal anomalies detected during this period were reported as having moderate to high radiative power (figure 33). Numerous thermal anomalies identified using the MODVOLC algorithm were also detected during this period, and showed the S-flank lava flows (figure 34).

Figure (see Caption) Figure 33. Plot showing the log radiative power of thermal anomalies at Veniaminof identified using MODIS data by the MIROVA system for the year ending on 28 February 2019. Courtesy of MIROVA.
Figure (see Caption) Figure 34. Map of thermal alert pixels at Veniaminof from the MODVOLC Thermal Alert System during 7 September-24 December 2018 (UTC). Courtesy of HIGP - MODVOLC Thermal Alert System.

Geologic Background. Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3700 years ago. The caldera rim is up to 520 m high on the north, is deeply notched on the west by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/); Anchorage Volcanic Ash Advisory Center (VAAC), Alaska Aviation Weather Unit, NWS NOAA US Dept of Commerce, 6930 Sand Lake Road, Anchorage, AK 99502-1845 USA (URL: http://vaac.arh.noaa.gov/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Atmospheric Effects

The enormous aerosol cloud from the March-April 1982 eruption of Mexico's El Chichón persisted for years in the stratosphere, and led to the Atmospheric Effects section becoming a regular feature of the Bulletin. Descriptions of the initial dispersal of major eruption clouds remain with the individual eruption reports, but observations of long-term stratospheric aerosol loading will be found in this section.

Atmospheric Effects (1980-1989)  Atmospheric Effects (1995-2001)

Special Announcements

Special announcements of various kinds and obituaries.

Special Announcements

Additional Reports

Reports are sometimes published that are not related to a Holocene volcano. These might include observations of a Pleistocene volcano, earthquake swarms, or floating pumice. Reports are also sometimes published in which the source of the activity is unknown or the report is determined to be false. All of these types of additional reports are listed below by subregion and subject.

Kermadec Islands


Floating Pumice (Kermadec Islands)

1986 Submarine Explosion


Tonga Islands


Floating Pumice (Tonga)


Fiji Islands


Floating Pumice (Fiji)


Andaman Islands


False Report of Andaman Islands Eruptions


Sangihe Islands


1968 Northern Celebes Earthquake


Southeast Asia


Pumice Raft (South China Sea)

Land Subsidence near Ham Rong


Ryukyu Islands and Kyushu


Pumice Rafts (Ryukyu Islands)


Izu, Volcano, and Mariana Islands


Acoustic Signals in 1996 from Unknown Source

Acoustic Signals in 1999-2000 from Unknown Source


Kuril Islands


Possible 1988 Eruption Plume


Aleutian Islands


Possible 1986 Eruption Plume


Mexico


False Report of New Volcano


Nicaragua


Apoyo


Colombia


La Lorenza Mud Volcano


Pacific Ocean (Chilean Islands)


False Report of Submarine Volcanism


Central Chile and Argentina


Estero de Parraguirre


West Indies


Mid-Cayman Spreading Center


Atlantic Ocean (northern)


Northern Reykjanes Ridge


Azores


Azores-Gibraltar Fracture Zone


Antarctica and South Sandwich Islands


Jun Jaegyu

East Scotia Ridge


Additional Reports (database)

08/1997 (BGVN 22:08) False Report of Mount Pinokis Eruption

False report of volcanism intended to exclude would-be gold miners

12/1997 (BGVN 22:12) False Report of Somalia Eruption

Press reports of Somalia's first historical eruption were likely in error

11/1999 (BGVN 24:11) False Report of Sea of Marmara Eruption

UFO adherent claims new volcano in Sea of Marmara

05/2003 (BGVN 28:05) Har-Togoo

Fumaroles and minor seismicity since October 2002

12/2005 (BGVN 30:12) Elgon

False report of activity; confusion caused by burning dung in a lava tube



False Report of Mount Pinokis Eruption (Philippines) — August 1997

False Report of Mount Pinokis Eruption

Philippines

7.975°N, 123.23°E; summit elev. 1510 m

All times are local (unless otherwise noted)


False report of volcanism intended to exclude would-be gold miners

In discussing the week ending on 12 September, "Earthweek" (Newman, 1997) incorrectly claimed that a volcano named "Mount Pinukis" had erupted. Widely read in the US, the dramatic Earthweek report described terrified farmers and a black mushroom cloud that resembled a nuclear explosion. The mountain's location was given as "200 km E of Zamboanga City," a spot well into the sea. The purported eruption had received mention in a Manila Bulletin newspaper report nine days earlier, on 4 September. Their comparatively understated report said that a local police director had disclosed that residents had seen a dormant volcano showing signs of activity.

In response to these news reports Emmanuel Ramos of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) sent a reply on 17 September. PHIVOLCS staff had initially heard that there were some 12 alleged families who fled the mountain and sought shelter in the lowlands. A PHIVOLCS investigation team later found that the reported "families" were actually individuals seeking respite from some politically motivated harassment. The story seems to have stemmed from a local gold rush and an influential politician who wanted to use volcanism as a ploy to exclude residents. PHIVOLCS concluded that no volcanic activity had occurred. They also added that this finding disappointed local politicians but was much welcomed by the residents.

PHIVOLCS spelled the mountain's name as "Pinokis" and from their report it seems that it might be an inactive volcano. There is no known Holocene volcano with a similar name (Simkin and Siebert, 1994). No similar names (Pinokis, Pinukis, Pinakis, etc.) were found listed in the National Imagery and Mapping Agency GEOnet Names Server (http://geonames.nga.mil/gns/html/index.html), a searchable database of 3.3 million non-US geographic-feature names.

The Manila Bulletin report suggested that Pinokis resides on the Zamboanga Peninsula. The Peninsula lies on Mindanao Island's extreme W side where it bounds the Moro Gulf, an arm of the Celebes Sea. The mountainous Peninsula trends NNE-SSW and contains peaks with summit elevations near 1,300 m. Zamboanga City sits at the extreme end of the Peninsula and operates both a major seaport and an international airport.

[Later investigation found that Mt. Pinokis is located in the Lison Valley on the Zamboanga Peninsula, about 170 km NE of Zamboanga City and 30 km NW of Pagadian City. It is adjacent to the two peaks of the Susong Dalaga (Maiden's Breast) and near Mt. Sugarloaf.]

References. Newman, S., 1997, Earthweek, a diary of the planet (week ending 12 September): syndicated newspaper column (URL: http://www.earthweek.com/).

Manila Bulletin, 4 Sept. 1997, Dante's Peak (URL: http://www.mb.com.ph/).

Simkin, T., and Siebert, L., 1994, Volcanoes of the world, 2nd edition: Geoscience Press in association with the Smithsonian Institution Global Volcanism Program, Tucson AZ, 368 p.

Information Contacts: Emmanuel G. Ramos, Deputy Director, Philippine Institute of Volcanology and Seismology, Department of Science and Technology, PHIVOLCS Building, C. P. Garcia Ave., University of the Philippines, Diliman campus, Quezon City, Philippines.


False Report of Somalia Eruption (Somalia) — December 1997

False Report of Somalia Eruption

Somalia

3.25°N, 41.667°E; summit elev. 500 m

All times are local (unless otherwise noted)


Press reports of Somalia's first historical eruption were likely in error

Xinhua News Agency filed a news report on 27 February under the headline "Volcano erupts in Somalia" but the veracity of the story now appears doubtful. The report disclosed the volcano's location as on the W side of the Gedo region, an area along the Ethiopian border just NE of Kenya. The report had relied on the commissioner of the town of Bohol Garas (a settlement described as 40 km NE of the main Al-Itihad headquarters of Luq town) and some or all of the information was relayed by journalists through VHF radio. The report claimed the disaster "wounded six herdsmen" and "claimed the lives of 290 goats grazing near the mountain when the incident took place." Further descriptions included such statements as "the volcano which erupted two days ago [25 February] has melted down the rocks and sand and spread . . . ."

Giday WoldeGabriel returned from three weeks of geological fieldwork in SW Ethiopia, near the Kenyan border, on 25 August. During his time there he inquired of many people, including geologists, if they had heard of a Somalian eruption in the Gedo area; no one had heard of the event. WoldeGabriel stated that he felt the news report could have described an old mine or bomb exploding. Heavy fighting took place in the Gedo region during the Ethio-Somalian war of 1977. Somalia lacks an embassy in Washington DC; when asked during late August, Ayalaw Yiman, an Ethiopian embassy staff member in Washington DC also lacked any knowledge of a Somalian eruption.

A Somalian eruption would be significant since the closest known Holocene volcanoes occur in the central Ethiopian segment of the East African rift system S of Addis Ababa, ~500 km NW of the Gedo area. These Ethiopian rift volcanoes include volcanic fields, shield volcanoes, cinder cones, and stratovolcanoes.

Information Contacts: Xinhua News Agency, 5 Sharp Street West, Wanchai, Hong Kong; Giday WoldeGabriel, EES-1/MS D462, Geology-Geochemistry Group, Los Alamos National Laboratory, Los Alamos, NM 87545; Ayalaw Yiman, Ethiopian Embassy, 2134 Kalorama Rd. NW, Washington DC 20008.


False Report of Sea of Marmara Eruption (Turkey) — November 1999

False Report of Sea of Marmara Eruption

Turkey

40.683°N, 29.1°E; summit elev. 0 m

All times are local (unless otherwise noted)


UFO adherent claims new volcano in Sea of Marmara

Following the Ms 7.8 earthquake in Turkey on 17 August (BGVN 24:08) an Email message originating in Turkey was circulated, claiming that volcanic activity was observed coincident with the earthquake and suggesting a new (magmatic) volcano in the Sea of Marmara. For reasons outlined below, and in the absence of further evidence, editors of the Bulletin consider this a false report.

The report stated that fishermen near the village of Cinarcik, at the E end of the Sea of Marmara "saw the sea turned red with fireballs" shortly after the onset of the earthquake. They later found dead fish that appeared "fried." Their nets were "burned" while under water and contained samples of rocks alleged to look "magmatic."

No samples of the fish were preserved. A tectonic scientist in Istanbul speculated that hot water released by the earthquake from the many hot springs along the coast in that area may have killed some fish (although they would be boiled rather than fried).

The phenomenon called earthquake lights could explain the "fireballs" reportedly seen by the fishermen. Such effects have been reasonably established associated with large earthquakes, although their origin remains poorly understood. In addition to deformation-triggered piezoelectric effects, earthquake lights have sometimes been explained as due to the release of methane gas in areas of mass wasting (even under water). Omlin and others (1999), for example, found gas hydrate and methane releases associated with mud volcanoes in coastal submarine environments.

The astronomer and author Thomas Gold (Gold, 1998) has a website (Gold, 2000) where he presents a series of alleged quotes from witnesses of earthquakes. We include three such quotes here (along with Gold's dates, attributions, and other comments):

(A) Lima, 30 March 1828. "Water in the bay 'hissed as if hot iron was immersed in it,' bubbles and dead fish rose to the surface, and the anchor chain of HMS Volage was partially fused while lying in the mud on the bottom." (Attributed to Bagnold, 1829; the anchor chain is reported to be on display in the London Navy Museum.)

(B) Romania, 10 November 1940. ". . . a thick layer like a translucid gas above the surface of the soil . . . irregular gas fires . . . flames in rhythm with the movements of the soil . . . flashes like lightning from the floor to the summit of Mt Tampa . . . flames issuing from rocks, which crumbled, with flashes also issuing from non-wooded mountainsides." (Phrases used in eyewitness accounts collected by Demetrescu and Petrescu, 1941).

(C) Sungpan-Pingwu (China), 16, 22, and 23 August 1976. "From March of 1976, various large anomalies were observed over a broad region. . . . At the Wanchia commune of Chungching County, outbursts of natural gas from rock fissures ignited and were difficult to extinguish even by dumping dirt over the fissures. . . . Chu Chieh Cho, of the Provincial Seismological Bureau, related personally seeing a fireball 75 km from the epicenter on the night of 21 July while in the company of three professional seismologists."

Yalciner and others (1999) made a study of coastal areas along the Sea of Marmara after the Izmet earthquake. They found evidence for one or more tsunamis with maximum runups of 2.0-2.5 m. Preliminary modeling of the earthquake's response failed to reproduce the observed runups; the areas of maximum runup instead appeared to correspond most closely with several local mass-failure events. This observation together with the magnitude of the earthquake, and bottom soundings from marine geophysical teams, suggested mass wasting may have been fairly common on the floor of the Sea of Marmara.

Despite a wide range of poorly understood, dramatic processes associated with earthquakes (Izmet 1999 apparently included), there remains little evidence for volcanism around the time of the earthquake. The nearest Holocene volcano lies ~200 km SW of the report location. Neither Turkish geologists nor scientists from other countries in Turkey to study the 17 August earthquake reported any volcanism. The report said the fisherman found "magmatic" rocks; it is unlikely they would be familiar with this term.

The motivation and credibility of the report's originator, Erol Erkmen, are unknown. Certainly, the difficulty in translating from Turkish to English may have caused some problems in understanding. Erkmen is associated with a website devoted to reporting UFO activity in Turkey. Photographs of a "magmatic rock" sample were sent to the Bulletin, but they only showed dark rocks photographed devoid of a scale on a featureless background. The rocks shown did not appear to be vesicular or glassy. What was most significant to Bulletin editors was the report author's progressive reluctance to provide samples or encourage follow-up investigation with local scientists. Without the collaboration of trained scientists on the scene this report cannot be validated.

References. Omlin, A, Damm, E., Mienert, J., and Lukas, D., 1999, In-situ detection of methane releases adjacent to gas hydrate fields on the Norwegian margin: (Abstract) Fall AGU meeting 1999, Eos, American Geophysical Union.

Yalciner, A.C., Borrero, J., Kukano, U., Watts, P., Synolakis, C. E., and Imamura, F., 1999, Field survey of 1999 Izmit tsunami and modeling effort of new tsunami generation mechanism: (Abstract) Fall AGU meeting 1999, Eos, American Geophysical Union.

Gold, T., 1998, The deep hot biosphere: Springer Verlag, 256 p., ISBN: 0387985468.

Gold, T., 2000, Eye-witness accounts of several major earthquakes (URL: http://www.people.cornell.edu/ pages/tg21/eyewit.html).

Information Contacts: Erol Erkmen, Tuvpo Project Alp.


Har-Togoo (Mongolia) — May 2003

Har-Togoo

Mongolia

48.831°N, 101.626°E; summit elev. 1675 m

All times are local (unless otherwise noted)


Fumaroles and minor seismicity since October 2002

In December 2002 information appeared in Mongolian and Russian newspapers and on national TV that a volcano in Central Mongolia, the Har-Togoo volcano, was producing white vapors and constant acoustic noise. Because of the potential hazard posed to two nearby settlements, mainly with regard to potential blocking of rivers, the Director of the Research Center of Astronomy and Geophysics of the Mongolian Academy of Sciences, Dr. Bekhtur, organized a scientific expedition to the volcano on 19-20 March 2003. The scientific team also included M. Ulziibat, seismologist from the same Research Center, M. Ganzorig, the Director of the Institute of Informatics, and A. Ivanov from the Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences.

Geological setting. The Miocene Har-Togoo shield volcano is situated on top of a vast volcanic plateau (figure 1). The 5,000-year-old Khorog (Horog) cone in the Taryatu-Chulutu volcanic field is located 135 km SW and the Quaternary Urun-Dush cone in the Khanuy Gol (Hanuy Gol) volcanic field is 95 km ENE. Pliocene and Quaternary volcanic rocks are also abundant in the vicinity of the Holocene volcanoes (Devyatkin and Smelov, 1979; Logatchev and others, 1982). Analysis of seismic activity recorded by a network of seismic stations across Mongolia shows that earthquakes of magnitude 2-3.5 are scattered around the Har-Togoo volcano at a distance of 10-15 km.

Figure (see Caption) Figure 1. Photograph of the Har-Togoo volcano viewed from west, March 2003. Courtesy of Alexei Ivanov.

Observations during March 2003. The name of the volcano in the Mongolian language means "black-pot" and through questioning of the local inhabitants, it was learned that there is a local myth that a dragon lived in the volcano. The local inhabitants also mentioned that marmots, previously abundant in the area, began to migrate westwards five years ago; they are now practically absent from the area.

Acoustic noise and venting of colorless warm gas from a small hole near the summit were noticed in October 2002 by local residents. In December 2002, while snow lay on the ground, the hole was clearly visible to local visitors, and a second hole could be seen a few meters away; it is unclear whether or not white vapors were noticed on this occasion. During the inspection in March 2003 a third hole was seen. The second hole is located within a 3 x 3 m outcrop of cinder and pumice (figure 2) whereas the first and the third holes are located within massive basalts. When close to the holes, constant noise resembled a rapid river heard from afar. The second hole was covered with plastic sheeting fixed at the margins, but the plastic was blown off within 2-3 seconds. Gas from the second hole was sampled in a mechanically pumped glass sampler. Analysis by gas chromatography, performed a week later at the Institute of the Earth's Crust, showed that nitrogen and atmospheric air were the major constituents.

Figure (see Caption) Figure 2. Photograph of the second hole sampled at Har-Togoo, with hammer for scale, March 2003. Courtesy of Alexei Ivanov.

The temperature of the gas at the first, second, and third holes was +1.1, +1.4, and +2.7°C, respectively, while air temperature was -4.6 to -4.7°C (measured on 19 March 2003). Repeated measurements of the temperatures on the next day gave values of +1.1, +0.8, and -6.0°C at the first, second, and third holes, respectively. Air temperature was -9.4°C. To avoid bias due to direct heating from sunlight the measurements were performed under shadow. All measurements were done with Chechtemp2 digital thermometer with precision of ± 0.1°C and accuracy ± 0.3°C.

Inside the mouth of the first hole was 4-10-cm-thick ice with suspended gas bubbles (figure 5). The ice and snow were sampled in plastic bottles, melted, and tested for pH and Eh with digital meters. The pH-meter was calibrated by Horiba Ltd (Kyoto, Japan) standard solutions 4 and 7. Water from melted ice appeared to be slightly acidic (pH 6.52) in comparison to water of melted snow (pH 7.04). Both pH values were within neutral solution values. No prominent difference in Eh (108 and 117 for ice and snow, respectively) was revealed.

Two digital short-period three-component stations were installed on top of Har-Togoo, one 50 m from the degassing holes and one in a remote area on basement rocks, for monitoring during 19-20 March 2003. Every hour 1-3 microseismic events with magnitude <2 were recorded. All seismic events were virtually identical and resembled A-type volcano-tectonic earthquakes (figure 6). Arrival difference between S and P waves were around 0.06-0.3 seconds for the Har-Togoo station and 0.1-1.5 seconds for the remote station. Assuming that the Har-Togoo station was located in the epicentral zone, the events were located at ~1-3 km depth. Seismic episodes similar to volcanic tremors were also recorded (figure 3).

Figure (see Caption) Figure 3. Examples of an A-type volcano-tectonic earthquake and volcanic tremor episodes recorded at the Har-Togoo station on 19 March 2003. Courtesy of Alexei Ivanov.

Conclusions. The abnormal thermal and seismic activities could be the result of either hydrothermal or volcanic processes. This activity could have started in the fall of 2002 when they were directly observed for the first time, or possibly up to five years earlier when marmots started migrating from the area. Further studies are planned to investigate the cause of the fumarolic and seismic activities.

At the end of a second visit in early July, gas venting had stopped, but seismicity was continuing. In August there will be a workshop on Russian-Mongolian cooperation between Institutions of the Russian and Mongolian Academies of Sciences (held in Ulan-Bator, Mongolia), where the work being done on this volcano will be presented.

References. Devyatkin, E.V. and Smelov, S.B., 1979, Position of basalts in sequence of Cenozoic sediments of Mongolia: Izvestiya USSR Academy of Sciences, geological series, no. 1, p. 16-29. (In Russian).

Logatchev, N.A., Devyatkin, E.V., Malaeva, E.M., and others, 1982, Cenozoic deposits of Taryat basin and Chulutu river valley (Central Hangai): Izvestiya USSR Academy of Sciences, geological series, no. 8, p. 76-86. (In Russian).

Geologic Background. The Miocene Har-Togoo shield volcano, also known as Togoo Tologoy, is situated on top of a vast volcanic plateau. The 5,000-year-old Khorog (Horog) cone in the Taryatu-Chulutu volcanic field is located 135 km SW and the Quaternary Urun-Dush cone in the Khanuy Gol (Hanuy Gol) volcanic field is 95 km ENE. Analysis of seismic activity recorded by a network of seismic stations across Mongolia shows that earthquakes of magnitude 2-3.5 are scattered around the Har-Togoo volcano at a distance of 10-15 km.

Information Contacts: Alexei V. Ivanov, Institute of the Earth Crust SB, Russian Academy of Sciences, Irkutsk, Russia; Bekhtur andM. Ulziibat, Research Center of Astronomy and Geophysics, Mongolian Academy of Sciences, Ulan-Bator, Mongolia; M. Ganzorig, Institute of Informatics MAS, Ulan-Bator, Mongolia.


Elgon (Uganda) — December 2005

Elgon

Uganda

1.136°N, 34.559°E; summit elev. 3885 m

All times are local (unless otherwise noted)


False report of activity; confusion caused by burning dung in a lava tube

An eruption at Mount Elgon was mistakenly inferred when fumes escaped from this otherwise quiet volcano. The fumes were eventually traced to dung burning in a lava-tube cave. The cave is home to, or visited by, wildlife ranging from bats to elephants. Mt. Elgon (Ol Doinyo Ilgoon) is a stratovolcano on the SW margin of a 13 x 16 km caldera that straddles the Uganda-Kenya border 140 km NE of the N shore of Lake Victoria. No eruptions are known in the historical record or in the Holocene.

On 7 September 2004 the web site of the Kenyan newspaper The Daily Nation reported that villagers sighted and smelled noxious fumes from a cave on the flank of Mt. Elgon during August 2005. The villagers' concerns were taken quite seriously by both nations, to the extent that evacuation of nearby villages was considered.

The Daily Nation article added that shortly after the villagers' reports, Moses Masibo, Kenya's Western Province geology officer visited the cave, confirmed the villagers observations, and added that the temperature in the cave was 170°C. He recommended that nearby villagers move to safer locations. Masibo and Silas Simiyu of KenGens geothermal department collected ashes from the cave for testing.

Gerald Ernst reported on 19 September 2004 that he spoke with two local geologists involved with the Elgon crisis from the Geology Department of the University of Nairobi (Jiromo campus): Professor Nyambok and Zacharia Kuria (the former is a senior scientist who was unable to go in the field; the latter is a junior scientist who visited the site). According to Ernst their interpretation is that somebody set fire to bat guano in one of the caves. The fire was intense and probably explains the vigorous fuming, high temperatures, and suffocated animals. The event was also accompanied by emissions of gases with an ammonia odor. Ernst noted that this was not surprising considering the high nitrogen content of guano—ammonia is highly toxic and can also explain the animal deaths. The intense fumes initially caused substantial panic in the area.

It was Ernst's understanding that the authorities ordered evacuations while awaiting a report from local scientists, but that people returned before the report reached the authorities. The fire presumably prompted the response of local authorities who then urged the University geologists to analyze the situation. By the time geologists arrived, the fuming had ceased, or nearly so. The residue left by the fire and other observations led them to conclude that nothing remotely related to a volcanic eruption had occurred.

However, the incident emphasized the problem due to lack of a seismic station to monitor tectonic activity related to a local triple junction associated with the rift valley or volcanic seismicity. In response, one seismic station was moved from S Kenya to the area of Mt. Elgon so that local seismicity can be monitored in the future.

Information Contacts: Gerald Ernst, Univ. of Ghent, Krijgslaan 281/S8, B-9000, Belgium; Chris Newhall, USGS, Univ. of Washington, Dept. of Earth & Space Sciences, Box 351310, Seattle, WA 98195-1310, USA; The Daily Nation (URL: http://www.nationmedia.com/dailynation/); Uganda Tourist Board (URL: http://www.visituganda.com/).