Logo link to homepage

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

Pacaya (Guatemala) Strombolian explosions, multiple lava flows, and the formation of a small cone during February-July 2020

Sangeang Api (Indonesia) Two ash plumes and small thermal anomalies during February-June 2020

Stromboli (Italy) Strombolian explosions persist at both summit craters during January-April 2020

Nevado del Ruiz (Colombia) Lava dome confirmed inside Arenas crater; intermittent thermal anomalies and ash emissions, January-June 2020

Asosan (Japan) Daily ash emissions continue through mid-June 2020 when activity decreases

Aira (Japan) Near-daily explosions with ash plumes continue, large block ejected 3 km from Minamidake crater on 4 June 2020

Nevados de Chillan (Chile) Explosions and pyroclastic flows continue; new dome emerges from Nicanor crater in June 2020

Kerinci (Indonesia) Intermittent ash emissions during January-early May 2020

Tinakula (Solomon Islands) Intermittent small thermal anomalies and gas-and-steam plumes during January-June 2020

Ibu (Indonesia) Frequent ash emissions and summit incandescence; Strombolian explosions in March 2020

Suwanosejima (Japan) Frequent explosions, ash plumes, and summit incandescence in January-June 2020

Bagana (Papua New Guinea) Ash plumes during 29 February-2 March and 1 May 2020



Pacaya (Guatemala) — August 2020 Citation iconCite this Report

Pacaya

Guatemala

14.382°N, 90.601°W; summit elev. 2569 m

All times are local (unless otherwise noted)


Strombolian explosions, multiple lava flows, and the formation of a small cone during February-July 2020

Pacaya, located in Guatemala, is a highly active volcano that has previously produced continuous Strombolian explosions, multiple lava flows, and the formation of a small cone within the crater due to the constant deposition of ejected material (BGVN 45:02). This reporting period updates information from February through July 2020 consisting of similar activity that dominantly originates from the Mackenney crater. Information primarily comes from reports by the Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH) in Guatemala and various satellite data.

Strombolian explosions were recorded consistently throughout this reporting period. During February 2020, explosions ejected incandescent material 100 m above the Mackenney crater. At night and during the early morning the explosions were accompanied by incandescence from lava flows. Multiple lava flows were active during most of February, traveling primarily down the SW and NW flanks and reaching 500 m on 25 February. On 5 February the lava flow on the SW flank divided into three flows measuring 200, 150, and 100 m. White and occasionally blue gas-and-steam emissions rose up to 2.7 km altitude on 11 and 14 February and drifted in multiple directions. On 16 February Matthew Watson utilized UAVs (Unmanned Aerial Vehicle) to take detailed, close up photos of Pacaya and report that there were five active vents at the summit exhibiting lava flows from the summit, gas-and-steam emissions, and small Strombolian explosions (figure 122).

Figure (see Caption) Figure 122. Drone image of active summit vents at Pacaya on 16 February 2020 with incandescence and white gas-and-steam emissions. Courtesy of Matthew Watson, University of Bristol, posted on 17 February 2020.

Activity remained consistent during March with Strombolian explosions ejecting material 100 m above the crater accompanied by occasional incandescence and white and occasionally blue gas-and-steam emissions drifting in multiple directions. Multiple lava flows were detected on the NW and W flanks reaching as far as 400 m on 9-10 March.

In April, frequent Strombolian explosions were accompanied by active lava flows moving dominantly down the SW flank and white gas-and-steam emissions. These repeated explosions ejected material up to 100 m above the crater and then deposited it within the Mackenney crater, forming a small cone. On 27 April seismicity increased at 2140 due to a lava flow moving SW as far as 400 m (figure 123); there were also six strong explosions and a fissure opened on the NW flank in front of the Los Llanos Village, allowing gas-and-steam to rise.

Figure (see Caption) Figure 123. Infrared image of Pacaya on 28 April 2020, showing a lava flow approximately 500 m long and moving down the S flank on the day after seismicity increased and six strong explosions were detected. Courtesy of ISIVUMEH (Reporte Volcán de Pacaya July 2020).

During May, Strombolian explosions continued to eject incandescent material up to 100 m above the Mackenney crater, accompanied by active lava flows on 1-2, 17-18, 22, 25-26, and 29-30 May down the SE, SW, NW, and NE flanks up to 700 m on 30 May. White gas-and-steam emissions continued to be observed up to 100 m above the crater drifting in multiple directions. Between the end of May and mid-June, the plateau between the Mackenney cone and the Cerro Chiquito had become inundated with lava flows (figure 124).

Figure (see Caption) Figure 124. Aerial views of the lava flows at Pacaya to the NW during a) 18 September 2019 and b) 16 June 2020 showing the lava flow advancement toward the Cerro Chiquito. Courtesy of INSIVUMEH (Reporte Volcán de Pacaya July 2020).

Lava flows extended 700 m on 8 June down multiple flanks. On 9 June, a lava flow traveled N and NW 500 m and originating from a vent on the N flank about 100 m below the Mackenney crater. Active lava flows continued to originate from this vent through at least 19 June while white gas-and-steam emissions were observed rising 300 m above the crater. At night and during the early mornings of 24 and 29 June Strombolian explosions were observed ejecting incandescent material up to 200 m above the crater (figure 125). These explosions continued to destroy and then rebuild the small cone within the Mackenney crater with fresh ejecta. Active lava flows on the SW flank were mostly 100-600 m long but had advanced to 2 km by 30 June.

On 10 July a 1.2 km lava flow divided in two which moved on the NE and N flanks. On 11 July, another 800 m lava flow divided in two, on the N and NE flanks (figure 126). On 14 and 19 July, INSIVUMEH registered constant seismic tremors and stated they were associated with the lava flows. No active lava flows were observed on 18-19 July, though some may have continued to advance on the SW, NW, N, and NE flanks. On 20 July, lava emerged from a vent at the NW base of the Mackenney cone near Cerro Chino, extending SE. Strombolian explosions ejected incandescent material up to 200 m above the crater on 22 July, accompanied by active incandescent lava flows on the SW, N, NW, NE, and W flanks. Three lava flows on the NW flank were observed on 22-24 July originating from the base of the Mackenney cone. Explosive activity during 22 July vibrated the windows and roofs of the houses in the villages of San Francisco de Sales, El Patrocinio, El Rodeo, and others located 4 km from the volcano. The lava flow activity had decreased by 25 July, but remnants of the lava flow on the NW flank persisted with weak incandescence observed at night, which was no longer observed by 26 July. Strombolian explosions continued to be detected through the rest of the month, accompanied by frequent white gas-and-steam emissions that extended up to 2 km from the volcano; no active lava flows were observed.

Figure (see Caption) Figure 125. Photos of Pacaya on 11 July 2020 showing Strombolian explosions and lava flows moving down the N and NE flanks. Courtesy of William Chigna, CONRED, posted on 12 July 2020.
Figure (see Caption) Figure 126. Infrared image of Pacaya on 20 July 2020 showing a hot lava flow accompanied by gas-and-steam emissions. Courtesy of INSIVUMEH (BEPAC 47 Julio 2020-22).

During February through July 2020, multiple lava flows and thermal anomalies within the Mackenney crater were detected in Sentinel-2 thermal satellite imagery (figure 127). These lava flows were observed moving down multiple flanks and were occasionally accompanied by white gas-and-steam emissions. Thermal anomalies were also recorded by the MIROVA (Middle InfraRed Observation of Volcanic Activity) system during 10 August through July 2020 within 5 km of the crater summit (figure 128). There were a few breaks in thermal activity from early to mid-March, late April, early May, and early June; however, each of these gaps were followed by a pulse of strong and frequent thermal anomalies. According to the MODVOLC algorithm, 77 thermal alerts were recorded within the summit crater during February through July 2020.

Figure (see Caption) Figure 127. Sentinel-2 thermal satellite images of Pacaya showing thermal activity (bright yellow-orange) primarily as lava flows originating from the summit crater during February to July 2020 frequently accompanied by white gas-and-steam emissions. All images with "Atmospheric penetration" (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 128. The MIROVA thermal activity graph (Log Radiative Power) at Pacaya during 10 August to July 2020 shows strong, frequent thermal anomalies through late July with brief gaps in activity during early to mid-March, late April, early May, and early June. Courtesy of MIROVA.

Geologic Background. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.

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/); 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); Matthew Watson, School of Earth Sciences at the University of Bristol (Twitter: @Matthew__Watson, https://twitter.com/Matthew__Watson); William Chigna, CONRED (URL: https://twitter.com/william_chigna).


Sangeang Api (Indonesia) — August 2020 Citation iconCite this Report

Sangeang Api

Indonesia

8.2°S, 119.07°E; summit elev. 1912 m

All times are local (unless otherwise noted)


Two ash plumes and small thermal anomalies during February-June 2020

Sangeang Api is a 13-km-wide island located off the NE coast of Sumbawa Island, part of Indonesia's Lesser Sunda Islands. Documentation of historical eruptions date back to 1512. The most recent eruptive episode began in July 2017 and included frequent Strombolian explosions, ash plumes, and block avalanches. The previous report (BGVN 45:02) described activity consisting of a new lava flow originating from the active Doro Api summit crater, short-lived explosions, and ash-and-gas emissions. This report updates information during February through July 2020 using information from the Darwin Volcanic Ash Advisory Center (VAAC) reports, Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, or CVGHM) reports, and various satellite data.

Volcanism during this reporting period was relatively low compared to the previous reports (BGVN 44:05 and BGVN 45:02). A Darwin VAAC notice reported an ash plume rose 2.1 km altitude and drifted E on 10 May 2020. Another ash plume rose to a maximum of 3 km altitude drifting NE on 10 June, as seen in HIMAWARI-8 satellite imagery.

The MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data detected a total of 12 low power thermal anomalies within 5 km from the summit during February through May 2020 (figure 42). No thermal anomalies were recorded during June and July according to the MIROVA graph. Though the MODVOLC algorithm did not detect any thermal signatures between February to July, many small thermal hotspots within the summit crater could be seen in Sentinel-2 thermal satellite imagery (figure 43).

Figure (see Caption) Figure 42. Thermal anomalies at Sangeang Api from 10 August 2019 through July 2020 recorded by the MIROVA system (Log Radiative Power) were infrequent and low power during February through May 2020. No thermal anomalies were detected during June and July. Courtesy of MIROVA.
Figure (see Caption) Figure 43. Sentinel-2 thermal satellite imagery using “Atmospheric penetration” (bands 12, 11, 8A) rendering showed small thermal hotspots (orange-yellow) at the summit of Sangeang Api during February through June 2020. Courtesy of Sentinel Hub Playground.

Geologic Background. Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, Doro Api and Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.

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/); 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/); 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).


Stromboli (Italy) — August 2020 Citation iconCite this Report

Stromboli

Italy

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

All times are local (unless otherwise noted)


Strombolian explosions persist at both summit craters during January-April 2020

Stromboli is a stratovolcano located in the northeastern-most part of the Aeolian Islands composed of two active summit vents: the Northern (N) Crater and the Central-South (CS) Crater that are situated at the head of the Sciara del Fuoco, a large scarp that runs from the summit down the NW side of the volcano. The ongoing eruption began in 1934 and has been characterized by regular Strombolian explosions in both summit craters, ash plumes, and occasional lava flows (BGVN 45:08). This report updates activity from January to April 2020 with information primarily from daily and weekly reports by Italy's Istituto Nazionale di Geofisica e Vulcanologia (INGV) and various satellite data.

Activity was consistent during this reporting period. Explosion rates ranged from 1-20 per hour and were of variable intensity, producing material that rose from less than 80 to over 250 m above the vents (table 8). Strombolian explosions were often accompanied by gas-and-steam emissions, spattering, and lava flows which has resulted in fallout deposited on the Sciara del Fuoco and incandescent blocks rolling toward the coast up to a few hundred meters down the slopes of the volcano. According to INGV, the average SO2 emissions measured 300-650 tons/day.

Table 8. Summary of activity at Stromboli during January-April 2020. Low-intensity activity indicates ejecta rising less than 80 m, medium-intensity is ejecta rising less than 150 m, and high-intensity is ejecta rising over 200 m above the vent. Data courtesy of INGV.

Month Activity
Jan 2020 Strombolian activity and degassing continued with some spattering. Explosion rates varied from 2-20 per hour. Ejected material rose 80-150 m above the N crater and 150-200 m above the CS crater. A small cone is growing on the S1 crater and has produced some explosions and ejected coarse material mixed with fine ash. The average SO2 emissions measured 300 tons/day.
Feb 2020 Strombolian activity and degassing continued. Explosion rates varied from 2-14 per hour. Ejected material rose 80-200 m above the N crater and 80-250 m above the CS crater. The average SO2 emissions measured 300 tons/day.
Mar 2020 Strombolian activity and degassing continued with discontinuous spattering. Explosion rates varied from 1-16 per hour. Ejected material rose 80-150 m above the N crater and 150-250 m above the CS crater. Intense spattering was observed in the N crater. The average SO2 emissions measured 300-650 tons/day.
Apr 2020 Strombolian activity and degassing continued with spattering. Explosion rates varied from 1-17 per hour. Ejected material rose 80-150 m above the N crater and 150-250 m above the CS crater. Spattering was observed in the N crater. The average SO2 emissions measured 300-650 tons/day.

During January 2020, explosive activity mainly originated from three vents in the N crater and at least three vents in the CS crater. Ejecta from numerous Strombolian explosions covered the slopes on the upper Sciara del Fuoco, some of which rolled hundreds of meters down toward the coast. Explosion rates varied from 2-12 per hour in the N crater and 9-14 per hour in the CS crater; ejected material rose 80-200 m above the craters. According to INGV, a small cone growing in the S1 crater produced some explosions that ejected coarse material mixed with fine ash. On 18 and 19 January a lava flow was observed, both of which originated in the N crater. In addition, two explosions were detected in the N crater that was associated with two landslide events.

Explosive activity in February primarily originated from 2-3 eruptive vents in the N crater and at least three vents in the CS crater (figure 177). The Strombolian explosions ejected material 80-250 m above the craters, some of which fell onto the upper part of the Sciara. Explosion rates varied from 3-12 per hour in the N crater and 2-14 per hour in the CS crater (figure 178). On 3 February a short-lived lava flow was reported in the N crater.

Figure (see Caption) Figure 177. A drone image showed spattering accompanied by gas-and-steam emissions at Stromboli rising above the N crater on 15 February 2020. Courtesy of INGV (Rep. No. 08/2020, Stromboli, Bollettino Settimanale, 10/02/2020 - 16/02/2020, data emissione 18/02/2020).
Figure (see Caption) Figure 178. a) Strombolian explosions during the week of 17-23 February 2020 in the N1 crater of Stromboli were seen from Pizzo Sopra La Fossa. b) Spattering at Stromboli accompanied by white gas-and-steam emissions was detected in the N1 and S2 craters during the week of 17-23 February 2020. c) Spattering at Stromboli accompanied by a dense ash plume was seen in the N1 and S2 craters during the week of 17-23 February 2020. All photos by F. Ciancitto, courtesy of INGV (Rep. No. 09/2020, Stromboli, Bollettino Settimanale, 17/02/2020 - 23/02/2020, data emissione 25/02/2020).

Ongoing explosive activity continued into March, originating from three eruptive vents in the N crater and at least three vents in the CS crater. Ejected lapilli and bombs rose 80-250 m above the craters resulting in fallout covering the slopes in the upper Sciara del Fuoco with blocks rolling down the slopes toward the coast and explosions varied from 4-13 per hour in the N crater and 1-16 per hour in the CS crater. Discontinuous spattering was observed during 9-19 March. On 19 March, intense spattering was observed in the N crater, which produced a lava flow that stretched along the upper part of the Sciara for a few hundred meters. Another lava flow was detected in the N crater on 28 March for about 4 hours into 29 March, which resulted in incandescent blocks breaking off the front of the flow and rolling down the slope of the volcano. On 30 March a lava flow originated from the N crater and remained active until the next day on 31 March. Landslides accompanied by incandescent blocks rolling down the Sciara del Fuoco were also observed.

Strombolian activity accompanied by gas-and-steam emissions continued into April, primarily produced in 3-4 eruptive vents in the N crater and 2-3 vents in the CS crater. Ejected material from these explosions rose 80-250 m above the craters, resulting in fallout products covering the slopes on the Sciara and blocks rolling down the slopes. Explosions varied from 4-15 per hour in the N crater and 1-10 per hour in the CS crater. On 1 April a thermal anomaly was detected in satellite imagery accompanied by gas-and-steam and ash emissions downstream of the Sciara del Fuoco. A lava flow was observed on 15 April in the N crater accompanied by gas-and-steam and ash emissions; at the front of the flow incandescent blocks detached and rolled down the Sciara (figure 179). This flow continued until 16 April, ending by 0956; a thermal anomaly persisted downslope from the lava flow. Spatter was ejected tens of meters from the vent. Another lava flow was detected on 19 April in the N crater, followed by detached blocks from the front of the flow rolling down the slopes. Spattering continued during 20-21 April.

Figure (see Caption) Figure 179. A webcam image of an ash plume accompanied by blocks ejected from Stromboli on 15 April 2020 rolling down the Sciara del Fuoco. Courtesy of INGV via Facebook posted on 15 April 2020.

Moderate thermal activity occurred frequently during 16 October to April 2020 as recorded in the MIROVA Log Radiative Power graph using MODIS infrared satellite information (figure 180). The MODVOLC thermal alerts recorded a total of 14 thermal signatures over the course of nine different days between late February and mid-April. Many of these thermal signatures were captured as hotspots in Sentinel-2 thermal satellite imagery in both summit craters (figure 181).

Figure (see Caption) Figure 180. Low to moderate thermal activity at Stromboli occurred frequently during 16 October-April 2020 as shown in the MIROVA graph (Log Radiative Power). Courtesy of MIROVA.
Figure (see Caption) Figure 181. Thermal anomalies (bright yellow-orange) at Stromboli were observed in thermal satellite imagery from both of the summit vents throughout January-April 2020. Images with Atmospheric Penetration rendering (bands 12, 11, 8A); courtesy of Sentinel Hub Playground.

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

Information Contacts: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/en/, Facebook: https://www.facebook.com/ingvvulcani/); 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).


Nevado del Ruiz (Colombia) — August 2020 Citation iconCite this Report

Nevado del Ruiz

Colombia

4.892°N, 75.324°W; summit elev. 5279 m

All times are local (unless otherwise noted)


Lava dome confirmed inside Arenas crater; intermittent thermal anomalies and ash emissions, January-June 2020

Columbia’s broad, glacier-capped Nevado del Ruiz has an eruption history documented back 8,600 years, and historical observations since 1570. It’s profound notoriety stems from an eruption on 13 November 1985 that produced an ash plume and pyroclastic flows onto the glacier, triggering large lahars that washed down 11 valleys, inundating most severely the towns of Armero (46 km W) and Chinchiná (34 km E) where approximately 25,000 residents were killed. It remains the second deadliest volcanic eruption of the 20th century after Mt. Pelee killed 28,000 in 1902. Ruiz remained quiet for 20 years after the September 1985-July 1991 eruption until a new explosive event occurred in February 2012; a series of explosive events lasted into 2013. Renewed activity beginning in November 2014 included ash and gas-and-steam plumes, ashfall, and the appearance of a lava dome inside the Arenas crater in August 2015 which has regularly displayed thermal anomalies through 2019. This report covers ongoing activity from January-June 2020 using information primarily from reports by the Servicio Geologico Colombiano (SGC) and the Observatorio Vulcanológico y Sismológico de Manizales, the Washington Volcanic Ash Advisory Center (VAAC) notices, and various sources of satellite data.

Gas and ash emissions continued at Nevado del Ruiz throughout January-June 2020; they generally rose to 5.8-6.1 km altitude with the highest reported plume at 7 km altitude during early March. SGC confirmed the presence of the growing lava dome inside Arenas crater during an overflight in January; infrared satellite imagery indicated a continued heat source from the dome through April. SGC interpreted repeated episodes of ‘drumbeat seismicity’ as an indication of continued dome growth throughout the period. Small- to moderate-density sulfur dioxide emissions were measured daily with satellite instruments. The MIROVA graph of thermal activity indicated a heat source consistent with a growing dome from January through April (figure 102).

Figure (see Caption) Figure 102. The MIROVA graph of thermal activity at Nevado del Ruiz from 2 July 2019 through June 2020 indicated persistent thermal anomalies from mid-November 2019-April 2020. Courtesy of MIROVA.

Activity during January-March 2020. During January 2020 some of the frequent tremor seismic events were associated with gas and ash emissions, and several episodes of “drumbeat” seismicity were recorded; they have been related by SGC to the growth of the lava dome on the floor of the Arenas crater. An overflight on 10 January, with the support of the Columbian Air Force, confirmed the presence of the dome which was first proposed in August 2015 (BGVN 42:06) (figure 103). The Arenas crater had dimensions of 900 x 980 m elongate to the SW-NE and was about 300 m deep (figure 104). The dome inside the crater was estimated to be 173 m in diameter and 60 m high with an approximate volume of 1,500,000 m3 (figures 105 and 106). In addition to the dome, the scientists also noted ash deposits on the summit ice cap (figure 107). The Washington VAAC reported an ash plume on 19 January that rose to 5.5 km altitude and drifted SW, dissipating quickly. On 30 January they reported an ash plume visible in satellite imagery extending 15 km NW from the summit at 5.8 km altitude. A single MODVOLC alert was issued on 15 January and data from the VIIRS satellite instrument reported thermal anomalies inside the summit crater on 14 days of the month. Sulfur dioxide plumes with DU values greater than 2 were recorded by the TROPOMI satellite instrument daily during the month.

Figure (see Caption) Figure 103. SGC confirmed the presence of a lava dome inside the Arenas crater at Nevado del Ruiz on 10 January 2020. The dome is shown in brown, and zones of fumarolic activity are labelled around the dome. Courtesy of SGC (El Nuevo Domo de Lava del Volcán Nevado del Ruiz y la Geomorfología Actual del Cráter Arenas 2020).
Figure (see Caption) Figure 104. A view of the Arenas crater at the summit of Nevado del Ruiz on 10 January 2020 (left) is compared with a view from 2010 (right). They were both taken during overflights supported by the Colombian Air Force (FAC). Ash deposits on the ice fields are visible in both images. Fumarolic activity rises from the inner walls of the crater in January 2020. Courtesy of SGC (El Nuevo Domo de Lava del Volcán Nevado del Ruiz y la Geomorfología Actual del Cráter Arenas 2020).
Figure (see Caption) Figure 105. The dome inside the Arenas crater at Nevado del Ruiz appeared dark against the crater rim and ash-covered ice field on 10 January 2020. Features observed include (A) the edge of the Arenas crater, (B) a secondary crater 150 m in diameter located to the west, (C) interior cornices, (D) the lava dome, (E) a depression in the center of the dome caused by possible subsidence and cooling of the lava, (F) a source of gas and ash emission with a diameter of approximately 15 m (secondary crater), and (G, H, and I) several sources of gas emission located around the crater. Courtesy of SGC (El Nuevo Domo de Lava del Volcán Nevado del Ruiz y la Geomorfología Actual del Cráter Arenas 2020).
Figure (see Caption) Figure 106. Images of the summit of Nevado del Ruiz captured by the PlanetScope satellite system on 14 March 2018 (A) and 10 January 2020 (B) show the lava dome at the bottom of Arenas crater. Courtesy Planet Lab Inc. and SGC (El Nuevo Domo de Lava del Volcán Nevado del Ruiz y la Geomorfología Actual del Cráter Arenas 2020).
Figure (see Caption) Figure 107. Ash covered the snow and ice field around the Arenas crater at the summit of Nevado del Ruiz on 10 January 2020. The lava dome is the dark area on the right. Courtesy of SGC (posted on Twitter @sgcol).

The Washington VAAC reported multiple ash plumes during February 2020. On 4 February an ash plume was observed in satellite imagery drifting 35 km W from the summit at 5.8 km altitude. The following day a plume rose to 6.1 km altitude and extended 37 km W from the summit before dissipating by the end of the day (figure 108). On 6 February an ash cloud was observed in satellite imagery centered 45 km W of the summit at 5.8 km altitude. Although it had dissipated by midday, a hotspot remained in shortwave imagery until the evening. Late in the day another plume rose to 6.7 km altitude and drifted W. Diffuse ash was seen in satellite imagery on 13 February fanning towards the W at 5.8 km altitude. On 18 February at 1720 UTC the Bogota Meteorological Weather Office (MWO) reported an ash emission drifting NW at 5.8 km altitude; a second plume was reported a few hours later at the same altitude. Intermittent emissions continued the next day at 5.8-6.1 km altitude that reached as far as 50 km NW before dissipating. A plume on 21 February rose to 6.7 km altitude and drifted W (figure 109). Occasional emissions on 25 February at the same altitude reached 25 km SW of the summit before dissipating. A discrete ash emission around 1550 UTC on 26 February rose to 6.1 km altitude and drifted W. Two similar plumes were reported the next day. On 28 and 29 February plumes rose to 5.8 km altitude and drifted W.

Figure (see Caption) Figure 108. Emissions rose from the Arenas crater at Nevado del Ruiz on 5 February 2020. The Washington VAAC reported an ash plume that day that rose to 6.1 km altitude and drifted 37 km W before dissipating. Courtesy of Camilo Cupitre.
Figure (see Caption) Figure 109. Emissions rose from the Arenas crater at Nevado del Ruiz around 0600 on 21 February 2020. The Washington VAAC reported ash emissions that day that rose to 6.7 km altitude and drifted W. Courtesy of Manuel MR.

SGC reported several episodes of drumbeat type seismicity on 2, 8, 9, and 27 February which they attributed to effusion related to the growing lava dome in the summit crater. Sentinel-2 satellite imagery showed ring-shaped thermal anomalies characteristic of dome growth within Arenas crater several times during January and February (figure 110). The VIIRS satellite instrument recorded thermal anomalies on twelve days during February.

Figure (see Caption) Figure 110. Persistent thermal anomalies from Sentinel-2 satellite imagery during January and February 2020 suggested that the lava dome inside Nevado del Ruiz’s Arenas crater was still actively growing. Atmospheric penetration rendering (bands 12, 11, 8A) courtesy of Sentinel Hub Playground.

On 4, 14, and 19 March 2020 thermal anomalies were visible in Sentinel-2 satellite data from within the Arenas crater. Thermal anomalies were recorded by the VIIRS satellite instrument on eight days during the month. Several episodes of drumbeat seismicity were recorded during the first half of the month and on 30-31 March. Distinct SO2 plumes with DU values greater than 2 were recorded by the TROPOMI satellite instrument daily throughout February and March (figure 111). The Washington VAAC reported an ash emission on 1 March that rose to 5.8 km altitude and drifted NW; it was centered 15 km from the summit when detected in satellite imagery. The next day a plume was seen in satellite imagery moving SW at 7.0 km altitude, extending nearly 40 km from the summit. Additional ash emissions were reported on 4, 14, 15, 21, 28, 29, and 31 March; the plumes rose to 5.8-6.7 km altitude and drifted generally W, some reaching 45 km from the summit before dissipating.

Figure (see Caption) Figure 111. Distinct SO2 plumes with Dobson values (DU) greater than 2 were recorded by the TROPOMI satellite instrument daily during February and March 2020. Ecuador’s Sangay produced smaller but distinct plumes most of the time as well. Dates are shown at the top of each image. Courtesy of NASA’s Sulfur Dioxide Monitoring Page.

Activity during April-June 2020. The Washington VAAC reported an ash emission that rose to 6.7 km altitude and drifted W on 1 April 2020. On 2 April, emission plumes were visible from the community of Tena in the Cundinamarca municipality which is located 100 km ESE (figure 112). The unusually clear skies were attributed to the reduction in air pollution in nearby Bogota resulting from the COVID-19 Pandemic quarantine. On 4 April the Bogota MWO reported an emission drifting SW at 5.8 km altitude. An ash plume on 8 April rose to 6.7 km altitude and drifted W. On 25 April the last reported ash plume from the Washington VAAC for the period rose to 6.1 km altitude and was observed in satellite imagery moving W at 30 km from the summit; after that, only steam and gas emissions were observed.

Figure (see Caption) Figure 112. On the evening of 2 April 2020, emission plumes from Nevado del Ruiz were visible from Santa Bárbara village in Tena, Cundinamarca municipality which is located 100 km ESE. The unusually clear skies were attributed to the reduction in air pollution in the nearby city of Bogota resulting from the COVID-19 Pandemic quarantine. Photo by Williama Garcia, courtesy of Semana Sostenible (3 April 2020).

Distinct SO2 plumes with DU values greater than 2 were recorded by the TROPOMI satellite instrument daily throughout the month. On 13 April, a Sentinel-2 thermal image showed a hot spot inside the Arenas crater largely obscured by steam and clouds. Cloudy images through May and June prevented observation of additional thermal anomalies in satellite imagery, but the VIIRS thermal data indicated anomalies on 3, 4, and 26 April. SGC reported low-energy episodes of drumbeat seismicity on 4, 9, 10, 12, 15, 16, 20, and 23 April which they interpreted as related to growth of the lava dome inside the Arenas crater. The seismic events were located 1.5-2.0 km below the floor of the crater.

Small emissions of ash and gas were reported by SGC during May 2020 and the first half of June, with the primary drift direction being NW. Gas and steam plumes rose 560-1,400 m above the summit during May and June (figure 113). Drumbeat seismicity was reported a few times each month. Sulfur dioxide emissions continued daily; increased SO2 activity was recorded during 10-13 June (figure 114).

Figure (see Caption) Figure 113. Gas and steam plumes rose 560-1,400 m above the summit of Nevado del Ruiz during May and June 2020, including in the early morning of 11 June. Courtesy of Carlos-Enrique Ruiz.
Figure (see Caption) Figure 114. Increased SO2 activity during 10-13 June 2020 at Nevado del Ruiz was recorded by the TROPOMI instrument on the Sentinel-5P satellite. Sangay also emitted SO2 on those days. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Geologic Background. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than 200 km2. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.

Information Contacts: El Servicio Geológico Colombiano (SGC), Diagonal 53 No. 34-53 - Bogotá D.C., Colombia (URL: https://www.sgc.gov.co/volcanes, https://twitter.com/sgcol); 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/); 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/); NASA Worldview (URL: https://worldview.earthdata.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Camilo Cupitre (URL: https://twitter.com/Ccupitre/status/1225207439701704709); Manuel MR (URL: https://twitter.com/ElPlanetaManuel/status/1230837262088384512); Semana Sostenible (URL: https://sostenibilidad.semana.com/actualidad/articulo/fumarola-del-nevado-del-ruiz-fue-captada-desde-tena-cundinamarca/49597); Carlos-Enrique Ruiz (URL: https://twitter.com/Aleph43/status/1271800027841794049).


Asosan (Japan) — July 2020 Citation iconCite this Report

Asosan

Japan

32.884°N, 131.104°E; summit elev. 1592 m

All times are local (unless otherwise noted)


Daily ash emissions continue through mid-June 2020 when activity decreases

Japan's 24-km-wide Asosan caldera on the island of Kyushu has been active throughout the Holocene. Nakadake has been the most active of 17 central cones for 2,000 years; all historical activity is from Nakadake Crater 1. The largest ash plume in 20 years occurred on 8 October 2016. Asosan remained quiet until renewed activity from Crater 1 began in mid-April 2019; explosions with ash plumes continued through the first half of 2020 and are covered in this report. The Japan Meteorological Agency (JMA) provides monthly reports of activity; the Tokyo Volcanic Ash Advisory Center (VAAC) issues aviation alerts reporting on possible ash plumes, and Sentinel-2 satellite images provide data on ash emissions and thermal activity.

The Tokyo VAAC issued multiple daily reports of ash plumes from Nakadake Crater 1 from 1 January-14 June 2020. They were commonly at 1.8-2.1 km altitude, and often drifted E or S. JMA reported that ashfall continued downwind from the ash plumes until mid-June; seismic activity was relatively high during January and February and decreased steadily after that time. The measured SO2 emissions ranged from 1,000-4,900 tons per day through mid-June and dropped to 500 tons per day during the second half of June. Intermittent thermal activity was recorded at the crater through mid-May.

Explosive activity during January-June 2020. Ash plumes rose up to 1.1 km above the crater rim at Nakadake Crater 1 during January 2020 (figure 70). Ashfall was confirmed downwind of an explosion on 7 January. During February, ash plumes rose up to 1.7 km above the crater, and ashfall was again reported downwind. The crater camera provided by the Aso Volcano Museum occasionally observed incandescence at the floor of the crater during both months. Incandescence was also occasionally observed with the Kusasenri webcam (3 km W) and was seen on 20 February from a webcam in Minamiaso village (8 km SW).

Figure (see Caption) Figure 70. Ash plumes rose up to 1.1 km above the Nakadake Crater 1 at Asosan during January 2020 (left) and up to 1.7 km above the crater during February 2020 (right) as seen in these images from the Kusasenri webcam. Ashfall was reported downwind multiple times. Courtesy of JMA (Volcanic activity commentary material for Mt. Aso, January and February 2020).

During March 2020, ash plumes rose as high as 1.3 km. Ashfall was reported on 9 March in Ichinomiyamachi, Aso City (figure 71). In field surveys conducted on the 18th and 25th, there was no visible water inside the crater, and high-temperature grayish-white plumes were observed. The temperature at the base of the plume was measured at 300°C (figure 72).

Figure (see Caption) Figure 71. Ashfall from Asosan appeared on 9 March 2020 in Ichinomiyamachi, Aso City around 10 km N. Courtesy of JMA (Volcanic activity commentary material for Mt. Aso, March 2020).
Figure (see Caption) Figure 72. During a field survey of Nakadake Crater 1 at Asosan on 25 March 2020, JMA staff observed a gray ash plume rising from the crater floor (left). The maximum temperature of the ash plume was measured at about 300°C with an infrared thermal imaging device (right). Courtesy of JMA (Volcanic activity commentary material for Mt. Aso, March 2020).

Occasional incandescence was observed at the bottom of the crater during April and May 2020; ash plumes rose 1.1 km above the crater on most days in April and were slightly higher, rising to 1.8 km during May, although activity was more intermittent (figure 73). A brief increase in SO2 activity was reported by JMA during field surveys on 7 and 8 May; satellite data captured small plumes of SO2 on 1 and 6 May (figure 74). A brief increase in tremor amplitude was reported by JMA on 16 May.

Figure (see Caption) Figure 73. Although activity at Asosan’s Nakadake Crater 1 was more intermittent during April and May 2020 than earlier in the year, ash plumes were still reported most days and incandescence was seen at the bottom of the crater multiple times until 15 May. Left image taken 11 May 2020 from the Kusachiri webcam; right image taken from the crater webcam on 10 May provided by the Aso Volcano Museum. Courtesy of JMA (Volcanic activity commentary material for Mt. Aso, May 2020).
Figure (see Caption) Figure 74. The TROPOMI instrument on the Sentinel-5P satellite detected small but distinct SO2 plumes from Asosan on 1 and 6 May 2020. Additional small plumes are visible from Aira caldera’s Sakurajima volcano. Courtesy of NASA’s Global Sulfur Dioxide Monitoring Page.

The last report of ash emissions at Nakadake Crater 1 from the Tokyo VAAC was on 14 June 2020. JMA also reported that no eruption was observed after mid-June. On 8 June they reported an ash plume that rose 1.4 km above the crater. During a field survey on 16 June, only steam was observed at the crater; the plume rose about 100 m (figure 75). In addition, a small plume of steam rose from a fumarole on the S crater wall.

Figure (see Caption) Figure 75. A steam plume rose about 100 m from the floor of Nakadake Crater 1 on 16 June 2020. A small steam plume was also observed by the S crater wall. Courtesy of JMA (Volcanic activity commentary material for Mt. Aso, June 2020).

Thermal activity during January-June 2020. Sentinel-2 satellite data indicated thermal anomalies present at Nakadake Crater 1 on 2 January, 6 and 21 February, 16 April, and 11 May (figure 76). In addition, thermal anomalies from agricultural fires appeared in satellite images on 11 February, 7 and 17 March (figure 77). The fires were around 5 km from the crater, thus they appear on the MIROVA thermal anomaly graph in black, but are likely unrelated to volcanic activity (figure 78). No thermal anomalies were recorded in satellite data from the Nakadake Crater 1 after 11 May, and none appeared in the MIROVA data as well.

Figure (see Caption) Figure 76. Thermal anomalies appeared at Asosan’s Nakadake Crater 1 on 2 January, 6 and 21 February, 16 April and 11 May 2020. On 2 January a small ash plume drifted SSE from the crater (left). On 6 February a dense ash plume drifted S from the crater (center). Only a small steam plume was visible above the crater on 21 February (right). Images use Atmospheric penetration rendering (bands 12, 11, 8A), courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 77. Thermal anomalies from agricultural fires located about 5 km from the crater appeared in satellite images on 11 February, and 7 and 17 March 2020. Although a dense ash plume drifted SSE from the crater on 11 February (left), no thermal anomalies appear at the crater on these dates. Images use Atmospheric penetration rendering (bands 12, 11, 8A), courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 78. The MIROVA project plot of Log Radiative Power at Asosan from 29 June 2019 through June 2020 shows only a few small thermal alerts within 5 km of the summit crater during January-June 2020, and a spike in activity during February and March located around 5 km away. These data correlate well with the Sentinel-2 satellite data that show intermittent thermal anomalies at the summit throughout January-May and agricultural fires located several kilometers from the crater during February and March. Courtesy of MIROVA.

Geologic Background. The 24-km-wide Asosan caldera was formed during four major explosive eruptions from 300,000 to 90,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. The last of these, the Aso-4 eruption, produced more than 600 km3 of airfall tephra and pyroclastic-flow deposits. A group of 17 central cones was constructed in the middle of the caldera, one of which, Nakadake, is one of Japan's most active volcanoes. It was the location of Japan's first documented historical eruption in 553 CE. The Nakadake complex has remained active throughout the Holocene. Several other cones have been active during the Holocene, including the Kometsuka scoria cone as recently as about 210 CE. Historical eruptions have largely consisted of basaltic to basaltic-andesite ash emission with periodic strombolian and phreatomagmatic activity. The summit crater of Nakadake is accessible by toll road and cable car, and is one of Kyushu's most popular tourist destinations.

Information Contacts: Japan Meteorological Agency (JMA), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.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/); 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).


Aira (Japan) — July 2020 Citation iconCite this Report

Aira

Japan

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

All times are local (unless otherwise noted)


Near-daily explosions with ash plumes continue, large block ejected 3 km from Minamidake crater on 4 June 2020

Sakurajima rises from Kagoshima Bay, which fills the Aira Caldera near the southern tip of Japan's Kyushu Island. Frequent explosive and occasional effusive activity has been ongoing for centuries. The Minamidake summit cone has been the location of persistent activity since 1955; the adjacent Showa crater on its E flank has also been intermittently active since 2006. Numerous explosions and ash-bearing emissions have been occurring each month at either Minamidake or Showa crater since the latest eruptive episode began in late March 2017. This report covers ongoing activity at Minamidake from January through June 2020; the Japan Meteorological Agency (JMA) provides regular reports on activity, and the Tokyo VAAC (Volcanic Ash Advisory Center) issues tens of reports each month about the frequent ash plumes.

Activity continued during January-June 2020 at Minamidake crater with tens of explosions each month. The Tokyo VAAC issued multiple daily reports of ash emissions during January and February. Less activity occurred during the first half of March but picked up again with multiple daily reports from mid-March through mid-April. Emissions were more intermittent but continued through early June, when activity decreased significantly. JMA reported explosions with ash plumes rising 2.5-4.2 km above the summit, and ejecta traveling generally up to 1,700 m from the crater, although a big explosion in early June send a large block of tephra 3 km from the crater (table 23). Thermal anomalies were visible in satellite imagery on a few days most months and were persistent in the MIROVA thermal anomaly data from November 2019 through early June 2020 (figure 94). Incandescence was often visible at night in the webcams through early June; the Showa crater remained quiet throughout the period.

Table 23. Monthly summary of eruptive events recorded at Sakurajima's Minamidake crater within the Aira Caldera, January through June 2020. The number of events that were explosive in nature are in parentheses. No events were recorded at the Showa crater during this time. Ashfall is measured at the Kagoshima Local Meteorological Observatory (KLMO), 10 km W of Showa crater. Data courtesy of JMA (January to June 2020 monthly reports).

Month Ash emissions (explosive) Max plume height above crater Max ejecta distance from crater Total amount of ashfall (g/m2) Total ashfall previous month
Jan 2020 104 (65) 2.5 km 1,700 m 75 (12 days) 280,000 tons
Feb 2020 129 (67) 2.6 km 1,800 m 21 (14 days) 230,000 tons
Mar 2020 26 (10) 3.0 km 1,700 m 3 (8 days) 360,000 tons
Apr 2020 51 (14) 3.8 km 1,700 m less than 0.5 (2 days) 160,000 tons
May 2020 51 (24) 4.2 km 1,300 m 19 (8 days) 280,000 tons
Jun 2020 28 (16) 3.7 km 3,000 m 71 (9 days) 150,000 tons
Figure (see Caption) Figure 94. Persistent thermal anomalies were recorded in the MIROVA thermal energy data for the period from 2 July 2019 through June 2020. Thermal activity increased in October 2019 and remained steady through May 2020, decreasing abruptly at the beginning of June. Courtesy of MIROVA.

Explosions continued at Minamidake crater during January 2020 with 65 ash plumes reported. The highest ash plume rose 2.5 km above the crater on 30 January, and incandescent ejecta reached up to 1,700 m from the Minamidake crater on 22 and 29 January (figure 95). Slight inflation of the volcano since September 2019 continued to be measured with inclinometers and extensometers on Sakurajima Island. Field surveys conducted on 15, 20, and 31 January measured the amount of sulfur dioxide gas released as very high at 3,400-4,700 tons per day, as compared with 1,000-3,000 tons in December 2019.

Figure (see Caption) Figure 95. An explosion at the Minamidake summit crater of Aira’s Sakurajima volcano on 29 January 2020 produced an ash plume that rose 2.5 km above the crater rim and drifted SE (left). On 22 January incandescent ejecta reached 1,700 m from the summit during explosive events. Courtesy of JMA (Sakurajima Volcanic Activity Commentary, January 2020).

About the same number of explosions produced ash plumes during February 2020 (67) as in January (65) (figure 96). On 10 February a large block was ejected 1,800 m from the crater, the first to reach that far since 5 February 2016. The tallest plume, on 26 February rose 2.6 km above the crater. Sentinel-2 satellite imagery indicated two distinct thermal anomalies within the Minamidake crater on both 1 and 6 February (figure 97). Activity diminished during March 2020 with only 10 explosions out of 26 eruptive events. On 21 March a large bomb reached 1,700 m from the crater. The tallest ash plume rose 3 km above the crater on 17 March. Scientists noted during an overflight on 16 March that a small steam plume was rising from the inner wall on the south side of the Showa crater; a larger steam plume rose to 300 m above the Minamidake crater and drifted S (figure 98). Sulfur dioxide emissions were similar in February (1,900 to 3,100 tons) and March (1,300 to 3,400 tons per day).

Figure (see Caption) Figure 96. An ash plume rose from the Minamidake crater at the summit of Aira’s Sakurajima volcano on 6 February 2020 at 1752 local time, as seen looking S from the Kitadake crater. Courtesy of JMA (Sakurajima Volcanic Activity Commentary, February 2020).
Figure (see Caption) Figure 97. Sentinel-2 satellite imagery revealed two distinct thermal anomalies within the Minamidake crater at Aira’s Sakurajima volcano on 1 and 6 February 2020. Images use Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub playground.
Figure (see Caption) Figure 98. During an overflight of Aira’s Sakurajima volcano on 16 March 2020, JMA captured this view to the SW of the Kitadake crater on the right, the steam-covered Minamidake crater in the center, and the smaller Showa crater on the left adjacent to Minamidake. Courtesy of JMA and the Maritime Self-Defense Force 1st Air Group P-1 (Sakurajima Volcanic Activity Commentary, March 2020).

During April 2020, ejecta again reached as far as 1,700 m from the crater; 14 explosions were identified from the 51 reported eruptive events, an increase from March. The tallest plume, on 4 April, rose 3.8 km above the crater (figure 99). The same number of eruptive events occurred during May 2020, but 24 were explosive in nature. A large plume on 9 May rose to 4.2 km above the rim of Minamidake crater, the tallest of the period (figure 100). On 20 May, incandescent ejecta reached 1,300 m from the summit. Sulfur dioxide emissions during April (1,700-2,100 tons per day) and May (1,200-2,700 tons per day) were slightly lower than previous months.

Figure (see Caption) Figure 99. A large ash plume at Aira’s Sakurajima volcano rose from Minamidake crater at 1621 on 4 April 2020. The plume rose to 3.8 km above the crater and drifted SE. Courtesy of JMA (Sakurajima Volcanic Activity Commentary, April 2020).
Figure (see Caption) Figure 100. Activity continued at Aira’s Sakurajima volcano during May 2020. A large plume rose to 4.2 km above the summit and drifted N in the early morning of 9 May (left). The Kaigata webcam located at the Osumi River National Highway Office captured abundant incandescent ejecta reaching 1,300 m from the crater during the evening of 20 May. Courtesy of JMA (Sakurajima Volcanic Activity Commentary, May 2020).

A major explosion on 4 June 2020 produced 137 Pa of air vibration at the Seto 2 observation point on Sakurajima Island. It was the first time that air vibrations exceeding 100 Pa have been observed at the Seto 2 station since the 21 May 2015 explosion at the Showa crater. The ash plume associated with the explosion rose 1.5 km above the crater rim. During an 8 June field survey conducted in Higashisakurajima-cho, Kagoshima City, a large impact crater believed to be associated with this explosion was located near the coast 3 km SSW from Minamidake. The crater formed by the ejected block was about 6 m in diameter and 2 m deep (figure 101); fragments found nearby were 10-20 cm in diameter (figure 102). A nearby roof was also damaged by the blocks. Smaller bombs were found in Kurokami-cho, Kagoshima City, around 4- 5 km E of Minamidake on 5 June; the largest fragment was 5 cm in diameter. Multiple ash plumes rose to 3 km or more above the summit during the first ten days of June; explosions on 4 and 5 June reached 3.7 km above the crater (figure 103). Larger than normal inflation and deflation before and after the explosions was recorded during early June in the inclinometers and extensometers located on the island. Incandescence at the summit was observed at night through the first half of June. The Tokyo VAAC issued multiple daily ash advisories during 1-10 June after which activity declined abruptly. Two brief explosions on 23 June and one on 28 June were the only two additional ash explosions reported in June.

Figure (see Caption) Figure 101. A large crater measuring 6 m wide and 2 m deep was discovered 3 km from the Minamidake crater in Higashisakurajima, part of Kagoshima City, on 8 June 2020. It was believed to be from the impact of a large block ejected during the 4 June explosion at Aira’s Sakurajima volcano. Photo courtesy of Kagoshima City and JMA (Sakurajima Volcanic Activity Commentary, June 2020).
Figure (see Caption) Figure 102. Fragments 10-30 cm in diameter from a large bomb that traveled 3 km from Minamidake crater on Sakurajima were found a few days after the 4 June 2020 explosion at Aira. Courtesy of JMA, photo courtesy of Kagoshima City (Sakurajima Volcanic Activity Commentary, June 2020).
Figure (see Caption) Figure 103. An ash plume rose 3.7 km above the Minamidake crater at Aira’s Sakurajima volcano on 5 June 2020 and was recorded in Sentinel-2 satellite imagery. Image uses Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub playground.

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

Information Contacts: Japan Meteorological Agency (JMA), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.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/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Nevados de Chillan (Chile) — July 2020 Citation iconCite this Report

Nevados de Chillan

Chile

36.868°S, 71.378°W; summit elev. 3180 m

All times are local (unless otherwise noted)


Explosions and pyroclastic flows continue; new dome emerges from Nicanor crater in June 2020

Nevados de Chillán is a complex of late-Pleistocene to Holocene stratovolcanoes in the Chilean Central Andes. An eruption started with a phreatic explosion and ash emission on 8 January 2016 from a new crater (Nicanor) on the E flank of the Nuevo crater, itself on the NW flank of the large Volcán Viejo stratovolcano. Strombolian explosions and ash emissions continued throughout 2016 and 2017; a lava dome within the Nicanor crater was confirmed in early January 2018. Explosions and pyroclastic flows continued during 2018 and 2019, with several lava flows appearing in late 2019. This report covers continuing activity from January-June 2020 when ongoing explosive events produced ash plumes, pyroclastic flows, and the growth of new dome inside the crater. Information for this report is provided primarily by Chile's Servicio Nacional de Geología y Minería (SERNAGEOMIN)-Observatorio Volcanológico de Los Andes del Sur (OVDAS), and by the Buenos Aires Volcanic Ash Advisory Center (VAAC).

Explosions with ash plumes rising up to three kilometers above the summit area were intermittent from late January through early June 2020. Some of the larger explosions produced pyroclastic flows that traveled down multiple flanks. Thermal anomalies within the Nicanor crater were recorded in satellite data several times each month from February through June. A reduction in overall activity led SERNAGEOMIN to lower the Alert Level from Orange to Yellow (on a 4-level, Green-Yellow-Orange-Red scale) during the first week of March, although tens of explosions with ash plumes were still recorded during March and April. Explosive activity diminished in early June and SERNAGEOMIN reported the growth of a new dome inside the Nicanor crater. By the end of June, a new flow had extended about 100 m down the N flank. Thermal activity recorded by the MIROVA project showed a drop in thermal energy in mid-December 2019 after the lava flows of September-November stopped advancing. A decrease in activity in January and February 2020 was followed by an increase in thermal and explosive activity in March and April. Renewed thermal activity from the growth of a new dome inside the Nicanor crater was recorded beginning in mid-June (figure 52).

Figure (see Caption) Figure 52. MIROVA thermal anomaly data for Nevados de Chillan from 8 September 2019 through June 2020 showed a drop in thermal activity in mid-December 2019 after the lava flows of September-November stopped advancing. A decrease in activity in January and February 2020 was followed by an increase in explosive activity in March and April. Renewed thermal activity from the growth of a new dome inside the Nicanor crater was recorded beginning in mid-June. Courtesy of MIROVA.

Weak gas emissions were reported daily during January 2020 until a series of explosions began on the 21st. The first explosion rose 100 m above the active crater; the following day, the highest explosion rose 1.6 km above the crater. The Buenos Aires VAAC reported pulse emissions visible in satellite imagery on 21 and 24 January that rose to 3.9-4.3 km altitude and drifted SE and NE, respectively. Intermittent explosions continued through 26 January. Incandescent ejecta was observed during the night of 28-29 January. The VAAC reported an isolated emission on 29 January that rose to 5.2 km altitude and drifted E. A larger explosion on 30 January produced an ash plume that SERNAGEOMIN reported at 3.4 km above the crater (figure 53). It produced pyroclastic flows that traveled down ravines on the NNE and SE flanks. The Washington VAAC reported on behalf of the Buenos Aires VAAC that an emission was observed in satellite imagery on 30 January that rose to 4.9 km altitude and was moving rapidly E, reaching 15 km from the summit at midday. The altitude of the ash plume was revised two hours later to 7.3 km, drifting NNE and rapidly dissipating. Satellite images identified two areas of thermal anomalies within the Nicanor crater that day. One was the same emission center (CE4) identified in November 2019, and the second was a new emission center (CE5) located 60 m NW.

Figure (see Caption) Figure 53. A significant explosion and ash plume from the Nicanor crater at Nevados de Chillan on 30 January 2020 produced an ash plume reported at 7.3 km altitude. The left image was taken within one minute of the initial explosion. Images posted by Twitter accounts #EmergenciasÑuble (left) and T13 (right); original photographers unknown.

When the weather permitted, low-altitude mostly white degassing was seen during February 2020, often with traces of fine-grained particulate material. Incandescence at the crater was observed overnight during 4-5 February. The Buenos Aires VAAC reported an emission on 14 February visible in the webcam. The next day, an emission was visible in satellite imagery at 3.9 km altitude that drifted E. Episodes of pulsating white and gray plumes were first observed by SERNAGEOMIN beginning on 18 February and continued through 25 February (figure 54). The Buenos Aires VAAC reported pulses of ash emissions moving SE on 18 February at 4.3 km altitude. Ash drifted E the next day at 3.9 km altitude and a faint plume was briefly observed on 20 February drifting N at 3.7 km altitude before dissipating. Sporadic pulses of ash moved SE from the volcano on 22 February at 4.3 km altitude, briefly observed in satellite imagery before dissipating. Thermal anomalies were visible from the Nicanor crater in Sentinel-2 satellite imagery on 23 and 28 February.

Figure (see Caption) Figure 54. An ash emission at Nevados de Chillan on 18 February 2020 was captured in Sentinel-2 satellite imagery drifting SE (left). Thermal anomalies within the Nicanor crater were measured on 23 (right) and 28 February. Images use Atmospheric penetration rendering (bands 12, 11, 8a); courtesy of Sentinel Hub Playground.

Only low-altitude degassing of mostly steam was reported for the first half of March 2020. When SERNAGEOMIN lowered the Alert Level from Orange to Yellow on 5 March, they reduced the affected area from 5 km NE and 3 km SW of the crater to a radius of 2 km around the active crater. Thermal anomalies were recorded at the Nicanor crater in Sentinel-2 imagery on 4, 9, 11, 16, and 19 March (figure 55). A new series of explosions began on 19 March; 44 events were recorded during the second half of the month (figure 56). Webcams captured multiple explosions with dense ash plumes; on 25 and 30 March the plumes rose more than 2 km above the crater. Fine-grained ashfall occurred in Las Trancas (10 km SW) on 25 March. Pyroclastic flows on 25 and 30 March traveled 300 m NE, SE, and SW from the crater. Incandescence was observed at night multiple times after 20 March. The Buenos Aires VAAC reported several discrete pulses of ash that rose to 4.3 km altitude and drifted SE on 20 and 21 March, SW on 25 March, and SE on 29 and 30 March. Another ash emission rose to 5.5 km altitude later on 30 March and drifted SE.

Figure (see Caption) Figure 55. Sentinel-2 Satellite imagery of Nevados de Chillan during March 2020 showed thermal anomalies on five different dates at the Nicanor crater, including on 9, 11, and 16 March. A second thermal anomaly of unknown origin was also visible on 11 March about 2 km SW of the crater (center). Images use Atmospheric penetration rendering (bands 12, 11, 8a); courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 56. Forty-four explosive events were recorded at Nevados de Chillan during the second half of March 2020 including on 19 March. Courtesy of SERNAGEOMIN webcams and chillanonlinenoticia.

In their semi-monthly reports for April 2020, SERNAGEOMIN reported 94 explosive events during the first half of the month and 49 during the second half; many produced dense ash plumes. The Buenos Aires VAAC reported frequent intermittent ash emissions during 1-13 April reaching altitudes of 3.7-4.3 km (figure 57). They reported the plume on 8 April visible in satellite imagery at 7.3 km altitude drifting SE. An emission on 13 April was also visible in satellite imagery at 6.1 km altitude drifting NE.

Figure (see Caption) Figure 57. Sentinel-2 satellite imagery captured a strong thermal anomaly and an ash plume drifting SE from Nevados de Chillan on 10 April 2020. Image uses Atmospheric penetration rendering (bands 12, 11, 8a); courtesy of Sentinel Hub Playground.

During the second half of April 2020, SERNAGEOMIN reported that only one plume exceeded 2 km in height; on 21 April, it rose to 2.4 km above the crater (figure 58). The Buenos Aires VAAC reported isolated pulses of ash on 18, 26, 28, and 30 April. During the second half of April SERNAGEOMIN also reported that a pyroclastic flow traveled about 1,200 m from the crater rim down the SE flank. The ash from the pyroclastic flow drifted SE and S as far as 3.5 km. Satellite images showed continued activity from multiple emission centers around the crater. Pronounced scarps were noted on the internal walls of the crater, attributed to the deepening of the crater from explosive activity.

Figure (see Caption) Figure 58. Tens of explosions were reported at Nevados de Chillan during the second half of April 2020 that produced dense ash plumes. The plume on 21 April rose 2.4 km above the Nicanor crater. Photo by Josefa Carrasco Acuña from San Fabián de Alico; posted by Noticias Valpo Express.

Intermittent explosive activity continued during May 2020. The plumes contained abundant particulate material and were accompanied by periodic pyroclastic flows and incandescent ejecta around the active crater, especially visible at night. The Buenos Aires VAAC reported several sporadic weak ash emissions during the first week of May that rose to 3.7-5.2 km altitude and drifted NE. SERNAGEOMIN reported that only one explosion produced an ash emission that rose more than two km above the crater during the first two weeks of the month; on 6 May it rose to 2.5 km above the crater and drifted NE. They also observed pyroclastic flows on the E and SE flanks that day. Additional pyroclastic flows traveled 450 m down the S flank during the first half of the month, and similar deposits were observed to the N and NE. Satellite observations showed various emission points along the NW-trending lineament at the summit and multiple erosion scarps. Major erosion was noted at the NE rim of the crater along with an increase in degassing around the rim.

During the second half of May 2020 most of the ash plumes rose less than 2 km above the crater; a plume from one explosion on 22 May rose 2.2 km above the crater; the Buenos Aires VAAC reported the plume at 5.5 km altitude drifting NW (figure 59). Continuing pyroclastic emissions deposited material as far as 1.5 km from the crater rim on the NNW flank. There were also multiple pyroclastic deposits up to 500 m from the crater directed N and NE during the period. SERNAGEOMIN reported an increase in steam degassing between Nuevo-Nicanor and Nicanor-Arrau craters.

Figure (see Caption) Figure 59. Explosions produced dense ash plumes and pyroclastic flows at Nevados de Chillan multiple times during May 2020 including on 22 May. Courtesy of SERNAGEOMIN.

Webcam images during the first two weeks of June 2020 indicated multiple incandescent explosions. On 3 and 4 June plumes from explosions reached heights of over 1.25 km above the crater; the Buenos Aires VAAC reported them drifting NW at 3.9 km altitude. Incandescent ejecta on 6 June rose 760 m above the vent and drifted NE. In addition, pyroclastic flows were distributed on the N, NW, E and SE flanks. Significant daytime and nighttime incandescence was reported on 6, 9, and 10 June (figure 60). The VAAC reported emission pulses on 6 and 9 June drifting E and SE at 4.3 km altitude.

Figure (see Caption) Figure 60. Multiple ash plumes with incandescence were reported at Nevados de Chillan during the first ten days of June 2020 including on 6 June, after which explosive activity decreased significantly. Courtesy of SERNAGEOMIIN and Sismo Alerta Mexicana.

SERNAGEOMIN reported that beginning on the afternoon of 9 June 2020 a tremor-type seismic signal was first recorded, associated with continuous emission of gas and dark gray ash that drifted SE (figure 61). A little over an hour later another tremor signal began that lasted for about four hours, followed by smaller discrete explosions. A hybrid-type earthquake in the early morning of 10 June was followed by a series of explosions that ejected gas and particulate matter from the active crater. The vent where the emissions occurred was located within the Nicanor crater close to the Arrau crater; it had been degassing since 30 May.

Figure (see Caption) Figure 61. A tremor-type seismic signal was first recorded on the afternoon of 9 June 2020 at Nevados de Chillan. It was associated with the continuous emission of gas and dark gray ash that drifted SE, and incandescent ejecta visible after dark. View is to the S, courtesy of SERNAGEOMIN webcam, posted by Volcanology Chile.

After the explosions on the afternoon of 9 June, a number of other nearby vents became active. In particular, the vent located between the Nuevo and Nicanor craters began emitting material for the first time during this eruptive cycle. The explosion also generated pyroclastic flows that traveled less than 50 m in multiple directions away from the vent. Abundant incandescent material was reported during the explosion early on 10 June. Deformation measurements showed inflation over the previous 12 days.

SERNAGEOMIN identified a surface feature in satellite imagery on 11 June 2020 that they interpreted as a new effusive lava dome. It was elliptical with dimensions of about 85 x 120 m. In addition to a thermal anomaly attributed to the dome, they noted three other thermal anomalies between the Nuevo, Arrau, and Nicanor craters. They reported that within four days the base of the active crater was filled with effusive material. Seismometers recorded tremor activity after 11 June that was interpreted as associated with lava effusion. Incandescent emissions were visible at night around the active crater. Sentinel-2 satellite imagery recorded a bright thermal anomaly inside the Nicanor crater on 14 June (figure 62).

Figure (see Caption) Figure 62. A bright thermal anomaly was recorded inside the Nicanor crater at Nevados de Chillan on 14 June 2020. SERNAGEOMIN scientists attributed it to the growth of a new lava dome within the crater. Image uses Atmospheric penetration rendering (bands 12, 11, 8a); courtesy of Sentinel Hub Playground.

A special report from SERNAGEOMIN on 24 June 2020 noted that vertical inflation had increased during the previous few weeks. After 20 June the inflation rate reached 2.49 cm/month, which was considered high. The accumulated inflation measured since July 2019 was 22.5 cm. Satellite imagery continued to show the growth of the dome, and SERNAGEOMIN scientists estimated that it reached the E edge of the Nicanor crater on 23 June. Based on these images, they estimated an eruptive rate of 0.1-0.3 m3/s, about two orders of magnitude faster than the Gil-Cruz dome that emerged between December 2018 and early 2019.

Webcams revealed continued low-level explosive activity and incandescence visible both during the day and at night. By the end of June, webcams recorded a lava flow that extended 94 m down the N flank from the Nicanor crater and continued to advance. Small explosions with abundant pyroclastic debris produced recurring incandescence at night. Satellite infrared imagery indicated thermal radiance from effusive material that covered an area of 37,000 m2, largely filling the crater. DEM analysis suggested that the size of the crater had tripled in volume since December 2019 due largely to erosion from explosive activity since May 2020. Sentinel-2 satellite imagery showed a bright thermal anomaly inside the crater on 27 June.

Geologic Background. The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The largest stratovolcano, dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.

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/, https://twitter.com/Sernageomin); 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/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); #EmergenciasÑuble (URL: https://twitter.com/urgenciasnuble/status/1222943399185207296); T13, Channel 13 Press Department (URL: https://twitter.com/T13/status/1222951071443771394); Chillanonlinenoticia (URL: https://twitter.com/ChillanOnline/status/1240754211932995595); Noticias Valpo Express (URL: https://twitter.com/NoticiasValpoEx/status/1252715033131388928); Sismo Alerta Mexicana (URL: https://twitter.com/Sismoalertamex/status/1269351579095691265); Volcanology Chile (URL: https://twitter.com/volcanologiachl/status/1270548008191643651).


Kerinci (Indonesia) — July 2020 Citation iconCite this Report

Kerinci

Indonesia

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

All times are local (unless otherwise noted)


Intermittent ash emissions during January-early May 2020

Kerinci is a stratovolcano located in Sumatra, Indonesia that has been characterized by explosive eruptions with ash plumes and gas-and-steam emissions. The most recent eruptive episode began in April 2018 which has included intermittent explosions and ash plumes. The previous report (BGVN 44:12) described more recent activity consisting of intermittent gas-and-steam and ash plumes which occurred during June through early November 2019. This volcanism continued through May 2020, though little to no activity was reported during December 2019. The primary source of information for this report comes from Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM) and the Darwin Volcanic Ash Advisory Centre (VAAC).

Activity during December 2019 consisted of white gas-and-steam emissions rising 100-500 m above the summit. White and brown emissions continued intermittently through May 2020, rising to a maximum altitude of 1 km above the summit on 14 April. During 3-6 and 8-9 January 2020, the Darwin VAAC and PVMBG issued notices reporting brown volcanic ash rising 150-600 m above the summit drifting S and ESE (figure 19). PVMBG published a VONA notice on 24 January at 0828 reporting ash rising 400 m above the summit. Brown emissions continued intermittently throughout the reporting period. On 1 February, volcanic ash was observed rising 300-960 m above the summit and drifting NE; PVMBG reported continuing brown emissions during 1-3 February. During 16-17 February, two VONA notices reported that brown ash plumes rose 150-400 m above the summit and drifted SW accompanied by consistent white gas-and-steam emissions (figure 20).

Figure (see Caption) Figure 19. Brown ash plume rose 500-600 m above Kerinci on 4 January 2020. Courtesy of MAGMA Indonesia via Øystein Lund Andersen.
Figure (see Caption) Figure 20. White gas-and-steam emissions rose 400 m above Kerinci on 19 February 2020. Courtesy of MAGMA Indonesia via Øystein Lund Andersen.

During 1-16 and 25-26 March 2020 brown ash emissions were frequently observed rising 100-500 m above the summit drifting in multiple directions. During 6-8 and 10-15, April brown ash emissions were reported 50-1,000 m above the summit. The most recent Darwin VAAC and VONA notices were published on 14 April, reporting volcanic ash rising 400 and 600 m above the summit, respectively; however, PVMBG reported brown emissions rising up to 1,000 m. By 25-27 April brown ash emissions rose 50-300 m above the summit. Intermittent white gas-and-steam emissions continued through May. The last brown emissions seen in May were reported on the 7th rising 50-100 m above the summit.

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/); 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/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Øystein Lund Andersen (Twitter: @OysteinLAnderse, https://twitter.com/OysteinLAnderse, URL: http://www.oysteinlundandersen.com, images at https://twitter.com/OysteinLAnderse/status/1213658331564269569/photo/1 and https://twitter.com/OysteinLAnderse/status/1230419965209018369/photo/1).


Tinakula (Solomon Islands) — July 2020 Citation iconCite this Report

Tinakula

Solomon Islands

10.386°S, 165.804°E; summit elev. 796 m

All times are local (unless otherwise noted)


Intermittent small thermal anomalies and gas-and-steam plumes during January-June 2020

Tinakula is a remote stratovolcano located 100 km NE of the Solomon Trench at the N end of the Santa Cruz. In 1971, an eruption with lava flows and ash explosions caused the small population to evacuate the island. Volcanism has previously been characterized by an ash explosion in October 2017 and the most recent eruptive period that began in December 2018 with renewed thermal activity. Activity since then has consisted of intermittent thermal activity and dense gas-and-steam plumes (BGVN 45:01), which continues into the current reporting period. This report updates information from January-June 2020 using primary source information from various satellite data, as ground observations are rarely available.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed weak, intermittent, but ongoing thermal activity during January-June 2020 (figure 41). A small cluster of slightly stronger thermal signatures was detected in late February to early March, which is correlated to MODVOLC thermal alert data; four thermal hotspots were recorded on 20, 27, and 29 February and 1 March. However, observations using Sentinel-2 satellite imagery were often obscured by clouds. In addition to the weak thermal signatures, dense gas-and-steam plumes were observed in Sentinel-2 satellite imagery rising from the summit during this reporting period (figure 42).

Figure (see Caption) Figure 41. Weak thermal anomalies at Tinakula from 26 June 2019 through June 2020 as recorded by the MIROVA system (Log Radiative Power) were intermittent and clustered more strongly in late February to early March.
Figure (see Caption) Figure 42. Sentinel-2 satellite imagery shows ongoing gas-and-steam plumes rising from Tinakula during January through May 2020. Images with atmospheric penetration (bands 12, 11, 8a) rendering; courtesy of Sentinel Hub Playground.

Three distinct thermal anomalies were observed in Sentinel-2 thermal satellite imagery on 22 January, 11 April, and 6 May 2020, accompanied by some gas-and-steam emissions (figure 43). The hotspot on 22 January was slightly weaker than the other two days, and was seen on the W flank, compared to the other two that were observed in the summit crater. According to MODVOLC thermal alerts, a hotspot was recorded on 6 May, which corresponded to a Sentinel-2 thermal satellite image with a notable anomaly in the summit crater (figure 43). On 10 June no thermal anomaly was seen in Sentinel-2 satellite imagery due to the presence of clouds; however, what appeared to be a dense gas-and-steam plume was extending W from the summit.

Figure (see Caption) Figure 43. Sentinel-2 thermal satellite images showing a weak thermal activity (bright yellow-orange) on 22 January 2020 on the W flank of Tinakula (top) and slightly stronger thermal hotspots on 11 April (middle) and 6 May (bottom) in at the summit, which are accompanied by gas-and-steam emissions. Images with atmospheric penetration (bands 12, 11, 8a) rendering; courtesy of Sentinel Hub Playground.

Geologic Background. The small 3.5-km-wide island of Tinakula is the exposed summit of a massive stratovolcano at the NW end of the Santa Cruz islands. Similar to Stromboli, it has a breached summit crater that extends from the summit to below sea level. Landslides enlarged this scarp in 1965, creating an embayment on the NW coast. The satellitic cone of Mendana is located on the SE side. The dominantly andesitic volcano has frequently been observed in eruption since the era of Spanish exploration began in 1595. In about 1840, an explosive eruption apparently produced pyroclastic flows that swept all sides of the island, killing its inhabitants. Frequent historical eruptions have originated from a cone constructed within the large breached crater. These have left the upper flanks and the steep apron of lava flows and volcaniclastic debris within the breach unvegetated.

Information Contacts: MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Ibu (Indonesia) — July 2020 Citation iconCite this Report

Ibu

Indonesia

1.488°N, 127.63°E; summit elev. 1325 m

All times are local (unless otherwise noted)


Frequent ash emissions and summit incandescence; Strombolian explosions in March 2020

Ibu is an active stratovolcano located along the NW coast of Halmahera Island in Indonesia. Volcanism has recently been characterized by frequent ash explosions, ash plumes, and small lava flows within the crater throughout 2019 (BGVN 45:01). Activity continues, consisting of frequent white-and-gray emissions, ash explosions, ash plumes, and lava flows. This report updates activity through June 2020, using data from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC), and various satellites.

Volcanism during the entire reporting period dominantly consisted of white-and-gray emissions that rose 200-800 m above the summit drifting in multiple directions. The ash plume with the maximum altitude of 13.7 km altitude occurred on 16 May 2020. Sentinel-2 thermal satellite imagery detected multiple smaller hotspots within the crater throughout the reporting period.

Continuous ash emissions were reported on 6 February rising to 2.1 km altitude drifting E, accompanied by a hotspot visible in infrared satellite imagery. On 16 February, a ground observer reported an eruption that produced an ash plume rising 800 m above the summit drifting W, according to a Darwin VAAC notice. Ash plumes continued through the month, drifting in multiple directions and rising up to 2.1 km altitude. During 8-10 March, video footage captured multiple Strombolian explosions that ejected incandescent material and produced ash plumes from the summit (figures 21 and 22). Occasionally volcanic lightning was observed within the ash column, as recorded in video footage by Martin Rietze. This event was also documented by a Darwin VAAC notice, which stated that multiple ash emissions rose 2.1 km altitude drifting SE. PVMBG published a VONA notice on 10 March at 1044 reporting ash plumes rising 400 m above the summit. PVMBG and Darwin VAAC notices described intermittent eruptions on 26, 28, and 29 March, all of which produced ash plumes rising 300-800 m above the summit.

Figure (see Caption) Figure 21. Strombolian explosions recorded at the crater summit of Ibu during 8-10 March 2020 ejected incandescent ejecta and a dense ash plume. Video footage copyright by Martin Rietze, used with permission.
Figure (see Caption) Figure 22. Strombolian explosions recorded at the crater summit of Ibu during 8-10 March 2020 ejected incandescent ejecta and ash. Frequent volcanic lightning was also observed. Video footage copyright by Martin Rietze, used with permission.

A majority of days in April included white-and-gray emissions rising up to 800 m above the summit. A ground observer reported an eruption on 9 April, according to a Darwin VAAC report, and a hotspot was observed in HIMAWARI-8 satellite imagery. Minor eruptions were reported intermittently during mid-April and early to mid-May. On 12 May at 1052 a VONA from PVMBG reported an ash plume 800-1,100 m above the summit. A large short-lived eruption on 16 May produced an ash plume that rose to a maximum of 13.7 km altitude and drifted S, according to the Darwin VAAC report. By June, volcanism consisted predominantly of white-and-gray emissions rising 800 m above the summit, with an ash eruption on 15 June. This eruptive event resulted in an ash plume that rose 1.8 km altitude drifting WNW and was accompanied by a hotspot detected in HIMAWARI-8 satellite imagery, according to a Darwin VAAC notice.

The MIROVA (Middle InfraRed Observation of Volcanic Activity) system detected frequent hotspots during July 2019 through June 2020 (figure 23). In comparison, the MODVOLC thermal alerts recorded a total of 24 thermal signatures over the course of 19 different days between January and June. Many thermal signatures were captured as small thermal hotspots in Sentinel-2 thermal satellite imagery within the crater (figure 24).

Figure (see Caption) Figure 23. Thermal anomalies recorded at Ibu from 2 July 2019 through June 2020 as recorded by the MIROVA system (Log Radiative Power) were frequent and consistent in power. Courtesy of MIROVA.
Figure (see Caption) Figure 24. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) showed occasional thermal hotspots (bright orange) in the Ibu summit crater during January through June 2020. Courtesy of Sentinel Hub Playground.

Geologic Background. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, contained several small crater lakes through much of historical time. The outer crater, 1.2 km wide, is breached on the north side, creating a steep-walled valley. A large parasitic cone is located ENE of the summit. A smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. Only a few eruptions have been recorded in historical time, the first a small explosive eruption from the summit crater in 1911. An eruption producing a lava dome that eventually covered much of the floor of the inner summit crater began in December 1998.

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/); 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); Martin Rietze, Taubenstr. 1, D-82223 Eichenau, Germany (URL: https://mrietze.com/, https://www.youtube.com/channel/UC5LzAA_nyNWEUfpcUFOCpJw/videos, video at https://www.youtube.com/watch?v=qMkfT1e4HQQ).


Suwanosejima (Japan) — July 2020 Citation iconCite this Report

Suwanosejima

Japan

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

All times are local (unless otherwise noted)


Frequent explosions, ash plumes, and summit incandescence in January-June 2020

Suwanosejima is an active stratovolcano located in the northern Ryukyu Islands. Volcanism has previously been characterized by Strombolian explosions, ash plumes, and summit incandescence (BGVN 45:01), which continues to occur intermittently. A majority of this activity originates from vents within the large Otake summit crater. This report updates information during January through June 2020 using monthly reports from the Japan Meteorological Agency (JMA), the Tokyo Volcanic Ash Advisory Center (VAAC), and various satellite data.

During 3-10 January 2020, 13 explosions were detected from the Otake crater rising to 1.4 km altitude; material was ejected as far as 600 m away and ashfall was reported in areas 4 km SSW, according to JMA. Occasional small eruptive events continued during 12-17 January, which resulted in ash plumes that rose 1 km above the crater rim and ashfall was again reported 4 km SSW. Crater incandescence was visible nightly during 17-24 January, while white plumes rose as high as 700 m above the crater rim.

Nightly incandescence during 7-29 February, and 1-6 March, was accompanied by intermittent explosions that produced ash plumes rising up to 1.2 km above the crater rim (figure 44); activity during early February resulted in ashfall 4 km SSW. On 19 February an eruption produced a gray-white ash plume that rose 1.6 km above the crater (figure 45), resulting in ashfall in Toshima village (4 km SSW), according to JMA. Explosive events during 23-24 February ejected blocks onto the flanks. Two explosions were recorded during 1-6 March, which sent ash plumes as high as 900-1,000 m above the crater rim and ejected large blocks 300 m from the crater.

Figure (see Caption) Figure 44. Surveillance camera images of summit incandescence at Suwanosejima on 29 January (top left), 21 (middle left) and 23 (top right) February, and 25 March (bottom left and right) 2020. Courtesy of JMA (Monthly bulletin reports 511, January, February, and March 2020).
Figure (see Caption) Figure 45. Surveillance camera images of which and white-and-gray gas-and-steam emissions rising from Suwanosejima on 5 January (top), 19 February (middle), and 24 March 2020 (bottom). Courtesy of JMA (Monthly bulletin reports 511, January, February, and March 2020).

Nightly incandescence continued to be visible during 13-31 March, 1-10 and 17-24 April, 1-8, 15-31 May, 1-5 and 12-30 June 2020; activity during the latter part of March was relatively low and consisted of few explosive events. In contrast, incandescence was frequently accompanied by explosions in April and May. On 28 April at 0432 an eruption produced an ash plume that rose 1.6 km above the crater rim and drifted SE and E, and ejected blocks as far as 800 m from the crater. The MODVOLC thermal alerts algorithm also detected four thermal signatures during this eruption within the summit crater. An explosion at 1214 on 29 April caused glass in windows to vibrate up to 4 km SSW away while ash emissions continued to be observed following the explosion the previous day, according to the Tokyo VAAC.

During 1-8 May explosions occurred twice a day, producing ash plumes that rose as high as 1 km above the crater rim and ejecting material 400 m from the crater. An explosion on 29 May at 0210 produced an off-white plume that rose as high as 500 m above the crater rim and ejected large blocks up to 200 m above the rim. On 5 June an explosion produced gray-white plumes rising 1 km above the crater. Small eruptive events continued in late June, producing ash plumes that rose as high as 900 m above the crater rim.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed relatively stronger thermal anomalies in late February and late April 2020 with an additional six weaker thermal anomalies detected in early January (2), early February (1), mid-April (2), and mid-May (1) (figure 46). Sentinel-2 thermal satellite imagery in late January through mid-April showed two distinct thermal hotspots within the summit crater (figure 47).

Figure (see Caption) Figure 46. Prominent thermal anomalies at Suwanosejima during July-June 2020 as recorded by the MIROVA system (Log Radiative Power) occurred in late February and late April. Courtesy of MIROVA.
Figure (see Caption) Figure 47. Sentinel-2 thermal satellite images showing small thermal anomalies (bright yellow-orange) from two locations within the Otake summit crater at Suwanosejima. Images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

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

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


Bagana (Papua New Guinea) — July 2020 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)


Ash plumes during 29 February-2 March and 1 May 2020

Bagana lies in a nearly inaccessible mountainous tropical rainforest area of Bougainville Island in Papua New Guinea and is primarily monitored by satellite imagery of ash plumes and thermal anomalies. After a state of elevated activity that lasted through December 2018 (BGVN 43:05, 44:06, 44:12), the volcano entered a quieter period that persisted through at least May 2020. This report focuses on activity between December 2019 and May 2020.

Atmospheric clouds often obscured satellite views of the volcano during the reporting period. When the volcano could be observed, light-colored gas plumes were often observed (figure 43). Based on satellite and wind model data, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 29 February-2 March ash plumes rose to an altitude of 1.8-2.1 km and drifted SW and N. On 1 May an ash plume rose to an altitude of 3 km and drifted NW and W. According to both Darwin VAAC volcanic ash advisories, the Aviation Color Code was Orange (second highest of four hazard levels).

Figure (see Caption) Figure 43. Sentinel-2 image of Bagana, showing a gas plume drifting SE on 13 March 2020, during a period when the Darwin VAAC had not reported any ash explosions (Natural Color rendering, bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

During the reporting period, the MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system recorded only intermittent thermal anomalies, all of which were of low radiative power. Sulfur dioxide emissions detected by satellite-based instruments over this reporting period were at low levels.

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/); 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/); 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/).

Search Bulletin Archive by Publication Date

Select a month and year from the drop-downs and click "Show Issue" to have that issue displayed in this tab.

   

The default month and year is the latest issue available.

Bulletin of the Global Volcanism Network - Volume 34, Number 06 (June 2009)

Managing Editor: Richard Wunderman

Manda Hararo (Ethiopia)

Fissure eruption generates lava flows and large SO2 plume

Miyakejima (Japan)

Four minor eruptions between August 2006 and April 2009

NW Rota-1 (United States)

Ongoing eruption has created a new 40-m-high cone

Paluweh (Indonesia)

April 2009 spike in seismicity but no explosive activity or visible emissions

Redoubt (United States)

Dome growth apparently slows; threat level lowered

Rinjani (Indonesia)

Mid-2009 eruptions send lava flows to the caldera lake

Sangay (Ecuador)

Occasional ash plume activity continues

Sarychev Peak (Russia)

Widespread plumes from large 11-16 June 2009 eruption

Tafu-Maka (Tonga)

Submarine volcanism and lava flows on the Northeast Lau Spreading Center

Telica (Nicaragua)

Intermittent incandescence and ash explosions through January 2005

West Mata (Tonga)

Submarine effusive and explosive eruption seen at two vents in May 2009



Manda Hararo (Ethiopia) — June 2009 Citation iconCite this Report

Manda Hararo

Ethiopia

12.17°N, 40.82°E; summit elev. 600 m

All times are local (unless otherwise noted)


Fissure eruption generates lava flows and large SO2 plume

A large SO2 cloud in southern Afar, Ethiopia was detected by the OMI instrument aboard NASA's EOS-AURA satellite on 29 June 2009 (figure 28). The cloud appeared to originate from the Karbahi region of the Manda Hararo rift segment, a graben area with numerous active faults, fissures, and basalt flows. The cloud was similar in size to that observed during a basaltic fissure eruption in August 2007 (BGVN 32:07). As reported by Simon Carn, the 29 June 2009 cloud had a total mass of 3.864 kt, an area of 186,710 km2, and an SO2 max of 4.75 DU (Dobson Units). Other clouds were also seen, including a large one on 30 June.

Figure (see Caption) Figure 28. The eruptive SO2 cloud from Manda hararo over southern Afar region detected by the OMI instrument. Image acquired during 1021-1203 UTC on 29 June 2009. Courtesy of Simon Carn, Michigan Technological University.

MODIS satellite imagery from 2320 UTC on 28-29 June confirmed that the SO2 cloud was associated with thermal anomalies appearing in the immediate vicinity of the August 2007 eruption. According to Charles Holliday, METEOSAT real time Active Fire Monitoring data derived from METEOSAT imagery suggests the eruption began within 15 minutes of 1715 UTC on 28 June 2009, about 7 hours after a magnitude 4.4 earthquake, identified by the Addis Ababa Geophysical Observatory and the European-Mediterranean Seismological Centre.

A field team of scientists, including Gezahegn Yirgu, Tesfaye Kidane, Elias Lewi, Tesfaye Chernet, Girma Wolde Tinsae, David Ferguson, Talfan Barnie, and Osman Mohammed, reached the site of the thermal anomalies by helicopter on 4 July 2009 and spent about two hours on the scene. They found the eruption had emitted predominantly a'a basalt flows, approximately 2-3 m thick that originated from fissures approximately 4-5 km long. The vent areas contained scoria ramparts approximately 30-50 m high. The field team collected rock and gas samples and surveyed the erupted material using visible and FLIR (Forward-Looking Infrared) cameras from both the air and the ground. Hand samples suggested the erupted lava was feldspar-bearing porphyritic basalt. No lava effusion was observed, although some steam was seen at the fissure (figure 29).

Figure (see Caption) Figure 29. Oblique aerial photograph of Manda Hararo showing the eruptive fissure, scoria ramparts, and gas plume on 4 July 2009. Courtesy of Talfan Barnie, University of Cambridge.

The fissure itself was inaccessible over land because it was surrounded by hot rock and could only be observed from a distance. Only a small part of the margins of the flow were visited on the ground due to limited time, rough terrain, and high temperature and humidity. The lava flows appeared to have cooled significantly, with the FLIR recording typical temperatures of between 30 and 120°C for the flow surfaces, and a maximum temperature of 238°C observed from the air (figure 30). The team made gas measurements at hot cracks in the flow front where they smelled volcanic gases and the FLIR registered temperatures over 100°C. According to David Ferguson, the group used FLIR thermal images to determine a safe route for walking. While the front of the lava flow had a dark black crust, similar to that of much colder flows, the FLIR camera on land recorded temperatures of up to 162°C around the cracks and fissures of the flow surface.

Figure (see Caption) Figure 30. FLIR image of the 4 July 2009 eruption at Manda Hararo showing temperature distribution in and around the fissure. Courtesy of Talfan Barnie, University of Cambridge.

A 6 July ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) image from the eruption site shows a warm 6.3 x 1.4 km flow erupted from a NW-SE trending fissure (figure 31). The area of the flow field is 4.0 km2. The coordinates of the center of the flow field are 40.655, 12.256. A 9 July EO-1 ALI panchromatic image shows the flow at a higher resolution (figure 32).

Figure (see Caption) Figure 31. ASTER infrared image at Manda Hararo taken on 6 July 2009. The image shows a warm flow, 6.3 x 1.4 km, erupted from what looks like a NW-SE trending fissure. A clear pre-eruptive image from May 2009 shows nothing anomalous at this spot, indicating that the lava flow is new. The coordinates of the center of the flow field are 12.256°N, 40.655°E. Courtesy of Matt Patrick.
Figure (see Caption) Figure 32. An EO-1 ALI panchromatic image (10-m pixel size) showing the flow at Manda Hararo on 9 July 2009. Courtesy of Matt Patrick.

Geologic Background. As the southernmost axial range of western Afar, the Manda Hararo complex is located in the Kalo plain, SSE of Dabbahu volcano. The massive 105-km-long and 20-30 km wide complex represents an uplifted segment of a mid-ocean ridge spreading center. A small basaltic shield volcano is located at the N end of the complex, S of which is an area of abundant fissure-fed lava flows. Two basaltic shield volcanoes, the larger of which is Unda Hararo, occupy the center of the complex. The dominant Gumatmali-Gablaytu fissure system lies to the S. Voluminous fluid lava flows issued from these NNW-trending fissures, and solidified lava lakes occupy two large craters. The small Gablaytu shield volcano forms the SE-most end of the complex. Lava flows from Gablaytu and from Manda overlie 8,000-year-old sediments. Hot springs and fumaroles occur around Daorre lake. The first historical eruptions produced fissure-fed lava flows in 2007 and 2009.

Information Contacts: Gezahegn Yirgu, Dept of Earth Sciences, Addis Ababa University, P.O. Box 729/1033, Addis Ababa, Ethiopia; Simon Carn, Dept of Geological and Mining Engineering and Sciences, Michigan Technological Univ, 1400 Townsend Dr., Houghton, MI 49931, USA (URL: https://so2.gsfc.nasa.gov/); Afar Rift Consortium (URL: http://www.see.leeds.ac.uk/afar/); Charles Holliday, U.S. Air Force Weather Agency (AFWA)/XOGM, Offutt Air Force Base, NE 68113, USA; 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://modis.higp.hawaii.edu/); guardian.co.uk Science Blog (URL: https://www.theguardian.com/science/blog); David Ferguson, Dept of Earth Sciences, Univ of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom; Talfan Barnie, Dept of Geography, Univ of Cambridge, Downing Place, Cambridge CB2 3EN, United Kingdom (URL: http://www.geog.cam.ac.uk/people/barnie/); Afar Rift Consortium, School of Earth and Environment, Univ of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom (URL: http://www.see.leeds.ac.uk/afar/); Matt Patrick, HIGP/SOEST, Univ of Hawaii-Manoa, 1680 East-West Road, Honolulu, HI 96822, USA.


Miyakejima (Japan) — June 2009 Citation iconCite this Report

Miyakejima

Japan

34.094°N, 139.526°E; summit elev. 775 m

All times are local (unless otherwise noted)


Four minor eruptions between August 2006 and April 2009

Miyake-jima has had a recent history of periodic minor eruptions and gas emissions containing relatively high concentrations of sulfur dioxide (SO2). SO2 emissions in January 2006 averaged about 2,000-5,000 tons per day, and there was a minor eruption on 17 February 2006 (BGVN 31:03).

The Tokyo Volcanic Ash Advisory Center (VAAC) described an eruption on 23 August 2006 that generated plumes which rose to an altitude of about 1.5 km and drifted SE. Ash was not identified on satellite imagery. No additional eruption reports were received until January 2008. Based on information from the Japan Meteorological Agency (JMA), the Tokyo VAAC reported that an eruption plume on 7 January rose to an altitude of 1.2 km and drifted SE. The JMA also reported an eruption on 8 May 2008. Another eruption reported by JMA produced an ash plume that rose 600 m above the crater and drifted E on 1 April 2009.

Geologic Background. The circular, 8-km-wide island of Miyakejima forms a low-angle stratovolcano that rises about 1,100 m from the sea floor in the northern Izu Islands about 200 km SSW of Tokyo. The basaltic volcano is truncated by small summit calderas, one of which, 3.5 km wide, was formed during a major eruption about 2,500 years ago. Parasitic craters and vents, including maars near the coast and radially oriented fissure vents, dot the flanks of the volcano. Frequent historical eruptions have occurred since 1085 CE at vents ranging from the summit to below sea level, causing much damage on this small populated island. After a three-century-long hiatus ending in 1469, activity has been dominated by flank fissure eruptions sometimes accompanied by minor summit eruptions. A 1.6-km-wide summit caldera was slowly formed by subsidence during an eruption in 2000; by October of that year the crater floor had dropped to only 230 m above sea level.

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


NW Rota-1 (United States) — June 2009 Citation iconCite this Report

NW Rota-1

United States

14.601°N, 144.775°E; summit elev. -517 m

All times are local (unless otherwise noted)


Ongoing eruption has created a new 40-m-high cone

An oceanographic research expedition during 3-17 April 2009 visited NW Rota-1 submarine volcano, located about 100 km N of Guam in the Mariana arc. Scientists visited the volcano with research ressel Thomas G. Thompson, making dives with the Jason remotely operated vehicle (ROV). The volcano was erupting almost all of the time with varying amplitude. This volcano was previously observed erupting during ROV dives in March 2004 (BGVN 29:03) and April 2006 (BGVN 31:05) on National Oceanographic and Atmospheric Agency (NOAA) Ocean Exploration expeditions, and by the Japanese in October 2005 and February 2008 (<BGVN 32:02).

A hydrophone deployed from February 2008 until February 2009, operated under the direction of Robert Dziak, measured almost continuous signals from the volcano during the 1-year period. This hydrophone will record data for another year, but it lacks telemetry, so NOAA intends to retrieve its data in 6-12 months. Prior to the deployment of the hydrophone activity was observed using a ROV only during brief visits.

On the expedition blog, William Chadwick noted that with NW Rota-1 apparently nearly continuously active since at least 2003, the volcano can provide a natural laboratory for learning about underwater eruptions, how submarine volcanoes grow, and how they affect the ocean environment. Scientists are able to get close to the eruptive vent because the pressure of the ocean above keeps the energy of the eruptions subdued, allowing them to gain a view of what is happening in the vent. For example, scientists watched lava slowly being pushed up and out of the eruptive vent while the sea floor shuddered and quaked and huge blocks were bulldozed out of the way to make room for new lava emerging from the vent.

The volcano had grown considerably since 2006, producing a new cone ~ 40 m high and ~ 300 m wide. Despite the ongoing eruption, with ash and rocks falling everywhere and an extreme chemical environment, a thriving ecosystem was present. The population of animals and microbes had both increased relative to 2006 and become more diverse, including new species not yet found elsewhere.

At the end of the 2009 cruise, an array of instruments (hydrophone and chemical sensors) was left to monitor events over the next year. Moorings on the flanks will look for landslides and debris flows. Chadwick's group plans to return in 2010 to continue investigations. On his blog site are some video highlights from the 2009 expedition showing activity at the Brimstone eruptive vent at the top of the new cone.

Geologic Background. A submarine volcano detected during a 2003 NOAA bathymetric survey of the Mariana Island arc was found to be hydrothermally active and named NW Rota-1. The basaltic to basaltic-andesite seamount rises to within 517 m of the sea surface SW of Esmeralda Bank and lies 64 km NW of Rota Island and about 100 km north of Guam. When Northwest Rota-1 was revisited in 2004, a minor submarine eruption from a vent named Brimstone Pit on the upper south flank about 40 m below the summit intermittently ejected a plume several hundred meters high containing ash, rock particles, and molten sulfur droplets that adhered to the surface of the remotely operated submersible vehicle. The active vent was funnel-shaped, about 20 m wide and 12 m deep. NW Rota-1 is a large submarine volcano with prominent structural lineaments about a kilometer apart cutting across the summit of the edifice and down the NE and SW flanks.

Information Contacts: William W. Chadwick, Oregon State University and NOAA Vents Program, Newport, Oregon; 2115 SE OSU Drive, Newport, OR 97365 USA (URL: http://nwrota2009.blogspot.com/); Robert G. Dziak, Oregon State University and NOAA Vents Program, Newport, Oregon; 2115 SE OSU Drive, Newport, OR 97365 USA.


Paluweh (Indonesia) — June 2009 Citation iconCite this Report

Paluweh

Indonesia

8.32°S, 121.708°E; summit elev. 875 m

All times are local (unless otherwise noted)


April 2009 spike in seismicity but no explosive activity or visible emissions

During 1-17 April 2009, seismicity increased at Paluweh (table 1), prompting the Center of Volcanology and Geological Hazard Mitigation (CVGHM) to raise the Alert Level from 1 to 2 (Waspada) on 18 April. CVGHM staff in the observation post did not see any gas or ash emissions. Visitors were requested to stay away from the active crater adjacent to the peak.

Table 1. Average number of daily seismic events recorded from Paluweh, April 2009. Courtesy of CVGHM.

Date Deep volcanic earthquakes (daily average) Shallow volcanic earthquakes (daily average)
01-03 Apr 2009 2 2
04-05 Apr 2009 17 18
06-10 Apr 2009 6 11
11-13 Apr 2009 6 10
14-15 Apr 2009 22 10
16 Apr 2009 23 15

Explosive activity had most recently been observed in May 1984 and previously during November 1980-September 1981 (SEAN 06:01, 06:02, 06:08, and 06:09), October 1973, and October 1972-January 1973. Activity in December 1963-March 1966 included lava flows, pyroclastic flows, and fatalities.

An unconfirmed news report of activity in January 2005, not reported in the Bulletin, was later found to be false. The CVGHM staff found no activity at the volcano.

As background on hazard considerations, the mouth of the principal crater opens to the S, where there is plantation agriculture almost to the volcano's peak. In the advent of a future crisis, evacuation would be complicated because a safer area is about two hours journey by motor vessel, and leaving the island might not be possible during storms or rough seas. CVGHM is in continuous contact with the provincial and regional governments, some monitor of Paluweh occurs from the hamlet of Ropa on the N-central coast of the big island of Flores, to Paluweh's S. Regional civil-defense agencies (such as SATKORLAK-PB, the Provincial Coordinating Unit for Disaster Management) and district government agencies of Sikka and Ende (such as SATLAK-PB, the Local Coordinating Body for Disaster Relief) are continually apprised of the activity level.

Geologic Background. Paluweh volcano, also known as Rokatenda, forms the 8-km-wide island of Palu'e north of the volcanic arc that cuts across Flores Island. The broad irregular summit region contains overlapping craters up to 900 m wide and several lava domes. Several flank vents occur along a NW-trending fissure. The largest historical eruption occurred in 1928, when strong explosive activity was accompanied by landslide-induced tsunamis and lava dome emplacement. Pyroclastic flows in August 2013 resulted in fatalities.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.go.id/).


Redoubt (United States) — June 2009 Citation iconCite this Report

Redoubt

United States

60.485°N, 152.742°W; summit elev. 3108 m

All times are local (unless otherwise noted)


Dome growth apparently slows; threat level lowered

Major eruptions took place at Redoubt between 15 March and 4 April 2009 (BGVN 34:04) (figure 22-24). Subsequent to those eruptions, through mid-May 2009, the lava dome continued to grow. That growth was often associated with occasional rockfalls, and small plumes, some of which contained ash and sulfur dioxide. The eruption had significant economic impacts including to the aviation industry (BGVN 34:04). The current report summarizes activity from mid-May to 30 June 2009.

Figure (see Caption) Figure 22. View of the face of Redoubt taken on 2 July 2009. Courtesy of AVO/USGS and Cyrus Read.
Figure (see Caption) Figure 23. Redoubt fall deposit laid down on 23 March 2009. Taken at station RDW-C in July 2009. Courtesy of AVO/ADGGS and Kate Bull.
Figure (see Caption) Figure 24. View looking towards Redoubt, 1 July 2009. Courtesy of the AVO/ADGGS and Kate Bull.

Alaska Volcano Observatory (AVO) reported seismicity from Redoubt during 13 May to 23 June 2009 remained above background levels. Signals disclosed rock avalanches, discrete earthquakes. Minor volcanic tremor continued. Growth of the lava dome in the summit crater (figure 25) continued, and by 15 May the dome's volume was an estimated 30-60 million cubic meters. By 12 June, the dome was an estimated 1 km long, 460 m wide, and 200 m high. AVO warned that the unstable lava dome could fail with little or no warning, leading to significant ash emissions and possible lahars in the Drift River valley. Occasional rockfalls originating from unstable slopes of the lava dome produced minor ash clouds near the summit.

Figure (see Caption) Figure 25. A series of Forward Looking InfraRed (FLIR) thermal images showing the Redoubt dome's gradual cooling. The new dome has been extruding since 4 April 2009. Temperature scales are at right. Note the average temperature of the rubbly area between the vent at the top of the dome and the block top at the N base of the dome (circle) varied between -1.0 to 1.4°C. Courtesy of AVO/USGS and Rick Wessles.

Vigorous steam emissions from the margins of the lava dome were seen on the web camera. At times, incandescence was observed in nighttime images. During an overflight on 16 May, scientists observed a turquoise lake along the S margin of the dome, and a hot, vigorous, persistent fumarole on the W wall of the upper gorge.

By late June 2009, AVO reported declining seismicity. The lower seismicity and gas emissions, along with occasional observations, suggested that dome growth had significantly slowed. On 30 June, AVO lowered the Alert Level to Advisory and the Aviation Color Code to Yellow.

Aviation encounter on 26 March 2009. The Montreal VAAC received news that a plane for a Canadian carrier encountered a volcanic cloud over southern British Columbia, near Kelowna, at approximately 0000 UTC on 26 March 2009. At that time, to the best knowledge of the VAAC, the plume from the initial eruption of Redoubt (23 March) consisted of considerable amounts of SO2, but no ash. A full inspection of the plane found no ash.

Geologic Background. Redoubt is a glacier-covered stratovolcano with a breached summit crater in Lake Clark National Park about 170 km SW of Anchorage. Next to Mount Spurr, Redoubt has been the most active Holocene volcano in the upper Cook Inlet. The volcano was constructed beginning about 890,000 years ago over Mesozoic granitic rocks of the Alaska-Aleutian Range batholith. Collapse of the summit 13,000-10,500 years ago produced a major debris avalanche that reached Cook Inlet. Holocene activity has included the emplacement of a large debris avalanche and clay-rich lahars that dammed Lake Crescent on the south side and reached Cook Inlet about 3,500 years ago. Eruptions during the past few centuries have affected only the Drift River drainage on the north. Historical eruptions have originated from a vent at the north end of the 1.8-km-wide breached summit crater. The 1989-90 eruption had severe economic impact on the Cook Inlet region and affected air traffic far beyond the volcano.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA; Associated Press (URL: http://www.ap.org/); Dov Bensimon, Montréal VAAC, 2121 North Service Road, Trans-Canada Highway, Dorval, Quebec H9P 1J3, Canada.


Rinjani (Indonesia) — June 2009 Citation iconCite this Report

Rinjani

Indonesia

8.42°S, 116.47°E; summit elev. 3726 m

All times are local (unless otherwise noted)


Mid-2009 eruptions send lava flows to the caldera lake

Eruptions at Rinjani (figures 8 and 9) between October 2004 and January 2005 (BGVN 30:02) was the first activity noted since September 1995. On 29 April 2009, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) again detected an increase in earthquakes and tremor, with eruptions from Barujari's cone beginning 2 May 2009 and continuing through 21 June 2009.

Figure (see Caption) Figure 8. Map of Rinjani National Park's campsites and relative elevations. Courtesy of Rinjani Trek Centre (RTC).
Figure (see Caption) Figure 9. Diagram of Rinjani showing the Barujari volcanic cone surrounded by Lake Segara Anak. Courtesy of Bohari Adventures.

According to a 4 May news article in the Jakarta Post, the first 2 May eruption consisted of four tectonic earthquakes, each lasting between 70 and 120 seconds. Heriyadi Rachmat, head of the East Nusa Tenggara province's mining, energy and mineral resources agency, stated in the article that "the peak of the activity was on Saturday 2 May with four tremors and the eruption of thick ash." This activity prompted CVGHM to raise the Alert Level from 1 to 2 (on a scale of 1 to 4). The head of the Mt. Rinjani National Park confirmed that, as of 3 May, the park had been officially closed to hikers. At that time, around 50 hikers were asked to come down from the mountain. Rinjani, a popular tourist destination, attracts an average of 9,000 hikers per year, 4,000 of whom are foreigners.

During May and June 2009, seismic activity consisted of numerous eruption signals, while observers saw ash plumes, incandescent material, and lava flows (table 3). CVGHM recorded the largest numbers of seismic signals between 7 and 31 May. In detail, during that interval there were 1,897 eruptive earthquakes, 2,163 low-frequency earthquakes, 1,341 harmonic tremor episodes, 3,249 air blasts, 17 shallow volcanic earthquakes, 39 deep volcanic earthquakes, seven local tectonic earthquakes, and three long-distance tectonic earthquakes. Although the volcano was frequently obscured by fog, people still saw impressive eruptions from the observation post at Sembalun Lawang. They noted continuous eruptions with ejected glowing material reaching 200 m in height above the vent, and thrown laterally out to a radius of 500 m from the summit. A great amount of ash, cinders, and incandescent material fell into the caldera, while smaller fragments were blown away.

Table 3. Earthquakes, tremor (both harmonic and non-harmonic with variable maximum amplitudes and durations), air blasts, and other observations between 2 May and 21 June 2009. Key: LD is long distance tectonic, SV is shallow volcanic, LT is local tectonic, DV is deep volcanic. Courtesy of CVGHM and the Darwin VAAC.

Date Eruptive earthquake Low-frequency tremor Harmonic tremor Airblasts Other earthquakes Observations
02 May 2009 -- -- -- -- -- Dense brown ash plume to 4.7 km altitude; booming noise.
03 May 2009 21 13 -- -- -- Recorded during 1800-2400.
04 May 2009 85 12 1 7 1 LD Ash eruption produced white to brown plume to 4.2-4.4 km altitude, drifting N.
05 May 2009 83 2 45 -- -- --
06 May 2009 83 22 30 53 Three volcanic --
07 May 2009 92 43 29 88 -- Recorded between 0000 and 1800; thick white plume.
07-31 May 2009 1,897 2,154 1,341 3,249 17 SV, 39 DV, 7 LT, 3 LD 163 eruptions with dense white and gray plumes rising to 3.8-4.1 km altitude.
01-06 Jun 2009 240 569 493 316 5 SV,10 DV, 2 LT, 6 LD --
07-15 Jun 2009 -- Continuous -- -- 3 DV Dense white plumes to 1.3-2.7 km altitude.
16 Jun 2009 -- Continuous -- -- 1 LD Dense white plumes to 1.3-1.5 km altitude.
21 Jun 2009 -- -- -- -- -- Ash plumes to altitude of 3.0 km; drifted N.

Lava flowed into the caldera lake and then extended 100 m beyond the shoreline. CVGHM and Darwin Volcanic Ash Advisory Center (VAAC) reports also noted several ash plumes over the summit, including those of dense white and grayish color that rose 50-400 m above Sembalun Lawang observatory from 7 May through 29 May.

Potential hazards. As of 16 June 2009, the status of Rinjani remained at Alert Level 2. CVGHM recommended remaining at least 4 km from the Barujari vent, noting potential risks from ashfall and incandescent rocks both within the caldera and in the surrounding areas (figure 10). In addition, CVGHM cautioned that landslides could enter Lake Segara Anak, causing an overflow that could form lahars.

Figure (see Caption) Figure 10. A hazard map showing risk areas at Rinjani. Note the lahars extend beyond the two concentric circular areas, reaching the sea on the N to NW outer flanks. Date of publication and exact details of authorship uncertain. Courtesy of CVGHM.

Geologic Background. Rinjani volcano on the island of Lombok rises to 3726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the east, but the west side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak (Samalas) caldera. The caldera formed during one of the largest Holocene eruptions globally in 1257 CE, which truncated Samalas stratovolcano. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the east end of the caldera. Historical eruptions dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.

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/); The Jakarta Post (URL: http://www.thejakartapost.com/news/2009/05/04/mt-baru-jari-spews-ash.html); Rinjani Trekking Centre, Jalan Barakuda 10, BTN Griya Batu Bolong Senggigi, Senggigi-West Lombok 83355, Lombok-NTB-Indonesia (URL: http://www.rinjanimountain.com/rinjani-information-center.htm); Bohari Adventures, Jalan Cendrawasih 8, Cakranegara Mataram 83231, Lombok-NTB-Indonesia (URL: http://www.trekkingrinjani.com/).


Sangay (Ecuador) — June 2009 Citation iconCite this Report

Sangay

Ecuador

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

All times are local (unless otherwise noted)


Occasional ash plume activity continues

Our most recent reports on Sangay noted occasional steam and/or ash plumes between 11 October 2006 and 28 December 2007 (BGVN 33:03) and thermal anomalies between 27 March and 4 December 2008 (BGVN 34:01). The current report continues to tabulate this persistently erupting volcano's plumes from 28 December 2007 to 31 July 2009 (table 3), and thermal anomalies from 4 December 2008 to 10 August 2009 (table 4).

Table 3. Sangay ash plume activity, reported for 29 December 2008 to July 2009. NR signifies not reported and no plumes were observed 29-31 December 2008. TA is thermal anomaly. Courtesy of the Washington Volcanic Ash Advisory Center.

Date Maximum Altitude Bearing Remarks
05 Jan 2009 7 km S --
09 Feb 2009 7.9 -- --
10 Mar 2009 5.5 W TA detected
15 Jun 2009 -- WNW TA reported by VAAC
26 Jun 2009 7.6 W --
23 Jul 2009 7.9 -- --

Table 4. Thermal anomalies at Sangay based on MODIS-MODVOLC data during 4 December 2008 to 10 August 2009 (continued from the list in BGVN 34:01). Courtesy HIGP Thermal Alerts System.

Date (UTC) Time (UTC) Pixels Satellite
10 Mar 2009 0645 1 Aqua
10 Aug 2009 0340 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, 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) 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/).


Sarychev Peak (Russia) — June 2009 Citation iconCite this Report

Sarychev Peak

Russia

48.092°N, 153.2°E; summit elev. 1496 m

All times are local (unless otherwise noted)


Widespread plumes from large 11-16 June 2009 eruption

On 11 June 2009 one of the largest historical eruptions in the Kuril Islands began?from Sarychev Peak (figure 1). A report from the Sakhalin Volcanic Eruption Response Team (SVERT) covered events through June, and included both remote-sensing and on-the-scene observations by Russian scientists. Other contributors include astronauts and remote-sensing specialists. Synonyms for the volcano include Fue-san, Matsuwa-jima, Matua-jima, and Sarnicheff.

Figure (see Caption) Figure 1. Broad-scale maps of the Kuril Islands showing regional geography and the location of Sarychev Peak. Base maps are courtesy of the Sakhalin Volcanic Eruption Response Team (SVERT). Representative aviation routes on the inset map are from Casadevall and Thompson (1995).

Monitoring. Volcano monitoring is conducted by SVERT in the southern and central Kurils, and by KVERT in the northern Kurils (figure 1). The region is well known for severe weather, including summertime cloudy and foggy conditions; volcano monitoring has depended heavily on remote-sensing methods.

With respect to civil aviation, the Kuril Islands are the responsibility of the Tokyo Volcanic Ash Advisory Center (VAAC). A zone without designated VAAC jurisdiction over N-central Russia is ~ 1,400 km N. The substantial plumes caused concern about that zone's ambiguous status and the whereabouts of Sarychev's ash.

This part of the North Pacific is sparsely populated but is one of the world's most heavily traveled air corridors, crossed by flights linking Europe and North America to northern Asia (including Japan, parts of China, Hong Kong, and Korea). Injecting ash into these flight routes, Sarychev's eruption triggered diversions or delays to an unknown number of flights. Reliable sources indicated that some aircraft diversions over Russia, and other unexpected factors, cost as much as $100,000 USD per flight.

Precursors and initial eruption, 11 June 2009. Before the June 2009 eruption the volcano was dormant with substantial fumarolic activity. Visitors looking into the crater in August 2008 encountered thick fog, but did heard noises. On 6 June 2009 specialists came to the island to service an autonomous GPS station. Photographs documented increased gas emissions.

SVERT's report stated that the first signs of eruption came as a result of satellite observations acquired on 11 June 2009. Distinct then were both a thermal anomaly and weak ash emissions. During the eruption, ashfalls were widespread and noted at sites including Raikoke, Rasshua, Ushishir, Ketoi, the Simushir islands, the northern part of Urup Island, and widespread on Sakhalin Island.

On the night of 11-12 June, the scientific research ship George Steller passed near the island without anyone noticing an eruption, according to an oral report from the expedition chief Vladimir Burkanov.

Space Station photograph, 12 June 2009. A stunning photo of the plume taken on 12 June 2009 (figure 2) from the International Space Station (ISS) shows not only a highly complex ash cloud, but at least two or three distinct (different colored) volcanic clouds hugging the ground surface and traveling radially out from the vent. One is an unmistakable, light-colored pyroclastic flow, narrowing as it progresses out over the island until ultimately hidden by the edge of the weather clouds. Another set are broader, dark-colored clouds, presumably other pyroclastic flows.

Figure (see Caption) Figure 2. A digital photograph of a Sarychev Peak's eruption plume taken by astronauts on 12 June 2009 from the International Space Station. N is to the upper right. [Astronaut photograph ISS020-E-9048; acquired 12 June at 22:16 UTC with a Nikon D2XS digital camera fitted with a 400 mm lens; Nadir point 48.8°N, 157.5°E]. Courtesy of NASA Earth Observatory.

The vertical plume looks dense and well confined; absent is the strongly spreading upper region common in many eruptive plumes (an umbrella cloud). The top of this cloud is bulbous, and trailing below it is a narrower, columnar lower segment colored in shades of brown and cream. At the time of this writing no clear analysis of the plume height has come to our attention. Older dispersed plumes are also apparent at distance (some at the left edge of this photo) and on satellite imagery from 12 June, with airborne ash covering a considerable area and extending in more than one direction.

Capping the ash cloud's bulbous top and in a ring just below it, lies a strikingly smooth, white portion of the plume, a feature called a pileus cloud (figure 2). It results from a slab of uncontaminated air pushed upward ahead of the rapidly rising darker zone. Pileus clouds sometimes form above mountain tops and convectively rising weather clouds. For the pileus cloud to form, the lifted air layer must have sufficient moisture (relative humidity). The underlying clouds often punch through the pileus clouds, a process that seems to have started here. The lower clouds that result are sometimes described as cloud skirts (the ring in this case).

The hole in the weather clouds centered above the volcano is likely in part due to meteorological conditions; such holes often occur similarly centered over islands in the Kuril chain. This may result, for example, from an island's landmass warming moist air or forcing it upwards to mix with dryer air, resulting in a local loss of cloud cover; such an effect might combine with downwind eddies. A broader 12 June ISS image shows a series of holes in regional weather clouds in a pattern aligned broadly over the Kuriles. Another explanation, with many adherants, is that the hole may have been caused or influenced by effects associated with dynamics of the eruption and plume propagation (Wilkinson, 2009).

The opportune ISS flyover resulted in 29 still images of the eruption taken over a 1-minute interval. NASA used the photos to create a series of animations, also available on the NASA Earth Observatory website. The ISS orbits at ~ 400 km altitude and ~ 27,500 km/hour. Patrick Vantuyne created a red-blue stereo image of the 12 June plume, posted by NASA as a "Picture of the Day."

Satellite-based observations. SVERT reported that the energetic phase of the eruption, during 11-16 June, encompassed more than ten large explosions (figures 3 and 4). Resulting ash clouds rose up to altitudes of 8-16 km and, according to some estimates, up to 21 km. Ash plumes stretched N to W for 1,500 km, and E for more than 3,000 km. Comparative analysis of ASTER-Terra satellite images indicated newly formed territory amounted to 1.4 km2. The area of island covered by June 2009 pyroclastic flows was more than 8 km2. The preliminary estimated minimum volume of eruptive rock was 0.4 km3.

Figure (see Caption) Figure 3. A MODIS satellite image of the Sarychev Peak eruption plume from 16 June 2009. In colored versions the plume is black. As it spread W, part of the plume took the form of a large spiral, portions of which extended at least as far W as Sakhalin Island. The plume also appears in thinner strands to the NE of the source. Courtesy of SVERT and MODIS.
Figure (see Caption) Figure 4. False-color ASTER images from 27 May 2007 and 30 June 2009 showing before-and-after scenes of Sarychev Peak's eruption. The 2007 photo shows remnant seasonal snow on the island and some cloud over the summit. N is towards the top and the long-axis of Matua (large island) is ~ 12 km and the diameter of Toporkovyi (small island) is ~ 1 km. The eruption's effects were strong to the NW, around the volcano, but fieldwork confirmed that they left both the SE end of Matua Island and all of the flat Toporkovyi Island comparatively untouched. Comparison of images shows that pyroclastic flows extended the shoreline of the island, particularly NE and SW of the volcano. Courtesy of ASTER and SVERT.

Broader imagery of the region also indicated more diffuse high-altitude ash clouds. Starting on 12 June, the ash spread hundreds of kilometers both E and W and to lesser extent N, a large elongate mass high in the atmosphere that closed off a huge critical area to commercial air carriers and created new problems not seen before by aviation authorities.

According to Simon Carn, the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite tracked a sulfur dioxide plume across the northern Pacific from Sakhalin Island and mainland Russia and E as far as Alaska (figure 5). Carn's tentative conclusion was that the eruption was also the largest sulfur dioxide event so far in 2009.

Figure (see Caption) Figure 5. SO2 emissions from Sarychev Peak during 10-17 June 2009 led to this composite picture of gas plumes. The emissions were measured by the OMI satellite and its support team. Note concentration-pathlength scale at bottom, in Dobson Units (DU). Courtesy of Simon Carn.

By early July both atmospheric lidar instruments and the CALIPSO limb-sounding satellite had documented extended aerosol layers at 10-20 km altitude over the Northern Hemisphere. There were two potential sources for these aerosols, fires and the Sarychev Peak eruption. Fires due to biomass burning were seen around this time in both the Yukon and Alaska. Fire-generated aerosols are now known to reach 20 km altitudes (Mike Fromm, personal communication, and Fromm and others, 2004). According to Fromm, the Sarychev Peak eruptions must have at least contributed to high-altitude aerosols. As recent as mid-August, the atmospheric limb-sounding satellite CALYPSO had detected pronounced aerosol layers at 22-23 km altitude, layers also seen on MODIS visible-wavelength imagery. Fromm concluded the aerosol burden was larger than the substantial August-September 2008 eruption at Kasatochi (Alaska).

The microwave limb-sounding (MLS) satellite Aura can detect multiple gases. According to a NASA website, in mid-June 2009 it detected clear signals of both SO2 and HCl across a large span of the North Pacific.

Continuing activity during 16-28 June 2009. After 16 June, the eruptions entered a less energetic stage. Weak explosions continued and contained small amounts of tephra. The SVERT team visited the island during 26-28 June. Intense gas emissions came from still-hot deposits. Satellite data confirmed these gas emissions, which continued through at least 20 July. Field work and satellite observations led the team to consider the eruption to be VEI 4.

Good views of the island were obtained from the sea during the 26-28 June visit by SVERT (figures 6-8). One component of fieldwork involved the GPS-aided mapping of pyroclastic deposits seen along the seashore. The team used an inflatable boat to access the shoreline (figure 9). The bulk of pyroclastic flows reached the sea (figures 10 and 11), and although wave action had substantially eroded the deposits along the coastline, the deposits clearly continued out into the sea. Weakly eroded underwater pyroclastic flows sometimes returned distinctive reflections on echo soundings. The soundings and other observations also revealed submerged deposits emitting gases and still-stirring hydrothermal exchanges.

Figure (see Caption) Figure 6. Photo of steam rising from Sarychev Peak as seen from the N at some time during 26-28 June. Rugged fringing older rocks can be seen protecting a beach front and tephra-covered landscape. Courtesy of SVERT.
Figure (see Caption) Figure 7. Photos of steam rising from the pyroclastic flows as seen from the N at some time during 26-28 June. The steaming peak is faintly visible in the background. Courtesy of SVERT.
Figure (see Caption) Figure 8. Photos of Sarychev Peak seen from the S, the side of the island least impacted by the eruption, where the landscape remained green and vegetated. The support vessel seen here brought scientists to the Island and gave them safe lodging during the expedition. Courtesy of SVERT.
Figure (see Caption) Figure 9. The field crew on a beach to inspect Sarychev Peak's recent pyroclastic flows. By the time of their 26-28 June visit, waves had eroded the fresh deposits that must have once covered this beach face. Massive, jointed rocks in the cliff backing the beach are older rocks; new deposits drape the upper cliff. Note steaming peak in the background. SVERT volcanologists (from left): Dmitrii Kozlov, Igor Koroteev, Artyom Degterev, Rafael Zharkov (far right), and Alexander Rybin (front right). Courtesy of SVERT.
Figure (see Caption) Figure 10. Rubbly surface of a 2009 pyroclastic flow ("pumice flow") on Sarychev Peak's W flanks. Field gear at flow front provides scale. Note the lobate form and comparatively large and consistent grain size. Courtesy of SVERT.
Figure (see Caption) Figure 11. Exposed tephra stratigraphy from the Sarychev Peak eruption. The scientist is standing before fresh tephra deposits along the seashore with his feet on the beach. To his side lies a well-exposed ~ 2-m-thick pyroclastic flow deposit capped by fine-grained tephra of probable air-fall origin. The fine air-fall unit covers the surface in the distance, coloring it a uniform gray. Courtesy of SVERT.

The field inspection revealed three pyroclastic flows from the eruption. The team also recognized other pyroclastic material, including volcanic bombs, scoria flows, and ash. Compositionally, the field analysis suggested the eruptions were basaltic andesite. In accord with the density of the fresh blocky deposits along the sea cliff, and the clasts within them (figure 11), the team saw no floating pumice.

The intense fumarolic discharges escaping the pyroclastic flows reached ~ 500°C. Fumaroles were seen most frequently associated with impacts from large volcanic bombs, and from fissures. Areas of fumarolic exhalation included sublimated minerals such as native sulfur (figure 12). The team also encountered a pond with hot water (figure 13).

Figure (see Caption) Figure 12. Two examples of sublimated mineral zones seen on the pyroclastic-flow surfaces from the Sarychev Peak eruption. Many such mineralized areas appeared related to bomb impacts (top). Other areas were elongate, some several meters long (bottom). Courtesy of SVERT.
Figure (see Caption) Figure 13. Small pond encountered on Sarychev's flanks. Cliffs and talus slopes behind the pond are tephra-draped older rocks. The green-hued water had been heated and mineralized by contact with recent eruptive products. The scientist standing in the pond estimated that the temperature was ~ 21°C. Courtesy of SVERT.

Biological impacts. Prior to the eruption, the island was teeming with life and the SVERT team photographically documented many biological impacts (eg., surviving birds congregated at damaged or destroyed rookeries). The eruptions of June 2009 divided Matua Island into two sectors with a sharp and nearly linear boundary between them (eg., figure 5). On the NW side, nearest Sarychev Peak, its eruption left a dead zone. Many plants were buried by hot tephra, leaving a landscape devoid of vegetation on the current ground surface. This dead zone was bounded to the S by a deep ravine where a large mudflow had occurred, destroying ferns, thick growths of alder, and grass cover.

To the SE, ashfall damaged small plants, including rhododendron, crowberry, cassiopea, and phylodoce. Perhaps 10-15% of sites visited there had ash over 10 cm thick. Especially near the dead zone, many small plants suffered burial, yet they continued to blossom. Blossoming cowberry was buried in areas with thick ashfall.

Among high brush in the S part of the island, alder generally suffered little, but in some areas of ashfall (between Kruglaya mountain and the slopes of the volcano) it showed some leaf damage. The leaves of mountain ash displayed yellow rims and discolored spots. High-grasses located in the SE sector were little affected by ashfall.

In the dead zone, some bird colonies remained on the old lava flows supporting the island's capes. It was difficult to estimate how many birds had died or lost nests. Many seagulls sat on the warm surfaces of the steaming pyroclastic flows. Wounded and dead seagulls found on the surfaces of pyroclastic flows were probably killed by burns after the eruption. Near the NW part of Matua Island, the team saw large flocks of sea birds aloft.

On the 28th, SVERT visited seal habitats on the S portion of the island where they counted 20 eared seals and 10 fur seals. On a cape along Matua's W coast they encountered another seven eared seals. The team found no living land animals on the NW sector. On the SE sector, they found dead mice and three dead foxes.

Additional geological background from SVERT. The modern edifice of Sarychev Peak occupies the bulk of Matua Island but is centered towards the NW (figure 5). The island's SE side is flat, with average elevations of 30-40 m. The island's S and E sides are covered with brush and grass.

Before 25 August 1945, Matua Island supported a Japanese army base with as many as 4,000 residents. After 1945, the Soviet army occupied the island and maintained meteorological and seismic stations until a sharp decline in inhabitants at the end of the 1990's. The island still contains runways and structures. In recent years, the only people on the island were occasional visitors.

The geologic literature discusses Pliocene basaltic andesite volcanoes in this region (including Toporkovyi Island and the SE part of Matua). It is probable that these are part of an ancient shield volcano. In the SE part of Matua Island is a somma of an ancient caldera (Gorshkov 1967; Markhinin 1964; Andreev and others, 1978), making Sarychev Peak an intracaldera stratovolcano. It is formed by alternating lava and tephra of mainly basalt to andesite composition (Gorshkov 1967; Andreev et.al 1978).

According to Gorshkov (1967), after the major 1946 eruption the crater had both a diameter and depth of ~ 250 m, with steep, sometimes overhanging crater walls and a floor of solid lava. Modern lava flows consisted of two-pyroxene basalts and basaltic andesites vented from the central cone, forming small tongues near the crater.

After the 1960 eruption, field observers encountered dense fog and were thus unable to describe the crater (Shilov, 1962). According to eye-witnesses, the crater's N walls may have collapsed.

The 1976 eruption included strong emissions. Lava flows extended the W, SW, and NW slopes (Andreev and others, 1978). This eruption left the crater with a diameter of ~ 200 m and a flat bottom at a depth 50-70 m below the rim.

References. Andreev, V.N., Shantser, A.E., Khrenov, A.P., Okrugin, V.M., and Hechaev V.N., 1978, Eruption of the volcano Sarychev Peak in 1976: Bull.of volcanological stations, no. 55, p. 35-40.

Casadevall, T., and Thompson, T., 1995, World map of volcanoes and principal aeronautical features (1:34,268,000): U.S. Geological Survey, Geophysical Investigations Map GP-1011.

Fedorchenko, V.I., Abdurakhmanov, A.I., and Rodionova, R.I., 1989, Volcanism of Kurile Island arc: geology and petrogenesis: M. Nauka, p. 239.

Fromm, M., Bevilacqua, R., Stocks, B., and Servranckx, R., 2004, New Directions: Eruptive transport to the stratosphere: add fire-convection to volcanoes: Atmospheric Environment, v. 38, p. 163-165.

Glavadskii, S.N., and Efremov, G.K., 1948, Eruption of the volcano Sarychev Peak in the November 1946: Bull.of volcanological stations, no. 15, p. 48-12.

Gorshkov, G.S., 1948, Volcano Sarychev Peak: Bull.of volcanological stations, no. 15, p. 3-7.

Gorshkov, G.S., 1967, Volcanism of the Kurile Island arc: M. Nauka

Markhinin, E.K, 1964, Sarychev volcano: Bull. of volcanological stations, no. 35, p. 44-58.

Shilov, V.N., 1962, The eruption of volcano Sarychev Peak in 1960: The book of Sakhalin. v. 12, p.143-149.

Wilkinson, M.J., 2009, Sarychev Peak Eruption, Kurile Islands (caption): NASA Earth Observatory, posted 22 June 2009 (URL: http://earthobservatory.nasa.gov/IOTD/view.php?id=38985).

Geologic Background. Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5-km-wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows, prior to activity in 2009, had descended in all directions, often forming capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760s and include both quiet lava effusion and violent explosions. Large eruptions in 1946 and 2009 produced pyroclastic flows that reached the sea.

Information Contacts: Sakhalin Volcanic Eruptions Response Team (SVERT), Institute of Marine Geology and Geophysics (IMG & G) Far East Division Russian Academy of Sciences, 1B Science St., Yuzhno-Sakhalinsk, 693022, Russia (URL: http://www.imgg.ru/); B.W. Levin, A.V. Rybin, M.V. Chibisoba, and V.B. Gur'yanov, IMG & G; N.G. Razzhigaeva, Pacific Institute of Geography, Far East Division Russian Academy of Sciences, 7 Radio St., Vladivostok, 690041, Russia (URL: http://tig.dvo.ru/tig/); International Space Station (ISS) Expedition 20 (astronauts Gennady Padalka, Frank De Winne, Roman Romanenko, Robert Thirsk, Michael Barratt, Nicole Stott, Tim Kopra, and Koichi Wakata) (URL: http://www.nasa.gov/mission_pages/station/expeditions/expedition20/); Simon A. Carn, Department of Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive Houghton, MI 49931 USA; Mike Fromm, Computational Physics, Inc, 2750 Prosperity Ave, Fairfax, VA 22031, USA; NASA Astronomy Picture of the Day (URL: http://apod.nasa.gov/apod/ap090625.html); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/).


Tafu-Maka (Tonga) — June 2009 Citation iconCite this Report

Tafu-Maka

Tonga

15.37°S, 174.23°W; summit elev. -1400 m

All times are local (unless otherwise noted)


Submarine volcanism and lava flows on the Northeast Lau Spreading Center

The following is the first Bulletin report about this submarine volcanic area in the S part of the Northeast Lau Spreading Center (NELSC) (figure 1). An informal paper by Resing and others (2009) reported that two recent eruption sites were discovered in the NE Lau Basin during a November 2008 scientific expedition aboard the research vessel RV Thompson. The first eruption site discovered was within the NELSC and contained two active submarine volcanoes, Tafu and Maka (figure 2). During the expedition a conductivity/temperature/depth (CTD)/rosette package was used to measure the physical and chemical nature of hydrothermal systems, and the Thompson's multibeam sonar provided high resolution bathymetry and seafloor backscatter imagery. Another expedition in May 2009 revealed fresh lava flows near the Maka cone.

Figure (see Caption) Figure 1. Bathymetric map of NE Lau area showing two eruption areas (circled) discovered during the 2009 expedition, West Mata and NELSC where volcanoes Tafu and Maka are located. Contour interval 500 m. Inset location map shows the Fiji Islands (~ 860 km WNW) and Samoa (~ 270 km NE), along with the East Lau Spreading Center (ELSC), Central Lau Spreading Center (CLSC), and Fonulalei Spreading Center (FSC). Courtesy of Resing and others (2009).
Figure (see Caption) Figure 2. Multibeam bathymetry of the Tafu-Maka ridge eruption site along the southern segment of the Northeast Lau Spreading Center (NELSC). Contour interval 100 m. Courtesy of Resing and others (2009).

Expedition during 13-28 November 2008. The Tafu-Maka eruption site was discovered on the neovolcanic zone of the southernmost segment of the NELSC at a depth of ~ 1,650 m depth (figure 1). Plumes characterized by high levels of turbidity, concentrations of volcanic glass shards, large temperature anomalies, pH anomalies, hydrogen, and methane were detected up to 800 m above the seafloor at several locations above this ridge between the Tafu and Maka features (figure 2). Volcanic glass and other clastic material were present in filtered particulate samples from the plume. Such high-rising plumes in this type of hydrographic setting have been reliable indicators of massive hydrothermal discharge associated with seafloor eruptions. The observed levels of hydrogen in plumes have only been associated with the interaction of molten rock and seawater. In addition, near-bottom temperature anomalies of ~ 0.5°C, measured with the CTDO (conductivity/temperature/depth/oxygen) package, coincided with high levels of H2 and CH4 on the neovolcanic ridge north of Maka.

Prior work in the area (German and others, 2006) had located an intense hydrothermal plume over Maka, and this plume was relocated and sampled in 2008. According to Resing, a survey in August 2008 using a commercial ROV funded by Nautilus Minerals, Inc., discovered a very active black smoker field underlying this plume. The vent was apparently at the boiling temperature, based on video observations. The 2008 dive found no hydrothermal activity during a traverse of the presumed eruption site on the ridge axis. There were also plumes at depths below the neovolcanic ridge. Many of these plumes were probably formed by fallout and/or bottom gravity flows of volcaniclastic material such as described from the erupting submarine volcano NW Rota-1 in the Mariana arc (BGVN 31:05 and 33:02).

Ed Baker, another scientist on the 2008 expedition, observed that many more plumes were found, and much higher above the seafloor, than expected. Instruments that were lowered above the summit of Tafu, the larger of the two (which rises some 500 m above the ridge, to a depth of ~ 1,400 m), found scant evidence of activity. Above Maka, with a summit 150 m deeper at, there was a plume found at a depth of 700 m. Instruments identified distinct layers, each chemical rich, some thick, some thin, until the instruments stopped at 1,560 m depth just above the summit.

Expedition during 5-13 May 2009. Inspection with the ROV Jason during another cruise in May 2009 documented a lava flow along the NELSC, draped and folded over the seafloor near Maka, that scientists named "Puipui," meaning "curtain" in Tongan. In a blog posting on the expedition website, Ken Rubin noted that the combination of steep topography, gas-rich fluid magma, and an apparently very fast lava effusion event, created a range of lava forms over a short spatial distance. The pre-eruption land surface strongly controlled where and how the young lava flowed. Ridges of old rock less than 2 m high dammed the flow in places, where it flowed in thin flat sheets between the high ground. Nearer the volcanic vents, which appear to be located along a narrow ridge, lava cascaded 10 m or more down steep rock faces, forming lava sheets. Rubin also reported that in other places the lava ponded, crusted over, and then drained out, leaving collapse pits and revealing chambers with lava shells held up by pillars of fresh rock.

References. Falloon, T.J., Danyushevsky, L.V., Crawford, T.J., Maas, R.W., Eggins, S.M., Bloomer, S.H., Wright, D.J., Zlobin, S.K., and Stacey, A.R., 2007, Multiple mantle plume components involved in the petrogenesis of subduction-related lavas from the northern termination of the Tonga Arc and northern Lau Basin: Evidence from the geochemistry of arc and backarc submarine volcanics: Geochemistry, Geophysics, Geosystems, v. 8, Q09003, doi:10.1029/2007GC001619.

German, C.R., Baker, E.T., Connelly, D.P., Lupton, J.E.. Resing, J., Prien, R.D., Walker, S.L., Edmonds, H.N., and Langmuir, C.H., 2006, Hydrothermal exploration of the Fonualei Rift and spreading center and the North East Lau Spreading Center: Geochemistry, Geophysics, Geosystems, v. 7, Q11022, doi: 10.1029/2006GC001324.

Resing, J., Lupton, J., Embley, R., Baker, E., and Lilley, M. (compilers), 2009, Preliminary findings from the North Lau eruption sites, informal report, 2/5/09 (URL: http://www.ridge2000.org/science/downloads/email/Nlaupreliminaryfindings25.pdf).

Geologic Background. Two submarine volcanoes, Tafu and Maka, lie along a NE-SW-trending ridge segment on the southern part of the NE Lau Spreading Center (NELSC). The NELSC is a back-arc spreading center in the northeast part of the Lau Basin. Tafu (Tongan for "source of fire") rises to about 1400 m below sea level at the NE end of the ridge segment, and Maka (Tongan for "rock") reaches 1560 m below sea level at the SW end of the ridge segment. A November 2008 NOAA Vents Program expedition discovered submarine hydrothermal plumes consistent with very recent (days to weeks?) submarine lava effusion from Maka volcano. A return visit in May 2009 documented the freshly emplaced lava flow at Maka.

Information Contacts: 2008 Expedition to Lau Basin (website), NOAA/PMEL VENTS Program, Hatfield Marine Science Center, 2115 S.E. OSU Dr., Newport, OR 97365, USA (URL: https://www.pmel.noaa.gov/eoi/laubasin.html); 2009 Lau Basin Eruption Exploration Expedition (blog), NOAA/PMEL VENTS Program (URL: http://laueruptions.blogspot.com/).


Telica (Nicaragua) — June 2009 Citation iconCite this Report

Telica

Nicaragua

12.606°N, 86.84°W; summit elev. 1036 m

All times are local (unless otherwise noted)


Intermittent incandescence and ash explosions through January 2005

Intermittent ash explosions and crater incandescence were seen during 2000-2002, along with high levels of seismicity related to degassing and constant low tremor (BGVN 34:05). Strong gas emissions were typical in the first half of 2003, with incandescence often noted later in the year. Activity during 2004 included occasional ash explosions as well as incandescence. After small ash explosions in late January 2005 no volcanism was noted for the remainder of the year, with observers primarily noting crater wall collapses and degassing. The Nicaraguan Territorial Studies Institute (INETER) monitors activity; visits to the crater described below are by INETER staff (primarily Pedro Perez) unless otherwise noted, though scientists from other institutions may have also been present. Some observations were also made by a local resident who maintains the local seismic station.

Activity during 2003. In January 2003 gas emissions at Telica fluctuated in their intensity. Dense gas prevented observations of incandescence. During a crater visit on 6 May an observer heard a pressurized sound, smelled sulfur, and saw blue gases. Eucalyptus trees 2 km E of the crater appeared to have been burned by the acidic gases. There was a bluish glow in the crater on 25 June and a strong smell of sulfur. To the W of the volcano several trees dropped the bulk of their leaves due to acid rain. Gas emissions remained almost constant at a moderate level.

On 31 July a high pressure noise was heard and incandescence was observed in the center of the crater. Pressurized gases emerging on 22 August from the vent at the bottom of the crater emitted a loud, jet-like sound. As in July, the vent also showed incandescence and emitted a sulfur odor. Satellite images on 24 September showed a column of gas. On 7 October incandescent was again observed, along with a strong odor of sulfur. There was a collapse of material in the SE sector.

Activity during 2004. On 20 January 2004 a wavelike sound was heard, open fissures emitted little gas, and glow was observed in the crater (figure 14). A small ash explosion on 31 March at about 0856 was reported by the caretaker of the Tel3 seismic station. On 28 April an observer noted that internal collapses had covered almost half of the southern part of the crater floor with debris. As a result incandescence in the crater was difficult to detect.

Figure (see Caption) Figure 14. Photograph of the crater at Telica, showing incandescence on 20 January 2004. Courtesy of P. Perez (INETER).

A seismic swarm N of Telica lasted from 9 to 14 June. The earthquakes had magnitudes up to 2.4 and depths between 1 and 9 km, with some being felt by local residents in the Aguas Calientes area. On 28 June a seismic signal similar to that of an explosion was detected. INETER received no reports of ashfall in surrounding areas. Reports for July-September were not available. Ash explosions occurred from the crater on 5 and 11 November. On 10 December there was significant gas and ash output, with sounds of breaking rocks inside the crater. Unlike the previous months, no incandescence was seen.

Activity during 2005. On 29 January 2005 the volcano produced small ash explosions with abundant gases. The next day when INETER technician Pedro Pérez visited he heard jet-like sounds and smelled strong gas emissions. Low gas emissions persisted during February-April. On 15 May a small earthquake swarm lasted about ten hours. Observers to the crater on 1 May noted small blue gas emissions and sulfur odor, but no incandescence. Collapses were also seen in the W and S portions of the crater.

On 30 June observers saw minor gas emissions and new material in the eruptive fissure from crater wall collapses. Activity was low on 9 August (figure 15), no sounds heard, but the crater walls had some precipitates from the gas emissions. On a 7 September visit additional collapses of the crater walls were observed along with significant gas emission. Small gas emissions were observed by a monitoring webcam for almost the entire month of December.

Figure (see Caption) Figure 15. Photograph showing the Telica crater on 9 August 2005. Rockfall debris from crater wall collapses can be seen on the crater floor. Courtesy of P. Perez (INETER).

Geologic Background. Telica, one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. This volcano group consists of several interlocking cones and vents with a general NW alignment. Sixteenth-century eruptions were reported at symmetrical Santa Clara volcano at the SW end of the group. However, its eroded and breached crater has been covered by forests throughout historical time, and these eruptions may have originated from Telica, whose upper slopes in contrast are unvegetated. The steep-sided cone of Telica is truncated by a 700-m-wide double crater; the southern crater, the source of recent eruptions, is 120 m deep. El Liston, immediately E, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby.

Information Contacts: Wilfried Strauch, Instituto Nicaraguense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni//geofisica.html).


West Mata (Tonga) — June 2009 Citation iconCite this Report

West Mata

Tonga

15.1°S, 173.75°W; summit elev. -1174 m

All times are local (unless otherwise noted)


Submarine effusive and explosive eruption seen at two vents in May 2009

This is the first Bulletin report on West Mata, a small seamount ~ 200 km SW of Samoa, the scene of inferred ongoing eruptions when visited during November 2008 and an unambiguous eruption at multiple vents when visited during May 2009. West Mata is located in the NE Lau basin ~ 35 km E of the closest portion of the Lau spreading center (figure 1) and ~ 70 km NE of a now-erupting portion of the NE Lau spreading center (NELSC). Investigations of this site were made on two research cruises conducted in the region by the research ressel RV Thompson during November 2008 and May 2009.

Figure (see Caption) Figure 1. Bathymetric map of NE Lau area showing two eruption areas (circled) discovered during the 2009 expedition, West Mata and NELSC where volcanoes Tafu and Maka are located. Contour interval 500 m. Inset location map shows the Fiji Islands (~ 860 km WNW) and Samoa (~ 270 km NE), along with the East Lau Spreading Center (ELSC), Central Lau Spreading Center (CLSC), and Fonulalei Spreading Center (FSC). Courtesy of Resing and others (2009).

Expedition during 13-28 November 2008. During the 2008 expedition, water column measurements were made, including a conductivity, temperature, and depth (CTD) rosette package to characterize the physical and chemical nature of hydrothermal systems. The RV Thompson's multibeam sonar provided high-resolution bathymetry and seafloor backscatter imagery. West Mata volcano (figure 2) was very likely erupting lava flows and/or pyroclastic material at this time. The intense plume rising ~ 175 m from the summit that was characterized by high values of turbidity, hydrogen, delta helium-3 (d3He), oxidation-reduction potential (Eh), and pH. The acoustic backscatter over portions of the volcano was uniformly high, indicating geologically young seafloor.

Figure (see Caption) Figure 2. Multibeam bathymetry of West and East Mata volcanoes. Contour interval is 200 m. Taken from Resing and others (2009).

Although the marine optical backscatter was dominated by elemental sulfur and particulate iron, there was also an abundance of large mineral and/or glass shards in the plume. The larger clastic materials were composed almost exclusively of Mg-silicates, with lesser Ca-Mg-silicates. These compositions were consistent with the eruption of boninites (glass olivine-bronzite andesite that contains little or no feldspar) that previously have only been observed at inactive volcanoes. These chemical and geological characteristics match well with those of NW Rota-1 in the southern Mariana arc, which has been undergoing submarine Strombolian eruptions for at least 4 years (BGVN 29:03, 31:05, and 33:02).

Resing and others (2009) reported that the acoustic backscatter appeared to show extensive deposits of clastic material draping the volcano and extending over a recent lava flow at its eastern end, suggesting a recent and continuous state of eruption. Finally, they note that East Mata (figure 3), a similar volcano ~ 10 km closer to the Tofua arc, is also hydrothermally active, albeit less intense than West Mata.

Figure (see Caption) Figure 3. The two Jason ROV dives at West Mata volcano discovered not just one active volcanic vent, but two, Hades and Prometheus. Both vents were obscured much of the time by billowing sulfurous gas emissions, but bright orange lava was seen in both vents. The orange glowing lava was visible for minutes at a time. Text courtesy of Dave Clague (on expedition blog); bathymetric chart courtesy of NOAA Vents website.

Expedition during 5-13 May 2009. On 6-7 May, scientists onboard the RV Thompson used the Jason 2 ROV (remotely operated vehicle) to observe eruptions from two vents of West Mata (figure 3), Prometheus (at or near the summit) and Hades (slightly to the SW). According to Dave Clague, writing on the expedition blog, the deeper vent, Hades, sits on the SW rift. It was erupting both effusively and explosively at the same time on both days (6-7 May). Small bursts were occurring at one end of an erupting fissure ~ 5 m long at a depth of 1,208 m, while pillow lavas were being extruded from the other end. By the next night (7 May) the activity had become more vigorous, sometimes blowing glowing bubbles as much as a meter across from the fissure.

Clague noted that the second, shallower vent, Prometheus, was located very near the summit of the volcano and about 100 meters away from Hades, the first vent. The eruption here was entirely explosive with low-level, but nearly continuous fire fountains throwing ejecta into the water during both dives. Both vents were often obscured by sulfur gas emissions, but incandescence was visible for minutes at a time. According to an article on the Discovery News website, Jason 2 approached the vent and was promptly buried in ~ 45 kg of debris. Huge gas bubbles, maybe 1 m in diameter, were observed coming out of West Mata.

References. Resing, J., Lupton, J., Embley, R., Baker, E., and Lilley, M. (compilers), 2009, Preliminary findings from the North Lau eruption sites, informal report, 2/5/09 (URL: http://www.ridge2000.org/science/downloads/email/Nlaupreliminaryfindings25.pdf).

Geologic Background. West Mata, a submarine volcano rising to within 1174 m of the sea surface, is located in the northeastern Lau Basin at the northern end of the Tonga arc, about 200 km SW of Samoa. West Mata volcano lies about 7 km west of another submarine volcano, East Mata; both lie at the northern end of the Tonga arc, north of the historically active Curacoa submarine volcano. The two volcanoes were discovered during a November 2008 NOAA Vents Program expedition, and West Mata was found to be producing submarine hydrothermal plumes consistent with a recent or lava effusion. A return visit in May 2009 documented explosive and effusive activity from two closely spaced vents, one at the summit, and the other on the SW rift zone.

Information Contacts: 2009 Lau Basin Eruption Exploration Expedition (blog), NOAA/PMEL VENTS Program (URL: http://laueruptions.blogspot.com/); National Oceanographic and Atmospheric Agency (NOAA) Vents Program (URL: http:/www.pmel.noaa.gov/vents/); Discovery News (URL: http://dsc.discovery.com/news/2009/06/05/undersea-eruption.html).

Atmospheric Effects

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

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

Special Announcements

Special announcements of various kinds and obituaries.

Special Announcements  Obituaries

Misc 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 subject.

Additional Reports  False Reports