Recently Published Bulletin Reports
Ebeko (Russia) Continued explosions, ash plumes, and ashfall; June-November 2020
Kuchinoerabujima (Japan) Intermittent thermal anomalies and small eruptions in May and August 2020
Nyamuragira (DR Congo) Numerous thermal anomalies and gas emissions from the lava lake through November 2020
Raung (Indonesia) Explosions with ash plumes and a thermal anomaly at the summit crater, July-October 2020
Sinabung (Indonesia) Explosions begin again on 8 August 2020; dome growth confirmed in late September
Heard (Australia) Persistent thermal anomalies in the summit crater from June through October 2020
Sabancaya (Peru) Daily explosions produced ash plumes, SO2 plumes, and thermal anomalies during June-September 2020
Rincon de la Vieja (Costa Rica) Frequent small phreatic explosions with intermittent ash plumes during April-September 2020
Fuego (Guatemala) Daily explosions, ash emissions, and block avalanches during August-November 2020
Kikai (Japan) Explosion on 6 October 2020 and thermal anomalies in the crater
Manam (Papua New Guinea) Intermittent ash plumes, thermal anomalies, and SO2 emissions in April-September 2020
Karymsky (Russia) New eruption during April-July 2020; ash explosions in October 2020
Ebeko
Russia
50.686°N, 156.014°E; summit elev. 1103 m
All times are local (unless otherwise noted)
Continued explosions, ash plumes, and ashfall; June-November 2020
Volcanism at Ebeko, located on the N end of the Paramushir Island in the Kuril Islands, has been ongoing since October 2016, characterized by frequent moderate explosions, ash plumes, and ashfall in Severo-Kurilsk (7 km ESE) (BGVN 45:05). Similar activity during this reporting period of June through November 2020 continues, consisting of frequent explosions, dense ash plumes, and occasional ashfall. Information for this report primarily comes from the Kamchatka Volcanic Eruptions Response Team (KVERT) and satellite data.
Activity during June was characterized by frequent, almost daily explosions and ash plumes that rose to 1.6-4.6 km altitude and drifted in various directions, according to KVERT reports and information from the Tokyo VAAC advisories using HIMAWARI-8 satellite imagery and KBGS (Kamchatka Branch of the Geophysical Service) seismic data. Satellite imagery showed persistent thermal anomalies over the summit crater. On 1 June explosions generated an ash plume up to 4.5 km altitude drifting E and S, in addition to several smaller ash plumes that rose to 2.3-3 km altitude drifting E, NW, and NE, according to KVERT VONA notices. Explosions on 11 June generated an ash plume that rose 2.6 km altitude and drifted as far as 85 km N and NW. Explosions continued during 21-30 June, producing ash plumes that rose 2-4 km altitude, drifting up to 5 km in different directions (figure 26); many of these eruptive events were accompanied by thermal anomalies that were observed in satellite imagery.
Explosions continued in July, producing ash plumes rising 2-5.2 km altitude and drifting for 3-30 km in different directions. On 3, 6, 15 July explosions generated an ash plume that rose 3-4 km altitude that drifted N, NE, and SE, resulting in ashfall in Severo-Kurilsk. According to a Tokyo VAAC advisory, an eruption on 4 July produced an ash plume that rose up to 5.2 km altitude drifting S. On 22 July explosions produced an ash cloud measuring 11 x 13 km in size and that rose to 3 km altitude drifting 30 km SE. Frequent thermal anomalies were identified in satellite imagery accompanying these explosions.
In August, explosions persisted with ash plumes rising 1.7-4 km altitude drifting for 3-10 km in multiple directions. Intermittent thermal anomalies were detected in satellite imagery, according to KVERT. On 9 and 22 August explosions sent ash up to 2.5-3 km altitude drifting W, S, E, and SE, resulting in ashfall in Severo-Kurilsk. Moderate gas-and-steam activity was reported occasionally during the month.
Almost daily explosions in September generated dense ash plumes that rose 1.5-4.3 km altitude and drifted 3-5 km in different directions. Moderate gas-and-steam emissions were often accompanied by thermal anomalies visible in satellite imagery. During 14-15 September explosions sent ash plumes up to 2.5-3 km altitude drifting SE and NE, resulting in ashfall in Severo-Kurilsk. On 22 September a dense gray ash plume rose to 3 km altitude and drifted S. The ash plume on 26 September was at 3.5 km altitude and drifted SE (figure 27).
During October, near-daily ash explosions continued, rising 1.7-4 km altitude drifting in many directions. Intermittent thermal anomalies were identified in satellite imagery. During 7-8, 9-10, and 20-22 October ashfall was reported in Severo-Kurilsk.
Explosions in November produced dense gray ash plumes that rose to 1.5-5.2 km altitude and drifted as far as 5-10 km, mainly NE, SE, E, SW, and ENE. According to KVERT, thermal anomalies were visible in satellite imagery throughout the month. On clear weather days on 8 and 11 November Sentinel-2 satellite imagery showed ashfall deposits SE of the summit crater from recent activity (figure 28). During 15-17 November explosions sent ash up to 3.5 km altitude drifting NE, E, and SE which resulted in ashfall in Severo-Kurilsk on 17 November. Similar ashfall was observed on 22-24 and 28 November due to ash rising to 1.8-3 km altitude (figure 29). Explosions on 29 November sent an ash plume up to 4.5 km altitude drifting E (figure 29). A Tokyo VAAC advisory reported that an ash plume drifting SSE on 30 November reached an altitude of 3-5.2 km.
MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows a pulse in low-power thermal activity beginning in early June through early August (figure 30). On clear weather days, the thermal anomalies in the summit crater are observed in Sentinel-2 thermal satellite imagery, accompanied by occasional white-gray ash plumes (figure 31). Additionally, the MODVOLC algorithm detected a single thermal anomaly on 26 June.
Geologic Background. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.
Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Kamchatka Branch of the Geophysical Service, Russian Academy of Sciences (KB GS RAS) (URL: http://www.emsd.ru/); 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).
Kuchinoerabujima (Japan) — November 2020
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Kuchinoerabujima
Japan
30.443°N, 130.217°E; summit elev. 657 m
All times are local (unless otherwise noted)
Intermittent thermal anomalies and small eruptions in May and August 2020
Kuchinoerabujima encompasses a group of young stratovolcanoes located in the northern Ryukyu Islands. All historical eruptions have originated from the Shindake cone, with the exception of a lava flow that originated from the S flank of the Furudake cone. The current eruptive period began in January 2020 and has been characterized by small explosions, ash plumes, ashfall, a pyroclastic flow, and gas-and-steam emissions. This report covers activity from May to October 2020, which includes small explosions, ash plumes, crater incandescence, and gas-and-steam emissions. The primary source of information for this report comes from monthly and annual reports from the Japan Meteorological Agency (JMA) and advisories from the Tokyo Volcanic Ash Advisory Center (VAAC).
Volcanism at Kuchinoerabujima remained relatively low during May through October 2020, according to JMA. During this time, SO2 emissions ranged from 40 to 3,400 tons/day; occasional gas-and-steam emissions were reported, rising to a maximum of 900 m above the crater. Sentinel-2 satellite images showed a particularly strong thermal anomaly in the Shindake crater on 1 May (figure 10). The thermal anomaly decreased in power after 1 May and was only visible on clear weather days, which included 19 August and 3 and 13 October. Global Navigation Satellite System (GNSS) observations identified continued slight inflation at the base of the volcano during the entire reporting period.
Three small eruptions were detected by JMA on 5, 6, and 13 May, which produced an ash plume rising 500 m above the crater on each day, resulting in ashfall on the downwind flanks. Incandescence was observed at night using a high-sensitivity surveillance camera (figure 11). On 5 and 13 May the Tokyo VAAC released a notice that reported ash plumes rising 0.9-1.2 km altitude, drifting NE and S, respectively. On 20 May weak fumaroles were observed on the W side of the Shindake crater. The SO2 emissions ranged from 700-3,400 tons/day.
Activity during June and July decreased compared to May, with gas-and-steam emissions occurring more prominently. On 22 June weak incandescence was observed, accompanied by white gas-and-steam emissions rising 700 m above the crater. Weak crater incandescence was also seen on 25 June. The SO2 emissions measured 400-1,400 tons/day. White gas-and-steam emissions were again observed on 31 July rising to 800 m above the crater. The SO2 emissions had decreased during this time to 300-700 tons/day.
According to JMA, the most recent eruptive event occurred on 29 August at 1746, which ejected bombs and was accompanied by some crater incandescence, though the eruptive column was not visible due to the cloud cover. However, white gas-and-steam emissions could be seen rising 1.3 km above the Shindake crater drifting SW. The SO2 emissions measured 200-500 tons/day. During August, the number of volcanic earthquakes increased significantly to 1,032, compared to the number in July (36).
The monthly bulletin for September reported white gas-and-steam emissions rising 900 m above the crater on 9 September and on 11 October the gas-and-steam emissions rose 600 m above the crater. Seismicity decreased between September and October from 1,920 to 866. The SO2 emissions continued to decrease compared to previous months, totaling 80-400 tons/day in September and 40-300 tons/day in October.
Geologic Background. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.
Information Contacts: Japan Meteorological Agency (JMA), 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).
Nyamuragira (DR Congo) — December 2020
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Nyamuragira
DR Congo
1.408°S, 29.2°E; summit elev. 3058 m
All times are local (unless otherwise noted)
Numerous thermal anomalies and gas emissions from the lava lake through November 2020
Nyamuragira (also known as Nyamulagira) is a shield volcano in the Democratic Republic of the Congo with a 2 x 2.3 km caldera at the summit. A summit crater lies in the NE part of the caldera. In the recent past, the volcano has been characterized by intra-caldera lava flows, lava emissions from its lava lake, thermal anomalies, gas-and-steam emissions, and moderate seismicity (BGVN 44:12, 45:06). This report reviews activity during June-November 2020, based on satellite data.
MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed numerous thermal anomalies associated with the volcano during June-November 2020, although some decrease was noted during the last half of August and between mid-October to mid-November (figure 91). Between six and seven thermal hotspots per month were identified by MODVOLC during June-November 2020, with as many as 4 pixels on 11 August. In the MODVOLC system, two main hotspot groupings are visible, the largest being at the summit crater, on the E side of the caldera.
Sentinel-2 satellite images showed several hotspots in the summit crater throughout the reporting period (figure 92). By 26 July and thereafter, hotspots were also visible in the SW portion of the caldera, and perhaps just outside the SW caldera rim. Gas-and-steam emissions from the lava lake were also visible throughout the period.
Geologic Background. Africa's most active volcano, Nyamuragira, is a massive high-potassium basaltic shield about 25 km N of Lake Kivu. Also known as Nyamulagira, it has generated extensive lava flows that cover 1500 km2 of the western branch of the East African Rift. The broad low-angle shield volcano contrasts dramatically with the adjacent steep-sided Nyiragongo to the SW. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Historical eruptions have occurred within the summit caldera, as well as from the numerous fissures and cinder cones on the flanks. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Historical lava flows extend down the flanks more than 30 km from the summit, reaching as far as Lake Kivu.
Information Contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; 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/exp).
Raung (Indonesia) — December 2020
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Raung
Indonesia
8.119°S, 114.056°E; summit elev. 3260 m
All times are local (unless otherwise noted)
Explosions with ash plumes and a thermal anomaly at the summit crater, July-October 2020
A massive stratovolcano in easternmost Java, Raung has over sixty recorded eruptions dating back to the late 16th Century. Explosions with ash plumes, Strombolian activity, and lava flows from a cinder cone within the 2-km-wide summit crater have been the most common activity. Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM) has installed webcams to monitor activity in recent years. An eruption from late 2014 through August 2015 produced a large volume of lava within the summit crater and formed a new pyroclastic cone in the same location as the previous one. The eruption that began in July 2020 is covered in this report with information provided by PVMBG, the Darwin Volcanic Ash Advisory Center (VAAC), and several sources of satellite data.
The 2015 eruption was the largest in several decades; Strombolian activity was reported for many months and fresh lava flows covered the crater floor (BGVN 45:09). Raung was quiet after the eruption ended in August of that year until July of 2020 when seismicity increased on 13 July and brown emissions were first reported on 16 July. Tens of explosions with ash emissions were reported daily during the remainder of July 2020. Explosive activity decreased during August, but thermal activity didn’t decrease until mid-September. The last ash emissions were reported on 3 October and the last thermal anomaly in satellite data was recorded on 7 October 2020.
Eruption during July-October 2020. No further reports of activity were issued after August 2015 until July 2020. Clear Google Earth imagery from October 2017 and April 2018 indicated the extent of the lava from the 2015 eruption, but no sign of further activity (figure 31). By August 2019, many features from the 2015 eruption were still clearly visible from the crater rim (figure 32).
PVMBG reported that the number and type of seismic events around the summit of Raung increased beginning on 13 July 2020, and on 16 July the height of the emissions from the crater rose to 100 m and the emission color changed from white to brown. About three hours later the emissions changed to gray and white. The webcams captured emissions rising 50-200 m above the summit that included 60 explosions of gray and reddish ash plumes (figure 33). The Raung Volcano Observatory released a VONA reporting an explosion with an ash plume that drifted N at 1353 local time (0653 UTC). The best estimate of the ash cloud height was 3,432 m based on ground observation. They raised the Aviation Color Code from unassigned to Orange. About 90 minutes later they reported a second seismic event and ash cloud that rose to 3,532 m, again based on ground observation. The Darwin VAAC reported that neither ash plume was visible in satellite imagery. The following day, on 17 July, PVMBG reported 26 explosions between midnight and 0600 that produced brown ash plumes which rose 200 m above the crater. Based on these events, PVMBG raised the Alert Level of Raung from I (Normal) to II (Alert) on a I-II-III-IV scale. By the following day they reported 95 explosive seismic events had occurred. They continued to observe gray ash plumes rising 100-200 m above the summit on clear days and 10-30 daily explosive seismic events through the end of July; plume heights dropped to 50-100 m and the number of explosive events dropped below ten per day during the last few days of the month.
After a long period of no activity, MIROVA data showed an abrupt return to thermal activity on 16 July 2020; a strong pulse of heat lasted into early August before diminishing (figure 34). MODVOLC thermal alert data recorded two alerts each on 18 and 20 July, and one each on 21 and 30 July. Satellite images showed no evidence of thermal activity inside the summit crater from September 2015 through early July 2020. Sentinel-2 satellite imagery first indicated a strong thermal anomaly inside the pyroclastic cone within the crater on 19 July 2020; it remained on 24 and 29 July (figure 35). A small SO2 signature was measured by the TROPOMI instrument on the Sentinel-5P satellite on 25 July.
After an explosion on 1 August 2020 emissions from the crater were not observed again until steam plumes were seen rising 100 m on 7 August. They were reported rising 100-200 m above the summit intermittently until a dense gray ash plume was reported by PVMBG on 11 August rising 200 m. After that, diffuse steam plumes no more than 100 m high were reported for the rest of the month except for white to brown emissions to 100 m on 21 August. Thermal anomalies of a similar brightness to July from the same point within the summit crater were recorded in satellite imagery on 3, 8, 13, 18, and 23 August. Single MODVOLC thermal alerts were reported on 1, 8, 12, and 19 August.
In early September dense steam plumes rose 200 m above the crater a few times but were mostly 50 m high or less. White and gray emissions rose 50-300 m above the summit on 15, 20, 27, and 30 September. Thermal anomalies were still present in the same spot in Sentinel-2 satellite imagery on 2, 7, 12, 17, and 27 September, although the signal was weaker than during July and August (figure 36). PVMBG reported gray emissions rising 100-300 m above the summit on 1 October 2020 and two seismic explosion events. Gray emissions rose 50-200 m the next day and nine explosions were recorded. On 3 October, emissions were still gray but only rose 50 m above the crater and no explosions were reported. No emissions were observed from the summit crater for the remainder of the month. Sentinel-2 satellite imagery showed a hot spot within the summit crater on 2 and 7 October, but clear views of the crater on 12, 17, and 22 October showed no heat source within the crater (figure 37).
Geologic Background. Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively.
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/); 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/); 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/); 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/); Google Earth (URL: https://www.google.com/earth/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Tom Pfeiffer, Volcano Discovery (URL: http://www.volcanodiscovery.com/); MJ (URL: https://twitter.com/MieJamaludin/status/1167613617191043072).
Sinabung (Indonesia) — November 2020
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Sinabung
Indonesia
3.17°N, 98.392°E; summit elev. 2460 m
All times are local (unless otherwise noted)
Explosions begin again on 8 August 2020; dome growth confirmed in late September
Indonesia’s Sinabung volcano in north Sumatra has been highly active since its first confirmed Holocene eruption during August and September 2010. It remained quiet after the initial eruption until September 2013, when a new eruptive phase began that continued through June 2018. A summit dome emerged in late 2013 and produced a large lava “tongue” during 2014. Multiple explosions produced ash plumes, block avalanches, and deadly pyroclastic flows during the eruptive period. A major explosion in February 2018 destroyed most of the summit dome. After a pause in eruptive activity from September 2018 through April 2019, explosions resumed during May and June 2019. The volcano was quiet again until an explosion on 8 August 2020 began another eruption that included a new dome. This report covers activity from July 2019 through October 2020 with information provided by Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), referred to by some agencies as CVGHM or the Indonesian Center of Volcanology and Geological Hazard Mitigation, the Darwin Volcanic Ash Advisory Centre (VAAC), and the Badan Nacional Penanggulangan Bencana (National Disaster Management Authority, BNPB). Additional information comes from satellite instruments and local news reports.
Only steam plumes and infrequent lahars were reported at Sinabung during July 2019-July 2020. A new eruption began on 8 August 2020 with a phreatic explosion and dense ash plumes. Repeated explosions were reported throughout August; ashfall was reported in many nearby communities several times. Explosions decreased significantly during September, but SO2 emissions persisted. Block avalanches from a new growing dome were first reported in early October; pyroclastic flows accompanied repeated ash emissions during the last week of the month. Thermal data suggested that the summit dome continued growing slowly during October.
Activity during July 2019-October 2020. After a large explosion on 9 June 2019, activity declined significantly, and no further emissions or incandescence was reported after 25 June (BGVN 44:08). For the remainder of 2019 steam plumes rose 50-400 m above the summit on most days, occasionally rising to 500-700 m above the crater. Lahars were recorded by seismic instruments in July, August, September, and December. During January-July 2020 steam plumes were reported usually 50-300 m above the summit, sometimes rising to 500 m. On 21 March 2020 steam plumes rose to 700 m, and a lahar was recorded by seismic instruments. Lahars were reported on 26 and 28 April, 3 and 5 June, and 11 July.
A swarm of deep volcanic earthquakes was reported by PVMBG on 7 August 2020. This was followed by a phreatic explosion with a dense gray to black ash plume on 8 August that rose 2,000 m above the summit and drifted E; a second explosion that day produced a plume that rose 1,000 m above the summit. According to the Jakarta Post, ash reached the community of Berastagi (15 km E) along with the districts of Naman Teran (5-10 km NE), Merdeka (15 km NE), and Dolat Rayat (20 km E). Continuous tremor events were first recorded on 8 August and continued daily until 26 August. Two explosions were recorded on 10 August; the largest produced a dense gray ash plume that rose 5,000 m above the summit and drifted NE and SE (figure 77). The Darwin VAAC reported the eruption clearly visible in satellite imagery at 9.7 km altitude and drifting W. Later they reported a second plume drifting ESE at 4.3 km altitude. After this large explosion the local National Disaster Management Authority (BNPB) reported significant ashfall in three districts: Naman Teran, Berastagi and Merdeka. Emissions on 11 and 12 August were white and gray and rose 100-200 m. Multiple explosions on 13 August produced white and gray ash plumes that rose 1,000-2,000 m above the summit. Explosions on 14 August produced gray and brown ash plumes that rose 1,000-4,200 m above the summit and drifted S and SW (figure 77). The Darwin VAAC reported that the ash plume was partly visible in satellite imagery at 7.6 km altitude moving W; additional plumes were moving SE at 3.7 km altitude and NE at 5.5 km altitude.
White, gray, and brown emissions rose 800-1,000 m above the summit on 15 and 17 August. The next day white and gray emissions rose 2,000 m above the summit. The Darwin VAAC reported an ash plume visible at 5.2 km altitude drifting SW. A large explosion on 19 August produced a dense gray ash plume that rose 4,000 above the summit and drifted S and SW. Gray and white emissions rose 500 m on 20 August. Two explosions were recorded seismically on 21 August, but rainy and cloudy weather prevented observations. White steam plumes rose 300 m on 22 August, and a lahar was recorded seismically. On 23 August, an explosion produced a gray ash plume that rose 1,500 m above the summit and pyroclastic flows that traveled 1,000 m down the E and SE flanks (figure 78). Continuous tremors were accompanied by ash emissions. White, gray, and brown emissions rose 600 m on 24 August. An explosion on 25 August produced an ash plume that rose 800 m above the peak and drifted W and NW (figure 79). During 26-30 August steam emissions rose 100-400 m above the summit and no explosions were recorded. Dense gray ash emissions rose 1,000 m and drifted E and NE after an explosion on 31 August. Significant SO2 emissions were associated with many of the explosions during August (figure 80).
Explosive activity decreased substantially during September 2020. A single explosion reported on 5 September produced a white and brown ash plume that rose 800 m above the summit and drifted NNE. During the rest of the month steam emissions rose 50-500 m above the summit before dissipating. Two lahars were reported on 7 September, and one each on 11 and 30 September. Although only a single explosion was reported, anomalous SO2 emissions were present in satellite data on several days.
The character of the activity changed during October 2020. Steam plumes rising 50-300 m above the summit were reported during the first week and a lahar was recorded by seismometers on 4 October. The first block avalanches from a new dome growing at the summit were reported on 8 October with material traveling 300 m ESE from the summit (figure 81). During 11-13 October block avalanches traveled 300-700 m E and SE from the summit. They traveled 100-150 m on 14 October. Steam plumes rising 50-500 m above the summit were reported during 15-22 October with two lahars recorded on 21 October. White and gray emissions rose 50-1,000 m on 23 October. The first of a series of pyroclastic flows was reported on 25 October; they were reported daily through the end of the month when the weather permitted, traveling 1,000-2,500 m from the summit (figure 82). In addition, block avalanches from the growing dome were observed moving down the E and SE flanks 500-1,500 m on 25 October and 200-1,000 m each day during 28-31 October (figure 83). Sentinel-2 satellite data indicated a very weak thermal anomaly at the summit in late September; it was slightly larger in late October, corroborating with images of the slow-growing dome (figure 84).
Geologic Background. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.
Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); 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/); The Jakarta Post, 3rd Floor, Gedung, Jl. Palmerah Barat 142-143 Jakarta 10270 (URL: https://www.thejakartapost.com/amp/news/2020/08/08/mount-sinabung-erupts-again-after-year-of-inactivity.html);Rizal (URL: https://twitter.com/Rizal06691023/status/1319452375887740930); CultureVolcan (URL: https://twitter.com/CultureVolcan/status/1321156861173923840).
Heard (Australia) — November 2020
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Heard
Australia
53.106°S, 73.513°E; summit elev. 2745 m
All times are local (unless otherwise noted)
Persistent thermal anomalies in the summit crater from June through October 2020
The remote Heard Island is located in the southern Indian Ocean and contains the Big Ben stratovolcano, which has had intermittent activity since 1910. The island’s activity, characterized by thermal anomalies and occasional lava flows (BGVN 45:05), is primarily monitored by satellite instruments. This report updates activity from May through October 2020 using information from satellite-based instruments.
MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed frequent thermal activity in early June that continued through July (figure 43). Intermittent, slightly higher-power thermal anomalies were detected in late August through mid-October, the strongest of which occurred in October. Two of these anomalies were also detected in the MODVOLC algorithm on 12 October.
Sentinel-2 thermal satellite imagery showed a single thermal anomaly on 3 May. In comparison to the MIROVA graph, satellite imagery showed a small pulse of strong thermal activity at the summit of Big Ben in June (figure 44). Some of these thermal anomalies were accompanied by gas-and-steam emissions. Persistent strong thermal activity continued through July. Starting on 2 July through at least 17 July two hotspots were visible in satellite imagery: one in the summit crater and one slightly to the NW of the summit (figure 45). Some gas-and-steam emissions were seen rising from the S hotspot in the summit crater. In August the thermal anomalies had decreased in strength and frequency but persisted at the summit through October (figure 45).
Geologic Background. Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben because of its extensive ice cover. The historically active Mawson Peak forms the island's high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported at this isolated volcano, but observations are infrequent and additional activity may have occurred.
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).
Sabancaya
Peru
15.787°S, 71.857°W; summit elev. 5960 m
All times are local (unless otherwise noted)
Daily explosions produced ash plumes, SO2 plumes, and thermal anomalies during June-September 2020
Sabancaya, located in Peru, is a stratovolcano that has been very active since 1986. The current eruptive period began in November 2016 and has recently been characterized by lava dome growth, daily explosions, ash plumes, ashfall, SO2 plumes, and ongoing thermal anomalies (BGVN 45:06). Similar activity continues into this reporting period of June through September 2020 using information from weekly reports from the Observatorio Vulcanologico INGEMMET (OVI), the Instituto Geofisico del Peru (IGP), and various satellite data. The Buenos Aires Volcanic Ash Advisory Center (VAAC) issued a total of 520 reports of ongoing ash emissions during this time.
Volcanism during this reporting period consisted of daily explosions, nearly constant gas-and-ash plumes, SO2 plumes, and persistent thermal anomalies in the summit crater. Gas-and-ash plumes rose to 1.5-4 km above the summit crater, drifting up to 35 km from the crater in multiple directions; several communities reported ashfall every month except for August (table 7). Sulfur dioxide emissions were notably high and recorded almost daily with the TROPOMI satellite instrument (figure 83). The satellite measurements of the SO2 emissions exceeded 2 DU (Dobson Units) at least 20 days each month of the reporting period. These SO2 plumes sometimes persisted over multiple days and ranged between 1,900-10,700 tons/day. MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows frequent thermal activity through September within 5 km of the summit crater, though the power varied; by late August, the thermal anomalies were stronger compared to the previous months (figure 84). This increase in power is also reflected by the MODVOLC algorithm that detected 11 thermal anomalies over the days of 31 August and 4, 6, 13, 17, 18, 20, and 22 September 2020. Many of these thermal hotspots were visible in Sentinel-2 thermal satellite imagery, occasionally accompanied by gas-and-steam and ash plumes (figure 85).
Table 7. Persistent activity at Sabancaya during June through September included multiple daily explosions that produced ash plumes rising several kilometers above the summit and drifting in multiple directions; this resulted in ashfall in communities within 35 km of the volcano. Satellite instruments recorded daily SO2 emissions. Data courtesy of OVI-INGEMMET, IGP, and the NASA Global Sulfur Dioxide Monitoring Page.
Month |
Avg. daily explosions by week |
Max plume heights (km above the crater) |
Plume drift (km) and direction |
Communities reporting ashfall |
Minimum days with SO2 over 2 DU |
SO2 emissions per day (tons) by week |
Jun 2020 |
20, 10, 9, 13 |
1.5-4 |
30 km, SE, S, SW, NE, W, E |
Chivay, Achoma, Ichupampa, Yanque, and Coporaque, Sallali, Madrigal, Lari, and Ichupampa |
28 |
8,400, 2,200, 3,100, 7,600 |
Jul 2020 |
20, 15, 11, 12, 19 |
2-2.6 |
15-30 km E, NE, NW, SE, SW, S, W |
Achoma and Chivay |
23 |
4,400, 6,000, 1,900, 2,100, 5,900 |
Aug 2020 |
18, 12, 9, 29 |
1.7-3.6 |
20-30 km W, SW, SE, S, E, NW |
- |
20 |
2,300, 3,800, 5,300, 10,700 |
Sep 2020 |
39, 35, 33, 38, 40 |
1.8-3.5 |
25-35 km SE, S, SW, W, E, NE, N, NW, W |
Lari, Achoma, Maca, Chivay, Taya, Huambo, Huanca, and Lluta |
28 |
9,700, 2,600, 8,800, 7,800, 4,100 |
OVI detected slight inflation on the N part of the volcano, which continued to be observed throughout the reporting period. Persistent thermal anomalies caused by the summit crater lava dome were observed in satellite data. The average number of daily explosions during June ranged from 18 during 1-7 June to 9 during 15-21 June, which generated gas-and-ash plumes that rose 1.5-4 km above the crater and drifted 30 km SE, S, SW, NE, W, and E (figure 86). The strongest sulfur dioxide emissions were recorded during 1-7 June measuring 8,400 tons/day. On 20 June drone video showed that the lava dome had been destroyed, leaving blocks on the crater floor, though the crater remained hot, as seen in thermal satellite imagery (figure 85). During 22-28 June there were an average of 13 daily explosions, which produced ash plumes rising to a maximum height of 4 km, drifting NE, E, and SE. As a result, ashfall was reported in the districts of Chivay, Achoma, Ichupampa, Yanque, and Coporaque, and in the area of Sallali. Then, on 27 June ashfall was reported in several areas NE of the volcano, which included the districts of Madrigal, Lari, Achoma, Ichupampa, Yanque, Chivay, and Coporaque.
Slight inflation continued to be monitored in July, occurring about 4-6 km N of the crater, as well as on the SE flank. Daily explosions continued, producing gas-and-ash plumes that rose 2-2.6 km above the crater and drifting 15-30 km E, NE, NW, SE, SW, S, and W (figure 87). The number of daily explosions increased slightly compared to the previous month, ranging from 20 during 1-5 July to 11 during 13-19 July. SO2 emissions that were measured each week ranged from 1,900 to 6,000 tons/day, the latter of which occurred during 6-12 July. Thermal anomalies continued to be observed in thermal satellite data over the summit crater throughout the month. During 6-12 July gas-and-ash plumes rose 2.3-2.5 km above the crater, drifting 30 km SE, E, and NE, resulting in ashfall in Achoma and Chivay.
OVI reported continued slight inflation on the N and SE flanks during August. Daily explosive activity had slightly declined in the first part of the month, ranging from 18 during the 3-9 August to 9 during 17-23 August. Dense gray gas-and-ash plumes rose 1.7-3.6 km above the crater, drifting 20-30 km in various directions (figure 88), though no ashfall was reported. Thermal anomalies were observed using satellite data throughout the month. During 24-30 August a pulse in activity increased the daily average of explosions to 29, as well as the amount of SO2 emissions (10,700 tons/day); nighttime incandescence accompanied this activity. During 28-29 August higher levels of seismicity and inflation were reported compared to the previous weeks. The daily average of explosions increased again during 31 August-6 September to 39; nighttime incandescence remained.
Increased volcanism was reported during September with the daily average of explosions ranging from 33 during 14-20 September to 40 during 28 September-4 October. The resulting gas-and-ash plumes rose 1.8-3.5 km above the crater drifting 25-35 km in various directions (figure 89). SO2 flux was measured by OVI ranging from 2,600 to 9,700 tons/day, the latter of which was recorded during 31 August to 6 September. During 7-13 September an average of 35 explosions were reported, accompanied by gas-and-ash plumes that rose 2.6-3.5 km above the crater and drifting 30 km SE, SW, W, E, and S. These events resulted in ashfall in Lari, Achoma, and Maca. The following week (14-20 September) ashfall was reported in Achoma and Chivay. During 21-27 September the daily average of explosions was 38, producing ash plumes that resulted in ashfall in Taya, Huambo, Huanca, and Lluta. Slight inflation on the N and SE flanks continued to be monitored by OVI. Strong activity, including SO2 emissions and thermal anomalies over the summit crater persisted into at least early October.
Geologic Background. Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.
Information Contacts: Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa, Peru (URL: http://ovi.ingemmet.gob.pe); Instituto Geofisico del Peru (IGP), Calle Badajoz N° 169 Urb. Mayorazgo IV Etapa, Ate, Lima 15012, Perú (URL: https://www.gob.pe/igp); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); 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).
Rincon de la Vieja (Costa Rica) — October 2020
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Rincon de la Vieja
Costa Rica
10.83°N, 85.324°W; summit elev. 1916 m
All times are local (unless otherwise noted)
Frequent small phreatic explosions with intermittent ash plumes during April-September 2020
Rincón de la Vieja is a remote volcanic complex in Costa Rica that contains an acid lake. Frequent weak phreatic explosions have occurred since 2011 (BGVN 44:08). The most recent eruption period began in January 2020, which consisted of small phreatic explosions, gas-and-steam plumes, pyroclastic flows, and lahars (BGVN 45:04). This reporting period covers April through September 2020, with activity characterized by continued small phreatic explosions, three lahars, frequent gas-and-steam plumes, and ash plumes. The primary source of information for this report is the Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA) using weekly bulletins and the Washington Volcanic Ash Advisory Center (VAAC).
Small, frequent, phreatic explosions were common at Rincón de la Vieja during this reporting period. One to several eruptions were reported on at least 16 days in April, 15 days in May, 8 days in June, 10 days in July, 18 days in August, and 13 days in September (table 5). Intermittent ash plumes accompanied these eruptions, rising 100-3,000 m above the crater and drifting W, NW, and SW during May and N during June. Occasional gas-and-steam plumes were also observed rising 50-2,000 m above the crater rim.
Table 5. Monthly summary of activity at Rincón de la Vieja during April through September 2020. Courtesy of OVSICORI-UNA.
Month |
Minimum total days of eruptions |
Ash plume height (m above the crater) |
Notable plume drift |
Gas-and-steam plume height (m above the crater) |
Apr 2020 |
16 |
200-1,000 |
- |
50-1,500 |
May 2020 |
15 |
200-3,000 |
W, NW, SW |
200-2,000 |
Jun 2020 |
8 |
100-2,000 |
N |
- |
Jul 2020 |
10 |
1,000 |
- |
- |
Aug 2020 |
18 |
500-1,000 |
- |
500 |
Sep 2020 |
13 |
700 |
- |
50 |
During April small explosions were detected almost daily, some of which generated ash plumes that rose 200-1,000 m above the crater and gas-and-steam emissions that rose 50-1,500 m above the crater. On 4 April an eruption at 0824 produced an ash plume that rose 1 km above the crater rim. A small hydrothermal explosion at 0033 on 11 April, recorded by the webcam in Sensoria (4 km N), ejected water and sediment onto the upper flanks. On 15 April a phreatic eruption at 0306 resulted in lahars in the Pénjamo, Azufrada, and Azul rivers, according to local residents. Several small explosions were detected during the morning of 19 April; the largest phreatic eruption ejected water and sediment 300 m above the crater rim and onto the flanks at 1014, generated a lahar, and sent a gas-and-steam plume 1.5 km above the crater (figure 30). On 24 April five events were recorded by the seismic network during the morning, most of which produced gas-and-steam plumes that rose 300-500 m above the crater. The largest event on this day occurred at 1020, ejecting water and solid material 300 m above the crater accompanied by a gas-and-steam plume rising up to 1 km.
Similar frequent phreatic activity continued in May, with ash plumes rising 200-1,500 m above the crater, drifting W, NW, and SW, and gas-and-steam plumes rising up to 2 km. On 5 May an eruption at 1317 produced a gas-and-steam plume 200 m above the crater and a Washington VAAC advisory reported that an ash plume rose to 2.1 km altitude, drifting W. An event at 1925 on 9 May generated a gas-and-steam plume that rose almost 2 km. An explosion at 1128 on 15 May resulted in a gas-and-steam plume that rose 1 km above the crater rim, accompanied by a gray, sediment-laden plume that rose 400 m. On 21 May a small ash eruption at 0537 sent a plume 1 km above the crater (figure 31). According to a Washington VAAC advisory, an ash plume rose 3 km altitude, drifting NW on 22 May. During the early evening on 25 May an hour-long sequence of more than 70 eruptions and emissions, according to OVSICORI-UNA, produced low gas-and-steam plumes and tephra; at 1738, some ejecta was observed above the crater rim. The next day, on 26 May, up to 52 eruptive events were observed. An eruption at 2005 was not visible due to weather conditions; however, it resulted in a minor amount of ashfall up to 17 km W and NW, which included Los Angeles of Quebrada Grande and Liberia. A phreatic explosion at 1521 produced a gray plume that rose 1.5 km above the crater (figure 31). An eruption at 1524 on 28 May sent an ash plume 3 km above the crater that drifted W, followed by at least three smaller eruptions at 1823, 1841, and 1843. OVSICORI-UNA reported that volcanism began to decrease in frequency on 28-29 May. Sulfur dioxide emissions ranged between 100 and 400 tons per day during 28 May to 15 June.
There were eight days with eruptions in June, though some days had multiple small events; phreatic eruptions reported on 1-2, 13, 16-17, 19-20, and 23 June generated plumes 1-2 km above the crater (figure 32). During 2-8 June SO2 emissions were 150-350 tons per day; more than 120 eruptions were recorded during the preceding weekend. Ashfall was observed N of the crater on 4 June. During 9-15 June the SO2 emissions increased slightly to 100-400 tons per day. During 16-17 June several small eruptive events were detected, the largest of which occurred at 1635 on 17 June, producing an ash plume that rose 1 km above the crater.
Explosive hydrothermal activity was lower in June-September compared to January-May 2020, according to OVSICORI-UNA. Sporadic small phreatic explosions and earthquakes were registered during 22-25 and 29 July-3 August, though no lahars were reported. On 25 July an eruptive event at 0153 produced an ash plume that rose 1 km above the crater. Similar activity continued into August. On 5 and 6 August phreatic explosions were recorded at 0546 and 0035, respectively, the latter of which generated a plume that rose 500 m above the crater. These events continued to occur on 10, 16, 19-20, 22-25, 27-28, and 30-31 August, generating plumes that rose 500 m to 1 km above the crater.
On 3 September geologists observed that the acid lake in the main crater had a low water level and exhibited strong gas emissions; vigorous fumaroles were observed on the inner W wall of the crater, measuring 120°C. Gas-and-steam emissions continued to be detected during September, occasionally accompanied by phreatic eruptions. On 7 September an eruption at 0750 produced an ash plume that rose 50 m above the crater while the accompanying gas-and-steam plume rose 500 m. Several low-energy phreatic explosions occurred during 8-17, 20, and 22-28 September, characterized primarily by gas-and-steam emissions. An eruption on 16 September ejected material from the crater and generated a small lahar. Sulfur dioxide emissions were 100 tons per day during 16-21 September. On 17 September an eruption at 0632 produced an ash plume that rose 700 m above the crater (figure 33). A relatively large eruptive event at 1053 on 22 September ejected material out of the crater and into N-flank drainages.
Geologic Background. Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 km3 and contains at least nine major eruptive centers. Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5-km-wide caldera and has a 500-m-wide crater. A Plinian eruption producing the 0.25 km3 Río Blanca tephra about 3,500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16th century, have been from the prominent active crater containing a 500-m-wide acid lake located ENE of Von Seebach crater.
Information Contacts: Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica (URL: http://www.ovsicori.una.ac.cr/, https://www.facebook.com/OVSICORI/); 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).
Fuego (Guatemala) — December 2020
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Fuego
Guatemala
14.473°N, 90.88°W; summit elev. 3763 m
All times are local (unless otherwise noted)
Daily explosions, ash emissions, and block avalanches during August-November 2020
Guatemala's Volcán de Fuego has been erupting vigorously since 2002 with reported eruptions dating back to 1531. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars, including a series of explosions and pyroclastic flows in early June 2018 that caused several hundred fatalities. Eruptive activity consisting of explosions with ash emissions, block avalanches, and lava flows began again after a short break and has continued; activity during August-November 2020 is covered in this report. Daily reports are provided by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH); aviation alerts of ash plumes are issued by the Washington Volcanic Ash Advisory Center (VAAC). Satellite data provide valuable information about heat flow and emissions.
Summary of activity during August-November 2020. Eruptive activity continued at Fuego during August-November 2020, very similar to that during the first part of the year (table 22). Ash emissions were reported daily by INSIVUMEH with explosions often in the 6-12 per hour range. Most of the ash plumes rose to 4.5-4.7 km altitude and generally drifted SW, W, or NW, although rarely the wind direction changed and sent ash to the S and SE. Multiple daily advisories were issued throughout the period by the Washington VAAC warning aviators about ash plumes, which were often visible on the observatory webcam (figure 136). Some of the communities located SW of the volcano received ashfall virtually every day during the period. Block avalanches descended the major drainages daily as well. Sounds were heard and vibrations felt from the explosions most days, usually 7-12 km away. The stronger explosions could be felt and heard 20 km or more from the volcano. During late August and early September a lava flow was active on the SW flank, reaching 700 m in length during the second week of September.
Table 22. Eruptive activity was consistently high at Fuego throughout August – November 2020 with multiple explosions every hour, ash plumes, block avalanches, and near-daily ashfall in the communities in certain directions within 10-20 km of the volcano. Courtesy of INSIVUMEH daily reports.
Month |
Explosions per hour |
Ash Plume Heights (km) |
Ash plume distance (km) and direction |
Drainages affected by block avalanches |
Communities reporting ashfall |
Aug 2020 |
2-15 |
4.3-4.8 |
SW, W, NW, S, N, 8-20 km |
Seca, Taniluya, Ceniza, Trinidad, Las Lajas, Honda, Santa Teresa |
Panimaché I and II, Morelia, Rochela, Finca Palo Verde, Yepocapa, Santa Sofia, El Porvenir, Palo Verde, Sangre de Cristo, Santa Lucía Cotzumalguapa |
Sep 2020 |
3-16 |
4.3-4.9 |
W, SW, NW, N, S, 8-20 km |
Seca, Taniluya, Ceniza, Trinidad, Las Lajas, Honda, Santa Teresa |
Panimaché I and II, Morelia, Santa Sofía, Finca Palo Verde, Sangre de Cristo, Yepocapa, Porvenir, Yucales, Ojo de Agua, Finca La Conchita |
Oct 2020 |
3-19 |
4.1-4.8 |
SW, W, S, SE, N, E, 10-20 km |
Seca, Taniluya, Ceniza, Trinidad, Las Lajas, Honda, Santa Teresa |
Panimache I and II, Morelia, Sangre de Cristo, Yepocapa, La Rochela, El Porvenir, Ceilán, Santa Sofía, Yucales, Finca Palo Verde |
Nov 2020 |
4-14 |
4.0-4.8 |
S, SW, SE, W, NW, 10-35 km |
Seca, Taniluya, Ceniza, Trinidad, Las Lajas, Honda, Santa Teresa El Jute |
Panimaché I and II, Sangre de Cristo, Morelia, Ceilan, La Rochela, El Zapote, Santa Sofía, Yucales, San Juan Alotenango, Ciudad Vieja, San Miguel Dueñas y Antigua Guatemala, Palo Verde, El Porvenir, San Pedro Yepocapa, Quisaché, Santa Emilia |
The frequent explosions, block avalanches, and lava flows produced a strong thermal signal throughout the period that was recorded in both the MIROVA project Log Radiative Power graph (figure 137) and in numerous Sentinel-2 satellite images (figure 138). MODVOLC data produced thermal alerts 4-6 days each month. At least one lahar was recorded each month; they were most frequent in September and October.
Activity during August-November 2020. The number of explosions per hour at Fuego during August 2020 was most often 7-10, with a few days that were higher at 10-15. The ash plumes usually rose to 4.5-4.8 km altitude and drifted SW or W up to 15 km. Incandescence was visible 100-300 m above the summit crater on most nights. All of the major drainages including the Seca, Santa Teresa, Ceniza, Trinidad, Taniluyá, Las Lajas, and Honda were affected by block avalanches virtually every day. In addition, the communities of Panimaché I and II, Morelia, Santa Sofía, Finca Palo Verde, El Porvenir, San Pedro Yepocapa, and Sangre de Cristo reported ashfall almost every day. Sounds and vibrations were reported multiple days every week, often up to 12 km from the volcano, but occasionally as far as 20 km away. Lahars carrying blocks of rocks and debris 1-2 m in diameter descended the SE flank in the Las Lajas and Honda ravines on 6 August. On 27 August a lava flow 150 m long appeared in the Ceniza ravine. It increased in length over the subsequent few days, reaching 550 m long on 30 August, with frequent block avalanches falling off the front of the flow.
The lava flow in the Ceniza ravine was reported at 100 m long on 5 September. It grew to 200 m on 7 September and reached 700 m long on 12 September. It remained 200-350 m long through 19 September, although instruments monitored by INSIVUMEH indicated that effusive activity was decreasing after 16 September (figure 139). A second flow was 200 m long in the Seca ravine on 19 September. By 22 September, active flows were no longer observed. The explosion rate varied from a low of 3-5 on 1 September to a high of 12-16 on 4, 13, 18, and 22-23 September. Ash plumes rose to 4.5-4.9 km altitude nearly every day and drifted W, NW, and SW occasionally as far as 20 km before dissipating. In addition to the active flow in the Ceniza ravine, block avalanches persisted in the other ravines throughout the month. Ashfall continued in the same communities as in August, but was also reported in Yucales on 4 September along with Ojo de Agua and Finca La Conchita on 17 September. The Las Lajas, Honda, and El Jute ravines were the sites of lahars carrying blocks up to 1.5 m in diameter on 8 and 18 September. On 19 and 24 September lahars again descended Las Lajas and El Jute ravines; the Ceniza ravine had a lahar on 19 September.
The same activity continued during October 2020 with regard to explosion rates, plume altitudes, distances, and directions of drift. All of the major ravines were affected by block avalanches and the same communities located W and SW of the summit reported ashfall. In addition, ashfall was reported in La Rochela on 2, 3, 7-9 and 30 October, in Ceilán on 3 and 7-9 October, and in Yucales on 5, 14, 18 and 19 October. Multiple strong explosions with abundant ash were reported in a special bulletin on 14 October; high levels of explosive activity were recorded during 16-23 October. Vibrations and sounds were often felt up to 15 km away and heard as far as 25 km from the volcano during that period. Particularly strong block avalanches were present in the Seca and Ceniza ravines on 20, 25, and 30 October. Abundant rain on 9 October resulted in lahars descending all of the major ravines. The lahar in the Las Lajas ravine overflowed and forced the closure of route RN-14 road affecting the community of San Miguel on the SE flank (figure 140). Heavy rains on 15 October produced lahars in the Ceniza, Las Lajas, and Hondas ravines with blocks up to 2 m in diameter. Multiple lahars on 27 October affected Las Lajas, El Jute, and Honda ravines.
On 8 November 2020 a lahar descended the Seca ravine, carrying rocks and debris up to 1 meter in diameter. During the second week of November 2020, the wind direction changed towards the SE and E and brought ashfall to San Juan Alotenango, Ciudad Vieja, San Miguel Dueñas, and Antigua Guatemala on 8 November. Especially strong block avalanches were noted in the Seca and Ceniza ravines on 14, 19, 24, and 29 November. During a period of stronger activity in the fourth week of November, vibrations were felt and explosions heard more than 20 km away on 22 November and more than 25 km away on 27 November. In addition to the other communities affected by ashfall during August-November, Quisaché and Santa Emilia reported ashfall on 30 November.
Geologic Background. Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.
Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/ ); 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);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/); 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).
Kikai
Japan
30.793°N, 130.305°E; summit elev. 704 m
All times are local (unless otherwise noted)
Explosion on 6 October 2020 and thermal anomalies in the crater
Kikai is a mostly submarine caldera, 19-km-wide, just S of the Ryukyu Islands of Japan. At the NW rim of the caldera lies the island of Satsuma Iwo Jima (also known as Satsuma-Iojima and Tokara Iojima), and the island’s highest peak, Iodake, a steep stratovolcano. Recent weak ash explosions at Iodake occurred on 2 November 2019 and 29 April 2020 (BGVN 45:02, 45:05). The volcano is monitored by the Japan Meteorological Agency (JMA) and satellite sensors. This report covers the period May-October 2020. During this time, the Alert Level remained at 2 (on a 5-level scale).
Activity at Kikai has been relatively low since the previous eruption on 29 April 2020. During May through October occasional white gas-and-steam emissions rose 0.8-1.3 km above the Iodake crater, the latter of which was recorded in September. Emissions were intermittently accompanied by weak nighttime incandescence, according to JMA (figure 17).
A small eruption at 0757 on 6 October occurred in the NW part of the Iodake crater, which produced a grayish white plume rising 200 m above the crater (figure 18). Faint thermal anomalies were detected in Sentinel-2 thermal satellite imagery in the days just before this eruption (28 September and 3 October) and then after (13 and 23 October), accompanied by gas-and-steam emissions (figures 19 and 20). Nighttime crater incandescence continued to be observed. JMA reported that sulfur dioxide emissions measured 700 tons per day during October, compared to the previous eruption (400-2,000 tons per day in April 2020).
Geologic Background. Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world's largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.
Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).
Manam (Papua New Guinea) — October 2020
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Manam
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
Intermittent ash plumes, thermal anomalies, and SO2 emissions in April-September 2020
Manam, located 13 km off the N coast of Papua New Guinea, is a basaltic-andesitic stratovolcano with historical eruptions dating back 400 years. Volcanism has been characterized by low-level ash plumes, occasional Strombolian activity, lava flows, pyroclastic avalanches, and large ash plumes from Main and South, the two active summit craters. The current eruption period has been ongoing since 2014, typically with minor explosive activity, thermal activity, and SO2 emissions (BGVN 45:05). This reporting period updates information from April through September 2020, consisting of intermittent ash plumes from late July to mid-September, persistent thermal anomalies, and SO2 emissions. Information comes from Papua New Guinea's Rabaul Volcano Observatory (RVO), part of the Department of Mineral Policy and Geohazards Management (DMPGM), the Darwin Volcanic Ash Advisory Center (VAAC), and various satellite data.
Explosive activity was relatively low during April through late July; SO2 emissions and low power, but persistent, thermal anomalies were detected by satellite instruments each month. The TROPOMI instrument on the Sentinel-5P satellite recorded SO2 emissions, many of which exceeded two Dobson Units, that drifted generally W (figure 76). Distinct SO2 emissions were detected for 10 days in April, 4 days in May, 10 days in June, 4 days in July, 11 days in August, and 8 days in September.
Thermal anomalies recorded by the MIROVA (Middle InfraRed Observation of Volcanic Activity) system were sparse from early January through June 2020, totaling 11 low-power anomalies within 5 km of the summit (figure 77). From late July through September a pulse in thermal activity produced slightly stronger and more frequent anomalies. Some of this activity could be observed in Sentinel-2 thermal satellite imagery (figure 78). Occasionally, these thermal anomalies were accompanied by gas-and-steam emissions or ash plumes, as shown on 28 July. On 17 August a particularly strong hotspot was detected in the S summit crater. According to the MODVOLC thermal alert data, a total of 10 thermal alerts were detected in the summit crater over four days: 29 July (5), 16 August (1), and 3 (1) and 8 (3) September.
Activity during mid-July slightly increased compared to the previous months. On 16 July seismicity increased, fluctuating between low and moderate RSAM values through the rest of the month. In Sentinel-2 satellite imagery a gray ash plume was visible rising from the S summit crater on 28 July (figure 78). RSAM values gradually increased from a low average of 200 to an average of 1200 on 30 July, accompanied by thermal hotspots around the summit crater; a ground observer reported incandescent material was ejected from the summit. On 31 July into 1 August ash plumes rose to 4.3 km altitude, accompanied by an incandescent lava flow visible at the summit, according to a Darwin VAAC advisory.
Intermittent ash plumes continued to be reported by the Darwin VAAC on 1, 6-7, 16, 20, and 31 August. They rose from 2.1 to 4.6 km altitude, the latter of which occurred on 31 August and drifted W. Typically, these ash plumes extended SW, W, NW, and WSW. On 11 September another ash plume was observed rising 2.4 km altitude and drifting W.
Geologic Background. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
Information Contacts: Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea; 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/); 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).
Karymsky (Russia) — October 2020
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Karymsky
Russia
54.049°N, 159.443°E; summit elev. 1513 m
All times are local (unless otherwise noted)
New eruption during April-July 2020; ash explosions in October 2020
Karymsky is an active volcano, part of Kamchatka’s eastern volcanic zone. Eruptive activity has been frequent since 1996 and has included ash explosions, gas-and-steam and ash emissions, and thermal anomalies. The most recent eruptive period ended in September 2019 (BGVN 44:11) with a new one beginning in April 2020. Both eruptions consisted of moderate explosive activity and ash plumes. This report updates information from November 2019 through October 2020, which describes a short-lived eruption from April to July and renewed activity in October. Information comes from daily, weekly, and special reports from the Kamchatka Volcanic Eruptions Response Team (KVERT), the Tokyo Volcanic Ash Advisory Center (VAAC), and satellite data.
Activity at Karymsky after November 2019 primarily consisted of moderate gas-and-steam emissions and rare weak thermal anomalies in the summit crater (on 2, 8, and 17 December 2019, according to KVERT). No thermal activity was reported during January through March 2020.
Over the weeks of late March to early April 2020, minor amounts of ash were present in gas-and-steam emissions that led to trace ashfall deposits on the snowy flanks and were visible in satellite imagery (figure 47). A weak thermal anomaly was observed in satellite imagery on 6 April. On 13 April the Tokyo VAAC reported an ash plume to 2.1 km altitude drifting SE. Gas-and-steam emissions containing some ash rose 2 km altitude on 17 April and drifted up to 80 km SE on both 17 and 21 April, accompanied by a weak thermal anomaly seen in satellite data. On 18 April the Tokyo VAAC released an advisory noting an ash plume at 1.5-2.1 km altitude drifting S.
KVERT reported intermittent thermal anomalies during May, along with moderate gas-and-steam emissions. On 10 May gas-and-steam plumes containing some ash drifted 77 km SE while ash plumes observed in HIMAWARI-8 satellite imagery rose to 2.7 km altitude. A dense plume drifting S resulted in large ash deposits covering all but the N flank of the volcano by 14 May, as observed in Sentinel-2 natural color satellite imagery (figure 48). KVERT reported that ash continued to be observed during 24-31 May, rising to a maximum altitude of 7 km on 27 May and extending in multiple directions. On 29 and 31 May explosions generated ash plumes that rose to 6 and 4 km altitude, respectively, and both extended up to 380 km SW, SE, and E. MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows a pulse in thermal activity within 5 km of the summit crater starting in late May, reflecting the renewed activity (figure 49). On 1 June another strong brown-gray ash plume was seen rising from Karymsky, drifting SE in satellite imagery, depositing large amounts of ash on all flanks (figure 48).
Intermittent ash emissions and moderate explosive activity continued in June. During 1-4 June continuous ash plumes rose to a high of 4.6 km altitude and drifted up to 400 km generally E, according to KVERT and the Tokyo VAAC advisories. By 19 June, KVERT stated that possible Strombolian activity was occurring, accompanied by moderate gas-and-steam emissions and frequent thermal anomalies; Sentinel-2 thermal satellite imagery also showed a thermal anomaly in the crater (figure 50). Ash plumes and gas-and-steam plumes containing some amount of ash were seen drifting SW and NW on 30 June (figure 51).
Similar activity continued into July, which included possible Strombolian activity, moderate gas-and-steam emissions, and frequent thermal anomalies. On 14 July a gas-and-steam plume that contained some ash drifted 26 km SW (figure 52); the Tokyo VAAC advisory reported a continuous ash plume that rose 3 km altitude and drifted SW. During 27-30 July Strombolian and Vulcanian explosions generated ash plumes that rose 3-3.7 km altitude and extended 250 km SW and SE. The frequency of thermal anomalies seen in MIROVA decreased in July; the MODVOLC system detected one thermal hotspot on 28 July.
Activity decreased in August; thermal anomalies were reported on 5-7, 10, 18, and 21 August, the latter of which was last observed thermal anomaly, according to KVERT. Moderate gas-and-steam emissions continued to occur through the week of 3 September (figure 53). On 26 September, the Tokyo VAAC issued an advisory for a small ash plume that rose to 1.8 km altitude and extended SE.
After a brief period of little to no activity, Tokyo VAAC advisories on 10 and 11 October both reported small ash plumes that rose 1.8 km altitude and drifted SE. An ash plume on 17 October rose to 3.9 km altitude drifting E; on 20 October an ash plume drifted up to 50 km SE. KVERT reported that a new eruption began on 21 October; pilots observed explosions at 1430 that generated ash plumes up to 4 km altitude and extended 40 km SE (figure 54). Multiple ash plumes during that day rose up to 6.4 km altitude and drifted as far as 530 km SE, accompanied by a thermal anomaly. Frequent ash explosions continued through the end of the month, with the highest plume rising to an altitude of 6 km on 30 October. In late October two thermal anomalies were detected in MIROVA.
Geologic Background. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian with moderate explosive activity and occasional lava flows from the summit crater.
Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); 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); Bel-Kam-Tour, st. Elizova, 39 Paratunka Kamchatka Krai, 684000, Russia (URL: https://bel-kam-tour.business.site/); Russia Today (RT), Borovaya St., 3 bldg. 1, Moscow 111020 (URL: https://www.rt.com/).
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Bulletin of the Global Volcanism Network - Volume 42, Number 03 (March 2017)
Managing Editor: Edward Venzke
Axial Seamount (Undersea Features)
Research cruise and new bathymetry reveals lava flows from the 2015 eruption
Barren Island (India)
Intermittent ash plumes and thermal anomalies continue from July 2014 through February 2017
Gamalama (Indonesia)
Weak explosion generates ash plumes during 3-4 August 2016
Kavachi (Solomon Islands)
Evidence of regular explosive activity during 2006-2016 from satellite and direct observations
Kuchinoerabujima (Japan)
Explosions on 3 August 2014, 29-30 May 2015 (with pyroclastic flow), and 18-19 June 2015
Manam (Papua New Guinea)
Large ash plume to 19.8 km on 31 July 2015; persistent thermal anomalies during 2014-2016
Pavlof (United States)
Ash plume to 11 km on 27 March 2016 that drifted 1,200 km NE; multiple smaller ash events through July 2016
Poas (Costa Rica)
Phreatic explosions from the crater lake in June-August 2016
Sheveluch (Russia)
Lava dome extrusion continues with occasional explosions and ash plumes through February 2016
Soputan (Indonesia)
Ash plumes to over 12 km altitude, lava flows, pyroclastic flows, and Strombolian activity during January-February 2016
Axial Seamount (Undersea Features) — March 2017
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Axial Seamount
Undersea Features
45.95°N, 130°W; summit elev. -1410 m
All times are local (unless otherwise noted)
Research cruise and new bathymetry reveals lava flows from the 2015 eruption
The submarine Axial Seamount volcano is located about 470 km offshore of the Oregon coast. An eruption inferred to have started at 2230 on 23 April 2015 with an earthquake swarm (BGVN 40:03) was confirmed during a 14-29 August 2015 research cruise by the R/V Thompson. According to a personal communication on 23 June 2015 from Bill Chadwick (Oregon State University and NOAA), the length of the eruption is unknown, but it was "very likely days to weeks since the deflation lasted for about 10 days and the temperature signals lasted about a month."
The research cruise revealed new lava flows observed from bathymetric data and observations made during a remotely operated underwater vehicle ROV Jason dive. This eruption "produced the largest volume of erupted lava since monitoring and mapping began in the mid-1980's" (Chadwick and others, 2016). Two large lava flows from the N rift zone (8-16 km N of the summit caldera) were at most 127 m thick; some of the thicker areas had drained collapse features indicating molten interiors when emplaced. The ROV traversed the flows for about 2 km. New, thinner lava flows (figure 13) were also identified in the NE summit caldera and on the NE rim.
Three recently published papers, Chadwick and others (2016), Nooner and Chadwick (2016), and Wilcock and others (2016), detail the results of eruptive activity in 1998, 2011, and 2015, based on new data from a research cruise conducted after the 2015 eruption (figures 14 and 15). Scientists from the Monterey Bay Aquarium Research Institute (MBARI) issued a new seafloor map (figure 16) of the area of Axial north of the one shown in figure 14, based on underwater surveys conducted in August 2016, uncovering a number of previously undocumented flows from the 2015 eruption (Phys.org, 2016). MBARI ran identical sets of autonomous underwater vehicles (AUV) survey lines across the entire Axial caldera in 2011, 2014, 2015, and 2016, and during the 2016 survey the AUV collected seafloor samples (figure 13).
According to Wilcock and others (2016), the earthquake rates increases from less than 500 per day to as many as about 2000 per day prior to the eruption on 24 April 2015, then decreased rapidly over the next month following the seismic crisis to a background level of 20 per day. During the eruption there were 600 earthquakes measured every hour, and the seafloor at Axial dropped suddenly by about 2.4 m.
Precise pressure sensors measure vertical movements of the seafloor that take place as the volcano gradually inflates (see figure 14). Deformation of the Axial volcano seafloor as measured by pressure sensors (figure 17) indicated gradual inflation followed by rapid deflation during the three most recent eruptions in 1998, 2011, and 2015.
References: Chadwick, W.W., Jr., Paduan, J.B., Clague, D.A., Dreyer, B.M., Merle, S.G., Bobbitt, A.M., Caress, D.W., Philip, B.T., Kelley, D.S., and Nooner, S.L., 2016 (15 December), Voluminous eruption from a zoned magma body after an increase in supply rate at Axial Seamount, Geophysical Research Letters, v. 43, issue 23, pp. 12,063-12,070; DOI: 10.1002/2016GL071327.
Nooner, S.L., and Chadwick, W.W., Jr., 2016 (16 December), Inflation-predictable behavior and co-eruption deformation at Axial Seamount, Science, v. 354, issue 6318, pp. 1399-1403; DOI: 10.1126/science.aah4666.
Phys.org, 2016 (15 Dec), MBARI's seafloor maps provide new information about 2015 eruption at Axial Seamount (URL: https://phys.org/news/2016-12-mbari-seafloor-eruption-axial-seamount.html).
Wilcock, W.S.D., Tolstoy, M., Waldhauser, F., Garcia, C., Tan, Y.J., Bohnenstiehl, D.R., Caplan-Auerbach, J., Dziak, R.P., Arnulf, A.F., and Mann, M.E., 2016 (16 Dec), Seismic constraints on caldera dynamics from the 2015 Axial Seamount eruption, Science, v. 354, issue 6318, pp. 1395-1399; DOI: 10.1126/science.aah5563.
Geologic Background. Axial Seamount rises 700 m above the mean level of the central Juan de Fuca Ridge crest about 480 km W of Cannon Beach, Oregon, to within about 1400 m of the sea surface. It is the most magmatically robust and seismically active site on the Juan de Fuca Ridge between the Blanco Fracture Zone and the Cobb offset. The summit is marked by an unusual rectangular-shaped caldera (3 x 8 km) that lies between two rift zones and is estimated to have formed about 31,000 years ago. The caldera is breached to the SE and is defined on three sides by boundary faults of up to 150 m relief. Hydrothermal vents with biological communities are located near the caldera fault and along the rift zones. Hydrothermal venting was discovered north of the caldera in 1983. Detailed mapping and sampling efforts have identified more than 50 lava flows emplaced since about 410 CE (Clague et al., 2013). Eruptions producing fissure-fed lava flows that buried previously installed seafloor instrumentation were detected seismically and geodetically in 1998 and 2011, and confirmed shortly after each eruption during submersible dives.
Information Contacts: William Chadwick, Cooperative Institute for Marine Resources Studies (CIMRS), Oregon State University, and NOAA/PMEL Earth-Ocean Interactions Program, Hatfield Marine Science Center, 2115 S.E. OSU Dr., Newport, OR 97365, USA (URL: http://www.pmel.noaa.gov/eoi/).
Barren Island (India) — March 2017
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Barren Island
India
12.278°N, 93.858°E; summit elev. 354 m
All times are local (unless otherwise noted)
Intermittent ash plumes and thermal anomalies continue from July 2014 through February 2017
The eruptive activity at Barren Island that began in October 2013 continued through at least mid-June 2014 (BGVN 39:07). Another eruptive cycle began in March 2015 and continued through 28 February 2016, based on MODIS/MODVOLC thermal anomalies. However, MIROVA hotspots were regular through mid-May 2016, and then sporadic throughout the rest of 2016. The next clear episode began on 15 January 2017 and continued through at least February 2017. Scientists aboard a research ship observed explosions, fire fountains, and lava flows in January 2017.
Activity during October 2013-June 2014. Evidence of renewed activity in the form of lava flows was seen in MODVOLC thermal anomaly data beginning on 12 October 2013. Thermal alert pixels were frequent through 12 February 2014, followed by single anomalies on 12 March and 20 April 2014. Ash plumes were also observed during January-April 2014. Thermal infrared MODIS data processed by the MIROVA system revealed frequent anomalies in April through early May 2014, and in late May to early June; another anomaly was seen in mid-June 2014.
Activity during July 2014-June 2015. No thermal anomalies were seen in MIROVA data for at least five weeks (figure 24), between early June and late July 2014, and then continuing intermittently through the first half of March 2015. The only reported plumes during this time were in the week of 3-9 September 2014 and 22-28 April 2015, but in each case as could not be identified in satellite imagery.
A strong thermal signature resumed on 17 March 2015 (figure 24) and continued for about three weeks before decreasing in intensity. Lower-level thermal activity continued through the first half of June. Thermal anomalies seen in MODVOLC data also resumed on 17 March, and were frequent through 12 June. Eruptions of ash were observed during 5-7 and 12-13 June 2015, with plumes rising to an altitude of 2-3 km and drifting up to 55 km downwind (table 5).
Table 5. Ash plumes at Barren Island, June 2015-February 2016. Legend: Satellite=analysis of satellite images, wind=wind data. Data provided by the Darwin Volcanic Ash Advisory Centre.
Date |
Max. Altitude (km) |
Drift |
Basis of report |
2015 Jun 5-7 |
2.4-3 |
35-45 km NE, E |
Satellite, wind |
2015 Jun 12-13 |
2.1 |
25-55 km NE |
Pilot, satellite, wind |
2015 Aug 19 |
1.5 |
55 km E |
Satellite, wind |
2015 Sep 22 |
1.8 |
45 km E |
Satellite, wind |
2015 Oct 8-9 |
1.5-2.1 |
75-100 km NE |
Satellite, wind |
2016 Jan 3-4 |
1.5 |
85 km SW |
Satellite, wind |
2016 Jan 31-Feb 2 |
1.5 |
165 km SW |
Satellite, wind |
2016 Feb 14-15 |
1.5 |
Over 45 km W |
Satellite, wind |
Activity during July 2015-May 2016. Thermal activity paused again for approximately a month in the second half of June and first half of July 2015. Regular thermal anomalies in MODVOLC data stopped after 12 June and resumed on 16 July. Episodic clusters of anomalies with gaps of 1-3 weeks continued until 28 February 2016. Although MODVOLC data did not show thermal anomalies after February 2016, MIROVA data showed ongoing activity until approximately 17 May (figure 25).
A few ash plumes were seen during this period, on 19 August, 22 September, and 8-9 October 2015 (table 5). There were no reported plumes in November or December 2015, but were seen once again in January and February 2016. Plumes typically rose to an altitude of 1.5-2 km and drifted 45-100 km downwind; the longest plume extended 1665 km SW.
Activity during June 2016-February 2017. Eruptive activity apparently stopped around 16-17 May 2016 for at least seven weeks. MODIS thermal data captured by MIROVA showed a few anomalies (less than 20) from the second half of July through the first half of December 2016 (figure 25). Considering the remote location and rare direct observations at this island volcano, it is possible that the anomalies represent intermittent lava emissions. Regular thermal anomalies were recorded by both MIROVA and MODVOLC beginning on 15 January that were continuing at the end of February 2017.
The National Institute of Oceanography (NIO), part of the Indian Council of Scientific and Industrial Research (CSIR), reported activity on 23 January 2017. Scientists aboard a research vessel were collecting sea floor samples when they observed a sudden ash emission. The team moved closer, about 1.6 km from the volcano, and noted small eruptive episodes lasting 5-10 minutes. Ash emissions were visible in the daytime, and lava fountains feeding lava flows on the flanks were visible at night. The team revisited the volcano on 26 January and observed similar activity over four hours. They sampled sediments and water in the vicinity of the eruption and recovered volcanic ejecta.
Geologic Background. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S volcanic arc extending between Sumatra and Burma (Myanmar). It is the emergent summit of a volcano that rises from a depth of about 2250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the west, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. Historical eruptions have changed the morphology of the pyroclastic cone in the center of the caldera, and lava flows that fill much of the caldera floor have reached the sea along the western coast.
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/); The National Institute of Oceanography (NIO), Council of Scientific and Industrial Research (CSIR), New Delhi, India (URL: http://www.nio.org/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).
Gamalama (Indonesia) — March 2017
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Gamalama
Indonesia
0.8°N, 127.33°E; summit elev. 1715 m
All times are local (unless otherwise noted)
Weak explosion generates ash plumes during 3-4 August 2016
Intermittent weak explosions at Gamalama resulting in ash plumes have occurred for many decades, most recently in September 2012, December 2014, and July-September 2015 (BGVN 40:12). This report covers activity between 1 December 2015 and February 2017. Data were primarily drawn from reports issued by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Center for Volcanology and Geological Hazard Mitigation) and the Darwin Volcanic Ash Advisory Centre (VAAC).
During 1 January-6 March 2016, PVMBG noted that seismicity fluctuated but decreased overall; shallow volcanic earthquakes and signals indicating emissions appeared on 3 March and a series of deep volcanic earthquakes were detected on 6 March. The Alert Level remained at 2 (on a scale of 1-4), and visitors and residents were warned not to approach the crater within a 1.5-km radius.
PVMBG reported that, at 0628 on 3 August 2016, a weak explosion generated an ash plume that rose 500-600 m above the crater and drifted SE and S. Ash emissions decreased at 0655. Consistent with this, the Darwin VAAC, based on analyses of satellite imagery and wind model data, and information from PVMBG, reported that ash plumes reached a maximum altitude of 2.7 km (summit elevation is 1.7 km) and drifted S, SE, E, and NE. Ashfall was reported in areas on the SSE flank, including the Ake Huda area.
A news account (Jakarta Globe) stated that the Babullah Airport in Ternate, North Maluku, was closed for a day while volcanic ash was cleared from the runway (about 6 km ENE of the volcano). On 5 August PVMBG noted that seismicity continued to be elevated, although inclement weather prevented visual observations.
Geologic Background. Gamalama is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera, and is one of Indonesia's most active volcanoes. The island was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the thorough documentation of Gamalama's historical activity. Three cones, progressively younger to the north, form the summit. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano. Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63.
Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Center of 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/); Jakarta Globe (URL: http://jakartaglobe.id/).
Kavachi (Solomon Islands) — March 2017
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Kavachi
Solomon Islands
8.991°S, 157.979°E; summit elev. -20 m
All times are local (unless otherwise noted)
Evidence of regular explosive activity during 2006-2016 from satellite and direct observations
The submarine Kavachi volcano in the Solomon Islands south of Gatokae and Vangunu islands is frequently active but rarely observed. Consistent activity was reported for more than 4 years between November 1999 and August 2003. An 8-month period of quiet was broken with another explosive eruption above the ocean surface on 15 March 2004 (BGVN 30:03). No observations of ongoing activity are known over the next two years, though eruptions may have continued. Satellite imagery using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) during 2006-2016 frequently revealed evidence of activity, on at least 35 days, using the Visible Near Infrared (VNIR) bands. Very little ASTER imagery is available for Kavachi during 2001-2005.
ASTER images on 27 February and 24 March 2006 (figure 13) show renewed activity. Vigorous upwelling along with turbulent ash-laden water and a sulfur odor was witnessed on 6 April 2007 (BGVN 32:07). An ASTER image on 15 June 2007 (figure 14) showed pulses of discolored water originating from the vent, confirming ongoing activity. A small area of discolored water was next seen in satellite imagery on 12 December 2007. A small plume of discolored water appeared in ASTER imagery again on 26 February 2008. On 20 March 2008 the Landsat 7 Enhanced Thematic Mapper captured an image of an ash-and-steam eruption plume extending about 25 km NNE towards Gatokae (figure 15). The next satellite evidence of discolored water plumes were on 7 October 2008.
An image on 11 November 2009 showed a larger very bright spot above the summit, possibly indicating turbulent activity at the ocean surface. Evidence of activity became more frequent in 2010, with imagery showing plumes on 15 February, 19 March, 23 June, 11 September, and 30 November. Submarine plumes continued to be visible often in ASTER images the following year, on 1 January, 13 March, 9 May, and 16 October 2011. The next available satellite image with a discolored submarine plume from Kavachi was on 9 April 2012. Additional plumes were seen on 16 April, 3 June (figure 16), 31 August, and 26 November 2012.
Intermittent satellite evidence of ongoing activity continued in 2013 with a discolored water plumes on 28 April, 15 June, 8 July, 25 August, 10 September, and 8 December. On 24 September 2013, Brennan Phillips of the University of Rhode Island passed within 2 km of the main peak onboard the M/Y Alucia but "did not see any visual eruptive activity on the surface."
Although the imagery is not conclusive, many of the ASTER images after 3 June 2012 appeared to show a small island. On 9 January 2014 the ASTER imagery was much clearer, providing greater visual evidence that eruptive activity had built a small island from which discolored water plumes were emanating (figure 17). A few weeks later, on 29 January, the Earth Observing 1 (EO1) Advanced Land Imager (ALI) obtained an image of a submarine plume (BGVN 39:07) and turbulent source area similar to those seen in ASTER imagery. Additional activity was in evidence on 21 March and 8 May.
A cruise ship operated by EYOS Expeditions reported an eruption "at least four times" on 10 June 2014 (figure 18). The Expeditions' website noted that a staff member "spotted on the horizon discolored water and disturbances on the surface. As the vessel approached closer a few large plumes of water broke the surface about once every 10 minutes. Just before the ship left, however, [the] sea seemed to erupt and a massive plume of water and ash shot high into the air…." The island, or possibly an eruption exhibiting turbulence with abundant ash at the surface, appeared again on a 9 November 2014 image, and submarine plumes were evident in an 11 December 2014 image.
An expedition for National Geographic in January 2015 took place during a rare lull in volcanic activity that enabled access to the volcano for mapping and sampling. B. Phillips reported that no eruptive activity was seen while at the summit location on 12-14 and 18 January 2015, but there was a large surface plume and lots of off-gassing from the crater rim; ASTER imagery confirmed a plume of discolored water on 12 January. Autonomous cameras deployed directly into the crater observed sharks, reef fish, and what appear to larvaceans (National Geographic, 2015).
Satellite imagery showed discolored submarine plumes on 18 October 2015, but then not again until 26 August 2016. Eruptions were witnessed on a second visit by B. Phillips for National Geographic during 31 October-1 November 2016 (see National Geographic, 2017). Activity consisted of phreato-magmatic explosions approximately every 7 minutes that sent steam, ash, and incandescent tephra up to 50 m above the ocean surface. There was an occasional larger eruption roughly every hour. A remotely operated surface "drone" with a GoPro camera was right at the edge of the explosion but remained functional. Small lava particles stuck to the PVC hull of the vehicle itself were recovered and given to the Marine Geological Samples Laboratory (MGSL) of the Graduate School of Oceanography (GSO), University of Rhode Island."
Bathymetric survey. A paper by Phillips and others (2016) following the January 2015 visit included medium-resolution bathymetry of the main peak (figure 19), along with benthic imagery, biological observations, petrological and geochemical analysis of samples from the crater rim, measurement of water temperature and gas flux over the summit, and descriptions of the hydrothermal plume structure. Based on the bathymetry, the summit was described by Phillips and others (2016) as being oblong with a pockmarked crater measuring approximately 75 x 120 m, and a rim rising to an average of 24 m depth. The deepest soundings on the peak were about 70 m and indicated asymmetrical terrain surrounded by almost uniform flanks with 18° slopes that descend to depths greater than 1,000 m. They confirmed the existence of a "southwest extension," or secondary summit rising to 260 m depth 1.3 km SW of the main summit.
References: National Geographic, 2015, Sharks discovered inside underwater volcano (exclusive video) (URL: http://video.nationalgeographic.com/video/expedition-raw/150708-sciex-exraw-sharks-underwater-volcano; https://www.youtube.com/watch?v=0e3t18rrjOA).
National Geographic, 2017, Robot vs. Volcano: "Sometimes It's Just Fun to Blow Stuff Up" (exclusive) (URL: http://video.nationalgeographic.com/video/expedition-raw/170419-sciex-exraw-robot-vs-volcano-sometimes-just-fun-to-blow-stuff-up; https://www.youtube.com/watch?v=Ca0zAAIVK3E).
Phillips, B.T., Dunbabin, M., Henning, B., Howell, C., DeCiccio, A., Flinders, A., Kelley, K.A., Scott, J.J., Albert, S., Carey, S., Tsadok, R., and Grinham, A., 2016. Exploring the "Sharkcano": Biogeochemical observations of the Kavachi submarine volcano (Solomon Islands), Oceanography v. 29(4), p. 160-169 (https://doi.org/10.5670/oceanog.2016.85).
Geologic Background. Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is one of the most active submarine volcanoes in the SW Pacific, located in the Solomon Islands south of Vangunu Island. Sometimes referred to as Rejo te Kvachi ("Kavachi's Oven"), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported "fire on the water" prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.
Information Contacts: EYOS Expeditions, Knox House, 16-18 Finch Rd, Douglas, Isle of Man, IM1 2PT (URL: http://www.eyos-expeditions.com/2014/07/kavachi-volcano/, https://my.yb.tl/eyosexpeditions/1604/); Brennan Phillips, Harvard University, Wyss Institute for Biologically Inspired Engineering, Wood Lab, 60 Oxford St., Cambridge, MA 02138 USA; Image Database for Volcanoes, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST) (URL: https://gbank.gsj.jp/vsidb/image/index-E.html, https://gbank.gsj.jp/vsidb/image/Kavachi/aster_p1.html); USGS LandsatLook Viewer (URL: https://landsatlook.usgs.gov/).
Kuchinoerabujima (Japan) — March 2017
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Kuchinoerabujima
Japan
30.443°N, 130.217°E; summit elev. 657 m
All times are local (unless otherwise noted)
Explosions on 3 August 2014, 29-30 May 2015 (with pyroclastic flow), and 18-19 June 2015
Intermittent ash explosions during the last century have characterized activity at Japan's Kuchinoerabujima volcano, located at the northern end of the Ryukyu Islands approximately 260 km S of Nagasaki, Japan. Brief periods of higher seismicity had been detected in the last approximately 30 years, although no explosions had been recorded since 1980 (BGVN 35:11 and 38:01). A new explosion occurred on 3 August 2014, and activity remained elevated through June 2015. Information on the latest activity is provided by the Japan Meteorological Agency (JMA) monthly reports and aviation alerts are from the Tokyo Volcanic Ash Advisory Center (VAAC).
A modest explosion from Shindake crater on 3 August 2014 caused JMA to increase the Alert Level at the volcano. Activity decreased shortly after the explosion, and only steam plumes, fumarolic activity, and occasional incandescence were observed for the next nine months. A large explosion on 29 May 2015 generated a gray-black ash plume that rose to over 9 km altitude and sent pyroclastic flows down the flanks; JMA increased the Alert Level and ordered evacuation of local residents. Activity declined after a few days, and Shindake remained quiet until a smaller explosion on 18 June 2015. The ash plume did not exceed 1 km, but ashfall was reported in towns on neighboring islands and in areas up to 80 km E. Two additional smaller explosions were reported on 18 and 19 June. Seismicity decreased significantly after the 19 June explosion, but SO2 emissions remained elevated until October 2015. The JMA did not lower the Alert Level until June 2016.
Activity during August 2014-February 2015. JMA reported an eruption from the vicinity of Shindake crater around noon local time on 3 August 2014, with a gray plume rising more than 800 m above the crater rim. This led to an increase in the Alert Level from 1 (Normal) to 3 (Do not approach the volcano) on a 5-level scale. An overflight confirmed traces of ash on the W flank. The Tokyo VAAC reported that the plume rose to an altitude greater than 1.5 km and drifted N. On 5 August, seismicity decreased, and views from a remote web camera showed a white plume rising 50 m above the crater rim. For the rest of August, seismicity remained low and steam plumes rose 50 to 800 m above the crater.
During September 2014, white plumes were generally observed 200-800 m above the crater when visibility was not obscured by weather; seismicity remained low. Scientists conducting a field survey on 12 September found SO2 emissions at 300 metric tons per day (t/d), higher than the background value of 60 t/d measured on 21 May 2014. Occasional earthquakes were recorded in October 2014, and the volume of gas emissions remained relatively high compared with before the August eruption; steam-and-gas plumes rose to 600 m above the crater rim. During field surveys on 7 and 8 October scientists measured SO2 emissions of 500 t/d. Gas emissions rose from within the Shindake crater, around a thermally anomalous fissure at the W edge of the crater, as well as from a new fumarole on the SW flank of the crater. In November, plumes continued to rise as high as 1,000 m above the crater. In another survey on 9 December 2014, scientists found that SO2 levels had increased to 1,700 t/d.
Emissions of SO2 remained high during the second half of January 2015, ranging from 1,100 to 3,100 t/d. A M 2.2 seismic event located 5 km beneath the island was recorded on 24 January. Observations made during field surveys in February confirmed continued steam emissions, and thermal anomalies from the W crater rim fissure and the new fissure on the SW flank. SO2 emissions decreased slightly from January levels to a range of 400 to 2,700 t/d in February, and steam plumes continued to rise 400-700 m above the crater.
Activity during March-June 2015. Incandescence at night was first recorded at the Shindake Crater from 24 to 31 March 2015 with a high-sensitivity camera. Aerial observation on 25 March by JMA and JCG (Japan Coast Guard) indicated a temperature rise and continued fumarolic activity around the thermal anomaly W of the crater rim. SO2 emissions remained high in March (1,000 to 3,700 t/d) and April (900 to 2,600 t/d), and steam plumes rose to 1 km above the crater. Incandescence was occasionally observed at night during April and again during 18-22 May; fumarolic activity continued along with a rise in temperature at the W and SW fissures. Steam plumes were observed rising to 600 m above the crater in May.
According to JMA, at 0959 local time on 29 May 2015, a large explosive phreatomagmatic eruption generated a gray-black ash plume that rose to over 9 km altitude and drifted ESE (figure 5). The plume was reported by the Tokyo VAAC to be at 10.9 km altitude about an hour after the eruption. The largest of several pyroclastic flows descended NW from the SW side of the crater in the Mukaehama district and reached the coast. Based on these events, JMA raised the Volcanic Alert Level to 5 (Evacuate). Aerial observation conducted on the same day (in collaboration with the Kyushu Regional Bureau of the Ministry of Land, Infrastructure, Transport and Tourism) revealed additional pyroclastic flows moving in nearly all directions from the Shindake crater (figure 6) including flows reaching halfway down the mountain to the SW and SE of the crater. Seismicity increased immediately after the eruption, but had decreased by midday.
According to a news article (The Japan Times), all residents and visitors (141 people) were safely evacuated by a ferry, coast guard ship, and helicopter to neighboring Yakushima Island (25 km SE). A resident of Yakushima reported that ash reached the island. Later that day, ash plumes rose 200 m and drifted SW.
Ash plumes continued the next day, 30 May, rising only 1.2 km. A field team observed discolored trees on the SE and SW flanks, and fallen trees near the coast on the NW flank. Cloud cover prevented views of the eruption area, but the team was able to confirm continued fumarolic activity and incandescence in the W part of the crater. Seismicity continued at low levels, and during the first week of June white plumes rose 100-400 m above the crater rim.
Another smaller eruption on 18 June 2015 caused lapilli and ash to fall on the E side of the island. Ash was reported in Yakushima Town (44 km ESE on Yakushima Island), Nishinoomote City (80 km NE on Tanegashima Island), and Nakatane Town (72 km E on Tanegashima). Small eruptions also occurred at 1631 on 18 June and at 0943 on 19 June. Tokyo VAAC reported the larger 18 June eruption, but plume heights were below 1 km, and not observed on satellite. Aerial observations on 20 June by JMA revealed no traces of new pyroclastic-flow deposits around the crater or on the flanks.
Post-eruption observations through June 2016. Emissions of SO2 remained elevated during June 2015 (800-1,700 t/d), and decreased somewhat in July to 500-700 t/d. They decreased further to 200-300 t/d in August. Increased seismicity was recorded briefly from 1-3 and 6-11 August. SO2 emissions continued to decline in September, except for a spike of 700 t/d on 10 September. Thermal infrared observations taken during a field survey in October 2015 indicated a decrease in temperature around the fissure W of the crater rim since the 29 May eruption. Emissions of SO2 remained below 300 t/d for the remainder of 2015 and no further activity was reported, although the Alert Level remained at 5. On 14 June 2016, JMA lowered the Alert Level to 3; seismic activity and SO2 flux values were below levels detected prior to the May-June 2015 eruption.
Geologic Background. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.
Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Google Earth (URL: https://www.google.com/earth/); The Japan Times (URL: http://www.japantimes.co.jp/news/2015/05/29/national/volcano-erupts-isle-kagoshima-prompting-evacuation-order/).
Manam (Papua New Guinea) — March 2017
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Manam
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
Large ash plume to 19.8 km on 31 July 2015; persistent thermal anomalies during 2014-2016
The remote island of Manam, 13 km off the northern coast of mainland Papua New Guinea is a basaltic-andesitic stratovolcano that has a 400-year history of recorded evidence for recurring low-level ash plumes and occasional Strombolian emissions, lava flows, pyroclastic avalanches, and large ash plumes. Pyroclastic flows and Strombolian activity during much of 2012 and 2013 were accompanied by numerous ash plumes rising a few kilometers above the summit (BGVN 38:06, 39:08). Activity between January 2014 and January 2017, described below, includes persistent thermal anomalies during most of this time, and a major ash plume rising to nearly 20 km altitude on 31 July 2015.
Monitoring is done by Papua New Guinea's Rabaul Volcano Observatory (RVO), part of the Department of Mineral Policy and Geohazards Management (DMPGM). This information is supplemented with aviation alerts from the Darwin Volcanic Ash Advisory Center (VAAC). MODIS thermal anomaly satellite data is recorded by the University of Hawai'i's MODVOLC thermal alert recording system, and the Italian MIROVA system.
MIROVA thermal anomaly data suggests Manam was intermittently active from at least late June 2014 through the end of the year. A single ash plume was reported on 6 September and two more were observed on 21 and 22 December. The appearance of MODVOLC thermal anomalies in late January 2015 that grew more frequent through April indicated increasing activity along with sporadic low-level ash plumes in late February and late April. Persistent levels of thermal anomalies and ash plume reports continued in May through early July.
On 31 July 2015 at about 1130 local time a large explosion sent an ash plume to nearly 20 km altitude, spreading volcanic blocks and ash over a wide area, and injuring two people. A second substantial ash plume rose to 6.4 km on 8 August. This was followed by three more small plumes in August, one in September, and two in October 2015 (on 8 and 29) before the volcano quieted down for a few months.
Thermal anomalies were present at the end of January 2016, and an ash plume was observed on 4 March 2016. New thermal anomalies intensified until June and then tapered off in early July. Persistent but more intermittent thermal anomalies continued throughout the year and were ongoing as of early January 2017.
Activity during 2014. Numerous explosions during 2013 tapered off at the end of the year, with the last ash emissions reported on 15 December 2013. In January 2014, RSAM values were lower but still fluctuating above background levels. A report from RVO in early April noted that both summit craters remained quiet through March 2014, with no audible noises or incandescence visible at night. The seismicity remained within background levels of 160-180 RSAM and daily volcanic event counts ranged from 830 to 920. Tiltmeter data showed no significant short-term changes, but over the previous three months there was a gradual inflationary trend towards the summit area. The Alert Level was lowered to Stage 1.
A thermal anomaly appears at the very end of June 2014 in the first available MIROVA LRP data (figure 30). This is followed by additional thermal anomalies in August, October, and November. The Darwin VAAC reported a small ash plume on 6 September 2014 that rose to 2.1 km altitude (300 m above the summit) and drifted 37 km NW. It was visible on infrared satellite imagery for a few hours before dissipating. In their report for October 2014, RVO noted that Manam remained quiet for the month with no audible noises or incandescence; seismicity remained at low to moderate levels, and daily volcanic-event counts ranged between 860 and 920. They also observed that the long-term inflationary trend at the summit observed since the beginning of 2014 continued. Small amounts of white-gray ash drifting SE were reported by RVO on 21 and 22 December from the Southern Crater, with a plume height of only 200 m. They also noted continued E-W inflation.
Activity during 2015. RVO noted incandescence from the Main Crater beginning on 19 January 2015, growing stronger during the last week of the month, matching observations in the MIROVA data (figure 30). A MODVOLC thermal alert pixel appeared on 23 January. Seismicity also changed after the middle of the month when RSAM values rose above 200 on 16 January and went as high as 500 on 31 January, after which they declined rapidly and remained low during February.
In February 2015, seismicity was characterized by small to moderate sub-continuous and continuous volcanic tremors. Increased incandescence was also evident from the Main Crater during February. RVO reported weak-to-bright steady incandescence during 7-10, 21, and 26 February. MODVOLC captured two thermal alert pixels on 8 February, and MIROVA reported an anomaly at the end of the first week and during the last week of the month. An ash plume was observed in satellite data by the Darwin VAAC on 24 February; the plume rose to 3 km altitude (1.2 km above the summit) and drifted 37 km W. RSAM values rising to 500 by 18 March led RVO to raise the Alert Level that day to Stage 2. Visual observations were difficult due to weather during much of the month, but MODVOLC reported thermal alert pixels on 19 and 26 March, and MIROVA captured several anomalies at the beginning of a period of increased frequency and intensity of thermal anomalies that lasted through mid-June (figure 30).
RVO reported that during April 2015 both craters released variable amounts of white vapor. Clearer skies revealed incandescence from the Southern Crater during nine nights of the month and seven times from the Main Crater. This is consistent with satellite thermal anomaly observations by MODVOLC on six different days, with four of them being multiple pixel alerts, and numerous anomalies captured by MIROVA. Two ash eruptions were reported by the Darwin VAAC on 27 and 30 April. The first low-level plume rose to 2.4 km and was observed in satellite imagery extending over 100 km to the W before dissipating on 28 April. The second plume was observed at the same altitude drifting 150 km NW. Seismicity remained high during April, still characterized by discreet small to moderate low-frequency earthquakes, and RSAM values ranged between 300 and 650, increasing during the month. Ground deformation GPS measurements at the end of April confirmed the continuing inflationary trend recorded by the electronic tiltmeters since the last measurements taken in May 2013 (figure 31).
Multiple sources of satellite data confirmed that Manam was active during May 2015. MODVOLC thermal alert pixels were reported from MODIS data captured on 6 and 22 May; MIROVA thermal anomalies were frequent. Ash plumes were reported from visible satellite imagery by the Darwin VAAC on 13 May at 3 km altitude drifting 37 km NE; SO2 plumes were captured by NASA's OMI instrument on the Aura satellite on 2, 12, 13, and 20 May (figure 32).
During June and early July 2015 there were four series of Volcanic Ash advisory reports from the Darwin VAAC. The first, on 21 and 22 June, reported a 3-km-altitude ash plume that extended over 35 km N and NW. The second, from 28 to 30 June, had altitudes that started at 2.4 and rose to 3 km, and drifted 75 km NE. A third plume emerged late on 30 June and lasted through 1 July, drifting 130 km E at 2.4 km altitude. A fourth plume reported on 2 July was confirmed by RVO as only a steam plume with no ash, and was seen in satellite imagery drifting 45 km E at 2.4 km altitude. A single MODVOLC thermal alert pixel was recorded on 7 July.
RVO reported a significant eruption on 31 July 2015 from the Southern Crater beginning about 1130 local time. They observed that low roaring noises marked the onset of the explosion followed by continuous ejection of scoria until about 1330. Fist-sized volcanic debris was reported at Warisi village on the E side of the island. At Baliau on the N side, clasts were about 10-20 cm in diameter. Two people were reportedly knocked unconscious from the falling scoria. Strong emissions of dark gray ash clouds followed the ejection of scoria and continued into the early afternoon. By 1740 emissions consisted of light gray ash clouds. The news source One Papua New Guinea reported that fine ash began to fall over Bogia (25 km SW on the mainland) around 1245 local time.
The ash plume was initially observed in satellite imagery by the Darwin VAAC at 19.8 km altitude spreading out in all direction for 100 km. It was captured by the Japanese Himawari-8 satellite (figure 33); an animation of the imagery showing the eruption was provided by Miller et al. (2016). Four hours later, the plume was visible 370 km to the SW. A lower-altitude ash plume at 6.7 km was observed the next day extending over 100 km SW. A significant SO2 plume was partially captured by the Aura instrument on the OMI satellite the next day, and measured an SO2 mass of 3.206 kilotons.
The Darwin VAAC reported a new small ash plume on 6 August 2015 rising to 2.7 km drifting around 40 km to the NW, and another large ash plume on 8 August that initially rose to 6.4 km and drifted SSW. Pilots reported the ash at 5.8 km altitude about 90 km W of Kiunga Airport which is located 475 km SW of Manam. About 24 hours later, pilots reported another ash plume at 6 km altitude 150 km SE of the volcano. A hot spot was observed at the summit on 9 August; two MODVOLC thermal alert pixels appeared that day, and another one appeared on 15 August. A small plume was reported on 21 August, only rising to 2.1 km and drifting about 8 km ESE. This was followed two hours later by an ash plume observed 16 km NW at the same altitude, which continued to drift NW to 75 km before dissipating. Additional ash plumes were reported from 26-28 August rising to 2.4 km and drifting from 35 to 75 km, first NE, then N and NW; a small plume was reported on 31 August at 2.1 km drifting 75 km N before dissipating that day.
A single MODVOLC thermal alert pixel on 4 September was the last recorded in 2015. The next plume on 7 September was small, rising only to 2.1 km and drifting 75 km NW, briefly observed in one satellite before dissipating. It was a month until the next ash plume on 8 October 2015, when Darwin VAAC made a satellite observation of a plume at 1.8 km drifting 45 km NW. The last ash plume of 2015 was captured in satellite images on 29 October between 2.1 and 2.4 km altitude around 35 km NW.
Activity during 2016. The MIROVA data recorded thermal activity on about 29 January 2016 that increased in intensity and frequency in early March (figure 34). A small ash plume on 4 March rose to 3 km altitude and drifted about 90 km SE according to the Darwin VAAC. Increased thermal activity was recorded in MODVOLC thermal alert pixels and MIROVA data from early March through mid-July. There were no reports from the RVO during this time. The first MODVOLC alert was recorded on 7 March and they were persistent, almost every week, through the second week of July. On 13 July, an ash plume was observed by the Darwin VAAC in satellite imagery at 3 km altitude drifting 55 km W for a few hours before dissipating. After that, single-pixel MODVOLC thermal alerts were recorded on 20 September and 6 October. The MIROVA analysis of the MODIS data records a similar picture with a clear increase in the frequency and intensity of anomalies between early March and mid-July (figure 34); continuing pulses of thermal anomalies are present every month into January 2017.
Reference: Miller S D, Schmit T L, Seaman C J, Lindsey D T, Gunshor M M, Kohrs R A, Sumida Y, Hillger D, 2016, A Sight for Sore Eyes: The Return of True Color to Geostationary Satellites, Bulletin of the American Meteorological Society, vol. 97, no. 10. DOI: http://dx.doi.org/10.1175/BAMS-D-15-00154.1. Animated imagery of the 31 July 2015 eruption can be viewed at http://journals.ametsoc.org/doi/suppl/10.1175/BAMS-D-15-00154.1/suppl_file/10.1175_BAMS-D-15-00154.2.html .
Geologic Background. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
Information Contacts: Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea;
Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/);
Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/, http://modis.higp.hawaii.edu/);
MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/);
NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/);
Regional and Mesoscale Meteorology Branch (RAMMB) / Cooperative Institute for Research in the Atmosphere (CIRA), NOAA/NESDIS, Colorado State University, Fort Collins, CO 80523-1375, USA (URL: http://rammb.cira.colostate.edu/);
One Papua New Guinea (URL: http://www.onepng.com/2015/07/manam-volcano-erupts.html).
Pavlof (United States) — March 2017
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Pavlof
United States
55.417°N, 161.894°W; summit elev. 2493 m
All times are local (unless otherwise noted)
Ash plume to 11 km on 27 March 2016 that drifted 1,200 km NE; multiple smaller ash events through July 2016
Pavlof volcano, near the end of the Alaska Peninsula 970 km SW of Anchorage, frequently produces explosive eruptions from the summit vents and occasional lava flows. The largest confirmed historical eruption took place in 1911 when a fissure opened on the N flank; it has erupted more than 25 times since then. The last reported eruption in mid-November 2014 included lava fountaining from a vent just N of the summit, and flows of rock debris and ash descending the N flank, along with an ash plume that rose to around 9 km altitude and drifted 300 km NW. Pavlof was quiet in 2015, but then abruptly renewed activity in late March 2016. It is monitored primarily by the Alaska Volcano Observatory (AVO) and the Anchorage Volcanic Ash Advisory Center (VAAC).
A sudden vigorous eruption that began on 27 March 2016 lasted for about 20 hours, sending ash to 11 km altitude, producing a plume dispersed NE for 1,200 km, and a similarly large SO2 plume. The volcano was then quiet until a short-lived, smaller ash emission occurred in mid-May for eight days. Intermittent low-level ctivity picked up again from late June through late July 2016, characterized by minor emissions of dark-colored ash and steam rising to 4.5 km altitude. Fallout of ash was limited to the flanks of the volcano and the immediate area around Pavlof. The last report of ash emissions was on 30 July, although low-amplitude tremors and steam plumes persisted through August, and intermittent thermal anomalies from the summit continued through the end of 2016.
After a short and intense eruption between 12 and 15 November 2014 (BGVN 40:04), activity decreased quickly to background levels. The AVO had reduced the Aviation Color Code (ACC) from Red (highest) to Orange on 16 November, and from Orange to Yellow on 25 November. Seismicity remained slightly above background levels until early January. On 15 January 2015 the AVO reduced the ACC to the lowest level of Green where it remained for over a year until it was changed abruptly to Red on 28 March 2016 at the start of a new eruption.
AVO reported that seismicity began to increase at 1553 on 27 March 2016, characterized by a quick onset of continuous tremor. An ash plume rose to an altitude of 6.1 km, and by 1618 was drifting N (figure 13). During the night, lava fountaining from the summit crater was observed by mariners, pilots, and residents of nearby Cold Bay (60 km SW).
On 28 March, tremor levels remained high; lightning in the ash plume was detected in the morning, and infrasound data from a sensor network in Dillingham (470 km NE) indicated sustained ash emissions. At 0700 a continuous ash plume was evident in satellite images drifting more than 650 km NE, and a MODIS image captured at midday revealed the extent and substantial thickness of the cloud (figure 14). A SIGMET (significant meteorological information notice) issued by the National Weather Service (NWS) Alaska Aviation Weather Unit indicated that the maximum ash-cloud altitude was approaching 11 km. Strongly elevated surface temperatures also suggested the presence of lava flows.
The energetic ash-producing phase of the eruption lasted from 1600 AKDT (00:00 UTC) on 27 March until about 1230 AKDT (20:30 UTC) on 28 March, and produced an ash cloud that stretched NE over Bristol Bay and interior Alaska for over 1,200 km. As a result, over 40 Alaska Airlines flights to and from Fairbanks, Alaska, were cancelled according to NBC News. Minor ashfall (0.8 to 6.3 mm or 1/32 to 1/4 in) was reported in the nearby community of Nelson Lagoon (80 km NW) and trace ashfall (less than 0.8 mm) was confirmed near Dillingham (470 km NE). A large SO2 plume also drifted NE from the volcano extending all the way across Alaska to Yukon Territory and British Columbia in Canada (figure 15).
Seismicity and infrasound signals had decreased to low enough levels by 1230 on 28 March that the AVO lowered the Aviation Color Code to Orange and the Volcano Alert Level to Watch. However, seismic tremor remained above background levels. Ash emissions decreased through the night and were barely visible in a satellite image acquired at 0625 AKDT on 29 March. Remnant ash continued to drift over Bristol Bay and areas of interior Alaska. The webcam at Cold Bay recorded intermittent, low-level ash plumes rising as high as 4.6 km.
Thermal anomalies, measured by MODIS satellite sensors and analyzed by MODVOLC, appeared from 28 March (0025 UTC) through 29 March 2016 (1360 UTC), with 20 pixels recorded on 28 March. The MIROVA system also recorded an abrupt spike to 'Very High' thermal anomaly levels on 28 March, dropping slightly in the next two days (figure 16) and then disappearing a few days later. Low-power anomalies were detected on 2 and 6 April, and then ceased for several months.
The AVO reported that the intensity of the eruption greatly decreased during 29-30 March, although The Canadian Press reported that ash from the eruption had caused flights in and out of Yellowknife and Regina, Canada, to be cancelled on those dates. Elevated surface temperatures identified in satellite data and visual observations of low-level, intermittent ash plumes were noted during brief breaks in poor weather conditions during these days. Airwave signals, indicative of small explosions at the summit, were recorded on 3 April, but tremors had ceased by the next day. On 6 April AVO noted no signs of ash emissions or lava effusion during the previous week, and seismicity was at low levels. Thermal anomalies at the summit were occasionally visible, though likely indicating cooling processes of previously erupted lava. AVO lowered the Aviation Color Code to Yellow and Volcano Alert Level to Advisory on 6 April. After two more weeks of no activity, the ACC was lowered to Green/Normal on 22 April 2016.
On 13 May 2016 the AVO raised the Aviation Color Code back to Orange as a result of increased seismicity typically associated with minor eruptive activity. Four minor ash eruptive episodes were inferred from seismic data between 13 and 16 May. On 14 May, local observers in Cold Bay reported ash emissions below 5 km in the vicinity of the volcano. According to the Anchorage VAAC, on 15 May a minor eruption was noted on the Cold Bay web camera, but volcanic ash was not visible in satellite data. Elevated surface temperatures were detected in satellite data on 15 May. Periods of elevated volcanic tremor and a small explosion associated with minor ash emissions was noted on 17 May; observers in Cold Bay and Sand Point (90 km E) reported ash emissions interspersed with steam emissions. The Anchorage VAAC noted that strong winds caused resuspension of volcanic ash on the lee side of Pavlof on 17 and 18 May. The AVO lowered the ACC to Yellow on 20 May and noted that all volcanic ash clouds produced during the 13-17 May event were below 4.5 km altitude, and that no lava effusion or fountaining was detected. Weak seismic tremor and small explosions were observed on 21 May, after which activity ceased. The AVO lowered the ACC to Green on 17 June.
Seismic activity increased again on 30 June for about a week, prompting the AVO to raise the ACC to Yellow on 1 July 2016; minor steam emissions were also observed in the web camera. AVO technicians installed a new web camera in the Black Hills area north of the volcano near the Bering Sea coast in early July. On 11 July, weakly elevated surface temperatures were observed at the summit in satellite imagery and a steam and gas cloud extended SW for about 80 km. Minor ash emissions reaching a few tens of meters above the summit were observed that afternoon extending a few kilometers to the SW. Small ash emissions were again observed on 18 July along with an increase in seismic tremor for about 48 hours.
On 28 July a low-intensity eruption with vigorous degassing produced a steam-rich plume and minor ash emissions. As a result, the AVO raised the ACC to Orange. The drifting steam and ash cloud was below 4.6 km above sea level and dissipated rapidly. The Anchorage VAAC reported steam and minor ash emissions continuing through 30 July.
A decline in activity led AVO to lower the ACC to Yellow on 4 August. Periods of low-amplitude tremor continued, but no plumes or thermal signals at the summit were detected. Elevated surface temperatures at the summit were observed in satellite data on 8 August, and a low-level but persistent steam plume was visible in web camera images on 11 August. A large steam plume was noted by observers in Sand Point on 15 August. Elevated surface temperatures were detected through cloud cover in satellite data on 20 and 25 August. Low-level unrest continued through the fall with persistent degassing from the summit and elevated surface temperatures detected in satellite data. A robust steam plume on 31 August reached 4.6 km, but there was no evidence of ash and it dissipated rapidly.
Several times during late September during clear views, webcam images showed a persistent steam plume from the summit crater. Elevated surface temperatures in the summit crater were observed in satellite images on 25, 28, and 29 September, and again during 4-6, 13-14, and 16 October. In early November, the AVO determined that the summit crater was larger and more centrally located than before, as a result of the March 2016 explosion. The new crater geometry possibly allowed satellite sensors to more easily detect emissions of hot gases from the vent. Ongoing observations of moderately elevated surface temperatures (figure 16) likely reflect this change in the crater, and do not indicate new eruptive activity or rising magma. Seismicity remained slightly above background levels through the end of 2016, and the ACC remained at Yellow.
Geologic Background. The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing Strombolian to Vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption took place in 1911, at the end of a 5-year-long eruptive episode, when a fissure opened on the N flank, ejecting large blocks and issuing lava flows.
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 (URL: http://www.dggs.alaska.gov/); Anchorage Volcanic Ash Advisory Center (VAAC), Alaska Aviation Weather Unit, NWS NOAA US Dept of Commerce, 6930 Sand Lake Road, Anchorage, AK 99502-1845(URL: http://www.ssd.noaa.gov/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Colt Snapp (URL: https://twitter.com/colt_snapp/status/714345047173369856); The Canadian Press, via Vancouver Observer (URL: http://www.vancouverobserver.com/news/environment/flights-cancelled-and-out-regina-yellowknife-after-volcano-alaska); NBC News (URL: http://www.nbcnews.com/news/weather/pavlof-volcano-erupts-covering-400-miles-alaska-ash-n546956).
Poas
Costa Rica
10.2°N, 84.233°W; summit elev. 2708 m
All times are local (unless otherwise noted)
Phreatic explosions from the crater lake in June-August 2016
Poás is characterized by intermittent explosions from its hot crater lake. Several occurred in 2014 (BGVN 40:11). This report covers activity from 1 January 2015 through February 2017. There were no reports of activity during 2015 through May 2016. Phreatic eruptions were recorded between 5 June and 16 August 2016.
According to news articles (La Prensa Libre, Prensa Latina), phreatic explosions from the hot crater lake occurred multiple times in June 2016. Explosions at 0900 on 5 June, at 1854 on 13 June, and at 1952 on 14 June ejected water and steam many meters above the lake's surface. Three small explosions, lasting about five seconds each based on the seismic signals, occurred during 0600-0603 on 18 June and ejected water, steam, and debris no more than 50 m above the lake's surface. Phreatic explosions were also registered on 19 June.
According to the Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA), a small phreatic explosion from the lake was recorded at 0819 on 25 July 2016. The explosion ejected material 50 m above the lake surface.
News accounts (Q Costa Rica, La Prensa Libre) reported that at 1409 local time on 16 August 2016 an explosion sent a column of gas to a height of 100 m above the crater; the activity lasted 2 minutes. An OVSICORI-UNA video of this explosion was posted in the news articles.
Geologic Background. The broad, well-vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano, which is one of Costa Rica's most prominent natural landmarks, are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the 2708-m-high complex stratovolcano extends to the lower northern flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, is cold and clear and last erupted about 7500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world's most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since the first historical eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water.
Information Contacts: Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica (URL: http://www.ovsicori.una.ac.cr/); La Prensa Libre (URL: https://www.laprensalibre.cr/); Prensa Latina (URL: http://www.plenglish.com/); Q Costa Rica News (URL: http://qcostarica.com/).
Sheveluch
Russia
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
Lava dome extrusion continues with occasional explosions and ash plumes through February 2016
An eruption at Sheveluch has been ongoing since 1999, and recent activity there was previously described through August 2015 (BGVN 42:02). During September 2015-February 2016, the same type of activity prevailed, with lava dome extrusion, incandescence, hot block avalanches, fumarolic activity, and occasional strong explosions that generated ash plumes. The following data comes from Kamchatka Volcanic Eruption Response Team (KVERT) reports. During this period the Aviation Color Code remained at Orange (the second highest level on a four-color scale).
KVERT reported that during 1 September 2015-28 February 2016, lava-dome extrusion onto the N flank was accompanied by fumarolic activity, dome incandescence, hot avalanches, and ash explosions. Satellite images detected an almost daily, and sometimes intense, thermal anomaly over the dome. Ash plumes generated by occasional explosions, hot avalanches, and sometimes strong winds rose to altitudes of 2.5-7 km and drifted primarily SE during September-December 2015 (up to 185 km) and in more variable directions (up to 200 km) during January-March 2016. A series of photos taken in late 2015 shows characteristic types of activity, including small explosions and hot avalanches on 28 October (figure 39), an explosion and pyroclastic flow on 22 November (figure 40), and incandescence on 25 November (figure 41).
Thermal anomalies based on MODIS satellite instruments analyzed using the MODVOLC algorithm were frequent during the current reporting period, in contrast to March-August 2015 (BGVN 42:02). From September 2015-February 2016, thermal anomalies were detected 10-15 days each month. On 22 November, seven pixels were recorded.
Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.
Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); 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/).
Soputan (Indonesia) — March 2017
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Soputan
Indonesia
1.112°N, 124.737°E; summit elev. 1785 m
All times are local (unless otherwise noted)
Ash plumes to over 12 km altitude, lava flows, pyroclastic flows, and Strombolian activity during January-February 2016
Soputan stratovolcano on the northern tip of Indonesia's island of Sulawesi has had historically observed eruptions since the 18th century, possibly earlier. The locus of eruptions has included both the summit crater and a NE-flank vent that was active during 1906-1924. Since the 1980's, continuing lava-dome growth has been punctuated by ash explosions, lava flows, and Strombolian eruptions every few years. When these events last occurred between January and March 2015, they were accompanied by strong thermal anomalies and elevated seismicity which continued into early July 2015 (BGVN 41:05). This report covers the period from July 2015 through September 2016.
Increased seismicity in November 2015 signaled the beginning of a new eruptive episode, with explosions in January and February 2016. Soputan is monitored by PVMBG (Pusat Vulkanologi dan Mitigasi Bencana Geologi), Badan Nasional Penanggulangan Bencana (BNPB) which is the Indonesian National Disaster Management Agency, and aviation alerts are managed by the Darwin VAAC (Volcanic Ash Advisory Center). Information is also provided by the University of Hawaii's MODVOLC Thermal Alert System and the MIROVA project, an Italian collaboration; both groups analyze the MODIS satellite data for thermal anomalies related to volcanoes.
Soputan erupted a significant ash plume to over 12 km altitude on 4 January 2016 after a few months of increasing seismicity. Lava flows, Strombolian eruptions, and a pyroclastic flow were observed the next day. Another large ash plume to 13 km altitude occurred on 14 January. A series of explosions beginning on 6 February resulted in more ash plumes, lava flows, and Strombolian eruptions for about 24 hours, after which activity decreased significantly. Several villages within 20 km reported ashfall from these events. The last reported activity was on 7 February 2016, although thermal anomaly data extended well into April. Seismicity had declined significantly by mid-April when the Alert Level was lowered.
Activity during July-November 2015. PVMBG lowered the Alert Level to II (second lowest on a four-level scale) on 3 July 2015, citing reduced harmonic tremor and stable RSAM (Real-time Seismic amplitude measurements) at background levels compared with the eruptive activity between January and March 2015. They did not issue another update until 3 November 2015.
MODVOLC thermal alert information from MODIS (Moderate Resolution Imaging Spectroradiometer) satellite data indicated anomalies in the vicinity of Soputan twice in September and four times in October 2015, but the locations were far enough from the volcano to suggest that they were not related to volcanic activity. This is corroborated with the MIROVA (Middle InfraRed Observation of Volcanic Activity) data from this same period which also recorded increases in Volcanic Radiative Power (VRP) in September and October. The locations indicated by MIROVA are mostly greater than 5 km from the summit, also suggesting a non-volcanic source (figure 12).
Additional thermal anomaly signals in the MIROVA data from mid-September through early December 2015 appear to be sourced within 5 km of the summit (figure 12), but their origin is unknown. PVMBG makes no mention of active eruptions or ash plumes during this time. PVMBG maintained the Level II alert status and documented clear skies with diffuse white steam plumes rising between 20 and 200 m from the summit crater during the last half of October and November, unchanged since July. They noted, however, that the frequency of several types of earthquakes began a gradual increase in the middle of October.
Activity during January-September 2016. Elevated seismicity continued until 4 January 2016. Photos taken on 3 and 4 January showed an increase in the density of the white-to-light-gray emissions rising to 300 m above the summit (figure 13).
Dense reddish-white emissions rose 300 m above the summit early in the day on 4 January. A thermal image taken that day indicated that lava was present at the summit; PVMBG raised the Alert Level to III. Seismic amplitude (RSAM) values had also increased sharply in the preceding 12 hours, and tilt measurement data indicated significant inflation of the volcano. BNPB reported an ash eruption at 2053 local time, with a plume rising 2 km from the summit and drifting SE, and incandescent lava flowing down the E flank. Minor ashfall was reported in Langowan (12 km NE) in the Minahasa District. The Darwin VAAC raised the Aviation Color Code (ACC) to Red at 2230 local time and reported an ash plume at 12.8 km altitude drifting west 30 minutes later. This was followed in the next 24 hours by two more plumes that rose to 10.6 km and drifted NW to NE (figure 14). Continuous emissions rising to about 3.7 km were observed until early 7 January.
A Strombolian phase early on 5 January lasted about 40 minutes and sent incandescent material 250 m high, according to BNPB. Sounds resembling thunder followed, and then a pyroclastic flow traveled 2.5 km down the ENE flank. An ash cloud rose 6.5 km above the summit crater rim (8.3 km altitude) and drifted W. Several villages in the districts of West Langowan (8 km E), Tompaso (11 km NE), and East Ratahan (14 km SE) reported ashfall.
MODVOLC thermal alert pixels likely associated with the eruption were reported during 6-8 January. A small cluster on 10 January located on the NE flank possibly indicated flowing or cooling lava. The Darwin VAAC reported another large ash plume on 14 January that rose to 13.7 km and drifted 45 km NE before dissipating.
A new series of explosions began on 6 February 2016. Ash plumes rose to 7 km altitude, later dropping to the range of 4.3-6 km, with continuous emissions drifting up to 75 km WSW through the next day. PVMBG reported lava flows on the N and E flanks; Strombolian explosions witnessed from the observation post in the village of Silian (about 10 km from the volcano) ejected material 300 m high. BNPB reported Strombolian activity on 7 February with ejected material as high as 1,000 m above the summit crater. Pyroclastic flows were also observed moving up to 2 km down the E flank. Seismic amplitudes remained high, indicating the active movement of magma within the volcano. Ashfall was reported in multiple districts including Pasan (5 km SSE), Tombatu (16 km SSW), Belang (17 km SSE), and Ratatotok (20 km S). The MODIS thermal anomaly data resulted in a very strong (32 pixel) MODVOLC thermal alert on 6 February. This corresponded with the Volcanic Radiative Power (VRP) spike presented in the MIROVA information for the same period (figure 12).
For the rest of February, only diffuse white steam plumes rose 75 m, except for a 700-m-high plume reported on 12 February by PVMBG; three MODVOLC thermal alert pixels were recorded on 11 and one on 13 February. Minor steam emissions rose to 100 m at the end of March, but the frequency of earthquakes associated with avalanches and low-frequency earthquakes were still elevated above background levels. The intensity of the avalanche-related earthquakes began to decline in the second week in April according to PVMBG. No incandescence was observed at the summit by the third week of April, and the decreasing frequency and amplitude of the earthquakes led PVMBG to lower the Alert Level to II on 21 April 2016. Between May and mid-September 2016, emissions from the volcano were characterized by white plumes of variable density ranging from 20 to 300 m above the crater and seismicity remained low (figure 15). The Alert Level remained at II.
Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.
Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38 East Jakarta 13120 (URL: http://www.bnpb.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).