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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

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

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

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

Kerinci (Indonesia) A persistent gas-and-steam plume and intermittent ash plumes occurred from July 2018 through January 2019

Yasur (Vanuatu) Eruption continues with ongoing explosions and multiple active crater vents, August 2018-January 2019

Ambae (Vanuatu) Ash plumes and lahars in July 2018 cause evacuation of the island; intermittent gas-and-steam and ash plumes through January 2019

Agung (Indonesia) Ongoing intermittent ash plumes and frequent gas-and-steam plumes during August 2018-January 2019

Erebus (Antarctica) Lava lakes persist through 2017 and 2018

Villarrica (Chile) Intermittent Strombolian activity ejects incandescent bombs around crater rim, September 2018-February 2019



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 from about 13,000 to 5000 years ago was followed by formation of the modern edifice. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5000 years ago as a result of the most recent of 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).


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).


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 one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that 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 westward-younging vents, the most recent of which is 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/).


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 west 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 Shintake, formed after the NW side of Furutake was breached by an explosion. All historical eruptions have occurred from Shintake, although a lava flow from the S flank of Furutake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shintake 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/).


Kerinci (Indonesia) — February 2019 Citation iconCite this Report

Kerinci

Indonesia

1.697°S, 101.264°E; summit elev. 3800 m

All times are local (unless otherwise noted)


A persistent gas-and-steam plume and intermittent ash plumes occurred from July 2018 through January 2019

Kerinci is a frequently active volcano in Sumatra, Indonesia. Recent activity has consisted of intermittent explosions, ash, and gas-and-steam plumes. The volcano alert has been at Level II since 9 September 2007. This report summarizes activity during July 2018-January 2019 based on reports by The Indonesia volcano monitoring agency, Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), MAGMA Indonesia, notices from the Darwin Volcano Ash Advisory Center (Darwin VAAC), and satellite data.

Throughout this period dilute gas-and-steam plumes rising about 300 m above the summit were frequently observed and seismicity continued (figure 6). During July through January ash plumes were observed by the Darwin VAAC up to 4.3 km altitude and dispersed in multiple directions (table 7 and figure 7).

Figure (see Caption) Figure 6. Graph showing seismic activity at Kerinci from November 2018 through February 2019. Courtesy of MAGMA Indonesia.

Table 7. Summary of ash plumes (altitude and drift direction) for Kerinci during July 2018 through January 2019. The summit is at 3.5 km altitude. Data courtesy of the Darwin Volcanic Ash Advisory Center (VAAC) and MAGMA Indonesia.

Date Ash plume altitude (km) Ash plume drift direction
22 Jul 2018 4.3 SW
28-30 Sep 2018 4.3 SW, W
02 Oct 2018 4.3 SW, W
18-22 Oct 2018 4.3 N, W, WSW, SW
19 Jan 2019 4 E to SE
Figure (see Caption) Figure 7. Dilute ash plumes at Kerinci during July 2018-January 2019. Sentinel-2 natural color (bands 4, 3, 2) satellite images courtesy of Sentinel Hub Playground.

Based on satellite data, a Darwin VAAC advisory reported an ash plume to 4.3 km altitude on 22 July that drifted to the SW and S. Only one day with elevated thermal emission was noted in Sentinel-2 satellite data for the entire reporting period, on 13 September 2018 (figure 8). No thermal signatures were detected by MODVOLC. On 28-29 September there was an ash plume observed to 500-600 m above the peak that dispersed to the W. Several VAAC reports on 2 and 18-22 October detected ash plumes that rose to 4.3 km altitude and drifted in different directions. On 19 January from 0734 to 1000 an ash plume rose to 200 m above the crater and dispersed to the E and SE (figure 9).

Figure (see Caption) Figure 8. Small thermal anomaly at Kerinci volcano on 13 September 2018. False color (urban) image (band 12, 11, 4) courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 9. Small ash plume at Kerinci on 19 January 2018 that reached 200 m above the crater and traveled west. Courtesy of MAGMA Indonesia.

Geologic Background. Gunung Kerinci in central Sumatra forms Indonesia's highest volcano and is one of the most active in Sumatra. It is capped by an unvegetated young summit cone that was constructed NE of an older crater remnant. There is a deep 600-m-wide summit crater often partially filled by a small crater lake that lies on the NE crater floor, opposite the SW-rim summit. The massive 13 x 25 km wide volcano towers 2400-3300 m above surrounding plains and is elongated in a N-S direction. Frequently active, Kerinci has been the source of numerous moderate explosive eruptions since its first recorded eruption in 1838.

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/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Yasur (Vanuatu) — February 2019 Citation iconCite this Report

Yasur

Vanuatu

19.532°S, 169.447°E; summit elev. 361 m

All times are local (unless otherwise noted)


Eruption continues with ongoing explosions and multiple active crater vents, August 2018-January 2019

According to the Vanuatu Meteorology and Geo-Hazards Department (VMGD), which monitors Yasur, the volcano has been in essentially continuous Strombolian activity since Captain Cook observed ash eruptions in 1774, and undoubtedly before that time. VMGD reported that, based on visual observations and seismic data, activity continued through January 2019, with ongoing, sometimes strong, explosions. The Alert Level remained at 2 (on a scale of 0-4). VMGD reminded residents and tourists to remain outside the 395-m-radius permanent exclusion zone and warned that volcanic ash and gas could reach areas influenced by trade winds.

Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were recorded 6-15 days per month during the reporting period, sometimes with multiple pixels. The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, detected numerous hotspots every month. Active crater vents were also frequently visible in Sentinel-2 satellite imagery (figure 50).

Figure (see Caption) Figure 50. Sentinel-2 satellite color infrared image (bands 8, 4, 3) of Yasur on 17 November 2018 showing at least three distinct heat sources in the crater. Courtesy of Sentinel Hub Playground.

Geologic Background. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous Strombolian and Vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Located at the SE tip of Tanna Island, this mostly unvegetated pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone is largely contained within the small Yenkahe caldera, and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide, horseshoe-shaped caldera associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century.

Information Contacts: Geo-Hazards Division, Vanuatu Meteorology and Geo-Hazards Department, 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Ambae (Vanuatu) — February 2019 Citation iconCite this Report

Ambae

Vanuatu

15.389°S, 167.835°E; summit elev. 1496 m

All times are local (unless otherwise noted)


Ash plumes and lahars in July 2018 cause evacuation of the island; intermittent gas-and-steam and ash plumes through January 2019

Ambae is one of the active volcanoes of Vanuatu in the New Hebrides archipelago. Recent eruptions have resulted in multiple evacuations of the local population due to ashfall. The current eruption began in September 2017, with the initial episode ending in November that year. The second episode was from late December 2017 to early February 2018, and the third was during February-April 2018. The Alert Level was raised to 3 in March, then lowered to Level 2 again on 2 June 2018. Eruptive activity began again on 1 July and produced thick ash deposits that significantly impacted the population, resulting in the full evacuation of the Island of Ambae. This report summarizes activity from July 2018 through January 2019 and is based on reports by the Vanuatu Meteorology and Geo-hazards Department (VMGD), The Vanuatu Red Cross, posts on social media, and various satellite data.

On 1 July Ambae entered a new eruption phase, marked by an ash plume that resulted in ashfall on communities in the W to NW parts of Ambae Island and the NE part of Santo Island (figure 78). On 9-10 July VMGD reported that a small eruption continued with activity consisting of ongoing gas-and-steam emissions. An observation flight on 13 July confirmed that the eruption was centered at Lake Voui and consisted of explosions that ejected hot blocks with ongoing gas-and-steam and ash emissions. Populations on Ambae and a neighboring island could hear the eruption, smell the volcanic gases, and see incandescence at night.

Figure (see Caption) Figure 78. Ash plume at Ambae on 1 July 2018 that resulted in ashfall on the W to NW parts of the island, and on the NE part of Santo Island. Courtesy of VMGD.

On 16 July the Darwin VAAC reported an ash plume to 9.1 km that drifted to the NE. During 16-24 July daily ash plumes from the Lake Voui vent rose to altitudes of 2.3-9.1 km and drifted N, NE, E, and SE (figure 79 and 80). Radio New Zealand reported that on the 16th significant ash emission blocked out sunlight, making the underlying area dark at around 1600 local time. Much of E and N Ambae Island experienced heavy ashfall and the eruption could be heard over 30 km away. The Vanuatu Red Cross Society reported worsening conditions in the south on 24 July with ashfall resulting in trees falling and very poor visibility of less than 2 m (figures 81, 82, and 83). The Daily Post reported that by 19 July lahars had washed away two roads and other roads were blocked to western Ambae. Volcanologists who made their way to the area reported widespread damage (figure 84). The Alert Level was raised from level 2 to 3 (on a scale of 0-5) on 21 July due to an increase in ash emission and more sustained plumes, similar to March 2018 activity.

Figure (see Caption) Figure 79. Ash plumes produced by the Ambae eruption in July 2018 as seen in Terra/MODIS visible satellite images. Images courtesy of NASA Worldview.
Figure (see Caption) Figure 80. Sentinel-2 satellite image of an ash plume from Ambae in Vanuatu on 23 July 2018 with the inset showing the ash plume at the vent. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 81. Ashfall at Ambae, posted on 25 July 2018. Courtesy of the Vanuatu Red Cross Society.
Figure (see Caption) Figure 82. An ash plume at Ambae in July during a day and a half of constant ashfall, looking towards the volcano. Courtesy of Michael Rowe.
Figure (see Caption) Figure 83. Ashfall from the eruption at Ambae blocked out the sun near the volcano on 24 July 2018. Courtesy of the Vanuatu Red Cross Society.
Figure (see Caption) Figure 84. Impacts of ashfall near Ambae in July 2018. Photos by Nicholson Naki, courtesy of the Vanuatu Red Cross (posted on 22 July 2018).

At 2100 on 26 July the ongoing explosions produced an ash plume that rose to 12 km and spread NE, E, SE. A state of emergency was announced by the Government of Vanuatu with a call for mandatory evacuations of the island. Ash emissions continued through the next day (figure 85 and 86) with two episodes producing volcanic lightning at 1100-1237 and 1522-2029 on 27 July (figure 87). The Darwin VAAC reported ash plumes up to 2.4-6.4 km, drifting SE and NW, and pilots reported heavy ashfall in Fiji. Large SO2 plumes were detected accompanying the eruptions and moving towards the E (figure 88).

Figure (see Caption) Figure 85. Ash plumes at Ambae at 0830 and 1129 local time on 27 July 2018. The ash plume is significantly larger in the later image. Webcam images from Saratamata courtesy of VMGD.
Figure (see Caption) Figure 86. Two ash plumes from Ambae at 1200 on 27 July 2018 as seen in a Himawari-8 satellite image. Courtesy of Himawari-8 Real-time Web.
Figure (see Caption) Figure 87. Lightning strokes detected at Ambae on 27 July 2018. There were two eruption pulses, 1100-1237 (blue) and 1522-2029 local time (red) that produced 185 and 87 lightning strokes, respectively. Courtesy of William A. Brook, Ronald L. Holle, and Chris Vagasky, Vaisala Inc.
Figure (see Caption) Figure 88. Aura/OMI data showing the large SO2 plumes produced by Ambae in Vanuatu during 22-31 July 2018. Courtesy of NASA Goddard Space Flight Center.

Video footage showed a lahar blocking a road around 2 August. The government of Vanuatu told reporters that the island had been completely evacuated by 14 August. A VMGD bulletin on 22 August reported that activity continued with ongoing gas-and-steam and sometimes ash emissions; residents on neighboring islands could hear the eruption, smell volcanic gases, and see the plumes.

On 1 September at 2015 an explosion sent an ash plume to 4-11 km altitude, drifting E. Later observations in September showed a decrease in activity with no further explosions and plumes limited to white gas-and-steam plumes. On 21 September VMGD reported that the Lake Voui eruption had ceased and the Alert Level was lowered to 2.

Observed activity through October and November dominantly consisted of white gas-and-steam plumes. An explosion on 30 October at 1832 produced an ash plume that rose to 4-5 km and drifted E and SE. Satellite images acquired during July-November show the changing crater area and crater lake water color (figure 89). VMGD volcano alert bulletins on 6, 7, and 21 January 2019 reported that activity continued with gas-and-steam emissions (figure 90). Thermal energy continued to be detected by the MIROVA system through January (figure 91).

Figure (see Caption) Figure 89. The changing lakes of Ambae during volcanic activity in 2018. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 90. A steam plume at Ambae on 21 January 2019. Courtesy of VMGD.
Figure (see Caption) Figure 91. Log radiative power MIROVA plot of MODIS infrared data at Ambae for April 2018 through January 2019 showing the increased thermal energy during the July 2018 eruption and continued activity. Courtesy of MIROVA.

Geologic Background. The island of Ambae, also known as Aoba, is a massive 2500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

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/); Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html); 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/); NASA Worldview (URL: https://worldview.earthdata.nasa.gov/); 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/); Himawari-8 Real-time Web, developed by the NICT Science Cloud project in NICT (National Institute of Information and Communications Technology), Japan, in collaboration with JMA (Japan Meteorological Agency) and CEReS (Center of Environmental Remote Sensing, Chiba University) (URL: https://himawari8.nict.go.jp/); Vanuatu Red Cross Society (URL: https://www.facebook.com/VanuatuRedCross); William A. Brooks and Ronald L. Holle, Vaisala Inc., Tucson, Arizona, and Chris Vagasky, Vaisala Inc., Louisville, Colorado (URL: https://www.vaisala.com/); Michael Rowe, The University of Auckland, 23 Symonds Street, Auckland, 1010, New Zealand (URL: https://unidirectory.auckland.ac.nz/profile/michael-rowe); Radio New Zealand, 155 The Terrace, Wellington 6011, New Zealand (URL: https://www.radionz.co.nz/international/pacific-news/359231/vanuatu-provincial-capital-moves-due-to-volcano); Vanuatu Daily Post (URL: http://dailypost.vu/).


Agung (Indonesia) — February 2019 Citation iconCite this Report

Agung

Indonesia

8.343°S, 115.508°E; summit elev. 2997 m

All times are local (unless otherwise noted)


Ongoing intermittent ash plumes and frequent gas-and-steam plumes during August 2018-January 2019

Agung is an active volcano in Bali, Indonesia, that began its current eruptive episode in September 2017. During this time activity has included ash plumes, gas-and-steam plumes, explosions ejecting ballistic blocks onto the flanks, and lava extrusion within the crater.

This report summarizes activity from August 2018 through January 2019 based on information from 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), and satellite data.

During August 2018 through January 2019 observed activity was largely gas-and steam plumes up to 700 m above the crater (figures 39 and 40). In late December and January there were several explosions that produced ash plumes up to 5.5 km altitude, and ejected ballistic blocks.

Figure (see Caption) Figure 39. Graph showing the observed white gas-and-steam plumes and gray ash plumes at Agung during August 2018 through January 2019. The dates showing no data points coincided with cloudy days where the summit was not visible. Data courtesy of PVMBG.
Figure (see Caption) Figure 40. A white gas-and-steam plume at Agung on 21 December 2018. Courtesy of MAGMA Indonesia.

The Darwin VAAC reported an ash plume on 8-9 August based on satellite data, webcam footage, and ground report information. The ash plume rose to 4.3 km and drifted to the W. They also reported a diffuse ash plume to 3.3 km altitude on 16-17 August based on satellite and webcam data. During September through November there were no ash plumes observed at Agung; activity consisted of white gas-and-steam plumes ranging from 10-500 m above the crater.

Throughout December, when observations could be made, activity mostly consisted of white gas-and-steam plumes up to 400 m above the crater. An explosion occurred at 0409 on 30 December that lasted 3 minutes 8 seconds produced an ash plume rose to an altitude of 5.5 km and moved to the SE and associated incandescence was observed at the crater. Light Ashfall was reported in the Karangasem regency to the NE, including Amlapura City and several villages such as in Seraya Barat Village, Seraya Tengah Village, and Tenggalinggah Village (figure 41).

Figure (see Caption) Figure 41. A webcam image of an explosion at Agung that began at 0409 on 30 December 2018. Light Ashfall was reported in the Karangasem regency. Courtesy of PVMBG.

White gas-and-steam plumes continued through January 2019 rising as much as 600 m above the crater. Several Volcano Observatory Notices for Aviation (VONAs) were issued during 18-22 January. An explosion was recorded at 0245 on 19 January that produced an ash plume to 700 m above the crater and ejected incandescent blocks out to 1 km from the crater. On 21 January another ash plume rose to an estimated plume altitude of 5.1 km. The next morning, at 0342 on the 22nd, an ash plume to an altitude of 2 km that dispersed to the E and SE.

Satellite data shows continued low-level thermal activity in the crater throughout this period. MIROVA thermal data showed activity declining after a peak in July, and a further decline in energy in September (figure 42). Low-level thermal activity continued through December. Sentinel-2 thermal data showed elevated temperatures within the ponded lava in the crater (figure 43).

Figure (see Caption) Figure 42. Log radiative power MIROVA plot of MODIS infrared data for May 2018 through January 2019 showing thermal anomalies at Agung. The black data lines indicate anomalies more than 10 km from the crater, which are likely due to fires. Courtesy of MIROVA.
Figure (see Caption) Figure 43. Sentinel-2 thermal satellite images showing areas of elevated temperatures within the lava ponded in the Agung crater during August 2018 through January 2019. Courtesy of Sentinel Hub Playground.

Geologic Background. Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.

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/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.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/); 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).


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. The 3794-m-high Erebus 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 3200 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. 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).


Villarrica (Chile) — March 2019 Citation iconCite this Report

Villarrica

Chile

39.42°S, 71.93°W; summit elev. 2847 m

All times are local (unless otherwise noted)


Intermittent Strombolian activity ejects incandescent bombs around crater rim, September 2018-February 2019

Historical eruptions at Chile's Villarrica, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. An intermittently active lava lake at the summit has been the source of explosive activity, incandescence, and thermal anomalies for several decades. Sporadic Strombolian activity at the lava lake and small ash emissions have continued since the last large explosion on 3 March 2015. Similar continuing activity during September 2018-February 2019 is covered in this report, with information provided primarily by the Southern Andes Volcano Observatory (Observatorio Volcanológico de Los Andes del Sur, OVDAS), part of Chile's National Service of Geology and Mining (Servicio Nacional de Geología y Minería, SERNAGEOMIN), and Projecto Observación Villarrica Internet (POVI), part of the Fundacion Volcanes de Chile, a research group that studies volcanoes across Chile.

After ash emissions during July 2018 and an increase in of thermal activity from late July through early September 2018 (BGVN 43:10), Villarrica was much quieter through February 2019. Steam plumes rose no more than a few hundred meters above the summit and the number of thermal alerts decreased steadily. Intermittent Strombolian activity sent ejecta a few tens of meters above the summit crater, with larger bombs landing outside the crater rim. A small pyroclastic cone appeared at the surface of the lava lake, about 70 m below the rim, in November. The largest lava fountain rose 35 m above the crater rim in late January 2019.

Steam plumes rose no more than 300 m above the crater during September 2018 and were less than 150 m high in October; incandescence at the summit was visible during clear nights, although a gradual decrease in activity suggested a lowering of the lake level to SERNAGEOMIN. SERNAGEOMIN attributed an increase in LP seismic events from 1,503 in September to 5,279 in October to dynamics of the lava lake inside the summit crater; counts decreased gradually in the following months.

POVI reported webcam evidence of Strombolian activity with ejecta around the crater several times during November 2018. On 5 November the webcam captured an image of an incandescent bomb, more than a meter in diameter, that landed on the NW flank. The next day, explosions sent ejecta 50 m above the edge of the crater, and pyroclastic debris landed around the perimeter. Significant Strombolian explosions on 16 November sent incandescent bombs toward the W rim of the crater (figure 71). The POVI webcam in Pucón captured incandescent ejecta landing on the crater rim on 23 November. POVI scientists observed a small pyroclastic cone, about 10-12 m in diameter, at the bottom of the summit crater on 19 November (figure 72); it was still visible on 25 November.

Figure (see Caption) Figure 71. Strombolian activity at the summit of Villarrica was captured several times in the POVI webcam located in Pucón. An explosion on 5 November 2018 ejected a meter-sized bomb onto the NW flank (left). On 16 November, incandescent bombs were thrown outside the W rim of the crater (right). Courtesy of POVI (Volcán Villarrica, Resumen Gráfico del Comportamiento, November 2017 a Febrero 2019).
Figure (see Caption) Figure 72. A small pyroclastic cone was visible at the bottom of the summit crater at Villarrica (about 70 m deep) on 19 November 2018 (left); it was still visible on 25 November (right). Courtesy of POVI (Volcán Villarrica, Resumen Gráfico del Comportamiento, November 2017 a Febrero 2019).

During December 2018 webcam images showed steam plumes rising less than 350 m above the crater. Infrasound instruments identified two small explosions related to lava lake surface activity. SERNAGEOMIN noted a minor variation in the baseline of the inclinometers; continued monitoring indicated the variation was seasonal. A compilation by POVI of images of the summit crater during 2018 showed the evolution of the lava lake level during the year. It had dropped out of sight early in the year, rose to its highest level in July, and then lowered slightly, remaining stable for the last several months of the year (figure 73).

Figure (see Caption) Figure 73. Evolution of the lava pit at Villarrica during 2018. During July the lava lake level increased and for November and December no significant changes were observed. Courtesy of POVI (Volcán Villarrica, Resumen Gráfico del Comportamiento, November 2017 a Febrero 2019).

Between 25 December 2018 and 15 January 2019, financed with funds contributed by the Fundación Volcanes de Chile, POVI was able to install new HD webcams with continuous daily image recording, greatly improving the level of detail data available of the activity at the summit. POVI reported that after a five-week break, Strombolian explosions resumed on 3 January 2019; the lava fountains rose 20 m above the crater rim, and pyroclastic ejecta fell to the E. On 24 January the Strombolian explosions ejected ash, lapilli, and bombs up to 15 cm in diameter; the lava fountain was about 35 m high.

An explosion on 7 February reached about 29 m above the crater's edge; on 9 February a lava fountain three meters in diameter rose 17 m above the crater rim. Sporadic explosions were imaged on 12 February as well (figure 74). During a reconnaissance overflight on 24 February 2019, POVI scientists observed part of the lava pit at the bottom of the crater (figure 75). As of 28 February they noted a slight but sustained increase in the energy of the explosions. SERNAGEOMIN noted that steam plumes rose 400 m in January and 150 m during February, and incandescence was visible on clear nights during both months.

Figure (see Caption) Figure 74. Strombolian activity at Villarrica in January and February 2019 was imaged with a new HD webcam on several occasions. On 24 January 2019 explosions ejected ash, lapilli, and bombs up to 15 cm in diameter; the lava fountain was about 35 m high (left); on 12 February 2019 explosions rose about 19 m above the crater rim (right). Courtesy of POVI (Volcán Villarrica, Resumen Gráfico del Comportamiento, November 2017 a Febrero 2019).
Figure (see Caption) Figure 75. During a reconnaissance overflight on 24 February 2019, POVI scientists observed part of the lava pit at the bottom of the crater at Villarrica; gas and steam emissions and incandescence from small explosions were noted. Courtesy of POVI (Volcán Villarrica, Resumen Gráfico del Comportamiento, November 2017 a Febrero 2019).

Geologic Background. Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.

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/); Proyecto Observación Villarrica Internet (POVI) (URL: http://www.povi.cl/).

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Bulletin of the Global Volcanism Network - Volume 36, Number 01 (February 2011)

Managing Editor: Richard Wunderman

Bagana (Papua New Guinea)

Occasional ash plumes during 11 February-1 October 2010

Karangetang (Indonesia)

Eruption in August 2010 isolated 20,000 residents and caused four deaths

Kizimen (Russia)

Powerful fissure eruption in November 2010 ends ~82-year repose

Manam (Papua New Guinea)

Ashfall, pyroclastic flows, and seismicity in late December 2010

Merapi (Indonesia)

Eruption started 26 October 2010; 386 deaths, more than 300,000 evacuated

Rumble III (New Zealand)

Eruption in 2009 linked to over 100 m of sea floor collapse

Sangay (Ecuador)

Many plumes seen by pilots during past year ending February 2011

Taal (Philippines)

Intermittent non-eruptive unrest during 2008-2010



Bagana (Papua New Guinea) — February 2011 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)


Occasional ash plumes during 11 February-1 October 2010

This report discusses thermal anomalies and occasional ash plumes at Bagana during February into October 2010, with some satellite thermal data (MODVOLC) as late as early 2011. Our previous report (BGVN 35:02) also noted small lava flows, occasional ash plumes, and thermal anomalies from October 2009 through February 2010.

Historical records describe frequent eruptions since 1842. Bagana lacks instrumental monitoring and sits far from population centers. Many recent observations are remote-sensing based, although the Rabaul Volcano Observatory (RVO) produces reports with direct air- and ground-based observations. Bagana's flanks are covered with andesitic lava flows up to 50 m thick (Blake, 1968). The flows typically descend the mid-slope within the confines of tall lava levees, but emerge from the levees on the outer flanks to form sub-circular flow fields. Bagana's thick lava flows are visible in two photos below (figures 18 and 19).

Figure (see Caption) Figure 18. An International Space Station photo taken on 2 April 2007 showing a diffuse white vapor plume extending SSW from Bagana's summit. The volcano is known for ongoing activity and lava flows of noteworthy thickness (~ 50 m thick). The brown-to-olive colors of the volcano stand out amidst the green of tropical rain forest. Astronaut Photo ISS014-E-18844. Courtesy NASA.

Activity. Between 10 February 2010 and 1 October 2010, the Darwin Volcanic Ash Advisory Center (VAAC) reported one or a few ash plumes per month from Bagana. Many rose to ~3 km and drifted from 20-205 km (table 5). According to RVO, ash plumes were seen on 5 February and night-time incandescence was seen on 2, 12, 13, and 19 February. White vapor was emitted during 1-21 February. Sulfur dioxide plumes drifted ENE during 11-20 February and NNW on 20 and 21 February. Consistent with the thick lava flows, MODVOLC detected well over 100 thermal anomalies at Bagana in the year ending 10 February 2011.

Table 5. Summary of ash plumes from Bagana reported during 1 February-October 2010. Courtesy of the Darwin Volcanic Ash Advisory Centre (VAAC).

Date Altitude (km) Drift (distance and direction)
11-15 Feb 2010 2.4 18-150 km E, NE
19-20, 23, 25 and 27 Apr 2010 1.5-3 35-85 km S, SW, W, NW
06, 10-12 May 2010 2.4-3 55-75 km W, SW, WSW
25-28 May 2010 3 30-185 km NW, W, SW
13-14 Jun 2010 3 75-205 km SW, W
04 Jul 2010 2.4 75 km W
10-11 Jul 2010 2.4 75-150 km SW
13-15 Aug 2010 2.4 75 km SW, W
01 Oct 2010 2.4 75 km NW

Reference. Blake D H, 1968. Post Miocene volcanoes on Bougainville Island, Territory of Papua and New Guinea. Bull Volc, 32: 121-140

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/); Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; NASA Earth Observatory (URL: http://earthobservatory.nasa.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/); Image Science and Analysis Laboratory, NASA-Marshall Space Flight Center (URL: http://eol.jsc.nasa.gov, http://www.flickriver.com/photos/); VolcanoWallpapers (URL: http://www.volcanowallpapers.com/Volcano-Smoke/mount-bagana-volcano/).


Karangetang (Indonesia) — February 2011 Citation iconCite this Report

Karangetang

Indonesia

2.781°N, 125.407°E; summit elev. 1797 m

All times are local (unless otherwise noted)


Eruption in August 2010 isolated 20,000 residents and caused four deaths

A sudden eruption at Karangetang on 6 August 2010 occurred without warning and caused considerable damage. This report covers the interval from 6 August 2010 to mid-March 2011. Previously, the Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) had reported that, after explosions and lava flows during May and June 2009 and a pyroclastic flow and lahar in November 2009, seismicity had declined through early February 2010 (BGVN 35:01). On 12 February 2010, CVGHM had lowered the Alert Level to 2 (on a scale of 1-4).

According to news articles, an explosion on 6 August 2010 ejected hot clouds of gas and sent pyroclastic flows down the W flank. At least one house was buried and several other buildings, including a church, were damaged. A damaged bridge isolated about six villages and their ~20,000 residents, and communication links were lost. According to news reports (CNN and Associated Press), four people were confirmed dead and five were injured, and about 65 were evacuated. The Darwin Volcanic Ash Advisory Centre (VAAC) reported that an ash plume rose to an altitude of 9.1 km and drifted W on that same day.

The news reports cited CVGHM official Priyadi Kardono as noting that the volcano erupted just after midnight when water from heavy rains had penetrated the volcano's hot lava dome, causing the explosion. According to these reports, Kardono said volcanologists did not issue a warning about the eruption because there were no indications of increased volcanic activity. Kardono also noted that the explosion was not large, and the flow of volcanic debris had since decreased.

CVGHM reported that during 1-21 September 2010, lava traveled 75-500 m down Karangetang's flanks and avalanches traveled as far as 2 km down multiple drainages, to the S, E, and W. Incandescent material was ejected up to 500 m above the crater. Ashfall was reported in areas to the NW.

On 21 and 22 September incandescent material traveled down multiple drainages. Strombolian activity was observed on 22 September; material ejected 50 m high fell back down around the crater. That same day, the Alert level was raised to 3.

During November and early December 2010, CVGHM noted a drastic decrease in the occurrence of pyroclastic flows on Karangetang's flanks. Seismicity also decreased. The only reports were of white plumes that rose up to 300 m above the craters. The Alert Level was thus lowered to 2 on 13 December 2010.

According to CVGHM, the Alert Level was again raised from 2 to 3 on 11 March 2011 due to increased seismicity. According to news reports, lava flows were visible and blocks originating from the lava dome traveled as far as 2 km down the flanks, along with hot gas clouds. A Reuters News photo published in Okezone News showed a moderate Strombolian eruption venting from the summit on 11 March, with an apron of incandescent spatter dotting the upper slopes, and a swath of red spatter and bombs bouncing down one flank. Darwin VAAC reported that on that same day, an ash plume rose to an altitude of 2.4 km and drifted 55 km SW; on 13 March, another ash plume rose to an altitude of 3.7 km and drifted 37 km.

During 12-16 March, CVGHM stated that bluish gas plumes rose 50-150 m above the main crater. On 17 March lava flows traveled as far as 2 km from the main crater, accompanied by roaring and booming noises.

On 18 and 20 March lava flows traveled 1.5-1.8 km and collapses from the lava flow fronts generated avalanches that moved another 500 m. Avalanches from the crater traveled 3.8 km down the flanks. Multiple pyroclastic flows about 1.5-2.3 km long destroyed a bridge, damaged a house, and trapped 31 people (later rescued) between the flow paths. Later that day, pyroclastic flows traveled 4 km, reaching the shore. The Alert Level was raised to 4. According to news articles, 600-1,200 people were evacuated from villages on the W flank.

During the week after 20 March, seismicity and deformation declined. The number of new lava flows also declined.

MODVOLC Thermal Alerts. Thermal alerts derived from the Hawai'i Institute of Geophysics and Planetology Thermal Alerts System (MODVOLC) were reported through 19 February 2010 in BGVN 35:01. A significant number of alerts were measured on 19 March 2010 (14 pixels at 0215 UCT on Terra) and 23 March (1 pixel on Aqua), followed by ~5 months without measured alerts. Alerts reappeared during 16 August-19 October 2010. Alerts were absent between 20 October 2010 and 10 March 2011, followed by renewed alerts during 11-12 March 2011.

Geologic Background. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.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/); Okezone News (URL: http://news.okezone.com/read/2011/03/12/340/434280/gunung-muntahkan-lava-pijar); Associated Press (URL: http://www.ap.org/); Reuters (URL: http://www.reuters.com/); CNN (URL: http://www.cnn.com/); Straits Times (URL: http://www.straitstimes.com/); Novinite (URL: http://www.novinite.com/).


Kizimen (Russia) — February 2011 Citation iconCite this Report

Kizimen

Russia

55.131°N, 160.32°E; summit elev. 2334 m

All times are local (unless otherwise noted)


Powerful fissure eruption in November 2010 ends ~82-year repose

Eruption began here during mid-November 2010, the first since 1927-1928 (Brown and other, 2010). Ash plumes rose to ~10 km and were visible in satellite imagery as they traveled hundreds of kilometers during November 2010 through at least late February 2011. Our previous Bulletin (BGVN 35:02) reported that the number of earthquakes at Kizimen had increased substantially beginning in July 2009 (up to 120 earthquakes per day) through early April 2010 and that fumarolic temperatures increased in August. This report discusses activity since early April 2010.

After early April 2010, seismicity at Kizimen entered a quiescent phase until the Kamchatkan Volcanic Eruption Response Team (KVERT) reported increased seismic activity on 20 August and particularly during early November 2010. Based on information from a tourist center 10 km from Kizimen, KVERT noted that on 11 November 2010, strong gas-and-steam emissions resulted in a plume, possibly containing some ash, that rose to an altitude of 4 km.

According to the Kamchatkan Branch of Geophysical Survey (KG GS RAS), seismicity of the volcano was above background levels all week, and an M 4 earthquake occurred on 16 November 2010. Accroding to information from the Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 17 November an ash plume from Kizimen rose to an altitude of 3 km and drifted NE. KVERT noted the lack of satellite data about ash near Kizimen. The Level of Aviation Color Code remained at Green (on a scale that goes from low to high using these terms: Green, Yellow, Orange, and Red).

On 17 November 2010 (UTC), based on information from KB GS RAS and analysis of satellite imagery, the Tokyo VAAC reported that an ash plume rose to an altitude of 3 km and drifted NE. KVERT noted lightning in the ash plumes. The Aviation Color Code was raised to Red.

Seismic activity was above background levels during 19 November to 24 December 2010. On 20 November, volcanologists flying around Kizimen by helicopter observed several new fumaroles at the summit and SW flank. A small amount of "dust" covered the SW flank, possibly ash from the new fumaroles. Activity at the established old fumarole "Revuschaya" on the volcano's NE flank decreased. No thermal anomaly was noted from satellite images. The Level of Aviation Color Code was raised to Yellow.

On 9 December 2010, seismicity increased significantly and the Aviation Color Code level was raised to Orange. That same day, the Tokyo VAAC reported that, according to KB GS RAS, an explosion produced a plume that rose to an altitude of 2.7 km and drifted N. Ash was not identified in satellite images. A bright thermal anomaly was observed in satellite imagery the next day.

The beginning of the eruption Kizimen was captured in in a photo made by Don Page on 10 December from a commercial flight. The eruption start from long fissure on the SE slope (figure 5).

Figure (see Caption) Figure 5. Photo taken on 10 December 2010 at 0314 UTC (1414 local Kamchatka time; from Seat 36K of Air Canada Flight 063 from Vancouver, Canada, to Incheon-Seoul, Korea). A dark, angled (non-vertical) plume rises from the along the length of an elongate fissure network on the SE slope. [Photo: 981x656 pixels, with a Nikon D80 digital camera and an AF-S Nikkor 18-200 mm zoom lens (probably set at 200 mm).] Photo by Don Nelson Page (University of Alberta).

Evgeny Gordeev wrote a reply to Don Page thanking him for sharing the rare photos (figure 5) of the eruption's start and providing interpretation of the unusual genesis of the ash cloud. Gordeev told Page that he had documented the beginning of the Kizimen 10 December eruption, noting that the closest village to Kizimen is almost 100 km distant. Gordeev commented that the only practical way to monitor the volcano involves satellite images, which are discontinuous and not always of high resolution. "Your pictures help us enormously, mainly to recognize the vent of eruption. It is very unusual for volcanoes to erupt through [such a] long fissure on the slope. You are right, this fissure [is] very narrow and very long. After [this,] your pictures you will be very [well] known [by] volcanologists."

On 12 December 2010 an explosive eruption generated ash plumes that rose to an altitude of 3-3.5 km and drifted NW. Ash deposits in Kozyrevsk and Tigil, 110 and 308 km NW, respectively, were 5 mm thick. Later that day seismic activity decreased and the Aviation Color Code was lowered to Orange. Kronotsky National Park staff, residing at Ipuin (~16 km WSW), noted that the water level in Levaya Schapina river rose 60 cm after the explosions and remained elevated for the next two days. The water was also very muddy. During 14-24 December seismicity remained above background and a thermal anomaly over the lava dome was detected in satellite imagery.

KVERT noted that during 17-24 December 2010 the number of shallow seismic earthquakes increased from 110 events on 17 December to 304 events on 22 December. Volcanic tremor was detected on 23 December. During 26-28 December, seismicity also increased and there were possible small ash explosions and hot avalanches. A thermal anomaly over the lava dome was again seen in satellite imagery. On 27 December seismic analysis indicated that ash plumes that day possibly rose to altitudes of 3.5-4.5 km. Satellite imagery showed ash plumes drifting 140 km W at an altitude of 4 km. On 28 December, based on a Yelizovo Airport (UHPP) notice, the Tokyo VAAC reported an ash plume drifting W at an altitude of 3.7 km. The Aviation Color Code was raised to Red.

A thermal anomaly over Kizimen's lava dome was again observed in satellite imagery during 29 December 2010-1 January 2011 and an explosive eruption that began on 13 December continued. On 31 December seismicity increased and volcanic tremor was detected. Explosions occurred sporadically for a period of about 20 minutes. Ash plumes detected in satellite imagery rose to an altitude of 8 km and drifted SW. Ashfall at least 1 mm thick occurred in multiple areas 225-275 km SSW, including Petropavlovsk-Kamchatsky, Yelizovo, Paratunka, and Nalychevo. Ash plumes at an altitude of 4 km drifted 480-500 km SW; ash continued to accumulate in some areas.

Seismic data indicated increased activity on 3 January. Based on analysis of satellite imagery, the Tokyo VAAC reported that possible eruptions during 2-4 January produced plumes that rose to an altitude of 3-4.6 km and drifted S, E, and NE. Subsequent images on those same days showed ash emissions continuing, then dissipating. During 4-7 January seismicity remained high and variable and volcanic tremor continued. A thermal anomaly over the volcano was observed in satellite imagery. Explosions continued through 7 January 2011 producing ash plumes mostly below altitudes of 6-8 km as reported by pilots or observed in satellite imagery. These drifted more than 200 km SE. A large and bright thermal anomaly was observed in satellite imagery.

A pattern of high seismicity and ash emissions was noted during early January 2011. On 5 January ash plumes drifted more than 500 km ENE. Ashfall was reported on the Komandorsky Islands, 350-500 km E (figure 6).

Figure (see Caption) Figure 6. An ash plume rising from Kizimen and blowing to the ENE on 5 January 2011. Courtesy of A. Lobashevsky.

The Tokyo VAAC reported that ash continued to be observed in satellite imagery on 5 January. According to information from KVERT and analyses of satellite imagery, a possible eruption on 6 January produced a plume that rose to an altitude of 3.7 km and drifted E. Subsequent satellite images that same day showed continuing ash emissions. Ash plumes drifted NW on 9 January, and drifted NW again on 11 January 2011, at an altitude of 2.7 km.

KVERT reported that during 7-13 January 2011 they saw both a thermal anomaly over Kizimen in satellite imagery and pyroclastic flow deposits on the E flank. Seismicity recorded during 6-7 and 12 January was high but variable, and many shallow volcanic earthquakes as well as volcanic tremor continued to be detected. Ash plumes that rose to altitudes of 6-8 km during 5-13 January were seen drifting multiple directions, and appeared in satellite imagery to be drifting more than 275 km W and NW. On 12 January ashfall was reported in the villages of Anavgai and Esso, 140 km NW. Seismic data during 14-15 January suggested that ash plumes rose to altitudes of 4-5 km. Satellite images showed a bright thermal anomaly over the volcano and ash plumes drifting more than 180 km W on 15 January 2011. The Aviation Color Code level was lowered to Orange.

From 14 January through 1 February, KVERT reported that seismicity from Kizimen was high but variable, and many shallow volcanic earthquakes as well as volcanic tremor continued to be detected. Seismic data analyses suggested that ash plumes possibly rose to an altitude no higher than 6 km. Satellite images showed a daily bright thermal anomaly over the volcano, and ash plumes that drifted more than 200 km W during 15-16 and 20 January. Based on satellite data, the Tokyo VAAC also reported that during 23-25 January eruptions produced plumes that rose to altitudes of 4.9-10.1 km. Based on analyses of satellite imagery, the Tokyo VAAC reported that a possible eruption on 29 January produced a plume that rose to an altitude of 3.7 km and drifted SW. Photo and satellite images taken during late January through late February showed continuing ash emissions (figures 7 and 8).

Figure (see Caption) Figure 7. Two images of Kizimen taken on 26 January 2011. On the left photo (a), a dark pyroclastic flow rushes down the slopes of the volcano. Photo by Igor Shpilenok. On the right (b), a thermal infra-red (IR) image taken of a pyroclastic flow during an explosion (IR scale temperature appears at right). The pyroclastic flow originated from the summit of the lava dome and swept downward. (The infrared image shows radiated energy as areas of bright glow.) During this eruptive stage a pyroclastic surge spread out over the slopes. IR image by V. Droznin, S. Chirkov, and I. Dubrovskaya (IVS RAS).
Figure (see Caption) Figure 8. This satellite image taken on 25 February 2011 shows a vigorous ash-laden plume extending from Kizimen at an altitude of ~3 km, drifting towards the NE, and visible for more than 170 km. The white portion of the plume is likely rich in steam, while the tan plume is primarily ash. The ground E of Kizimen is coated in newly fallen ash not yet covered by fresh snow. To the S of the summit are several dark streaks. These are probably traces of pyroclastic flows. Thermal anomalies (red in colored versions of this Bulletin) show the presence of recent hot block-and-ash flows from summit dome collapses. The image was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. Courtesy of NASA/GSFC/METI/ERSDAC/JAROS.

Reference: Browne B., Izbekov, P., Eichelberger, J., and Churikova, T., 2010, Pre-eruptive storage conditions of the Holocene dacite erupted from Kizimen Volcano, Kamchatka: International Geology Review, v. 52, Issue 1 January 2010, p. 95-110.

Geologic Background. Kizimen is an isolated, conical stratovolcano that is morphologically similar to St. Helens prior to its 1980 eruption. The summit consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2334-m-high edifice was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2000-3500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of long-term lava dome growth have occurred. The latest eruptive cycle began about 3000 years ago with a large explosion and was followed by intermittent lava dome growth lasting about 1000 years. An explosive eruption about 1100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. Prior to 2010, only a single explosive eruption, during 1927-28, had been recorded in historical time.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanology and Seismology Russian Academy of Sciences, Far East Division, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); Sergey Senukov, Russia (URL: http://www.emsd.ru/) Valery Droznin and Sergey Chirkov, Institute of Volcanology and Seismology Russian Academy of Sciences, Far Eastern Branch, 9 Piip Boulevard, Petropavlovsk-Kamchatsky, 683006, Russia; A. Lobashevsky (URL: http://www.photokamchatka.ru/); I. Shpilenok (URL: http://shpilenok.livejournal.com/44922.html); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/); Don Nelson Page, Theoretical Physics Institute, 412 Physics Lab., University of Alberta, Edmonton, Alberta T6G 2J1, Canada.


Manam (Papua New Guinea) — February 2011 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)


Ashfall, pyroclastic flows, and seismicity in late December 2010

This report discusses Manam behavior during November 2010 to early 2011. As previously reported, during August-October 2010, lava fragments and ash plumes rose from Manam (BGVN 35:09). Similar activity continued through at least 4 January 2011. Over 10,000 former island residents remain in care centers on the mainland (see below).

During the reporting period, the Rabaul Volcano Observatory (RVO) reported that the Main Crater produced mostly white plumes that were occasionally laden with ash. Incandescent material was ejected at times and mainly fell back in and around the crater, but occasionally spilled into the SE and SW valleys.

Based on analysis of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that ash plumes during 14-16 November 2010 rose to an altitude of 2.7 km and drifted ~95 km NW.

RVO reported that light brown to dark gray ash plumes rose 400-500 m above the South Crater during late November. People living on the island reported occasional roaring and rumbling noises. A new episode of eruptive activity began at South Crater on 25 December and was characterized during 25-29 December by rising ash plumes and ejections of incandescent lava fragments. Electronic tilt measurements showed a strong inflationary trend during 24-26 December but this slowed down on 26 December.

On 30 December 2010, activity from South Crater increased and was reported by observers in Bogia (on the mainland 20 km SSW). A dense ash plume rose 3 km above the summit crater and drifted NW, causing light ashfall in Tabele (4 km SW of Manam). An observer at Tabele confirmed the eruption and also reported that three pyroclastic flows descended the SE valley, stopping within a few to several hundred meters from the coastline. The first and largest pyroclastic flow devastated a broad unpopulated area between Warisi (E of Manam) and Dugulava (S of Manam) villages. RVO increased the Alert Level to Stage 3. Later that day, both ash emissions and the ejection of incandescent fragments diminished.

During early January 2011, plumes, sometimes containing ash, continued to rise above the South and Main Craters. RVO reported low roaring from the South Crater and incandescence was reported at times. On 8 January, the Alert Level was lowered from Stage 3 to Stage 2.

Seismicity and MODVOLC thermal alerts. Seismic data were not available during late November because of technical problems. Seismicity was low on 24 December, increased slightly after 25 December, then reached a point after 27 December where it fluctuated at and above moderate level. RVO reported seismicity during early January 2011 to be at a moderately low to moderate level.

Between 16 October 2010 and 10 January 2011, MODVOLC detected thermal anomalies on 25 days, mostly during late November and December. After 10 January, no thermal anomalies were detected through at least 16 February.

Multi-year evacuation. The UN's IRIN (Integrated Regional Information Networks) discussed Manam evacuees in reports issued 5 May and 20 December 2010. The 5 May 2010 report stated that "Around 14,000 islanders have been living in three care centres in the mainland province of Madang since November 2004. In March 2010 there was discussion that the displaced persons might be allowed to voluntarily return home to Manam Island."

According to the report, "A July 2009 assessment by the National Disaster Centre, the UN, and Oxfam concluded that living on the island was not a viable option because of a lack of access to arable land and public services, and the risk of further volcanic activity."

"The decision to begin returning residents was taken following heightened tensions between islanders and local residents (they speak the same language), largely over land issues. With little to no assistance, many of the IDPs rely on local gardening as their only source of food and livelihood, meaning they often encroach on nearby land.

"In March 2010, the National Executive Council (NEC) approved the establishment of the Manam Task Force Committee to manage the needs of the displaced islanders, with the primary goal of finding a suitable location for their permanent relocation."

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), PO Box 386, Rabaul, Papua New Guinea; 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/).


Merapi (Indonesia) — February 2011 Citation iconCite this Report

Merapi

Indonesia

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

All times are local (unless otherwise noted)


Eruption started 26 October 2010; 386 deaths, more than 300,000 evacuated

This report represents a preliminary discussion of the deadly eruption at Merapi that started on 26 October 2010. That eruption included weeks of instability that generated pyroclastic (block-and-ash) flows, which became particularly vigorous and numerous in early November, with at least one surge reportedly traveling along the Gendol drainage to 15-16 km from the summit dome. Of particular note from a hazards perspective, the path of some of these deposits differed at times from those of the recent past (but we have yet to find maps showing the flow directions and associated dates). An abstract by Lavigne and others (2011) reported the volume of tephra erupted in the 2010 eruption at over 100 x 106 m3, ~10-fold higher than similar deposits after typical eruptions in the past few decades, and among the factors why ongoing lahars are likely to be a hazard.

Our summary covers events into late 2010, with recognition of ongoing seismicity, weaker emissions, and repeated lahars in early 2011. The bulk of this report is based on those from the Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) and their observatory dedicated to Merapi (MVO). According to CVGHM, the 2010 eruption was the biggest since the 1872 eruption. Eruptions in 1930 killed around 1,300 people. The last eruption of Merapi occurred during March 2006-August 2007 (BGVN 31:05, 31:06, 32:02, and 33:10). A table appears near the end of this report summarizing some key events and observations. Fatalities and scale of evacuations are discussed in a separate subsection below. Another subsection notes that at least one commercial airliner sustained serious in-flight engine damage.

Regional background and prior eruptive patterns. Merapi (figures 38, 39, and 40) is located in the central part of Java, and this region and the island as a whole have extremely high population density (roughly double that of Japan or Thailand). Substantial numbers of people live or vacation on the mountain. The most densely settled part of the mountain is the dangerous S side (figure 39).

Figure (see Caption) Figure 38. (Bottom) Two maps showing Merapi's location and (on the larger map) the distribution of block-and-ash flows that took place during 1954-1998. During that interval, these deposits went to the NW, W, and SW. From Hort and others (2006).
Figure (see Caption) Figure 39. A map of the S portion of Merapi showing population data in shaded patterns with key at left. The segments of circles depict distances from the summit. The 2010 eruptions sent pyroclastic flows through Merapi's SE quadrant, thus passing areas of elevated population. Taken from OCHA (8 November 2010).
Figure (see Caption) Figure 40. A set of simple diagrams illustrating Merapi in cross section (looking W; S is to the left) summarizing behavior that occurred during 1986-1994 (such a diagram has yet to be published for the 2010 eruption). The 1989 case shows VT earthquakes in the edifice (circles containing crosses). Taken from Ratdomopurbo and Poupinet (2000).

Figure 38 provides a summary of block-and ash-flow deposits from 1954-1998 (Hort and others, 2006; Schwarzkopf, 2001). The eruptions starting in October 2010 sent pyroclastic flows and possible surges at least 15 km in the volcano's W to S quadrant. Block-and-ash flows are pyroclastic flows formed by dome collapse and containing a substantial amount of broken dome fragments.

The inset map at the lower left shows Merapi with respect to the city of Yogyakarta (30 km SSW). Although the metro area of that city has a population of 1.6 million residents, the Indonesian statistical bureau estimated the 2010 populations of the ~30 km2 city of Yogyakarta at ~396,000 residents, and the broader region at ~3.5 million residents.

Figure 39 shows the summit and S part of Merapi, plotting population data by village at distances up to 20-25 km from the summit. This side of the volcano is by far the most densely populated, and was also crossed by numerous pyroclastic flows both historically and in the 2010 eruptions.

Figure 40 illustrates critical processes in Merapi's mode of eruption in the recent past. A significant portion of the dome is unconfined by the summit crater and the S side is free to descend the volcano's upper slopes endangering residents below. In the recent episode, CVGHM benefitted from daily access to satellite radar imagery that reliably depicted dome morphology despite weather and steam clouds. Vöge and Hort (2008) and Hort and others (2006) discuss monitoring dome instability using Doppler radar.

Monitoring and lead-up to the 26 October 2010 eruption. Since 2007, short swarms of volcanic earthquakes occurred (eg., on 31 October 2009, 6 December 2009, and 10 June 2010). Monitored parameters, including earthquakes, deformation, and gas emmisions increased significantly during September 2010. Steeper increases in seismicity appeared during 15-26 October with the main ramp-up during 20-26 October.

Figure 41 shows several histograms that depict Merapi seismic data and summarize the variations in hazard status. The CVGHM scale, which stretches from 1 (low) to 4 (high), makes a complete ascent and partial descent through the full range of those levels during the date range shown. The heavy vertical line between Alert Levels 3 and 4 took place on 25 October, slightly before the onset of the major eruption on 26 October.

Figure (see Caption) Figure 41. Three histograms describing Merapi seismicity during 1 September 2010 to 6 March 2011. Horizontal scale marked in weeks and extends from 1 September 2010 to 5 March 2011. Words along the top line show hazard status (on an increasing scale starting from 1 [Normal] and extending to 2 [Waspada]), to 3 [Siaga]), and finally to 4 [Awas] and then declining). The top panel contains seismically inferred rockfalls and avalanches (guguran in Indonesian). The middle panel shows multiphase (MP) earthquakes (shallow source, dominant frequency ~1.5 Hz). The bottom panel shows volcanic earthquakes of both A- and B-type (where VTA represents deep volcano-tectonic earthquakes, 2.5-5 km below the summit; VTB represents shallow volcano-tectonic earthquakes, less than ~1.5 km below the summit). Taken from CVGHM report of 7 March, with minor revisions by Bulletin editors.

Figure 42 presents typical waveforms for various types of earthquakes and tremor signals previously recorded at Merapi (Ratdomopurbo and Poupinet, 2000). Both multiphase (MP) and volcanic type-A (VTA) showed strong peaks in seismicity prior to the 26 October eruption's onset. Rockfalls on upper panel (labeled guguran) and type-b events on bottom panel both peaked on or near 26 October.

Figure (see Caption) Figure 42. Typical waveforms, tremor signals, and descriptive seismic terminology in use at Merapi. These include tremor, LF-low frequency (earthquakes nominally from shallow sources, dominant frequency between 3 and 4 Hz), VTA and VTB (volcano-tectonic A and B, where VTA represents deeper volcano-tectonic earthquakes, 2.5-5 km below the summit; and VTB represents shallower volcano-tectonic earthquake, less than ~1.5 km below the summit), and MP-multiphase earthquakes. Records are from Station PUS (~0.5 km E of summit), shown in the upper part of the figure, and from Station DEL (~3 km SE of the summit), in the lower part. From Ratdomopurbo and Poupinet (2000).

The onset of the 26 October explosion occurred ~19 hours after an M 7.7 tectonic earthquake along the trench near the Mentawai islands adjacent to Central Sumatra, 1,200 km NW of Merapi. This earthquake was followed by several aftershocks, including two prior to the eruption (M 6.1 and 6.2) and one after the eruption (M 5.8). One or more of these earthquakes triggered tsunamis that hit the remote Mentawai islands, sweeping entire villages to sea and killing at least 428 people. There, too, thousands of people were displaced. The two near-simultaneous crises taxed authorities, NGOs, and the natural hazards community (figure 43).

Figure (see Caption) Figure 43. A map emphasizing the locations of the M 7.7 tsunamigenic (tsunami-generating) earthquake and the eruption onset at Merapi, events of 25 and 26 October, respectively. (The earthquake time stated is incorrect—according to USGS cataloging, it registered at 1442 UTC on the 25th, which corresponds to 2142 local time that day. The eruption began at 1002 UTC on the 26th). Jakara is Indonesia's capital. Courtesy of Relief Web.

Except for the close timing and regional proximity, the linkage between the M 7.7 earthquake and the eruption remains ambiguous. However, many researchers have noted that tectonic earthquakes can seemingly trigger volcanic responses (eg., Delle Donne and others, 2010; Lowenstern, JB, Smith, RB, and Hill, DP, 2006; Manga and Brodsky, 2006).

In early September 2010, the pattern of increased volcanic seismicity began to appear with MP earthquakes averaging 10/day and VTA and VTB averaging 3/day, with a total daily seismic energy of 603 x 1012 erg.

Gas analyses in August 2010 showed concentrations of HCl of 0.8 % mol and H2O of 80 % mol. Declining levels of H2O (less than 90 %) and increased levels of HCl (>0.5 %) were interpreted to indicate increased activity.

In September, summit inflation increased markedly. Seismicity also increased beginning on 12 September, when an M 2.5 VTA earthquake and pyroclastic flows/avalanches occurred. On 13 September, VTA earthquakes occurred twice, and white plumes rose 800 m above the crater.

During 23-26 October, there were small steam-and-ash emissions. Inflation increased sharply on 24 October to a rate of 420 mm/day. The next day, CVGHM raised the Alert Level to 4, and recommended immediate evacuation for several communities within a 10-km radius. A Reuters photo by Dwi Oblo taken at sunrise on 26 October looking up at the dome and the prominent S-trending avalanche channel revealed comparatively calm conditions, with emissions consisting of a thick white steam plume blowing W from the dome.

Initial October eruptions. The first eruption occurred at 1702 on 26 October 2010, an event characterized by explosions and multiple pyroclastic flows that traveled S ~8 km down the Gendol and Kuning drainages, and to some extent WSW down the Bedog drainage. Most of the pyroclastic flows lasted 2-9 minutes, but the eruptions associated with the final two each lasted 35 minutes. The event killed 35 people including the renowned mystical guardian of Merapi, Mbah Mbahmarijan, at 7 km distance.

Figure 44 shows an exposed ridge affected by pyroclastic flows in a photo taken on 27 October.

Figure (see Caption) Figure 44. An exposed ridge at Merapi as it appeared the day after the 26 October eruption. Pyroclastic flows had reduced forest to stumps, leaving stripped and fallen trees. Courtesy of The Boston Globe website of Merapi photos (Ulet Ifansasti/Getty Images).

According to the Darwin Volcanic Ash Advisory Center (VAAC), an ash plume rose to an altitude of 18 km, followed by extrusion of lava in the summit crater.

By 27 October the lava dome had sustained damage and a new 200-m-diameter crater had formed at the summit. After that, lava extrusions built a small dome in the crater. A space-based estimate made from the ozone monitoring instrument (OMI) indicated the eruption on the 26th vented at least 3,000 metric tons of SO2 gas. According to the Darwin VAAC, ground-based reports indicated that another explosion occurred on 28 October 2010. Cloud cover prevented satellite observations.

Following the eruption and continuing through 4 November, intense tremor took place. It was felt by people up to 20 km from the volcano.

CVGHM reported that two pyroclastic flows occurred on 30 October following an early morning explosion, the third since 26 October. According to a news article, ash fell in Yogyakarta, 30 km SSW, causing low visibility. CVGHM noted four pyroclastic flows on 31 October.

Stronger eruptions in November. According to CVGHM, during 31 October-4 November, a lava dome grew rapidly within Merapi's summit crater. Collapses from the S side of the dome fed minor pyroclastic flows that extended several hundred meters into the upper part of the Gendol valley.

On 1 November, an explosion began mid-morning with a low-frequency earthquake, and avalanches occurred. About seven pyroclastic flows occurred during the next few hours (figure 45), traveling SSE a maximum runout distance of 4 km, and in another (possibly later) case that day, 9 km. The Darwin VAAC reported that the explosion produced an ash plume that rose to an altitude of 6.1 km. News reports noted flight diversions and cancellations in and out of the airports serving Solo (40 km E) and Yogyakarta.

Figure (see Caption) Figure 45. On 1 November 2010, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this thermal signature of Merapi's lava dome and hot pyroclastic flows. The thermal information is overlaid on a three-dimensional map of the volcano to show the approximate location of the pyroclastic flow. The three-dimensional data is from a global topographic model created using ASTER stereo observations. Courtesy of NASA Earth Observatory website (credit to Robert Simmon and Jesse Allen and NASA/GSFC/METI/ERSDAC/JAROS, and the U.S./Japan ASTER Science Team). Original caption by Holli Riebeek.

On 2 November, an ash plume was seen in satellite imagery drifting 75 km N at an altitude of 6.1 km. On the same day, CVGHM reported 26 pyroclastic flows. On 3 November, observers stationed at multiple posts reported ash plumes from pyroclastic flows. One pyroclastic flow traveled 10 km, prompting CVGHM to extend the hazard zone from a radius of 10 km to 15 km, and they recommended evacuations from several more communities. Another pyroclastic flow traveled 9 km SE later that day. Figure 46 shows a 2 November view of Merapi.

Figure (see Caption) Figure 46. Incandescent material spilled from Merapi's dome glows orange-red in colored versions of this long-exposure photograph taken on 2 November 2010 from ~25 km SSE of the summit (Klaten district). Condensate droplets in the thin (lenticular) clouds over the summit also reflect considerable light. Courtesy of The Boston Globe (Boston.com website); photo credit to Sonny Timbelaka (AFP/Getty Images).

CVGHM reported that, during 3-8 November, the eruption from Merapi continued at a vigorous pace, characterized by incandescent avalanches from the lava dome, pyroclastic flows, ash plumes, and occasional explosions.

Visual observations were often difficult due to inclement weather and eruption plumes. To overcome these challenges, people working on the crisis gained regular access to satellite radar data of high resolution (RADARSAT2). That data was made available 25 October through an agreement called the International Charter Space and Major Disasters.

According to the NASA Earth Observatory website, the strongest explosion during the 2010 eruption took place on 4-5 November, lasting more than 24 hours, when plumes rose to ~18 km altitude and drifted 110 km W. They claimed that some surges of pyroclastic material reached an 18 km runout distance (direction and damage unstated and several kilometers longer than some other observations). They also said that, according to local geologists, this explosion was the most violent one at Merapi since the 1870's. They noted that, by some estimates, the 4-5 November eruption was five times more intense than the one on 26 October.

A CVGHM report on the 4-5 November eruption stated that 38 pyroclastic flows had occurred before it ended. Although dense fog hampered visual observations, a CVGHM observer from Kaliurang post (~7 km S of the summit) saw 19 of those 38 flows travel ~4 km S. Another traveled 9 km SE. Ashfall was noted in some nearby areas. Satellite data indicated this explosion released much more SO2 than previous recent Merapi eruptions, ~300,000 metric tons.

Residents in towns up to 240 km away reported that 'heavy gray ash' blanketed trees, cars, and roads. On 5 November, rumbling sounds were heard in areas 30 km away, and pyroclastic flows continued to descend the flanks. Ash fell in Yogyakarta and "sand"-sized tephra fell within 15 km. CVGHM recommended evacuations from several more towns within a 20-km radius. Observations shortly after the 5 November eruption showed that the large lava dome of the previous week had been destroyed, and the summit crater had enlarged to a diameter of 300-400 m. However, by 6 November, another lava dome had grown, amassing, according to RADARSAT images 11 hours apart, at a rate of ~35 m3 per second.

Activity remained very intense on 6 November. Pyroclastic flows continued to descend the flanks; one flow traveled 4 km down the Senowo drainage to the W. Incandescent flashes from the lava dome were reported from observations posts, and incandescent material was ejected above the crater. Incandescent avalanches traveled 2 km down multiple drainages to the SSE, S, and SSW. The Darwin VAAC reported that ash plumes seen in satellite imagery rose to an altitude of 16.8 km on 5 and 6 November.

During this period, ashfall was heavy on Merapi's flanks, and was observed in multiple surrounding areas, including the villages of Selo (~5 km NNE) and Magelang (26 km WNW). In Muntilan village (18 km WSW), tephra and ash accumulated up to 4 cm. At the volcano, a new dome formed during 6-7 November 2010; it stood ~240 m in a NW-SE orientation, 140 m wide, and 40-50 m high.

On 7 November, the number of pyroclastic flows increased from the previous day. An explosion was heard, and ash plumes rose 6 km and drifted W. Lightning was seen from Yogyakarta. Pyroclastic flows traveled 5 km, and lava avalanches moved 600 m S and SW. The next day, ash plumes rose to altitudes of 6-7 km and were accompanied by rumbling sounds. According to the Darwin VAAC, satellite imagery during 7-8 November showed ash plumes at an altitude of 7.6 km drifting 165-220 km W and SW.

Figure 47 shows Merapi's erupted SO2 in the atmosphere during 4-8 November 2010. On 9 November, an SO2 cloud was seen over the Indian Ocean at altitudes of 12-15 km.

Figure (see Caption) Figure 47. SO2 concentration-pathlength (in Dobson units, with 100 DU as darkest colors) during 4-8 November 2010, as observed by the OMI on NASA's Aura spacecraft. OMI data provided courtesy of Simon Carn (Michigan Technical University). Courtesy of Natural Hazards NASA Earth Observatory website (image by Jesse Allen, and original caption by Michon Scott).

The European Space Agency (ESA) has created updates on SO2 gas retrieval from their Envisat, Eumetsat's MetOp, and NASA's Aura satellites. For the interval 4-13 November 2010, the peak atmospheric loading of SO2 appeared on 8 November at 227 kT SO2. The estimates can be seen presented as animations that depict complex rotating dispersal patterns. As seen in figure 47, significant portions of the gas blew over Western Australia. In Norwegian Institute for Air Research models shown in the article, many of the Merapi plumes centered around 15 km altitude, with tops and bottoms ~5 km above and below that height.

ESA (2010) quoted Andrew Tupper as saying, "The updates from ESA have been very useful to Darwin VAAC [Volcanic Ash Advisory Center] when received in real time, and we expect that in the post-event analysis we'll be able to show lots more potential value." The SO2 maps can help the aviation community avoid dangerous emissions from volcanoes.

ESA (2010) noted that they send SO2 email alerts in near-real time. The alerts link to a web page with a map showing the location of the sulphur dioxide peak.

Reduced eruptive vigor; lahars. Eruptions and seismicity generally dropped during mid-November 2010 into March 2011, but lahars became a problem. On 9 November, CVGHM noted a reduction in the intensity of activity; a single pyroclastic flow occurred in a 6-hour period. Rumbling sounds were accompanied by an ash plume that rose to an altitude of 4.5 km, and ashfall was reported in Selo (~5 km NNE). Lava-dome incandescence was again observed, and lava avalanches moved 800 m SSE.

During 10-11 November, seismicity continued to decrease. Lahar deposits were seen in multiple drainages, at a maximum distance of 16.5 km from the summit. On 10 November, plumes generally rose 0.8-1.5 km above the crater. Heavy ashfall was reported in areas to the WSW and WNW. A 3.5-km-long pyroclastic flow and a 200-m-long avalanche both traveled S in the Gendol drainage. Incandescence from the crater was observed through a closed-circuit television system at the Merapi museum (in the village of Kaliurang, ~7 km S of the summit). On 11 November, roaring was followed by light ashfall at the Ketep Merapi observation post, ~9 km NW of the summit. Plumes, brownish-black at times, rose 800 m above the crater and drifted W and NW, and one plume rose 1.5 km. Avalanches again proceeded S in the Gendol drainage.

According to the Darwin VAAC, during 12-21 November, ash plumes rose as high as 7.6 km and drifted in multiple directions. The SO2 concentration at high altitudes decreased. About 300,000 residents also began to return home after the "danger zone" was reduced in some areas due to decreased activity.

Between 10 November and 1 December, lahar deposits were seen in multiple drainages and in all rivers flowing from Merapi. CVGHM noted that several bridges had been damaged. On 29 November, a narrow tongue of lava was observed, and light-colored flow deposits extended S down several narrow channels (Gendol and Kuning drainages) at least 5 km from the summit.

According to CVGHM, seismicity declined further during 1-3 December, in number of volcanic earthquakes and their associated energy. Deformation measurements were either stable or did not show significant changes. Although fog often prevented visual observations, gas plumes were seen rising 500 m above the crater and drifting W. SO2 plumes were no longer detected in satellite imagery. On 4 December, the Alert Level was lowered to 3.

On 9 January, as seismicity continued to decrease, CVGHM lowered the Alert Level to 2. Plumes continued to rise above the crater and, on 12 January, avalanches descended the Krasak drainage, traveling 1.5 km SW. Lahars and high water during 15-23 January damaged infrastructure and caused temporary road closures. On 22 January, plumes rose 175 m above the crater and drifted E.

According to a news account (vivanews.com), Merapi spewed thick white plumes as of the first week of February 2011. CVGHM reported that gas plumes rose from Merapi during 28 February-6 March. The highest plume, on 5 March, rose 100 m and drifted E. The number of MP earthquakes was slightly lower compared to the previous week.

Analysis of the lahar problem emerged as this issue went to press. According to Lavigne and others (2011) the volume of pyroclastic debris from the 2010 eruptive episode was in excess of 100 x 106 m3, ~10-fold higher than similar deposits after more conventional eruptions. These deposits and subsequent lahars filled most of the protective Sabo-dam structures. The eruption coincided with the onset of the rainy season, an interval that usually brings 4 m of rain but due to La Niña conditions, is predicted to bring more rain than usual. The 50-year absence of lahars in Kuning and Woro drainages altered the perception of risk in residents there. Thousands of sand miners work in the riverbed of all lahar-prone channels.

Fatalities and scale of evacuations. As previously noted, on 26 October, pyroclastic flows killed ~35 people who 7 km from the summit. They had refused to evacuate the village of Kinahejo (Kinahrejo).

According to the U.S. Agency for International Development (USAID) (quoting the Government of Indonesia's National Disaster Management Agency-Badan Nasional Penanggulangan Bencana or BNPB), the 2010 eruptions killed 386 people, injured 131 people, and displaced initially more than 300,000 residents (USAID, 2011). According to Relief Web, the 11,000 displaced remained unable to return to their homes at least as late as January 2011.

Lahars followed the eruptive processes and caused at least one additional death and one injury. An 11 January IRIN News article stated that " . . . more than 300,000 people have been able to return home, another 11,000 remain displaced, living with family or in camps, according to the government's National Disaster Management Agency."

According to the UN's Integrated Regional Information Networks (IRIN News), a source of humanitarian news and analysis, rainfall triggered lahars on Merapi's flanks on 3 and 9 January 2011. This caused damage to houses, farms, and infrastructure in multiple villages in the Magelang district, 26 km WNW of Merapi. One death and an injury were reported. The flooded area reportedly affected an estimated 3,000 residents but the number evacuated was unstated. The flooding on 9 January was more intense and, according to IRIN News, the Red Cross evacuated dozens of people trapped in their homes.

Referring to the larger 2010 eruption and evacuees, the same 11 January IRIN article stated that " . . . more than 300,000 people have been able to return home, another 11,000 remain displaced, living with family or in camps, according to the government's National Disaster Management Agency." This article also quoted the same agency with regard to the 386 reported deaths and the 131 injuries from the 2010 eruption.

Airlines affected. According the Jakarta Post, a total of 13 international carriers stopped their flights to Jakarta on 6 November, citing concerns about volcanic ash in the air that could cause damage to their aircraft and engines, and thus jeopardize safety. They included Malaysia Airlines, Air Asia, Singapore Airlines, Emirate, Ethihad, Turkish Air, Japan Airlines, Lufthansa, and KLM.

Andrew Tupper at the Australian Bureau of Meteorology notified us that Indonesian media reported that a plane encountered a volcanic cloud N of Java ascribed to Merapi on 28 October 2010. The suspected ash-plume encounter occurred at altitudes in the range 9.1-11.6 km. An engine stall message alerted the crew, who also noted a strong burning odor that disappeared as the plane descended from 9.1 to 6.1 km altitude.

According to another news account (Kompas.com), possibly reporting the same incident, on 28 October, a Garuda Indonesia airplane with 383 passengers from Solo, Central Java, landed safely at Hang Nadim Airport, Batam, a scheduled refueling stop. Enroute, volcanic ash from Merapi had been sucked into the left engine of the Airbus 330 aircraft, disrupting the engine. Richard Wijaya, Operational Duty Manager of Garuda Indonesia in Batam, explained that the pilot had notified ground staff of the disruption before landing, and as soon as they landed in Batam, the engine was checked. The crew cancelled the next leg of the scheduled flight to Jeddah, Saudi Arabia.

On 2 November, an unspecified number of international airlines had to cancel flights to airports at Solo and Yogyakarta, as plumes blackened the sky. Poor visibility and heavy ash on the runway caused the cancellations. According to an ABC news report, Yogyakarta airport reopened on 20 November after being closed for ~2 weeks.

Data table. Table 20 summarizes currently available CVGHM reports on Merapi's behavior during September to 1 December 2010. In the first row, it presents some background values commonly seen at Merapi during non-eruption conditions. Seismic terminology in the table is equivalent to that seen in figure 42 (Ratdomopurbo and Poupinet, 2000). Note the rise in seismic energy on 19 September, various changes in Alert Level, and major events in bolded type. Comparative calm prevailed after early November, but lahars became a problem (see text). The table is intended to give readers an overview of the eruption rather than capture all the details.

Table 20. Preliminary summary of pyroclastic flows as well as some collateral observations, and hazard status changes relating to Merapi during early September through 22 November 2010. Pyroclastic flows (locally termed AP for awan panas, hot clouds) here are tallied both from seismic detection and visual observations, along with direction of travel. The table omits seismic data shown in figure 41. The "ber" (beruntun) refers to episodes of densely spaced signals indistinguishable from each other. Those signals were common beginning 4 November and complicated assessments of tremor (not shown). The pre-eruption seismic energy was less than 342 x 1012 erg (normal, non-eruptive conditions). Courtesy of CVGHM and A. Ratdomopurbo (personal communication).

Date Pyroclastic flows Related comments
Early Sep 2010 -- Seismic energy, 603 x 1012 ergs
19 Sep 2010 -- Seismic energy, ~6,000 x 1012 erg
20 Sep 2010 -- Alert Level raised to 2
21 Oct 2010 -- Alert Level raised to 3
25 Oct 2010 -- Regional M 7.7 earthquake; Alert Level raised to 4
26 Oct 2010 8 [Multiple (WSW, SE)] Initial eruption at 1702 LT
30 Oct 2010 2 Second explosive eruption; ashfall in city of Yogyakarta
31 Oct 2010 4 Eruption
01 Nov 2010 7 during several hr --
02 Nov 2010 26 Eruption; 9 and 10 km runout distances
03 Nov 2010 38 [At least 19 (S)] Eruption
04 Nov 2010 ber [Multiple] Eruption (over 24 hours)
05 Nov 2010 ber [Multiple] 4-5 Nov. eruption was largest 2010 eruption (ash plume to 16.8 km asl); runout distances of ~18 km(?); widespread ash fall; dome destruction
06 Nov 2010 5 [Multiple] Eruption, rapid dome extrusion
07 Nov 2010 ber [Multiple] Eruption
08 Nov 2010 7 Eruption
09 Nov 2010 2 [1 in 6 hr period] Weaker eruption
10 Nov 2010 1 [At least 1 (S)] Weaker eruption
11 Nov 2010 1 [At least 1 (S)] Weaker eruption
14 Nov 2010 2 [0 (none)] Weaker eruption
15 Nov 2010 [1] Weaker eruption
16 Nov 2010 [1] Weaker eruption
22 Nov 2010 [5] Eruption

References. Delle Donne, D., Harris, AJL, Ripepe, M, and Wright, R., 2010, Earthquake-induced thermal anomalies at active volcanoes, Geology, Sept. 2010; v. 38; pp. 771-774 [DOI: 10.1130/G30984.1].

European Space Agency (ESA), 2010, Satellites tracking Mt Merapi volcanic ash clouds, ESA News (online; 15 November 2010) (URL: http://www.esa.int/esaCP/SEMY0Y46JGG_index_0.html).

Hort, M, Vöge, FM., Seyfried, R, and Ratdomopurbo, A, 2006, In situ observation of dome instabilities at Merapi volcano, Indonesia: A new tool for volcanic hazard mitigation, Journal of Volcanology and Geothermal Research, v. 154, no. 3-4, p. 301-312.

Lavigne,F, de Bélizal, E, Cholik, N, Aisyah, N, Picquout, A, and Wulan Mei, ET, 2011, Lahar hazards and risks following the 2010 eruption of Merapi volcano, Indonesia, Geophysical Research Abstracts, v. 13, EGU2011-4400, 2011, EGU General Assembly 2011.

Lowenstern, JB, Smith, RB, and Hill, DP, 2006, Monitoring super-volcanoes: geophysical and geochemical signals at Yellowstone and other large caldera systems, Phil. Trans. R. Soc. A, 15 August 2006, v. 364, no. 1845, p. 2055-2072.

Manga, M. and Brodsky, E, 2006, Seismic triggering of eruptions in the far field: volcanoes and geysers, Annual Review of Earth and Planetary Sciences, v. 34, p. 263-291 [DOI: 10.1146/annurev.earth.34.031405.125125].

Ratdomopurbo, A, and Poupinet, G, 2000, An overview of the seismicity of Merapi volcano (Java, Indonesia), 1983-1994, Journal of Volcanology and Geothermal Research, v. 100, no. 1-4, p.193-214 (DOI: 10.1016/S0377-0273(00)00137-2).

Schwarzkopf, L, 2001, The 1995 and 1998 block and ash flow deposits at Merapi volcano, Central Java, Indonesia: implications for emplacement mechanisms and hazard mitigation. Ph.D. Thesis, University at Kiel, Kiel, Germany.

USAID (U.S. Agency for International Development), 2011 (February 4), Indonesia - Tsunami and Volcano, Fact Sheet 2, Fiscal Year 2011.

Vöge, FM, and Hort, M, 2008, Automatic classification of dome instabilities based on Doppler radar measurements at Merapi volcano, Indonesia: Part I. Geophysical Journal International, v. 172, no. 3, p. 1188-1206 (DOI: 10.1111/j.1365-246X.2007.03605.x).

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: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.go.id/); Merapi Volcano Observatory (MVO); 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/); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/); U.S. Agency for International Development (USAID) (URL: https://www.usaid.gov/); Antonius Ratdomopurbo, Nanyang Technological University, Earth Observatory of Singapore, Nanyang Avenue, Singapore (URL: http://www.earthobservatory.sg/); Andrew Tupper, Australian Bureau of Meteorology (URL: http://www.bom.gov.au/); European Geosciences Union (URL: http://www.egu.eu/); Badan Nasional Penanggulangan Bencana (BNPB - Indonesian National Disaster Management Agency) (URL: http://dibi.bnpb.go.id/); Relief Web (URL: https://reliefweb.int/); Kompas News, Jakarta, Indonesia (URL: http://www.Kompas.com); The Jakarta Post (URL: http://www.thejakartapost.com/); Reuters (URL: http://www.reuters.com/); Vivanews.com (URL: http://vivanews.com/); ABC News (Australia) (URL: http://www.abc.net.au/); The Boston Globe (URL: http://www.boston.com/bigpicture/2010/11/mount_merapis_eruptions.html); IRIN News (URL: http://www.IRINnews.org/).


Rumble III (New Zealand) — February 2011 Citation iconCite this Report

Rumble III

New Zealand

35.745°S, 178.478°E; summit elev. -220 m

All times are local (unless otherwise noted)


Eruption in 2009 linked to over 100 m of sea floor collapse

We reported in BGVN 34:07 that New Zealand scientists found evidence during a research cruise in 2009 of a recent large eruption at Rumble III, one of more than 30 big submarine volcanoes on the Kermadec Arc, NE of the Bay of Plenty on the N coast of New Zealand's North Island (figures 3 and 4). A newly available report of the 2009 cruise (Dodge, 2010) noted some new details, including the following: (1) since the last study of Rumble III volcano in 2007, significant volcanic activity had occurred; (2) the bathymetric profile of the seamount had changed since it was last mapped in 2007—the summit of Rumble III had collapsed and was ~100 m deeper, at 310 m, much of the 800-m-wide crater was filled by ash, and much of the W side of the volcano had slid down-slope; (3) volcanic flow deposits were documented in camera tows—lava boulders, hackley flow, truncated lobate or pillows, and talus were common; and (4) there was a massive abundance of ash, in particular draped across substrates in many areas, provided compelling evidence for a large eruption since 2007.

Figure (see Caption) Figure 3. Southwest Pacific from Samoa (NE) to New Zealand (SW), showing the location of Rumble III and other submarine volcanoes along the southern Kermadec Arc. Rumble III volcano is located ~ 350 km NE of the Bay of Plenty, New Zealand, 200 km NE of Auckland, and is one of a number of submarine volcanoes that delineate the active arc front in this region. Bathymetry data were satellite-derived (for deep water) and acquired using an EM 300 multibeam echo sounder (along the arc and Lau Basin). Satellite-derived bathymetry from Sandwell and Smith (1997); EM300 bathymetry data courtesy of New Zealand National Institute of Water and Atmospheric Research (NIWA). Map courtesy of National Oceanic and Atmospheric Agency (NOAA) Ocean Explorer web site; from New Zealand American Submarine Ring of Fire 2005 expedition plan.
Figure (see Caption) Figure 4. Bathymetric map of all available multibeam data as of 2009 for the Southern Havre Trough, between the Colville and Kermadec Ridges and N of the New Zealand's North Island. In the colored version of this figure, the bathymetry key (in meters) ranges from red at the surface to purple at depths of 5 to 6 km. The location of Rumble III submarine volcano is highlighted. The inset indicates the tracks and areas of individual surveys whose data comprise the map. Areas that are not covered use satellite data configured to fit the edges of multibeam data set. Courtesy of Wysoczanski and others (2010).

A press release dated 17 August 2010 by the New Zealand National Institute of Water and Atmospheric Research (NIWA) noted that, during an oceanographic cruise aboard NIWA's research vessel R/V Tangaroa in May-June 2010, scientists confirmed that (a) the W flank of the volcano had collapsed ~100 m or more, (b) collapse of 90 m was observed at its highest (shallowest) point, and (c) as much as 120 m collapse occurred in some places. The release noted that the collapse was caused by an eruption some time in the last 2 years.

Glassy, black basaltic rock filled with vesicles was dredged from the volcano. Richard Wysoczanski (NIWA) noted that the samples are the youngest-known rocks from the Kermadec Arc region, created some time between the years 2007 and 2009. It is notable that andesite samples were previously collected from the flank of the submarine volcano by Brothers (1967). Rumble III was last mapped using multibeam technology in 2002.

NIWA principal scientist Geoffrey Lamarche said that the observation of significant pieces of sea floor moving hundreds of meters in height over a short timespan of 8 years give insight into short-time movements of the seabed. Research of the Kermadec Arc is directed in part by NIWA's survey of the area for massive sulphide deposits that sometimes develop over hydrothermal vents.

On 28 February 2011, NIWA and GNS Science announced an upcoming research cruise of about 3 weeks in 2011 to investigate mineral deposits and hydrothermal activity at five major submarine volcanoes in the Kermadec Arc (Clark, Healy, Brothers, Rumble II West, and Rumble III; see figure 4).

References. Brothers, R.N., 1967, Andesite from Rumble III Volcano, Kermadec Ridge, southwest Pacific, Bulletin of Volcanology, v. 31, no. 1, pp. 17-19.

Dodge, E., 2010, Catastrophic volcanic activity at Rumble III volcano based on EM300 bathymetry and direct sea floor imaging, Senior Thesis for Oceanography 444, University of Washington, School of Oceanography, Seattle, WA.

Smith, W. H. F., and Sandwell, D.T., 1997, Global seafloor topography from satellite altimetry and ship depth soundings, Science, v. 277, p. 1957-1962+.

Todd, E., Gill, J.B., Wysoczanski, R.J., Handler, M.R., Wright, I.C., Gamble, J.A., 2010, Sources of constructional cross-chain volcanism in the southern Havre Trough: New insights from HFSE and REE concentration and isotope systematics, Geochemistrry Geophysics Geosystems. v. 11, Q04009, 31 pp, DOI: 10.1029/2009GC002888.

Wysoczanski, R.J., Todd, E., Wright, I.C., Leybourne, M.I., Hergt, J.M., Adam, C., and Mackay, K., 2010, Backarc rifting, constructional volcanism and nascent disorganised spreading in the southern Havre Trough backarc rifts (SW Pacific), Journal of Volcanology and Geothermal Research, v. 190, issues 1-2, p. 39-57.

Geologic Background. The Rumble III seamount, the largest of the Rumbles group of submarine volcanoes along the South Kermadec Ridge, rises 2300 m from the sea floor to within about 200 m of the sea surface. Collapse of the edifice produced a horseshoe-shaped caldera breached to the west and a large debris-avalanche deposit. Fresh-looking andesitic rocks have been dredged from the summit and basaltic lava from its flanks. Rumble III has been the source of several submarine eruptions detected by hydrophone signals.

Information Contacts: Roger Matthews, North Shore City Council, 1 The Strand, Takapuna Private Bag 93500, Takapuna, North Shore City, New Zealand; Richard Wysoczanski, New Zealand National Institute of Water and Atmospheric Research (NIWA) (URL: https://www.niwa.co.nz/); Geoffrey Lamarche, NIWA (URL: https://www.niwa.co.nz/); GNS Science, Wairakei Research Centre, Private Bag 2000, Taupo 3352, New Zealand (URL: http://www.gns.cri.nz/); National Oceanic and Atmospheric Agency (NOAA) Ocean Explorer (URL: http://oceanexplorer.noaa.gov/gallery/gallery.html).


Sangay (Ecuador) — February 2011 Citation iconCite this Report

Sangay

Ecuador

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

All times are local (unless otherwise noted)


Many plumes seen by pilots during past year ending February 2011

The last report discussed observations of ash plumes and MODVOLC thermal alerts at Sangay through February 2010 (BGVN 35:01). Intermittent reporting indicated that similar activity continued through at least February 2011, with plumes reaching up to 7.6 km altitude (table 7). Clouds obscured the view at times, and plumes were reported primarily by pilots and were sometimes visible on satellite imagery.

Table 7. Plumes reported at Sangay during April 2010-February 2011. No plumes were noted during March 2011. Courtesy of the Washington VAAC.

Date Type of plume Altitude Distance and direction Source
21 Apr 2010 Ash 6.7 km -- Pilot observation
06 May 2010 Ash -- -- Pilot observation
06 May 2010 Ash -- W Pilot observation and satellite imagery
22-23 Jul 2010 Diffuse plumes -- 65-115 km W Pilot observation and satellite imagery
21 and 23 Jul 2010 Occasional thermal anomalies -- -- Satellite imagery
19 Aug 2010 Ash-and-gas plumes, intermittent thermal anomalies -- 25 km W Satellite imagery
20 Aug 2010 Emission -- -- Pilot observation
30 Aug 2010 Ash -- -- Pilot observation (near Sangay)
05 Sep 2010 Ash 5.5 km -- Pilot observation
10 Sep 2010 Small plume and thermal anomaly -- -- Satellite imagery
13 Sep 2010 Gas with possible ash and a thermal anomaly -- W Tegucigalpa Meteorological Watch Office (MWO) (Honduras), pilot observation, and satellite imagery
21 Sep 2010 Ash 7.6 km -- Pilot observation
06 Oct 2010 Small ash clouds -- WNW Pilot observation and satellite imagery
14 Oct 2010 Pilot reported ash, only gas plumes drifting NW observed in satellite imagery -- NW Pilot observation and satellite imagery
29 Oct 2010 Steam and gas plume possibly with ash and a thermal anomaly -- -- Satellite imagery
05 Dec 2010 Ash -- -- Guayaquil MWO (Ecuador)
12 Jan 2011 Ash and thermal anomaly 6.7 km >45 km SW Pilot observation and satellite imagery
20 Jan 2011 Ash 7.6 km -- Pilot observation
27 Jan 2011 Small ash clouds -- N Satellite imagery
23 Feb 2011 Pilot reported ash, small cloud drifting NW in satellite imagery with no ash confirmed -- SSE Pilot observation and satellite imagery

On 5 December 2010, the Washington Volcanic Ash Advisory Center (VAAC) stated that Instituto Geofisico reported elevated seismicity.

The MODVOLC alert system issued thermal alerts for Sangay monthly during March 2010 through early October 2010. Then, alerts were absent until 11 January 2011 (table 8).

Table 8. Thermal alerts issued for Sangay by the MODVOLC system during March 2010-20 March 2011 (continued from the list in BGVN 35:01). The system uses the MODIS instrument on the Terra and Aqua satellites. Courtesy MODVOLC Thermal Alerts System.

Date (UTC) Time (UTC) Pixels Satellite
15 Mar 2010 0330 1 Terra
30 Apr 2010 0345 1 Terra
16 May 2010 0345 1 Terra
03 Jun 2010 0330 1 Terra
12 Jul 2010 0340 1 Terra
18 Aug 2010 0655 1 Aqua
28 Sep 2010 0650 2 Aqua
30 Sep 2010 0335 1 Terra
02 Oct 2010 0325 1 Terra
07 Oct 2010 0345 1 Terra
11 Jan 2011 0345 1 Terra
02 Mar 2011 0330 1 Terra

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: Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/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/).


Taal (Philippines) — February 2011 Citation iconCite this Report

Taal

Philippines

14.002°N, 120.993°E; summit elev. 311 m

All times are local (unless otherwise noted)


Intermittent non-eruptive unrest during 2008-2010

As previously reported (BGVN 32:01), during the last four months of 2006 Taal displayed restlessness. This report discusses Taal seismicity, deformation, and hydrothermal behavior (steaming, and temperature changes in lake water at Main Crater) that occurred intermittently during 2008, 2010, and 2011.

Taal (also known as Talisay) is a lake-filled, 15 x 20 km caldera located on SW Luzon Island 65 km S of Manila (figure 9). The lake engulfs a large island with several thousand residents, Volcano Island, the place where all historical eruptions have vented (figures 10 and 11). Restlessness described herein was not confined to the area beneath the island.

Figure (see Caption) Figure 9. Index map of the Philippines showing Manila (the Capital) and several major volcanoes including Taal. Courtesy of Lyn Topinka (US Geological Survey).
Figure (see Caption) Figure 10. A map showing Taal caldera and surroundings. Notice that the caldera lies at the intersection of major faults and the topographic margin extends well beyond the caldera lake's margin. Courtesy of NASA Earth Observing System (EOS) Volcanology and their slide set compiled by Peter Mouginis-Mark (University of Hawaii).
Figure (see Caption) Figure 11. Photo of the Taal caldera lake and Volcano Island taken from the N in November 1999. Courtesy of NASA Earth Observing System (EOS) Volcanology and their slide set compiled by Peter Mouginis-Mark (University of Hawaii).

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) announced in August 2008 that seismic unrest continued. On 28 August 2008, ten volcanic earthquakes occurred, two of which were felt and heard as rumbling sounds by residents in the Pira-Piraso village on Volcano Island. The earthquakes were located NE of the island near the Daang Kastila area (below Taal caldera's N rim) at estimated depths of 0.6-0.8 km. Surface observations indicated no change in the main crater lake area. The Alert Level remained at 1 (scale is 0-5, with 0 referring to No Alert).

On 8 June 2010, PHIVOLCS raised the Alert Level for Taal to 2 because of changes in several monitored parameters that began in late April. Since 26 April, the number and magnitude of volcanic earthquakes had increased. Most signals were high-frequency earthquakes, but at least one, on 2 June, was low-frequency. Steam emissions from the N and NE sides of Main Crater occasionally intensified. Deformation data showed slight inflation since 2004; measurements taken at the SE side of Taal on 7 June showed further inflation by 3 mm.

In addition to increased seismicity, the temperature of the Main Crater Lake increased from 32°C on 11 May to 34°C on 24 May. According to PHIVOLCS, the ratios of Mg:Cl and SO4:Cl, as well as total dissolved solids in the lake, all increased. Temperature measurements of the main crater lake did not increase further, remaining between 33-34°C.

PHIVOLCS proposed that the high frequency earthquakes could be the result of active rock fracturing associated with magma intrusion beneath the volcano, and that the fractures could serve as passageways through which hot gases from the intruding magma could escape into the lake.

According to news reports (Xinhua, Philippine Daily Inquirer), the more than 5,000 residents living near Taal were advised to evacuate their homes voluntarily. On 10 June, the Philippine Coast Guard sent five teams of divers and rescue swimmers with rubber boats and medical teams to its forward command post to help evacuate, if necessary, these residents. A news report (Philippine Daily Inquirer), however, indicated that most residents refused to leave without an official order.

The number of earthquakes recorded daily gradually declined to background levels beginning the second week of July 2010. Hydrothermal activity in the N and NE sides of the main crater and Daang Kastila also decreased. Precise leveling measurements conducted during 13-21 July along the NE, SE, and SW flanks detected minimal inflation. On 2 August, PHIVOLCS lowered the Alert Level to 1.

According to PHIVOLCS, seismic activity increased during the first week of September 2010. From 1-27 September 2010, a total of 274 volcanic earthquakes, or an average of 10 events/day, was recorded. However, given that field surveys conducted at the Main Crater and at the 1965-1977 "New Eruption" site (SW edge of Main Crater) indicated no anomalous thermal or surface activity.

PHIVOLCS reported that a December 2010 deformation survey showed slight inflation compared to a September 2010 survey. Field observations on 10 and 18 January revealed no significant changes. Weak steaming from a thermal area inside the main crater was noted and the lake temperature, acidity, and color were normal. During 15-16 January 2011, ten volcanic earthquakes were detected, two of which were felt by residents of Pira-Piraso, on the N side of the island. On 17 January three volcanic earthquakes were detected and on 18 January only one was reported. Between 18-30 January, up to seven daily volcanic earthquakes were detected by the seismic network.

Field observations during 23-25 January 2011 revealed an increase in the number of steaming vents inside the main crater and a drop in the lake level there. The lake water temperature and pH values remained normal. Visual observations on 27 January showed weak steaming at a thermal area in the crater.

Geologic Background. Taal is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. Though not topographically prominent, its prehistorical eruptions have greatly changed the landscape of SW Luzon. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all historical eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones that have grown about 25% in area during historical time. Powerful pyroclastic flows and surges from historical eruptions have caused many fatalities.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph).Pete Mouginis-Mark, Hawai'i Institute of Geophysics and Planetology (HIGP) 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://eos.higp.hawaii.edu/ppages/pinatubo/8.taal/?); Xinhua (URL: http://www.xinhuanet.com/english2010); Philippine Daily Inquirer (URL: http://www.inquirer.net/).

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.

View Atmospheric Effects Reports

Special Announcements

Special announcements of various kinds and obituaries.

View Special Announcements Reports

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/).