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Bulletin of the Global Volcanism Network

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

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

Recently Published Bulletin Reports

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) — December 2020 Citation iconCite this Report

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.

Figure (see Caption) Figure 26. Photo of a dense gray ash plume rising from Ebeko on 22 June 2020. Photo by L. Kotenko (color corrected), courtesy of IVS FEB RAS, KVERT.

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).

Figure (see Caption) Figure 27. Photos of dense ash plumes rising from Ebeko on 22 (left) and 26 (right) September 2020. Photos by S. Lakomov (color corrected), IVS FEB RAS, KVERT.

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.

Figure (see Caption) Figure 28. Sentinel-2 satellite imagery of a gray-white gas-and-ash plume at Ebeko on 8 (left) and 11 (right) November 2020, resulting in ashfall (dark gray) to the SE of the volcano. Images using “Natural Color” rendering (bands 4, 3, 2), courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 29. Photos of continued ash explosions from Ebeko on 28 October (left) and 29 November (right) 2020. Photos by S. Lakomov (left) and L. Kotenko (right), courtesy of IVS FEB RAS, KVERT.

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.

Figure (see Caption) Figure 30. A small pulse in thermal activity at Ebeko began in early June and continued through early August 2020, according to the MIROVA graph (Log Radiative Power). The detected thermal anomalies were of relatively low power but were persistent during this period. Courtesy of MIROVA.
Figure (see Caption) Figure 31. Sentinel-2 satellite imagery showed gray ash plumes rising from Ebeko on 11 June (top left) and 16 July (bottom left) 2020, accompanied by occasional thermal anomalies (yellow-orange) within the summit crater, as shown on 24 June (top right) and 25 August (bottom right). The ash plume on 11 June drifted N from the summit. Images using “Natural Color” rendering (bands 4, 3, 2) on 11 June (top left) and 16 July (bottom left) and the rest have “Atmospheric penetration” rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

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 Citation iconCite this Report

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.

Figure (see Caption) Figure 10. Sentinel-2 thermal satellite images showed a strong thermal anomaly (bright yellow-orange) in the Shindake crater at Kuchinoerabujima on 1 May 2020 (top left). Weaker thermal anomalies were also seen in the Shindake crater during 19 August (top right) and 3 (bottom left) and 13 (bottom right) October 2020. Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images; courtesy of Sentinel Hub Playground.

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.

Figure (see Caption) Figure 11. Webcam images of an eruption at Kuchinoerabujima on 6 May 2020 (top), producing a gray ash plume that rose 500 m above the crater. Crater incandescence was observed from the summit crater at night on 25 May 2020 (bottom). Courtesy of JMA (Monthly bulletin report 509, May 2020).

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 Citation iconCite this Report

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.

Figure (see Caption) Figure 91. MIROVA graph of thermal activity (log radiative power) at Nyamuragira during March 2020-January 2021. During June-November 2020, most were in the low to moderate range, with a decrease in power during November. Courtesy of MIROVA.

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.

Figure (see Caption) Figure 92. Sentinel-2 satellite images of Nyamuragira on 26 July (left) and 28 November (right) 2020. Thermal activity is present at several locations within the summit crater (upper right of each image) and in the SW part of the caldera (lower left). SWIR rendering (bands 12, 8A, 4). Courtesy of Sentinel Hub Playground.

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 Citation iconCite this Report

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).

Figure (see Caption) Figure 31. Little change can be seen at the summit of Raung in Google Earth images dated 19 October 2017 (left) and 28 April 2018 (right). The summit crater was full of black lava flows from the 2015 eruption. Courtesy of Google Earth.
Figure (see Caption) Figure 32. A Malaysian hiker celebrated his climbing to the summit of Raung on 30 August 2019. Weak fumarolic activity was visible from the base of the breached crater of the cone near the center of the summit crater, and many features of the lava flow that filled the crater in 2015 were still well preserved. Courtesy of MJ.

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.

Figure (see Caption) Figure 33. An ash plume rose from the summit of Raung on 16 July 2020 at the beginning of a new eruption. The last previous eruption was in 2015. Courtesy of Volcano Discovery and PVMBG.

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.

Figure (see Caption) Figure 34. MIROVA thermal anomaly data indicated renewed activity on 16 July 2020 at Raung as seen in this graph of activity from 13 October 2019 through September 2020. Satellite images indicated that the dark lines at the beginning of the graph are from a large area of fires that burned on the flank of Raung in October 2019. Heat flow remained high through July and began to diminish in mid-August 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 35. Thermal anomalies were distinct inside the crater of the pyroclastic cone within the summit crater of Raung on 19, 24, and 29 July 2020. Data is from the Sentinel-2 satellite shown with Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

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).

Figure (see Caption) Figure 36. The thermal anomaly at Raung recorded in Sentinel-2 satellite data decreased in intensity between August and October 2020. It was relatively strong on 13 August (left) but had decreased significantly by 12 September (middle) and remained at a lower level into early October (right). Data shown with Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground
Figure (see Caption) Figure 37. A small but distinct thermal anomaly was still present within the pyroclastic cone inside the summit crater of Raung on 7 October 2020 (left) but was gone by 12 October (middle) and did not reappear in subsequent clear views of the crater through the end of October. Satellite imagery of 7 and 12 October processed with Atmospheric penetration rendering (bands 12, 11, 8A). Natural color rendering (bands 4, 3, 2) from 17 October (right) shows no clear physical changes to the summit crater during the latest eruption. Courtesy of Sentinel Hub Playground.

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 Citation iconCite this Report

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.

Figure (see Caption) Figure 77. Numerous explosions were recorded at Sinabung during August 2020. An ash plume rose to 5,000 m above the summit on 10 August (left) and drifted both NE and SE. On 14 August gray and brown ash plumes rose 1,000-4,200 m above the summit and drifted S, SW, SE and NE (right) while ashfall covered crops SE of the volcano. Courtesy of PVMBG (Sinabung Eruption Notices, 10 and 14 August 2020).

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).

Figure (see Caption) Figure 78. On 23 August 2020 an explosion at Sinabung produced a gray ash plume that rose 1,500 m above the summit and produced pyroclastic flows that traveled 1,000 m down the E and SE flanks. Courtesy of PVMBG (Sinabung Eruption Notice, 23 August 2020).
Figure (see Caption) Figure 79. An explosion on 25 August 2020 at Sinabung produced an ash plume that rose 800 m above the peak and drifted W and NW. Courtesy of PVMBG (Sinabung Eruption Notice, 25 August 2020).
Figure (see Caption) Figure 80. Significant sulfur dioxide emissions were measured at Sinabung during August 2020 when near-daily explosions produced abundant ash emissions. A small plume was also recorded from Kerinci on 19 August 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

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).

Figure (see Caption) Figure 81. A new lava dome appeared at the summit of Sinabung in late September 2020. Block avalanches from the dome were first reported on 8 October. Satellite imagery indicating a thermal anomaly at the summit was very faint at the end of September and slightly stronger by the end of October. The dome grew slowly between 30 September (top) and 22 October 2020 (bottom). Photos taken by Firdaus Surbakti, courtesy of Rizal.
Figure (see Caption) Figure 82. Pyroclastic flows at Sinabung were accompanied ash emissions multiple times during the last week of October, including the event seen here on 27 October 2020. Courtesy of PVMBG and CultureVolcan.
Figure (see Caption) Figure 83. Block avalanches from the growing summit dome at Sinabung descended the SE flank on 28 October 2020. The dome is visible at the summit. Courtesy of PVMBG and MAGMA.
Figure (see Caption) Figure 84. A very faint thermal anomaly appeared at the summit of Sinabung in Sentinel 2 satellite imagery on 28 September 2020 (left). One month later on 28 October the anomaly was bigger, corroborating photographic evidence of the growing dome. Atmospheric penetration rendering (bands 12, 11, 8A) courtesy of Sentinel Hub Playground.

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 Citation iconCite this Report

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.

Figure (see Caption) Figure 43. A small pulse in thermal activity at Heard was detected in early June and continued through July 2020, according to the MIROVA system (Log Radiative Power). Thermal anomalies appeared again starting in late August and continued intermittently through mid-October 2020. Courtesy of MIROVA.

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).

Figure (see Caption) Figure 44. Thermal satellite images of Heard Island’s Big Ben volcano showed strong thermal signatures (bright yellow-orange) sometimes accompanied by gas-and-steam emissions drifting SE (top left) and NE (bottom right) during June 2020. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 45. Thermal satellite images of Heard Island’s Big Ben volcano showed persistent thermal anomalies (bright yellow-orange) near the summit during July through October 2020. During 14 (top left) and 17 (top right) July a second hotspot was visible NW of the summit. By 22 October (bottom right) the thermal anomaly had significantly decreased in strength in comparison to previous months. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

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) — October 2020 Citation iconCite this Report

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
Figure (see Caption) Figure 83. Sulfur dioxide plumes were captured almost daily from Sabancaya during June through September 2020 by the TROPOMI instrument on the Sentinel-5P satellite. Some of the largest SO2 plumes occurred on 19 June (top left), 5 July (top right), 30 August (bottom left), and 10 September (bottom right) 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 84. Thermal activity at Sabancaya varied in power from 13 October 2019 through September 2020, but was consistent in frequency, according to the MIROVA graph (Log Radiative Power). A pulse in thermal activity is shown in late August 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 85. Sentinel-2 thermal satellite imagery showed frequent gas-and-steam and ash plumes rising from Sabancaya, accompanied by ongoing thermal activity from the summit crater during June through September 2020. On 23 June (top left) a dense gray-white ash plume was visible drifting E from the summit. On 3 July (top right) and 27 August (bottom left) a strong thermal hotspot (bright yellow-orange) was accompanied by some degassing. On 1 September (bottom right) the thermal anomaly persisted with a dense gray-white ash plume drifting SE from the summit. Images using “Natural Color” rendering (bands 4, 3, 2) on 23 June 2020 (top left) and the rest have “Atmospheric penetration” rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

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.

Figure (see Caption) Figure 86. Multiple daily explosions at Sabancaya produced ash plumes that rose 1.5-4 km above the crater during June 2020. Images are showing 8 (left) and 27 (right) June 2020. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-24-2020/INGEMMET Semana del 08 al 14 de junio del 2020 and RSSAB-26-2020/INGEMMET Semana del 22 al 28 de junio del 2020).

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.

Figure (see Caption) Figure 87. Multiple daily explosions at Sabancaya produced ash plumes that rose 2-3.5 km above the crater during July 2020. Images are showing 7 (left) and 26 (right) July 2020. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-28-2020/INGEMMET Semanal: del 06 al 12 de julio del 2020 and RSSAB-30-2020/INGEMMET Semanal: del 20 al 26 de julio del 2020).

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.

Figure (see Caption) Figure 88. Multiple daily explosions at Sabancaya produced ash plumes that rose 1.7-3.6 km above the crater during August 2020. Images are showing 1 (left) and 29 (right) August 2020. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-31-2020/INGEMMET Semanal del 27 de julio al 02 de agosto del 2020 and RSSAB-35-2020/INGEMMET Semanal del 24 al 30 de agosto del 2020).

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.

Figure (see Caption) Figure 89. Multiple daily explosions at Sabancaya produced ash plumes that rose 1.8-2.6 km above the crater during September 2020. Images are showing 4 (left) and 27 (right) September 2020. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-36-2020/INGEMMET Semanal del 31 de agosto al 06 de septiembre del 2020 and RSSAB-39-2020/INGEMMET Semanal del 21 al 27 de septiembre del 2020).

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 Citation iconCite this Report

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.

Figure (see Caption) Figure 30. Webcam image of small hydrothermal eruptions at Rincón de la Vieja on 19 April 2020. Image taken by the webcam in Dos Ríos de Upala; courtesy of OVSICORI-UNA.

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.

Figure (see Caption) Figure 31. Webcam images of gray gas-and-steam and ash emissions at Rincón de la Vieja on 21 (left), and 27 (right) May 2020. Both images taken by the webcam in Dos Ríos de Upala and Sensoria; courtesy of OVSICORI-UNA.

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.

Figure (see Caption) Figure 32. Webcam images of gray gas-and-steam and ash plumes rising from Rincón de la Vieja on 1 (top left), 2 (top right), 7 (bottom left), and 13 (bottom right) June 2020. The ash plume on 1 June rose between 1.5 and 2 km above the crater. The ash plume on 13 June rose 1 km above the crater. Courtesy of OVSICORI-UNA.

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.

Figure (see Caption) Figure 33. Webcam image of an eruption plume rising above Rincón de la Vieja on 17 September 2020. Courtesy of OVSICORI-UNA.

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 Citation iconCite this Report

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
Figure (see Caption) Figure 136. Consistent daily ash emissions produced similar looking ash plumes at Fuego during August-November 2020. Plumes usually rose to 4.5-4.8 km altitude and drifted SW. Courtesy of INSIVUMEH.

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.

Figure (see Caption) Figure 137. The MIROVA graph of activity at Fuego for the period from 15 January through November 2020 suggested persistent moderate to high-level heat flow for much of the time. Courtesy of MIROVA.
Figure (see Caption) Figure 138. Atmospheric penetration rendering of Sentinel-2 satellite images (bands 12, 11, 8A) of Fuego during August-November 2020 showed continued thermal activity from block avalanches, explosions, and lava flows at the summit and down several different ravines. Courtesy of Sentinel Hub Playground.

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.

Figure (see Caption) Figure 139. Avalanche blocks descended the Ceniza ravine (left) and the Las Lajas ravine (right) at Fuego on 17 September 2020. The webcam that captured this image is located at Finca La Reunión on the SE flank. Courtesy of INSIVUMEH (BOLETÍN VULCANOLÓGICO ESPECIAL BEVFGO # 76-2020, 18 de septiembre de 2020, 14:30 horas).

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.

Figure (see Caption) Figure 140. Heavy rains on 9 October 2020 at Fuego caused lahars in all the major ravines. Debris from Las Lajas ravine overflowed highway RN-14 near the community of San Miguel on the SE flank, the area devastated by the pyroclastic flow of June 2018. Courtesy of INSIVUMEH (BEFGO #96 VOLCAN DE FUEGO- ZONA CERO RN-14, SAN MIGUEL LOS LOTES y BARRANCA LAS LAJAS, 09 de octubre de 2020).

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) — November 2020 Citation iconCite this Report

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).

Figure (see Caption) Figure 17. White gas-and-steam emissions rose 1 km above the crater at Satsuma Iwo Jima (Kikai) on 25 May (top) 2020. At night, occasional incandescence could be seen in the Iodake crater, as seen on 29 May (bottom) 2020. Both images taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, May 2nd year of Reiwa [2020]).

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).

Figure (see Caption) Figure 18. Webcam images of the eruption at Satsuma Iwo Jima (Kikai) on 6 October 2020 that produced an ash plume rising 200 m above the crater (top). Nighttime summit crater incandescence was also observed (bottom). Images were taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, October 2nd year of Reiwa [2020]).
Figure (see Caption) Figure 19. Weak thermal hotspots (bright yellow-orange) were observed at Satsuma Iwo Jima (Kikai) during late September through October 2020. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 20. Webcam image of a white gas-and-steam plume rising 1.1 km above the crater at Satsuma Iwo Jima (Kikai) on 27 October 2020. Image was taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, October 2nd year of Reiwa [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 Citation iconCite this Report

Manam

Papua New Guinea

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

All times are local (unless otherwise noted)


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.

Figure (see Caption) Figure 76. Distinct sulfur dioxide plumes rising from Manam and drifting generally W were detected using data from the TROPOMI instrument on the Sentinel-5P satellite on 28 April (top left), 24 May (top right), 16 July (bottom left), and 12 September (bottom right) 2020. Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 77. Intermittent thermal activity at Manam increased in power and frequency beginning around late July and continuing through September 2020, as shown on the MIROVA Log Radiative Power graph. Courtesy of MIROVA.
Figure (see Caption) Figure 78. Sentinel-2 thermal satellite images showing a persistent thermal anomaly (yellow-orange) at Manam’s summit craters (Main and South) each month during April through August; sometimes they were seen in both summit craters, as shown on 8 June (top right), 28 July (bottom left), and 17 August (bottom right). A particularly strong anomaly was visible on 17 August (bottom right). Occasional gas-and-steam emissions accompanied the thermal activity. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

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 Citation iconCite this Report

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.

Figure (see Caption) Figure 47. Sentinel-2 natural color satellite images showing ash deposits (dark gray) on the snowy flanks at Karymsky from just before the eruptive period began on 20 March 2020 (top left) through April 2020. Images with “Natural Color” (bands 4, 3, 2) rendering; courtesy of Sentinel Hub Playground.

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).

Figure (see Caption) Figure 48. Sentinel-2 natural color satellite images showing ash deposits (dark gray) on the all the snowy flanks at Karymsky on 14 May (left) and 1 June (right) 2020. Images with “Natural Color” (bands 4, 3, 2) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 49. A pulse of thermal activity at Karymsky during late May through July 2020 was seen in the MIROVA graph (Log Radiative Power). Courtesy of MIROVA.

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).

Figure (see Caption) Figure 50. Sentinel-2 thermal satellite images show a bright thermal hotspot (yellow-orange) in the summit crater of Karymsky during June 2020, sometimes accompanied by gas-and-steam emissions. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 51. Photos of an ash plume rising from Karymsky on 30 June drifting SW (top) and a fumarolic gas plume containing some amount of ash drifting NW (bottom). Both photos by A. Sokorenko; courtesy of IVS FEB RAS, KVERT.

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.

Figure (see Caption) Figure 52. Fumarolic activity at Karymsky on 14 July 2020. Photo has been color corrected. Photo by Ivan Nuzhdaev; courtesy of IVS FEB RAS, KVERT.

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.

Figure (see Caption) Figure 53. Minor gas-and-steam emissions rose from Karymsky on 2 September 2020. Photo by A. Gerasimov; courtesy of KVERT.

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.

Figure (see Caption) Figure 54. Frame from a video of the eruption at Karymsky on 21 October 2020. The ash plume is rising 6 km altitude. Video by Bel-Kam-Tour, courtesy of Russia Today.

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 44, Number 01 (January 2019)

Managing Editor: Edward Venzke

Aira (Japan)

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

Ambrym (Vanuatu)

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

Copahue (Chile-Argentina)

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

Erebus (Antarctica)

Lava lakes persist through 2017 and 2018

Kilauea (United States)

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

Poas (Costa Rica)

Frequent changes at the crater lake throughout 2018

Sangay (Ecuador)

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

Soputan (Indonesia)

Ash explosions on 3-4 October and 16 December 2018

Suwanosejima (Japan)

Multiple explosive events with incandescence and ash plumes during November 2018

Veniaminof (United States)

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



Aira (Japan) — January 2019 Citation iconCite this Report

Aira

Japan

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


Ambrym (Vanuatu) — January 2019 Citation iconCite this Report

Ambrym

Vanuatu

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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

Geologic Background. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides Arc. A thick, almost exclusively pyroclastic sequence, initially dacitic then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major Plinian eruption with dacitic pyroclastic flows about 1,900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.

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


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

Copahue

Chile-Argentina

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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


Erebus (Antarctica) — January 2019 Citation iconCite this Report

Erebus

Antarctica

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

All times are local (unless otherwise noted)


Lava lakes persist through 2017 and 2018

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

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

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

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

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

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


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

Kilauea

United States

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

Poas

Costa Rica

10.2°N, 84.233°W; summit elev. 2708 m

All times are local (unless otherwise noted)


Frequent changes at the crater lake throughout 2018

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

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

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

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

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

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

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

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

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

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

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

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

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


Sangay (Ecuador) — January 2019 Citation iconCite this Report

Sangay

Ecuador

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

All times are local (unless otherwise noted)


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

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

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

The NASA Fire Information for Resource Management System (FIRMS) thermal alert and the first thermal anomaly alert issued by the MODVOLC near-real-time thermal monitoring algorithm for this eruptive episode was on 14 August. The eruption onset was confirmed visually on 14 August when an incandescent lava flow was seen on the upper SE flank on a webcam image (figure 25). Sentinel-2 detected elevated temperatures at the summit and lava effusion on the ESE flank (figure 26).

Figure (see Caption) Figure 25. Visual confirmation of eruptive activity with incandescence on the upper SE flank of Sangay volcano on 14 August. Webcam image by ECU911 from the city of Macas, courtesy of Instituto Geofisico (14 August 2018 report).
Figure (see Caption) Figure 26. Sentinel-2 thermal satellite image showing the active central crater, Ñuñurco dome, and a lava flow (bright orange/yellow) on the ESE flank of Sangay on 25 August 2018. The bright blue indicates snow on the volcano and the white/light blue areas are meteoric clouds. Sentinel-2 false color (Urban) image (bands 12, 11, 4) courtesy of Sentinel Hub Playground.

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

Activity continued through October with lava emission. A Sentinel-2 thermal satellite image acquired on 24 October shows the lava flow on the ESE flank, with elevated thermal energy at the central crater and the Ñuñurco dome (figure 27). The final MODVOLC thermal alert was on 30 November 2018. During this time, lava flows were emitted and flowed down the ESE flank, and ash plumes were often produced and traveled to the W and NW (figure 28). From 2 December there was a substantial decrease in seismicity, ten times less than the previous months (figure 29). No further activity was noted in December.

Figure (see Caption) Figure 27. False color Sentinel-2 Satellite image of Sangay acquired on 24 October 2018 showing the active crater, the Ñuñurco dome, and a hot lava flow (bright orange/yellow) that has traveled more than 1.83 km. Sentinel-2 false color (Urban) image (bands 12, 11, 4) courtesy of Sentinel Hub Playground, figure labels and description courtesy of Instituto Geofisico (17 December 2018 report).
Figure (see Caption) Figure 28. The activity of Sangay during September, August, and November 2018. Small explosive events occurred at the main crater throughout the eruptive episode. The red outlines the active lava flow on the ESE flank and the yellow indicates the area impacted by rockfalls and possible collapse of the lava flow front. Annotated images courtesy of Instituto Geofisico (21 November 2018 report), webcam images taken by ECU-911 from the city of Macas.
Figure (see Caption) Figure 29. Chart showing the number of seismic events during the November-December 2018 activity at Sangay. The tremor was related to the lava flow activity, VT (volcano-tectonic) events are related to rock fracturing, LP (long-period) events are related to fluid movement, and explosions are the number of detected explosions. Between 25 and 88 explosions were detected per day prior to a decrease in seismicity on 2 December. Courtesy of Instituto Geofisico (17 December 2018 report).

Elevated temperatures on the volcano were detected from 14 August to 30 November (figure 30). During this period the Washington Volcanic Ash Advisory Center (VAAC) issued 164 alerts for ash plumes. The ash plumes occasionally exceeded 2 km above the crater but were typically below 1.4 km, drifting in different directions through time (figures 31 and 32). The continuous emission of lava produced flows that traveled 1-2 km from the vent. Rockfalls and possible small pyroclastic flows produced at the lava flow fronts reached a distance of 7 km from the crater. Due to a decrease in thermal activity, ash plumes, and seismicity, Instituto Geofisico declared the eruption over on 7 December, after 121 days of activity.

Figure (see Caption) Figure 30. Plot of MODIS (Moderate Resolution Imaging Spectroradiometer) thermal infrared satellite data analyzed by MIROVA from February 2018 to 2019. Top: the log radiative power of thermal anomalies showing through the eruptive episode. Bottom: The locations of the crater, dome, and lava flow as indicated by thermal anomalies, measured as the distance of the thermal anomalies from the vent in kilometers. Courtesy of MIROVA.
Figure (see Caption) Figure 31. The ash plume heights in meters above the Sangay crater during the 2018 August to December eruption period (top) with detected thermal energy (bottom). Ash plume heights were given by the Washington VAAC and thermal anomalies were calculated by the MODVOLC satellite algorithm. Courtesy of Instituto Geofisico (17 December 2018 report).
Figure (see Caption) Figure 32. A summary of ash plumes from Sangay during the August-December 2018 eruptive episode. A) The ash plume heights as reported by the Washington VAAC. The red line gives the average value for that month while the box represents the standard deviation. The maximum heights are indicated by the circles. B) The ash plume extents overlain over an image of Ecuador. Courtesy of Instituto Geofisico (21 November 2018 report).

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

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


Soputan (Indonesia) — January 2019 Citation iconCite this Report

Soputan

Indonesia

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

All times are local (unless otherwise noted)


Ash explosions on 3-4 October and 16 December 2018

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

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

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

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

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

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

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

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

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


Suwanosejima (Japan) — January 2019 Citation iconCite this Report

Suwanosejima

Japan

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

All times are local (unless otherwise noted)


Multiple explosive events with incandescence and ash plumes during November 2018

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

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

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

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

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

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

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

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

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

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


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

Veniaminof

United States

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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

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

Geologic Background. Veniaminof, on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 years ago. The caldera rim is up to 520 m high on the north, is deeply notched on the west by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.

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

Atmospheric Effects

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

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

Special Announcements

Special announcements of various kinds and obituaries.

Special Announcements  Obituaries

Misc Reports

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

Additional Reports  False Reports