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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

Sheveluch (Russia) New whaleback dome extruded in late September 2020; intermittent explosions

Erta Ale (Ethiopia) Thermal anomalies persist in the summit crater during May-September 2020

Merapi (Indonesia) Eruptions in April and June 2020 produced ash plumes and ashfall

Semeru (Indonesia) Ash plumes, lava flows, avalanches, and pyroclastic flows during March-August 2020

Kavachi (Solomon Islands) Discolored water plumes observed in satellite imagery during early September 2020

Krakatau (Indonesia) Eruption ends in mid-April 2020, but intermittent thermal anomalies continue

Raung (Indonesia) Eruptions confirmed during 2012- 2013; lava fills inner crater in November 2014-August 2015

Klyuchevskoy (Russia) Strombolian activity, gas-and-steam and ash plumes, and a lava flow during June-early July 2020

Fuego (Guatemala) Ongoing explosions, ash plumes, lava flows, and lahars during April-July 2020

Nishinoshima (Japan) Major June-July eruption of lava, ash, and sulfur dioxide; activity declines in August 2020

Turrialba (Costa Rica) New eruptive period on 18 June 2020 consisted of ash eruptions

Etna (Italy) Effusive activity in early April; frequent Strombolian explosions and ash emissions during April-July 2020



Sheveluch (Russia) — November 2020 Citation iconCite this Report

Sheveluch

Russia

56.653°N, 161.36°E; summit elev. 3283 m

All times are local (unless otherwise noted)


New whaleback dome extruded in late September 2020; intermittent explosions

The ongoing eruption at Sheveluch continued during May-October 2020, characterized by lava dome growth, strong fumarolic activity, and several explosions that generated plumes of resuspended ash. Activity waned between November 2019 and April 2020 (BGVN 45:05), and this less intense level of activity continued during the reporting period (table 15). The volcano is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT). The Aviation Color Code remained at Orange (the second highest level on a four-color scale) throughout.

Notable explosions took place on 13 June, 28 June, 2 August, 24 August, and 7-9 October 2020 (table 15), sending ash plumes more than 1 km above the summit that drifted to distances of between 75 and 310 km. Some of the plumes were described by KVERT as being composed of re-suspended ash. On 28 September a large dacitic block of lava, a “whaleback” dome, was first seen being extruded from the eastern part of the larger lava dome in the summit crater (figure 55); it was given the name “Dolphin” by KVERT.

Table 15. Explosions, ash plumes, and extrusive activity at Sheveluch during May-October 2020. Dates and times are UTC, not local. VONA is Volcano Observatory Notice for Aviation. Data courtesy of KVERT and the Tokyo Volcanic Ash Advisory Center (VAAC).

Dates Plume altitude Drift Distance and Direction Remarks
13 Jun 2020 5 km 120 km NE Webcam captured an explosion. VONA issued.
28 Jun 2020 -- 140 km E Plume of re-suspended ash. VONA issued.
02 Aug 2020 4.5 km SE, E Moderate explosion produced a small ash plume.
24 Aug 2020 -- 75 km ESE Plume of resuspended ash.
28 Sep 2020 -- -- A new lava block extruded from the E part of the lava dome was first visible.
07-09 Oct 2020 -- 310 km SE Plume of re-suspended ash. VONAs issued.
Figure (see Caption) Figure 55. Photo of the Sheveluch summit showing the new lava block (referred to as “Dolphin”) being extruded in eastern part the lava dome on 28 September 2020. Photo by Yu. Demyanchuk; courtesy of IVS FEB RAS, KVERT.

According to KVERT, a thermal anomaly was identified from the lava dome in the summit crater (figure 56) in satellite images every day during the reporting period, except for several days in August and September when weather clouds obscured the view. During the reporting period, thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, recorded hotspots from 2-13 days per month; after June, the number of days with hotspots gradually diminished every month. The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, detected frequent anomalies. NASA recorded high levels of sulfur dioxide above or near Sheveluch during several scattered days in May and June by the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Copernicus Sentinel-5 Precursor satellite, but very little drift was observed.

Figure (see Caption) Figure 56. Photo showing typical fumarolic activity from the lava dome at Sheveluch on 18 September 2020. Photo by Yu. Demyanchuk; courtesy of IVS FEB RAS, KVERT.

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); 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/).


Erta Ale (Ethiopia) — October 2020 Citation iconCite this Report

Erta Ale

Ethiopia

13.6°N, 40.67°E; summit elev. 613 m

All times are local (unless otherwise noted)


Thermal anomalies persist in the summit crater during May-September 2020

Erta Ale is an active basaltic volcano in Ethiopia, containing multiple active pit craters in the summit and southeastern caldera. Volcanism has been characterized by lava flows and large lava flow fields since 2017. This report describes continued thermal activity in the summit caldera during May through September 2020 using information from various satellite data.

Volcanism at Erta Ale was relatively low from May to early August 2020. Across all satellite data, thermal anomalies were identified for a total of 2 days in May, 7 days in June, 4 days in July, 11 days in August, and 15 days in September. Beginning in early June and into September 2020 the Sentinel-2 MODIS Thermal Volcanic Activity graph provided by the MIROVA system identified a small cluster of thermal anomalies in the summit area after a brief hiatus from early January 2020 (figure 99). By mid-August, a small pulse of thermal activity was detected by the MIROVA (Middle Infrared Observation of Volcanic Activity) system. Many of these thermal anomalies were seen in Sentinel-2 thermal satellite imagery on clear weather days from June to September.

Figure (see Caption) Figure 99. A small cluster of thermal anomalies were detected in the summit area of Erta Ale (red dots) during June-September 2020 as recorded by the Sentinel-2 MODIS Thermal Volcanic Activity data (bands 12, 11, 8A). Courtesy of MIROVA.

On 12 June a minor thermal anomaly was observed in the S pit crater; a larger anomaly was detected on 17 June in the summit caldera where there had been a previous lava lake (figure 100). In mid-August, satellite data showed thermal anomalies in both the N and S pit craters, but by 5 September only the N crater showed elevated temperatures (figure 101). The thermal activity in the N summit caldera persisted through September, based on satellite data from NASA VIIRS and Sentinel Hub Playground.

Figure (see Caption) Figure 100. Sentinel-2 thermal satellite imagery of Erta Ale on 17 June 2020 showing a strong thermal anomaly in the summit caldera. Sentinel-2 satellite image with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 101. Sentinel-2 thermal satellite imagery of Erta Ale showing thermal anomalies in the N and S pit craters on 21 (top left), 26 (top right), and 31 (bottom left) August 2020. On 5 September (bottom right) only the anomaly in the N crater remained. Sentinel-2 satellite image with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

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

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


Merapi (Indonesia) — October 2020 Citation iconCite this Report

Merapi

Indonesia

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

All times are local (unless otherwise noted)


Eruptions in April and June 2020 produced ash plumes and ashfall

Merapi, located just north of the city of Yogyakarta, Indonesia, is a highly active stratovolcano; the current eruption began in May 2018. Volcanism has recently been characterized by lava dome growth and collapse, small block-and-ash flows, explosions, ash plumes, ashfall, and pyroclastic flows (BGVN 44:10 and 45:04). Activity has recently consisted of three large eruptions in April and June, producing dense gray ash plumes and ashfall in June. Dominantly, white gas-and-steam emissions have been reported during April-September 2020. The primary reporting source of activity comes from Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG, the Center for Research and Development of Geological Disaster Technology, a branch of PVMBG), the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), and the Darwin Volcanic Ash Advisory Centre (VAAC).

Activity at Merapi dominantly consisted of frequent white gas-and-steam emissions that generally rose 20-600 m above the crater (figure 95). On 2 April an eruption occurred at 1510, producing a gray ash plume that rose 3 km above the crater, and accompanied by white gas-and-steam emissions up to 600 m above the crater. A second explosion on 10 April at 0910 generated a gray ash plume rising 3 km above the crater and drifting NW, accompanied by white gas-and-steam emissions rising 300 m above the crater (figure 96). Activity over the next six weeks consisted primarily of gas-and-steam emissions.

Figure (see Caption) Figure 95. Gas-and-steam emissions were frequently observed rising from Merapi as seen on 3 April (left) and 4 August (right) 2020. Courtesy of BPPTKG.
Figure (see Caption) Figure 96. Webcam image showed an ash plume rising 3 km above the crater of Merapi at 0917 on 10 April 2020. Courtesy of BPPTKG and MAGMA Indonesia.

On 8 June PVMBG reported an increase in seismicity. Aerial photos from 13 June taken using drones were used to measure the lava dome, which had decreased in volume to 200,000 m3, compared to measurements from 19 February 2020 (291,000 m3). On 21 June two explosions were recorded at 0913 and 0927; the first explosion lasted less than six minutes while the second was less than two minutes. A dense, gray ash plume reached 6 km above the crater drifting S, W, and SW according to the Darwin VAAC notice and CCTV station (figure 97), which resulted in ashfall in the districts of Magelang, Kulonprogo, and as far as the Girimulyo District (45 km). During 21-22 June the gas-and-steam emissions rose to a maximum height of 6 km above the crater. The morphology of the summit crater had slightly changed by 22 June. Based on photos from the Ngepos Post, about 19,000 m3 of material had been removed from the SW part of the summit, likely near or as part of the crater rim. On 11 and 26 July new measurements of the lava dome were taken, measuring 200,000 m3 on both days, based on aerial photos using drones. Gas-and-steam emissions continued through September.

Figure (see Caption) Figure 97. Webcam image showed an ash plume rising 6 km above the crater of Merapi at 0915 on 21 June 2020. Courtesy of BPPTKG.

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities.

Information Contacts: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Center for Research and Development of Geological Disaster Technology (URL: http://merapi.bgl.esdm.go.id/, Twitter: @BPPTKG); Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/).


Semeru (Indonesia) — October 2020 Citation iconCite this Report

Semeru

Indonesia

8.108°S, 112.922°E; summit elev. 3657 m

All times are local (unless otherwise noted)


Ash plumes, lava flows, avalanches, and pyroclastic flows during March-August 2020

Semeru in eastern Java, Indonesia, has been erupting almost continuously since 1967 and is characterized by ash plumes, pyroclastic flows, lava flows and lava avalanches down drainages on the SE flanks. The Alert Level has remained at 2 (on a scale of 1-4) since May 2012, and the public reminded to stay outside of the general 1-km radius from the summit and 4 km on the SSE flank. This report updates volcanic activity from March to August 2020, using primary information from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), the Darwin Volcanic Ash Advisory Centre (VAAC), and satellite data.

Activity at Semeru consisted of dominantly dense white-gray ash plumes rising 100-600 m above the crater, incandescent material that was ejected 10-50 m high and descended 300-2,000 from the summit crater, and lava flows measuring 500-1,000 m long. Two pyroclastic flows were also observed, extending 2.3 km from the summit crater in March and 2 km on 17 April.

During 1-2 March gray ash plumes rose 200-500 m above the crater, accompanied by incandescent material that was ejected 10-50 m above the Jonggring-Seloko Crater. Lava flows reaching 500-1,000 m long traveled down the Kembar, Bang, and Kobokan drainages on the S flank. During 4-10 March ash plumes up to 200 m high were interspersed with 100-m-high white gas-and-steam plumes. At the end of a 750-m-long lava flow on the S flank, a pyroclastic flow that lasted 9 minutes traveled as far as 2.3 km. During 25-31 March incandescent material found at the end of the lava flow descended 700-950 m from the summit crater (figure 42).

Figure (see Caption) Figure 42. Sentinel-2 thermal satellite imagery showed lava avalanches descending the SSE flank on 26 March 2020. Images using short-wave infrared (SWIR, bands 12, 8A, 4) rendering; courtesy of Sentinel Hub Playground.

Incandescent material continued to be observed in April, rising 10-50 m above the Jonggring-Seloko Crater. Some incandescent material descended from the ends of lava flows as far as 700-2,000 m from the summit crater. Dense white-gray ash plumes rose 100-600 m above the crater drifting N, SE, and SW. During 15-21 April incandescent lava flows traveled 500-1,000 m down the Kembar, Bang, and Kobokan drainages on the S flank. On 17 April at 0608 a pyroclastic flow was observed on the S flank in the Bang drainage measuring 2 km (figure 43). During 22-28 April lava blocks traveled 300 m from the end of lava flows in the Kembar drainage.

Figure (see Caption) Figure 43. A pyroclastic flow at Semeru on 17 April 2020 moving down the S flank toward Besuk Bang. Photo has been color corrected. Courtesy of PVMBG.

Similar activity continued in May, with incandescent material from lava flows in the Kembar and Kobokan drainages descending a maximum distance of 2 km during 29 April-12 May, and 200-1,200 m in the Kembar drainage during 13-27 May, accompanied by dense white-gray ash plumes rising 100-500 m above the crater drifting in different directions. White gas-and-steam plumes rose 300 m above the crater on 26-27 May. Dense white-to-gray ash plumes were visible most days during June, rising 100-500 m above the crater and drifting in various directions. During 3-9 June incandescent material from lava flows descended 200-1,600 m in the Kembar drainage.

Activity in July had decreased slightly and consisted of primarily dense white-gray ash plumes that ranged from 200-500 m above the crater and drifted W, SW, N, and S. Weather conditions often prevented visual observations. On 7 July an ash plume at 0633 rose 400 m drifting W. Similar ash activity was observed in August rising 200-500 m above the crater. On 14 and 16 August a Darwin VAAC advisory stated that white-gray ash plumes rose 300-400 m above the crater, drifting W and WSW; on 16 August a thermal anomaly was observed in satellite imagery. MAGMA Indonesia reported ash plumes were visible during 19-31 August and rose 200-400 m above the crater, drifting S and SW.

Hotspots were recorded by MODVOLC on 11, 6, and 7 days during March, April, and May, respectively, with as many as four pixels in March. Thermal activity decreased to a single hotspot in July and none in August. The MIROVA (Middle InfraRed Observation of Volcanic Activity) system recorded numerous thermal anomalies at the volcano during March-July; a lower number was recorded during August (figure 44). The NASA Global Sulfur Dioxide page showed high levels of sulfur dioxide above or near Semeru on 18, 24-25, and 29-31 March, and 9 April.

Figure (see Caption) Figure 44. Thermal anomalies at Semeru detected during March-June 2020. Courtesy of MIROVA.

Geologic Background. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia (Multiplatform Application for Geohazard Mitigation and Assessment in Indonesia), PVMBG, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); 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).


Kavachi (Solomon Islands) — October 2020 Citation iconCite this Report

Kavachi

Solomon Islands

8.991°S, 157.979°E; summit elev. -20 m

All times are local (unless otherwise noted)


Discolored water plumes observed in satellite imagery during early September 2020

Kavachi is an active submarine volcano in the SW Pacific, located in the Solomon Islands south of Gatokae and Vangunu islands. Volcanism has been characterized by phreatomagmatic explosions that ejected steam, ash, and incandescent bombs. The previous report described discolored water plumes extending from a single point during early 2018 and April 2020 (BGVN 45:05); similar activity was recorded for this current reporting period covering May through September 2020 and primarily using satellite data.

Activity at Kavachi is most frequently observed through satellite images and typically consists of discolored submarine plumes. On 2 September 2020 a slight yellow discoloration in the water was observed extending E from a specific point (figure 22). Similar faint plumes continued to be recorded on 5, 7, 12, and 17 September, each of which seemed to be drifting generally E from a point source above the summit where previous activity has occurred. On 7 September the discolored plume was accompanied by white degassing and possibly agitated water on the surface at the origin point (figure 22).

Figure (see Caption) Figure 22. Sentinel-2 satellite images of a discolored plume (light yellow) at Kavachi beginning on 2 September (top left) and continuing through 17 September 2020 (bottom right). The light blue circle on the 7 September image highlights the surface degassing and source of the discolored water plume. The white arrow on the bottom right image is pointing to the faint discolored plume. Images with “Natural color” rendering (bands 4, 3, 2); courtesy of Sentinel Hub Playground.

Geologic Background. Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is one of the most active submarine volcanoes in the SW Pacific, located in the Solomon Islands south of Vangunu Island. Sometimes referred to as Rejo te Kvachi ("Kavachi's Oven"), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported "fire on the water" prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.

Information Contacts: Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Krakatau (Indonesia) — October 2020 Citation iconCite this Report

Krakatau

Indonesia

6.102°S, 105.423°E; summit elev. 155 m

All times are local (unless otherwise noted)


Eruption ends in mid-April 2020, but intermittent thermal anomalies continue

Krakatau, located in the Sunda Strait between Indonesia’s Java and Sumatra Islands, experienced a major caldera collapse around 535 CE, forming a 7-km-wide caldera ringed by three islands. Presently, the caldera is underwater, except for three surrounding islands (Verlaten, Lang, and Rakata) and the active Anak Krakatau that was constructed within the 1883 caldera and has been the site of frequent eruptions since 1927. On 22 December 2018, a large explosion and flank collapse destroyed most of the 338-m-high island of Anak Krakatau (Child of Krakatau) and generated a deadly tsunami (BGVN 44:03). A larger explosion in December 2019 produced the beginnings of a new cone above the surface of crater lake (BGVN 45:02). The previous report (BGVN 45:06) described activity that included Strombolian explosions, ash plumes, and crater incandescence. This report updates information from June through September 2020 using information primarily from Indonesian Center for Volcanology and Geological Hazard Mitigation, also known as Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and satellite data.

A VONA notice from PVMBG reported that the last eruptive event at Krakatau was reported on 17 April 2020, though the eruptive column was not observed. Activity after that was relatively low through September 2020, primarily intermittent diffuse white gas-and-steam emissions, according to PVMBG. No activity was reported during June-August, except for minor seismicity. During 11-13, 16, and 18 September, the CCTV Lava93 webcam showed intermittent white gas-and-steam emissions rising 25-50 m above the crater.

The MIROVA (Middle InfraRed Observation of Volcanic Activity) graph of MODIS thermal anomaly data showed intermittent hotspots within 5 km of the crater from May through September (figure 113). Some of these thermal hotspots were also detected in Suomi NPP/VIIRS sensor data. Sentinel-2 thermal satellite imagery showed faint thermal anomalies in the crater during June; no thermal activity was detected after June (figure 114).

Figure (see Caption) Figure 113. Intermittent thermal activity at Anak Krakatau from 13 October 2019-September 2020 shown on a MIROVA Low Radiative Power graph. The power of the thermal anomalies decreased after activity in April but continued intermittently through September. Courtesy of MIROVA.
Figure (see Caption) Figure 114. Sentinel-2 thermal satellite images showing a faint thermal anomaly in the crater during 1 (left) and 11 (right) June 2020. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); NASA Worldview (URL: https://worldview.earthdata.nasa.gov/).


Raung (Indonesia) — September 2020 Citation iconCite this Report

Raung

Indonesia

8.119°S, 114.056°E; summit elev. 3260 m

All times are local (unless otherwise noted)


Eruptions confirmed during 2012- 2013; lava fills inner crater in November 2014-August 2015

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. Visual reports of activity have often come from commercial airline flights that pass near the summit; 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 in 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. Confirmation and details of eruptions in 2012, 2013, and 2014-2015 are covered in this report with information provided by PVMBG, the Darwin Volcanic Ash Advisory Center (VAAC), several sources of satellite data, and visitors to the volcano.

Newly available visual and satellite information confirm eruptions at Raung during October 2012-January 2013, June-July 2013, and extend the beginning of the 2015 eruption back to November 2014. The 2015 eruption was the largest in several decades; Strombolian activity was reported for many months and fresh lava flows covered the crater floor. Raung was quiet after the 2015 eruption ended in August of that year until July 2020.

Eruption during October 2012-January 2013. A MODVOLC thermal alert appeared inside the summit crater of Raung on 14 October 2012, followed by another four alerts on 16 October. Multiple daily alerts were reported on many days through 8 November, most within the main crater. Single alerts appeared on 29 November and 1 December 2012 (figure 9). PVMBG raised the Alert Level on 17 October from 1 to 2 due to increased seismicity and raised it further to Level 3 on 22 October. A local news report by Aris Yanto indicted that a minor Strombolian eruption occurred inside the crater on 19 October. Strombolian activity was also observed inside the inner crater on 5 November 2012 by visitors (figure 10); they reported loud rumbling sounds that could be heard up to 15 km from the crater.

Figure (see Caption) Figure 9. Thermal activity at Raung during October and November 2012 included multiple days of multi-pixel anomalies, with almost all activity concentrated within the summit crater. Strombolian activity was observed on 5 November. Image shows all pixels from 23 September-1 December 2012. Courtesy of MODVOLC.
Figure (see Caption) Figure 10. Strombolian activity was observed inside the inner crater of Raung on 5 November 2012 by visitors. They reported loud rumbling sounds that could be heard up to 15 km from the crater. Photo by Galih, courtesy of Volcano Discovery.

The Darwin VAAC issued an advisory of an eruption plume to 9.1 km altitude reported at 0237 UTC on 8 November 2012. In a second advisory about two hours later they noted that an ash plume was not visible in satellite imagery. A press article released by the Center for Volcanology and Geological Hazard Mitigation (PVMBG) indicated that gray ash plumes were observed on 6 January 2013 that rose 300 m above the summit crater rim. Incandescence was observed around the crater and thundering explosions were heard by nearby residents.

Eruption during June-July 2013. Two MODVOLC thermal alerts were measured inside the summit crater on 29 June 2013. A photo taken on 21 July showed minor Strombolian activity at the inner crater (figure 11). A weak SO2 anomaly was detected in the vicinity of Raung by the OMI instrument on the Aura satellite on 27 July. Thermal alerts were recorded on 29 and 31 July. When Google Earth imageryrom 14 March 2011 created by Maxar Technologies is compared with imagery from 29 July 2013 captured by Landsat/Copernicus, dark tephra is filling the inner crater in the 2013 image; it was not present in 2011 (figure 12).

Figure (see Caption) Figure 11. Strombolian activity was observed inside the inner crater at the summit of Raung on 21 July 2013. Photo by Agus Kurniawan, courtesy of Volcano Discovery.
Figure (see Caption) Figure 12. Satellite imagery from Google Earth showing the eroded pyroclastic cone inside the summit crater of Raung on 14 March 2011 (left) and 29 July 2013 (right). Dark tephra deposits filling the inner crater in the 2013 image were not present in 2011. The crater of the pyroclastic cone is 200 m wide; N is to the top of the images. Courtesy of Google Earth.

Eruption during November 2014-August 2015. Information about this eruption was previously reported (BGVN 41:12), but additional details are provided here. Landsat-8 imagery from 28 October 2014 indicated clear skies and little activity within the summit crater. Local observers reported steam plumes beginning in mid-November (figure 13). MODVOLC thermal alerts within the summit crater were issued on 28 and 30 November, and then 15 alerts were issued on seven days in December. Thermal Landsat-8 imagery from cloudy days on 29 November and 15 December indicated an anomaly over the area of the pyroclastic cone inside the summit crater (figure 14).

Figure (see Caption) Figure 13. Local observers reported steam plumes at Raung beginning in mid-November 2014; this one was photographed on 17 November 2014. Courtesy of Volcano Discovery.
Figure (see Caption) Figure 14. Satellite evidence of new eruptive activity at Raung first appeared on 29 November 2014. The true color-pansharpened Landsat-8 image of Raung from 28 October 2014 (left) shows the summit crater and an eroded pyroclastic cone with its own crater (the inner crater) with no apparent activity. Although dense meteoric clouds on 29 November (center) and 15 December 2014 (right) blocked true color imagery, thermal imagery indicated a thermal anomaly from the center of the pyroclastic cone on both dates. Courtesy of Sentinel Hub Playground.

In January 2015 the MODVOLC system identified 25 thermal anomalies in MODIS data, with a peak of eight alerts on 8 January. Visitors to the summit crater on 6 January witnessed explosions from the inner crater approximately every 40 minutes that produced gas and small amounts of ash and tephra. They reported lava flowing continuously from the inner crater onto the larger crater floor, and incandescent activity was seen at night (figure 15). Landsat-8 images from 16 January showed a strong thermal anomaly covering an area of fresh lava (figure 16).

Figure (see Caption) Figure 15. Visitors to the summit crater of Raung on 6 January 2015 witnessed explosions from the inner crater approximately every 40 minutes that produced abundant gas and small amounts of ash and tephra. Lava was flowing continuously from the inner crater onto the larger crater floor, and incandescent activity was observed at night. Photos by Sofya Klimova, courtesy of Volcano Discovery.
Figure (see Caption) Figure 16. On a clear 16 January 2015, Landsat-8 satellite imagery revealed fresh lava flows NW of the pyroclastic cone within the summit crater at Raung. A strong thermal anomaly matches up with the dark material, suggesting that it flowed NW from within the pyroclastic cone. Left image is true color-pansharpened rendering, right image is thermal rendering. Courtesy of Sentinel Hub Playground.

Satellite images were obscured by meteoric clouds during February 2015, but PVMBG reported gray and brown plumes rising 300 m multiple times and incandescence and rumbling on 14 February. Visitors to the summit crater during the second half of February reported Strombolian activity with lava fountains from the inner crater, at times as frequently as every 15 minutes (figure 17). Loud explosions and rumbling were heard 10-15 km away. MODVOLC thermal alerts stopped on 25 February and did not reappear until late June.

Figure (see Caption) Figure 17. A report issued on 25 February 2015 from visitors to the summit of Ruang noted large Strombolian explosions with incandescent ejecta and lava flowing across the crater floor. The fresh lava on the crater floor covered a noticeably larger area than that shown in early January (figure 15). Photo by Andi, courtesy of Volcano Discovery.

PVMBG raised the Alert Level to 2 in mid-March 2015. Weak thermal anomalies located inside and NW of the pyroclastic cone were present in satellite imagery on 21 March. PVMBG reported gray and brown emissions during March, April, and May rising as high as 300 m above the crater. Landsat imagery from 22 April showed a small emission inside the pyroclastic cone, and on 8 May showed a clearer view of the fresh black lava NW and SW of the pyroclastic cone (figure 18).

Figure (see Caption) Figure 18. Fresh lava was visible in Landsat-8 satellite imagery in April and May 2015 at Raung. A small emission was present inside the pyroclastic cone at the summit of Raung on 22 April 2015 (left). Fresh dark material is also evident in the SW quadrant of the summit crater that was not visible on 16 January 2015. A clear view on 8 May 2015 also shows the extent of the fresh black material around the pyroclastic cone (right). The summit crater is 2 km wide. Courtesy of Sentinel Hub Playground.

Nine MODVOLC thermal alerts appeared inside the summit crater on 21 June 2015 after no alerts since late February, suggesting an increase in activity. The Darwin VAAC issued the first ash advisory for 2015 on 24 June noting an aviation report of recent ash. The following day the Ujung Pandang Meteorological Weather Office (MWO) reported an ash emission drifting W at 3.7 km altitude. The same day, 25 June, Landsat-8 imagery clearly showed a new lava flow on the W side of the crater and a strong thermal anomaly. The thermal data showed a point source of heat widening SW from the center of the crater and a second point source of heat that appeared to be inside the pyroclastic cone. A small ash plume was visible over the cone (figure 19). Strombolian activity and ash plumes were reported by BNPB and PVMBG in the following days. On 26 June the Darwin VAAC noted the hotspot had remained visible in infrared imagery for several days. PVMBG reported an ash emission to 3 km altitude on 29 June.

Figure (see Caption) Figure 19. A new lava flow and strong thermal anomaly appeared inside the summit crater of Raung on 25 June 2015 in Landsat-8 imagery. The new flow was visible on the W side of the crater. The darker area extending SW from the rising ash plume is a shadow. The thermal data showed a point source of heat widening SW from the center of the crater and spreading out in the SW quadrant and a second point source of heat on the flank of the pyroclastic cone. Left image is True color-pansharpened rendering, and right image is thermal rendering. Courtesy of Sentinel Hub Playground.

Activity increased significantly during July 2015 (BGVN 41:12). Ash plumes rose as high as 6.7 km altitude and drifted hundreds of kilometers in multiple directions, forcing multiple shutdowns at airports on Bali and Lombok, as well as Banyuwangi and Jember in East Java. The Darwin VAAC issued 152 ash advisories during the month. Ashfall was reported up to 20 km W during July and 20-40 km SE during early August. Visitors to the summit in early July observed a new pyroclastic cone growing inside the inner crater from incandescent ejecta and dense ash emissions (figure 20). Landsat-8 imagery from 11 July showed a dense ash plume drifting SE, fresh black lava covering the 2-km-wide summit caldera floor, and a very strong thermal anomaly most intense at the center near the pyroclastic cone and cooler around the inner edges of the crater (figure 21). On 12 July, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured a view of an ash-and-gas plume drifting hundreds of kilometers SE from Raung (figure 22).

Figure (see Caption) Figure 20. A new pyroclastic cone was growing inside the inner crater at the summit of Raung when photographed by Aris Yanto in early July 2015. Courtesy of Volcano Discovery.
Figure (see Caption) Figure 21. Landsat-8 imagery of Raung during July 2015 indicated dense ash emissions and a large thermal anomaly caused by fresh lava. On 11 July a dense ash plume drifted SE and a strong thermal anomaly was centered inside the summit crater. The 2-km-wide crater floor was covered with fresh lava (compare with 25 June image in figure 19). Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 22. On 12 July 2015 the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured a natural-color view of a plume of ash and volcanic gases drifting hundreds of kilometers SE from Raung. Courtesy of NASA Earth Observatory.

A satellite image on 20 July showed fresh incandescent lava covering the floor of the summit crater and a dense ash plume drifting N from the summit (figure 23). Incandescent ejecta emerged from two vents on the new pyroclastic cone inside the inner crater on 26 July (figure 24). On 27 July a dense ash plume was visible again in satellite imagery drifting NW and the hottest part of the thermal anomaly was in the SE quadrant of the crater (figure 25). Substantial SO2 plumes were recorded by the OMI instrument on the Aura satellite during July and early August 2015 (figure 26).

Figure (see Caption) Figure 23. A satellite image of the summit of Raung on 20 July 2015 showed fresh, incandescent lava covering the floor of the summit crater and a dense ash plume drifting N from the summit. Thermal activity on the NE flank was likely the result of incandescent ejecta from the crater causing a fire. Image created by DigitalGlobe, captured by WorldView3, courtesy of Volcano Discovery.
Figure (see Caption) Figure 24. Incandescent ejecta emerged from two vents on the new pyroclastic cone growing inside the inner crater of Raung on 26 July 2015. Photo by Vianney Tricou, used with permission, courtesy of Volcano Discovery.
Figure (see Caption) Figure 25. Landsat-8 imagery of Raung during July 2015 indicated dense ash emissions and large thermal anomalies from fresh lava. The 2-km-wide crater floor was fully covered with fresh lava by 11 July. On 27 July the dense ash plume was drifting NW and the highest heat was concentrated in the SE quadrant of the crater. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 26. Substantial plumes of sulfur dioxide from Raung were measured by the OMI instrument on the AURA satellite during July and August 2015. The first plumes were measured in mid-June; they intensified during the second half of July and the first week of August, but had decreased by mid-August. Wind directions were highly variable throughout the period. The date is recorded above each image. Courtesy of NASA Global Sulfur Dioxide Page.

Significant ash emissions continued into early August 2015 with numerous flight cancellations. The Darwin VAAC reported ash plumes rising to 5.2 km altitude and extending as far as 750 km SE during the first two weeks in August (figure 27). Satellite imagery indicated a small ash plume drifting W from the center of the crater on 12 August and weak thermal anomalies along the E and S rim of the floor of the crater (figure 28). The summit crater was covered with fresh lava on 14 August when viewed by visitors, and ash emissions rose a few hundred meters above the crater rim from a vent in the SW side of the pyroclastic cone (figure 29). The visitors observed pulsating ash emissions rising from the SW vent on the large double-crater new cinder cone. The larger vent to the NE was almost entirely inactive except for two small, weakly effusive vents on its inner walls.

Figure (see Caption) Figure 27. A dense ash plume drifted many kilometers S from Raung on 2 August 2015 in this view from nearly 100 km W. Incandescence at the summit indicated ongoing activity from the major 2015 eruption. In the foreground is Lamongan volcano whose last known eruption occurred in 1898. Courtesy of Øystein Lund Andersen, used with permission.
Figure (see Caption) Figure 28. Landsat-8 satellite imagery of Raung indicated a small ash plume drifting W from the center of the crater on 12 August 2015. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 29. The summit crater of Raung on 14 August 2015 was filled with fresh lava from an eruption that began in November 2014. Ash emissions from a vent in the side of the newly grown pyroclastic cone within the crater rose a few hundred meters above the crater rim. Courtesy of Volcano Discovery.

The lengthy sequence of multiple daily VAAC reports that began in late June ended on 16 August 2015 with reports becoming more intermittent and ash plume heights rising to only 3.7-3.9 km altitude. Multiple discontinuous eruptions to 3.9 km altitude were reported on 18 August. The plumes extended about 100 km NW. The last report of an ash plume was from an airline on 22 August noting a low-level plume 50 km NW. Two MODVOLC alerts were issued that day. By 28 August only a very small steam plume was present at the center of the crater; the southern half of the edge of the crater floor still had small thermal anomalies (figure 30). The last single MODVOLC thermal alerts were on 29 August and 7 September. The Alert Level was lowered to 2 on 24 August 2015, and further lowered to 1 on 20 October 2016.

Figure (see Caption) Figure 30. By 28 August 2015 only a very small steam plume was present at the center of the summit crater of Raung, and the southern half of the edge of the crater floor only had weak thermal anomalies from cooling lava. 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/); 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/); 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/);Google Earth (URL: https://www.google.com/earth/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/, https://earthobservatory.nasa.gov/images/86213/eruption-of-raung-volcano); Tom Pfeiffer, Volcano Discovery (URL: http://www.volcanodiscovery.com/); Aris Yanto (URL: https://www.exploredesa.com/2012/11/mount-raung-produce-of-vulcanic-ash-plume-and-continue-eruption/); DigitalGlobe (URL: https://www.maxar.com/, https://twitter.com/Maxar/status/875449111398547457); Øystein Lund Andersen (URL: https://twitter.com/OysteinVolcano/status/1194879946042142726, http://www.oysteinlundandersen.com).


Klyuchevskoy (Russia) — September 2020 Citation iconCite this Report

Klyuchevskoy

Russia

56.056°N, 160.642°E; summit elev. 4754 m

All times are local (unless otherwise noted)


Strombolian activity, gas-and-steam and ash plumes, and a lava flow during June-early July 2020

Klyuchevskoy is a frequently active stratovolcano located in northern Kamchatka. Historical eruptions dating back 3,000 years have included more than 100 flank eruptions with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks. The previous report (BGVN 45:06) described ash plumes, nighttime incandescence, and Strombolian activity. Strombolian activity, ash plumes, and a strong lava flow continued. This report updates activity from June through August 2020 using weekly and daily reports from the Kamchatkan Volcanic Eruption Response Team (KVERT), the Tokyo Volcanic Ash Advisory (VAAC), and satellite data.

Moderate explosive-effusive activity continued in June 2020, with Strombolian explosions, frequent gas-and-steam emissions that contained some amount of ash, and an active lava flow. On 1 June a gas-and-steam plume containing some ash extended up to 465 km SE and E. The lava flow descended the SE flank down the Apakhonchich chute (figure 43). Occasionally, phreatic explosions accompanied the lava flow as it interacted with snow. Intermittent ash plumes, reported throughout the month by KVERT using video and satellite data and the Tokyo VAAC using HIMAWARI-8 imagery, rose to 5.5-6.7 km altitude and drifted in different directions up to 34 km from the volcano. On 12 and 30 June ash plumes rose to a maximum altitude of 6.7 km. On 19 June, 28-30 June, and 1-3 July some collapses were detected alongside the lava flow as it continued to advance down the SE flank.

Figure (see Caption) Figure 43. Gray ash plumes (left) and a lava flow descending the Apakhonchich chute on the SE flank, accompanied by a dark ash plume and Strombolian activity (right) were observed at the summit of Klyuchevskoy on 10 June 2020. Courtesy of E. Saphonova, IVS FEB RAS, KVERT.

During 1-3 July moderate Strombolian activity was observed, accompanied by gas-and-steam emissions containing ash and a continuous lava flow traveling down the Apakhonchich chute on the SE flank. On 1 July a Tokyo VAAC advisory reported an ash plume rising to 6 km altitude and extending SE. On 3 July the activity sharply decreased. KVERT reported there was some residual heat leftover from the lava flow and Strombolian activity that continued to cool through at least 13 July; KVERT also reported frequent gas-and-steam emissions, which contained a small amount of ash through 5 July, rising from the summit crater (figure 44). The weekly KVERT report on 16 July stated that the eruption had ended on 3 July 2020.

Figure (see Caption) Figure 44. Fumarolic activity continued in the summit crater of Klyuchevskoy on 7 July 2020. Courtesy of KSRS ME, Russia, KVERT.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows frequent and strong thermal activity within 5 km of the summit crater from March through June followed by a sharp and sudden decline in early July (figures 45). A total of six weak thermal anomalies were detected between July and August. According to the MODVOLC thermal algorithm, a total of 111 thermal alerts were detected at or near the summit crater from 1 June to 1 July, a majority of which were due to the active lava flow on the SE flank and Strombolian explosions in the crater. Sentinel-2 thermal satellite imagery frequently showed the active lava flow descending the SE flank as a strong thermal anomaly, sometimes even through weather clouds (figure 46). These thermal anomalies were also recorded by the Sentinel-2 MODIS Thermal Volcanic Activity data on a MIROVA graph, showing a strong cluster during June to early July, followed by a sharp decrease and then a hiatus in activity (figure 47).

Figure (see Caption) Figure 45. Thermal activity at Klyuchevskoy was frequent and strong during February through June 2020, according to the MIROVA graph (Log Radiative Power). Activity sharply decreased during July through August with six low-power thermal anomalies. Courtesy of MIROVA.
Figure (see Caption) Figure 46. Sentinel-2 thermal satellite images show the strong and persistent lava flow (bright yellow-orange) originating from the summit crater at Klyuchevskoy from 1 June through 1 July 2020. The lava flow was active in the Apakhonchich chute on the SE flank. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 47. Strong clusters of thermal anomalies were detected in the summit at Klyuchevskoy (red dots) during January through June 2020, as recorded by the Sentinel-2 MODIS Thermal Volcanic Activity data (bands 12, 11, 8A). Activity sharply decreased during July through August with few low-power thermal anomalies. Courtesy of MIROVA.

Geologic Background. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank 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/); 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/); 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).


Fuego (Guatemala) — September 2020 Citation iconCite this Report

Fuego

Guatemala

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

All times are local (unless otherwise noted)


Ongoing explosions, ash plumes, lava flows, and lahars during April-July 2020

Fuego, located in Guatemala, is a stratovolcano that has been erupting since 2002 with historical eruptions dating back to 1531. Volcanism is characterized by major ashfalls, pyroclastic flows, lava flows, and lahars. The previous report (BGVN 45:04) described recent activity that included multiple ash explosions, block avalanches, and intermittent lava flows. This report updates activity from April through July 2020 that consisted of daily explosions, ash plumes, block avalanches ashfall, intermittent lava flows, and lahars. The primary source of information comes from the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), the Washington Volcanic Ash Advisory Center (VAAC), and various satellite data.

Summary of activity during April-July 2020. Daily activity throughout April-July 2020 was characterized by multiple hourly explosions, ash plumes that rose to a maximum of 4.9 km altitude, incandescent pulses that reached 600 m above the crater, block avalanches into multiple drainages, and ashfall affecting nearby communities (table 21). The highest rate of explosions occurred on 2 and 3 April and 2 May with up to 16 explosions per hour. White degassing occurred frequently during the reporting period, rising to a maximum altitude of 4.5 km and drifting in multiple directions. Intermittent lava flows were observed each month in the Seca (Santa Teresa) and Ceniza drainages (figure 132); the number of flows decreased in June through July, which is represented in the MIROVA analysis of MODIS satellite data, where the strength and frequency of thermal activity slightly decreased (figure 133). Occasional lahars were detected descending several drainages on the W and SE flanks, sometimes carrying tree branches and large blocks up to 1 m in diameter.

Table 21. Activity summary by month for Fuego with information compiled from INSIVUMEH daily reports.

Month Number of explosions per hour Ash plume heights (km) Ash plume distance (km) and direction Drainages affected by block avalanches Villages reporting ashfall
Apr 2020 5-16 4.3-4.9 km 8-20 km E, NE, SE, W, NW, SW, S, N Taniluyá, Ceniza, Las Lajas, Trinidad, Seca, Honda, and Santa Teresa Morelia, Panimaché I and II, Sangre de Cristo, Santa Sofía, Finca Palo Verde, San Pedro Yepocapa, Las Cruces Quisache, La Rochela, Ceylan, and Osuna
May 2020 4-16 4.3-4.9 km 10-17 km S, SW, W, N, NE, E, SE Trinidad, Taniluyá, Ceniza, Las Lajas, Santa Teresa, Seca, and Honda Panimaché I, La Rochela, Ceilán, Morelia, San Andrés Osuna, Finca Palo Verde, Santa Sofía, Seilán, San Pedro Yepocapa, Alotenango, Ciudad Vieja, San Miguel Dueñas, and Antigua Guatemala
Jun 2020 3-15 4.2-4.9 km 10-25.9 km E, SE, S, N, NE, W, SW, NW Seca, Taniluyá, Ceniza, Trinidad, Las Lajas, Santa Teresa and Honda San Pedro Yepocapa, Sangre de Cristo, Panimaché I and II, Morelia, Finca Palo Verde, El Porvenir, Yucales, Santa Emilia, Santa Sofía
Jul 2020 1-15 4-4.9 km 10-24 km W, NW, SW, S, NE Trinidad, Taniluyá, Ceniza, Honda, Las Lajas, Seca, and Santa Teresa Panimaché I and II, Morelia, Santa Sofía, Finca Palo Verde, Sangre de Cristo, San Pedro Yepocapa, and El Porvenir
Figure (see Caption) Figure 132. Sentinel-2 thermal satellite images of Fuego between 9 April 2020 and 13 July 2020 showing lava flows (bright yellow-orange) traveling generally S and W from the summit crater. Some lava flows were accompanied by gas emissions (9 April, 9 May, and 24 May 2020). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 133. Thermal activity at Fuego was persistent and strong from 16 September through late May 2020, according to the MIROVA graph (Log Radiative Power). From early to mid-June activity seemed to stop briefly before resuming again at a lower rate. Courtesy of MIROVA.

Activity during April-May 2020. Activity in April 2020 consisted of 5-16 explosions per hour, generating ash plumes that rose 4.3-4.9 km altitude and drifted 8-20 km in multiple directions. Ashfall was reported in Morelia (9 km SW), Panimaché I and II (8 km SW), Sangre de Cristo (8 km WSW), Santa Sofía (12 km SW), Finca Palo Verde, San Pedro Yepocapa (8 km NW), Las Cruces Quisache (8 km NW), La Rochela, Ceylan, Osuna (12 km SW). The Washington VAAC issued multiple aviation advisories for a total of six days in April. Intermittent white gas-and-steam emissions reached 4.1-4.5 km altitude drifting in multiple directions. Incandescent ejecta was frequently observed rising 75-400 m above the crater; material ejected up to 600 m above the crater on 11 April. These constant explosions produced block avalanches that traveled down the Taniluyá (SW), Ceniza (SSW), Las Lajas (SE), Trinidad (S), Seca (W), Honda, and Santa Teresa (W) drainages. Effusive activity was reported on 6-13 and 15 April from the summit vent, traveling 150-800 m down the Ceniza drainage, accompanied by block avalanches in the front of the flow up to 1 km. Crater incandescence was also observed.

On 19-20 April a new lava flow descended the Ceniza drainage measuring 200-400 long, generating incandescent block avalanches at the front of the flow that moved up to 1 km. On 22 April lahars descended the Honda, Las Lajas, El Juté (SE), Trinidad, Ceniza, Taniluyá, Mineral, and Seca drainages and tributaries in Guacalate, Achiguate, and Pantaleón. During the evening of 23 April the rate of effusive activity increased; observatory staff observed a second lava flow in the Seca drainage was 170 m long and incandescent blocks from the flow traveled up to 600 m. Two lava flows in the Ceniza (130-400 m) and Seca (150-800 m) drainages continued from 23-28 April and had stopped by 30 April. On 30 April weak and moderate explosions produced ash plumes that rose 4.5-4.7 km altitude drifting S and SE, resulting in fine ashfall in Panimaché I, Morelia, Santa Sofía (figure 134).

Figure (see Caption) Figure 134. Photo of a small ash plume rising from Fuego on 30 April 2020. Photo has been slightly color corrected. Courtesy of William Chigna, CONRED.

During May 2020, the rate of explosion remained similar, with 4-16 explosions per hour, which generated gray ash plumes that rose 4.3-4.9 km altitude and drifted 10-17 km generally W and E. Ashfall was observed in Panimaché I, La Rochela, Ceilán, Morelia, San Andrés Osuna, Finca Palo Verde, Santa Sofía, Seilán, San Pedro Yepocapa, Alotenango (8 km ENE), Ciudad Vieja (13.5 km NE), San Miguel Dueñas (10 km NE), and Antigua Guatemala (18 km NE). The Washington VAAC issued volcanic ash advisory notices on six days in May. White gas-and-steam emissions continued, rising 4-4.5 km altitude drifting in multiple directions. Incandescent ejecta rose 100-400 m above the crater, accompanied by some crater incandescence and block avalanches in the Trinidad, Taniluyá, Ceniza, Las Lajas, Santa Teresa, Seca, and Honda drainages that moved up to 1 km and sometimes reached vegetated areas.

During 8-11 May a new 400 m long lava flow was detected in the Ceniza drainage, accompanied by constant crater incandescence and block avalanches traveling up to 1 km, according to INSIVUMEH. On 8 and 17 May moderate to strong lahars descended the Santa Teresa and Mineral drainages on the W flank and on 21 May they descended the Las Lajas drainage on the E flank and the Ceniza drainage on the SW flank. During 20-24 May a 100-400 m long lava flow was reported in the Ceniza drainage alongside degassing and avalanches moving up to 1 km and during 25-26 May a 150 m long lava flow was reported in the Seca drainage.

Activity during June-July 2020. The rate of explosions in June 2020 decreased slightly to 3-15 per hour, generating gray ash plumes that rose 4.2-4.9 km altitude and drifted 10-26 km in multiple directions (figure 135). As a result, intermittent ashfall was reported in San Pedro Yepocapa, Sangre de Cristo, Panimaché I and II, Morelia, Finca Palo Verde, El Porvenir (8 km ENE), Yucales (12 km SW), Santa Emilia, Santa Sofia, according to INSIVUMEH. VAAC advisories were published on eight days in June. Degassing persisted in the summit crater that rose 4.1-4.5 km altitude extending in different directions. Crater incandescence was observed occasionally, as well as incandescent pulses that rose 100-300 m above the crater. Block avalanches were observed descending the Seca, Taniluyá, Ceniza, Trinidad, Las Lajas, Santa Teresa, and Honda drainages, which could sometimes carry blocks up to 1 km in diameter.

On 2 June at 1050 a weak to moderate lahar was observed in the Las Lajas drainage on the SE flank. On 5 June, more lahars were detected in the Seca and Mineral drainages on the W flanks. A new lava flow was detected on 12 June, traveling 250 m down the Seca drainage on the NW flank, and accompanied by constant summit crater incandescence and gas emissions. The flow continued into 14 June, lengthening up to 300 m long. On 24 June weak and moderate explosions produced ash plumes that rose 4.3-4.7 km altitude drifting W and SW (figure 135). On 29 June at 1300 a weak lahar was reported in the Seca, Santa Teresa, and Mineral drainages on the W flank.

Figure (see Caption) Figure 135. Examples of small ash plumes at Fuego on 15 (left) and 24 (right) June 2020. Courtesy of William Chigna, CONRED.

Daily explosions and ash plumes continued through July 2020, with 1-15 explosions per hour and producing consistent ash plumes 4-4.9 km altitude drifting generally W for 10-24 km. These explosions resulted in block avalanches that descended the Trinidad, Taniluyá, Ceniza, Honda, Las Lajas, Seca, and Santa Teresa drainages. The number of white gas emissions decrease slightly compared to previous months and 4-4.4 km altitude. VAAC advisories were distributed on twenty different days in July. Incandescent ejecta was observed rising 100-350 m above the crater. Occasional ashfall was observed in Panimaché I and II, Morelia, Santa Sofía, Finca Palo Verde, Sangre de Cristo, San Pedro Yepocapa, and El Porvenir, according to INSIVUMEH.

On 4 July in the early morning, a lava flow began in the Seca drainage, which also produced some fine ash particles that drifted W. The lava flow continued into 5 July, measuring 150 m long. On the same day, weak to moderate lahars traveled only 20 m, carrying tree branches and blocks measuring 30 cm to 1 m. On 14, 24, and 29 July more lahars were generated in the Las Lajas drainages on the former date and both the Las Lajas and El Jute drainages on the two latter dates.

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/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); William Chigna, CONRED (URL: https://twitter.com/william_chigna).


Nishinoshima (Japan) — September 2020 Citation iconCite this Report

Nishinoshima

Japan

27.247°N, 140.874°E; summit elev. 25 m

All times are local (unless otherwise noted)


Major June-July eruption of lava, ash, and sulfur dioxide; activity declines in August 2020

Japan’s Nishinoshima volcano, located about 1,000 km S of Tokyo in the Ogasawara Arc, erupted above sea level in November 2013 after 40 years of dormancy. Activity lasted through November 2015 and returned during mid-2017, continuing the growth of the island with ash plumes, ejecta, and lava flows. A short eruptive event in July 2018 produced a small lava flow and vent on the side of the pyroclastic cone. The next eruption of ash plumes, incandescent ejecta, and lava flows began in early December 2019, resulting in significant growth of the island. This report covers the ongoing activity from March-August 2020 when activity decreased. Information is provided primarily from Japan Meteorological Agency (JMA) monthly reports and the Japan Coast Guard (JCG), which makes regular overflights to make observations.

Renewed eruptive activity that began on 5 December 2019 continued during March-August 2020 but appeared to wane by the end of August. Major lava flows covered all sides of the island, with higher levels of activity during late June and early July. Ash emissions increased significantly during June and produced dense black ash plumes that rose up to 6 km altitude in early July. Explosive activity produced lightning and incandescent jets that rose 200 m and large bombs that fell to the base of the pyroclastic cone. Lava flow activity diminished at the end of July. Ash emissions decreased throughout August and appeared to cease after 27 August 2020. The MIROVA plot clearly reflects the high levels of thermal activity between December 2019 and August 2020 (figure 80); this event was reported by JMA as the largest eruption recorded to date. Sulfur dioxide emissions were very high during late June through early August, producing emissions that drifted across much of the western Pacific region.

Figure (see Caption) Figure 80. The MIROVA plot of thermal activity at Nishinoshima from 14 October 2019 through August 2020 indicates the high levels between early December 2019 and late July 2020 that resulted from the eruption of numerous lava flows on all flanks of the pyroclastic cone, significantly enlarging the island. Courtesy of MIROVA.

The Japan Coast Guard (JCG) conducted overflights of Nishinoshima on 9 and 15 March 2020 (figure 81). During both visits they observed eruptive activity from the summit crater, including ash emissions that rose to an altitude of approximately 1,000 m and lava flowing down the N and SE flanks (figure 82). Large ejecta was scattered around the base of the pyroclastic cone. The lava flowing north had reached the coast and was producing vigorous steam as it entered the water on 9 March; whitish gas emissions were visible on the N flank of the cone at the source of the lava flow (figure 83). On 9 March yellow-green discolored water was noted off the NE shore. The lava flow on the SE coast produced a small amount of steam at the ocean entry point and a strong signal in thermal imagery on 15 March (figure 84). Multiple daily MODVOLC thermal alerts were issued during 1-10, 17-24, and 27-30 March. Landsat-8 visual and thermal imagery on 30 March 2020 confirmed that thermal anomalies on the N and SE flanks of the volcano continued.

Figure (see Caption) Figure 81. The Japan Coast Guard conducted an overflight of Nishinoshima on 9 March 2020 and observed ash emissions rising 1,000 m above the summit and lava flowing into the ocean off the N flank of the island. Courtesy of Japan Coast Guard (JCG) and JMA.
Figure (see Caption) Figure 82. Lava flows at Nishinoshima during February and March 2020 were concentrated on the N and SE flanks. The areas in blue indicate topographical changes due to lava flows and pyroclastic deposits from the previous measurement. The growth of the SE-flank flow decreased during March while the N-flank flow rate increased significantly. Left image shows changes between 14 and 28 February and right image shows the differences between 28 February and 13 March. The correlated image analysis uses ALOS-2 / PALSAR-2 and is carried out with the cooperation of JAXA through the activities of the Satellite Analysis Group of the Volcano Eruption Prediction Liaison Committee. The software was developed by the Japan National Research Institute for Earth Science and Disaster Prevention and uses the technical data C1-No 478 of the Geospatial Information Authority of Japan. Courtesy of JAXA and JMA (Volcanic activity commentary material on Nishinoshima, March 2020).
Figure (see Caption) Figure 83. Vigorous steam emissions on the N flank of Nishinoshima on 9 March 2020 were caused by the active flow on the N flank. Whitish steam and gas midway up the flank indicated the outlet of the flow. Ash emissions rose from the summit crater and drifted E. Courtesy of Japan Coast Guard and JMA.
Figure (see Caption) Figure 84. Infrared imagery from 15 March 2020 at Nishinoshima showed the incandescent lava flow on the SE flank (foreground), blocks of ejecta scattered around the summit and flanks of the pyroclastic cone, and the active N-flank flow (left). Courtesy of Japan Coast Guard and JMA.

Ash emissions were not observed at Nishinoshima during JCG overflights on 6, 16, and 19 April 2020, but gas-and-steam emissions were noted from the summit crater, and a yellow discoloration interpreted by JMA to be sulfur precipitation was observed near the top of the pyroclastic cone. The summit crater was larger than during previous visits. Steam plumes seen each of those days on the N and NE coasts suggested active ocean entry of lava flows (figure 85). A lava flow was observed emerging from the E flank of the cone and entering the ocean on the E coast on 19 and 29 April (figure 86). During the overflight on 29 April observers noted lava flowing southward from a vent on the E flank of the pyroclastic cone. A narrow, brown, ash plume was visible on 29 April at the summit crater rising to an altitude of about 1,500 m. Thermal observations indicated continued flow activity throughout the month. Multiple daily MODVOLC thermal alerts were recorded during 2-6, 10-11, 17-23, and 28-30 April. Significant growth of the pyroclastic cone occurred between early February and late April 2020 (figure 87).

Figure (see Caption) Figure 85. Multiple entry points of lava flowed into the ocean producing jets of steam along the N flank of Nishinoshima on 6 April 2020. Courtesy of JCG and JMA.
Figure (see Caption) Figure 86. Lava flowed down the E flank of Nishinoshima from a vent below the summit on 19 April 2020. The ocean entry produced a vigorous steam plume (left). Courtesy of JCG.
Figure (see Caption) Figure 87. The pyroclastic cone at Nishinoshima grew significantly in size between 4 February (left), 9 March (middle), and 19 April 2020 (right). View is to the E. Courtesy of JMA and JCG.

Infrared satellite imagery from 17 May 2020 showed a strong thermal anomaly at the summit and hot spots on the NW flank indicative of flows. Visible imagery confirmed emissions at the summit and steam plumes on the NW flank (figure 88). Gray ash plumes rose to about 1,800 m altitude on 18 May during the only overflight of the month made by the Japan Coast Guard. In addition, white gas emissions rose from around the summit area and large blocks of ejecta were scattered around the base of the pyroclastic cone (figure 89). Steam from ocean-entry lava on the N flank was reduced from previous months, but a new flow moving NW into the ocean was generating a steam plume and a strong thermal signature. Multi-pixel thermal alerts were measured by the MODVOLC system on 1-3, 9-10, 13-15, 18, and 26-30 May. Sulfur dioxide emissions had been weak and intermittent from March through early May 2020 but became more persistent during the second half of May. Although modest in size, the plumes were detectible hundreds of kilometers away from the volcano (figure 90).

Figure (see Caption) Figure 88. Landsat-8 satellite imagery of Nishinoshima from 17 May 2020 confirmed continued eruptive activity. Visible imagery showed emissions at the summit and steam plumes on the NW flank (left) and infrared imagery showed a strong thermal anomaly at the summit and anomalies on the NW flank indicative of lava flows (right). Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 89. Lava continued to enter the ocean at Nishinoshima during May 2020. A new lava flow on the NW flank produced a strong steam plume at an ocean entry (left) on 18 May 2020. In addition to a light gray plume of gas and ash, steaming blocks of ejecta were visible on the flanks of the pyroclastic cone. The strong thermal signature of the NW-flank flow in infrared imagery that same day showed multiple new lobes flowing to the ocean (right). Courtesy of JCG and JMA.
Figure (see Caption) Figure 90. Small but distinct SO2 emissions from Nishinoshima were recorded by the TROPOMI instrument on the Sentinel-5P satellite during the second half of May 2020. The plumes drifted tens to hundreds of kilometers away from the volcano in multiple directions as the wind directions changed. Nishinoshima is about 1,000 kilometers S of Tokyo. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Activity increased significantly during June 2020. Satellite imagery from 2 June revealed two intense thermal anomalies at the summit indicating a new crater, and lava flows active on the NW and NE flanks, all showing gas or steam emissions (figure 91). Dense brown and gray ash emissions were observed rising from the summit crater during JCG overflights on 7 and 15 June (figure 92). Plumes reached at least 1,500 m altitude, and ejecta reached the base of the pyroclastic cone. Between 5 and 19 June the lava flow on the WNW coast slowed significantly, while the flows to the N and E became significantly more active (figure 93). The Tokyo VAAC reported the first ash plume since mid-February on 12 June rose to 2.1 km and drifted NE. On 14 June they reported an ash plume extending E at 2.7 km altitude. Dense emissions continued to drift N and E at 2.1-2.7 km altitude until the last week of the month. The JCG overflight on 19 June observed darker ash emissions than two weeks earlier that drifted at least 180 km NE (figure 94) and incandescent tephra that exploded from the enlarged summit area where three overlapping craters trending E-W had formed.

Figure (see Caption) Figure 91. Landsat-8 satellite imagery on 2 June 2020 confirmed ongoing activity at Nishinoshima. Lava produced ocean-entry steam on the NE coast; a weak plume on the NW coast suggested reduced activity in that area (left). In addition, a dense steam plume drifted E from the summit, while a fainter plume adjacent to it also drifted E. The infrared image (right) indicated two intense anomalies at the summit, and weaker anomalies from lava flows on the NW and NE flanks. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 92. Lava flows at Nishinoshima entered the ocean on the N and NE coasts (left) on 7 June 2020, and dense, gray ash emissions rose to at least 1,500 m altitude. Courtesy of JCG.
Figure (see Caption) Figure 93. The lava flow on the WNW coast of Nishinoshima slowed significantly in early June 2020, while the flows to the N and E covered large areas of those flanks between 5 and 19 June. The areas in blue indicate topographical changes due to lava flows and pyroclastic deposits from the previous measurement. Left image shows the differences between 22 May and 5 June and right image shows changes between 5 and 19 June. The correlated image analysis uses ALOS-2 / PALSAR-2 and is carried out with the cooperation of JAXA through the activities of the Satellite Analysis Group of the Volcano Eruption Prediction Liaison Committee. The software was developed by the National Research Institute for Earth Science and Disaster Prevention and uses the technical data C1-No 478 of the Geospatial Information Authority of Japan. Courtesy of JAXA and JMA (Volcanic activity commentary material on Nishinoshima, June 2020).
Figure (see Caption) Figure 94. Ash emissions and explosive activity at Nishinoshima increased significantly during the second half of June. Dense black ash rose to 2.4 km altitude and drifted at least 180 km to the NE on 19 June 2020. Vigorous white steam plumes rose from the ocean on the E flank where a lava flow entered the ocean. Courtesy of JCG.

The Tokyo VAAC reported ash emissions that rose to 4.6 km altitude and drifted NE on 25 June. For the remainder of the month they rose to 2.7-3.9 km altitude and drifted N and NE. By the time of the JCG overflight on 29 June, the new crater that had opened on the SW flank had merged with the summit crater (figure 95). Dense black ash emissions rose to 3.4 km altitude and drifted NE, lava flowed down the SW flank into the ocean producing violent steam explosions, and incandescent tephra was scattered at least 200 m from the base of the pyroclastic cone from ongoing explosive activity (figure 96). Multiple layers of recent flow activity were visible along the SW coast (figure 97). Yellow-green discolored water encircled the entire island with a width of 1,000 m.

Figure (see Caption) Figure 95. The new crater on the SW flank of Nishinoshima had merged with the summit crater by 29 June 2020. Courtesy of JCG and JMA.
Figure (see Caption) Figure 96. Dense black ash emissions rose to 3.4 km altitude and drifted NE from the summit of Nishinoshima on 29 June 2020. Lava flowed down the SW flank into the ocean producing steam explosions, and incandescent tephra was scattered at least 200 m from the base of the pyroclastic cone from ongoing explosive activity at the summit (inset). Courtesy of JCG.
Figure (see Caption) Figure 97. Different textures of lava flows were visible along the SW flank of Nishinoshima on 29 June 2020. The active flow appeared dark brown and blocky, and produced steam explosions at the ocean entry site (right). Slightly older, brownish-red lava (center) still produced steam along the coastline. Courtesy of JCG.

MODVOLC thermal alerts reached their highest levels of the period during June 2020 with multi-pixel alerts recorded on most days of the month. Sulfur dioxide emissions increased steadily throughout June to the highest levels recorded for Nishinoshima; by the end of the month plumes of SO2 were drifting thousands of kilometers across the Pacific Ocean and being captured in complex atmospheric circulation currents (figure 98).

Figure (see Caption) Figure 98. Sulfur dioxide emissions at Nishinoshima increased noticeably during the second half of June 2020 as measured by the TROPOMI instrument on the Sentinel-5P satellite. Atmospheric circulation currents produced long-lived plumes that drifted thousands of kilometers from the volcano. Nishinoshima is 1,000 km S of Tokyo. Courtesy of NASA Sulfur Dioxide Monitoring Page.

By early July 2020, satellite data indicated that the NE quadrant of the island was covered with ash, and a large amount of new lava had flowed down the SW flank, creating fans extending into the ocean (figure 99). The Tokyo VAAC reported ash emissions that rose to 3.7-4.9 km altitude and drifted N during 1-6 July. The altitude increased to 6.1 km during 8 and 9 July, and ranged from 4.6-6.1 km during 10-14 July while the drift direction changed to NE. The marine meteorological observation ship "Ryofu Maru" reported on 11 July that dense black ash was continuously erupting from the summit crater and drifting W at 1,700 m altitude or higher. They observed large volcanic blocks scattered around the base of the pyroclastic cone, and ash falling from the drifting plume. During the night of 11 July incandescent lava and volcanic lightning rose to about 200 m above the crater rim (figure 100).

Figure (see Caption) Figure 99. By early July 2020, satellite data from Nishinoshima indicated that the NE quadrant of the island was covered with ash, and a large amount of new lava had flowed down the SW flank creating fans extending into the ocean. The areas in blue indicate topographical changes due to lava flows and pyroclastic deposits from the previous measurement. Left image shows differences between 5 and 19 June and the right image shows changes between 19 June and 3 July that included abundant ashfall on the NE flank. The correlated image analysis uses ALOS-2 / PALSAR-2 and is carried out with the cooperation of JAXA through the activities of the Satellite Analysis Group of the Volcano Eruption Prediction Liaison Committee. The software was developed by the National Research Institute for Earth Science and Disaster Prevention and uses the technical data C1-No 478 of the Geospatial Information Authority of Japan. Courtesy of JAXA and JMA (Volcanic activity commentary material on Nishinoshima, June 2020).
Figure (see Caption) Figure 100. High levels of activity were observed at Nishinoshima by crew members aboard the marine meteorological observation ship "Ryofu Maru” on 11 July 2020. Abundant ash emissions filled the sky and tephra fell out of the ash cloud for several kilometers downwind (left, seen from 6 km NE). Incandescent explosions rose as much as 200 m into the night sky (right, seen from 4 km E). Courtesy of JMA.

During 16-26 July 2020 the Tokyo VAAC reported ash emissions at 3.7-5.2 km altitude that drifted primarily N and NE. The vessel "Keifu Maru" passed Nishinoshima on 20 July and crewmembers observed continuing emissions from the summit of dense, black ash. JCG observed an ash plume rising to at least 2.7 km altitude during their overflight of 20 July. A large dome of fresh lava was visible on the SW flank of the island (figure 101). Lower ash emissions from 2.4-3.7 km altitude were reported by the Tokyo VAAC during 27-29 July, but the altitude increased to 5.5-5.8 km during the last two days of the month. During an overflight on 30 July by the National Research Institute for Earth Science and Disaster Prevention, dark and light gray ash emissions rose to 3.0 km altitude, but no flowing lava or large bombs were observed. They also noted thick deposits of brownish-gray ash on the N side of the island (figure 102).

Figure (see Caption) Figure 101. JCG observed an ash plume at Nishinoshima rising to at least 2.7 km altitude during their overflight of 20 July 2020. A large dome of fresh lava was visible on the SW flank of the island. Courtesy of JCG.
Figure (see Caption) Figure 102. Ash emissions changed from dark to light gray on 30 July 2020 at Nishinoshima as seen during an overflight by the National Research Institute for Earth Science and Disaster Prevention. Thick brownish-gray ash was deposited over the lava on the N side of the island. Courtesy of JMA (Information on volcanic activity in Nishinoshima, July 2020).

JMA reported a sharp decrease in the lava eruption rate during July with thermal anomalies decreasing significantly mid-month. Multiple daily MODVOLC thermal alerts were recorded during the first half of the month but were reduced to two or three per day during the last third of July. Throughout July, SO2 emissions were the highest recorded in modern times for Nishinoshima. High levels of emissions were measured daily, producing streams with high concentrations of SO2 that were caught up in rotating wind currents and drifted thousands of kilometers across the Pacific Ocean (figure 103).

Figure (see Caption) Figure 103. Complex atmospheric wind patterns carried the largest SO2 plumes recorded from Nishinoshima thousands of kilometers around the western Pacific Ocean during July 2020. Nishinoshima is about 1,000 km S of Tokyo. Top and bottom left images both show 6 July but at different scales. Courtesy of NASA Sulfur Dioxide Monitoring Page.

Thermal activity was greatly reduced during August 2020. Only one or two MODVOLC alerts were issued on 11, 18, 20, 21, 29, and 30 August, and no fresh lava flows were observed. The Tokyo VAAC reported ash emissions daily from 1-20 August. Plume heights were 4.9-5.8 km altitude during 1-4 August after which they dropped to 3.9 km altitude through 15 August. A brief pulse to 4.6 km altitude was recorded on 16 August, but then they dropped to 3.0 km or lower through the end of the month and became intermittent. The last ash emission was reported at 2.7 km altitude drifting W on 27 August.

No eruptive activity was observed during the Japan Coast Guard overflights on 19 and 23 August. High temperatures were measured on the inner wall of the summit crater on 19 August (figure 104). Steam plumes rose from the summit crater to about 2.5 km altitude during both visits (figure 105). Yellow-green discolored water was present on 23 August around the NW and SW coasts. No lava flows were observed, and infrared cameras did not measure any surface thermal anomalies outside of the crater. Very high levels of SO2 emissions were measured through 12 August when they began to noticeably decrease (figure 106). By the end of the month, only small amounts of SO2 were measured in satellite data.

Figure (see Caption) Figure 104. A strong thermal anomaly was still present inside the newly enlarged summit crater at Nishinoshima on 19 August 2020. Courtesy of JCG.
Figure (see Caption) Figure 105. Only steam plumes were observed rising from the summit crater of Nishinoshima during the 23 August 2020 overflight by the Japan Coast Guard. Courtesy of JCG.
Figure (see Caption) Figure 106. Sulfur dioxide emissions remained very high at Nishinoshima until 12 August 2020 when they declined sharply. Circulating air currents carried SO2 thousands of kilometers around the western Pacific region. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Geologic Background. The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74. Another eruption that began offshore in 2013 completely covered the previous exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since. The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m of the sea surface 9 km SSE.

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); Japan Coast Guard (JCG), Hydrographic and Oceanographic Department, 3-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8932, Japan (URL: https://www1.kaiho.mlit.go.jp/GIJUTSUKOKUSAI/kaiikiDB/kaiyo18-e1.htm); 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/); 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/); Japan Aerospace Exploration Agency-Earth Observation Research Center (JAXA-EORC), 7-44-1 Jindaiji Higashi-machi, Chofu-shi, Tokyo 182-8522, Japan (URL: http://www.eorc.jaxa.jp/); 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/).


Turrialba (Costa Rica) — September 2020 Citation iconCite this Report

Turrialba

Costa Rica

10.025°N, 83.767°W; summit elev. 3340 m

All times are local (unless otherwise noted)


New eruptive period on 18 June 2020 consisted of ash eruptions

Turrialba is a stratovolcano located in Costa Rica that overlooks the city of Cartago. Three well-defined craters occur at the upper SW end of a broad 800 x 2,200 m summit depression that is breached to the NE. Activity described in the previous report primarily included weak ash explosions and minor ash emissions (BGVN 44:11). This reporting period updates information from November 2019-August 2020; volcanism dominantly consists of ash emissions during June-August, based on information from daily and weekly reports by the Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA) and satellite data.

Volcanism during November 2019 through mid-June was relatively low, dominated by low SO2 emissions (100-300 tons/day) and typical low seismic tremors. A single explosion was recorded at 1850 on 7 December 2019, and two gas-and-steam plumes rose 800 m and 300 m above the crater on 25 and 27 December, respectively. An explosion was detected on 29 January 2020 but did not result in any ejecta. An overflight during the week of 10 February measured the depth of the crater (140 m); since the previous measurements made in February 2019 (220 m), the crater has filled with 80 m of debris due to frequent collapses of the NW and SE internal crater walls. Beginning around February and into at least early May 2020 the Sentinel-2 MODIS Thermal Volcanic Activity graph provided by the MIROVA system detected a small cluster of thermal anomalies (figure 52). Some of these anomalies were faintly registered in Sentinel-2 thermal satellite imagery during 10 and 25 April, with a more distinct anomaly occurring on 15 May (figure 53).

Figure (see Caption) Figure 52. A small cluster of thermal anomalies were detected in the summit area of Turrialba (red dots) during February-May 2020 as recorded by the Sentinel-2 MODIS Thermal Volcanic Activity data (bands 12, 11, 8A). Courtesy of MIROVA.
Figure (see Caption) Figure 53. Sentinel-2 thermal satellite imagery detected minor gas-and-steam emissions (left) and a weak thermal anomaly (right) in the summit crater at Turrialba on 11 January and 15 May 2020, respectively. Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.

On 18 June activity increased, which marked the start of a new eruptive period that produced ash emissions rising 100 m above the crater rim at 1714, 1723, and 1818. The next morning, 19 June, two more events at 1023 and 1039 resulted in ash emissions rising 100 m above the crater. During 23-26 June small ash emissions continued to occur each day, rising no higher than 100 m above the crater. A series of small ash eruptions that rose 100 m above the crater occurred during 28 and 29 June; four events were recorded at 0821, 1348, 1739, and 2303 on 28 June and five more were recorded at 0107, 0232, 0306, 0412, and 0818 on 29 June. The two events at 0107 and 0412 were accompanied by ballistics ejected onto the N wall of the crater, according to OVSICORI-UNA.

Almost daily ash emissions continued during 1-7 July, rising less than 100 m above the crater; no ash emissions were observed on 3 July. On 6 July, gas-and-steam and ash emissions rose hundreds of meters above the crater at 0900, resulting in local ashfall. Passive gas-and-steam emissions with minor amounts of ash were occasionally visible during 9-10 July. On 14 July an eruptive pulse was observed, generating brief incandescence at 2328, which was likely associated with a small ash emission. Dilute ash emissions at 1028 on 16 July preceded an eruption at 1209 that resulted in an ash plume rising 200 m above the crater. Ash emissions of variable densities continued through 20 July rising as high as 200 m above the crater; on 20 July incandescence was observed on the W wall of the crater. An eruptive event at 0946 on 29 July produced an ash plume that rose 200-300 m above the crater rim. During 30-31 July a series of at least ten ash eruptions were detected, rising no higher than 200 m above the crater, each lasting less than ten minutes. Some incandescence was visible on the SW wall of the crater during this time.

On 1 August at 0746 an ash plume rose 500 m above the crater. During 4-5 August a total of 19 minor ash emissions occurred, accompanied by ash plumes that rose no higher than 200 m above the crater. OVSICORI-UNA reported on 21 August that the SW wall of the crater had fractured; some incandescence in the fracture zone had been observed the previous month. Two final eruptions were detected on 22 and 24 August at 1253 and 2023, respectively. The eruption on 24 August resulted in an ash plume that rose to a maximum height of 1 km above the crater.

Geologic Background. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive edifice covers an area of 500 km2. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

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/); 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).


Etna (Italy) — September 2020 Citation iconCite this Report

Etna

Italy

37.748°N, 14.999°E; summit elev. 3320 m

All times are local (unless otherwise noted)


Effusive activity in early April; frequent Strombolian explosions and ash emissions during April-July 2020

Etna, located on the island of Sicily, Italy, is a stratovolcano that has had historical eruptions dating back 3,500 years. Its most recent eruptive period began in September 2013 and has continued through July 2020, characterized by Strombolian explosions, lava flows, and ash plumes. Activity has commonly originated from the summit areas, including the Northeast Crater (NEC), the Voragine-Bocca Nuova (or Central) complex (VOR-BN), the Southeast Crater (SEC, formed in 1978), and the New Southeast Crater (NSEC, formed in 2011). The newest crater, referred to as the "cono della sella" (saddle cone), emerged during early 2017 in the area between SEC and NSEC. Volcanism during this reporting period from April through July 2020 includes frequent Strombolian explosions primarily in the Voragine and NSEC craters, ash emissions, some lava effusions, and gas-and-steam emissions. Information primarily comes from weekly reports by the Osservatorio Etneo (OE), part of the Catania Branch of Italy's Istituo Nazionale di Geofisica e Vulcanologica (INGV).

Summary of activity during April-July 2020. Degassing of variable intensity is typical activity from all summit vents at Etna during the reporting period. Intra-crater Strombolian explosions and ash emissions that rose to a maximum altitude of 5 km on 19 April primarily originated from the Voragine (VOR) and New Southeast Crater (NSEC) craters. At night, summit crater incandescence was occasionally visible in conjunction with explosions and degassing. During 18-19 April small lava flows were observed in the VOR and NSEC craters that descended toward the BN from the VOR Crater and the upper E and S flanks of the NSEC. On 19 April a significant eruptive event began with Strombolian explosions that gradually evolved into lava fountaining activity, ejecting hot material and spatter from the NSEC. Ash plumes that were produced during this event resulted in ashfall to the E of Etna. The flows had stopped by the end of April; activity during May consisted of Strombolian explosions in both the VOR and NSEC craters and intermittent ash plumes rising 4.5 km altitude. On 22 May Strombolian explosions in the NSEC produced multiple ash plumes, which resulted in ashfall to the S. INGV reported that the pit crater at the bottom of BN had widened and was accompanied by degassing. Explosions with intermittent ash emissions continued during June and July and were primarily focused in the VOR and NSEC craters; mild Strombolian activity in the SEC was reported in mid-July.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows multiple episodes of thermal activity throughout the reporting period (figure 296). In early April, the frequency and power of the thermal anomalies began to decrease through mid-June; in July, they had increased in power again but remained less frequent compared to activity in January through March. According to the MODVOLC thermal algorithm, a total of seven alerts were detected in the summit craters during 10 April (1), 17 April (1), 24 April (2), 10 July (1), 13 July (1), and 29 July (1) 2020. These thermal hotspots were typically registered during or after a Strombolian event. Frequent Strombolian activity contributed to distinct SO2 plumes that drifted in different directions (figure 297).

Figure (see Caption) Figure 296. Multiple episodes of varying thermal activity at Etna from 14 October 2019 through July 2020 were reflected in the MIROVA data (Log Radiative Power). In early April, the frequency and power of the thermal anomalies decreased through mid-June. In July, the thermal anomalies increased in power, but did not increase in frequency. Courtesy of MIROVA.
Figure (see Caption) Figure 297. Distinct SO2 plumes from Etna were detected on multiple days during April to July 2020 due to frequent Strombolian explosions, including, 24 April (top left), 9 May (top right), 25 June (bottom left), and 21 July (bottom right) 2020. Captured by the TROPOMI instrument on the Sentinel 5P satellite, courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Activity during April-May 2020. During April, INGV reported Strombolian explosions that produced some ash emissions and intra-crater effusive activity within the Voragine Crater (VOR) and abundant degassing from the New Southeast Crater (NSEC), Northeast Crater (NEC), and from two vents on the cono della sella (saddle cone) that were sometimes accompanied by a modest amount of ash (figure 298). At night, summit crater incandescence was observed in the cono della salla. The Strombolian activity in the VOR built intra-crater scoria cones while lava flows traveled down the S flank of the largest, main cone. On 18 April effusive activity from the main cone in the VOR Crater traveled 30 m toward the Bocca Nuova (BN) Crater; the pit crater at the bottom of the BN crater had widened compared to previous observations. A brief episode of Strombolian explosions that started around 0830 on 19 April in the NSEC gradually evolved into modest lava fountaining activity by 0915, rising to 3 km altitude and ejecting bombs up to 100 m (figure 299). A large spatter deposit was found 50 m from the vent and 3-4 small lava flows were descending the NSEC crater rim; two of these summit lava flows were observed at 1006, confined to the upper E and S flanks of the cone. Around 1030, one or two vents in the cono della sella produced a gas-and-steam and ash plume that rose 5 km altitude and drifted E, resulting in ashfall on the E flank of Etna in the Valle del Bove, as well as between the towns of Zafferana Etnea (10 km SE) and Linguaglossa (17 km NE). At night, flashes of incandescence were visible at the summit. By 1155, the lava fountaining had gradually slowed, stopping completely around 1300. The NEC continued to produce gas-and-steam emissions with some intra-crater explosive activity. During the week of 20-26 April, Strombolian activity in the VOR intra-crater scoria cone ejected pyroclastic material several hundred meters above the crater rim while the lava flows had significantly decreased, though continued to travel on the E flank of the main cone. Weak, intra-crater Strombolian activity with occasional ash emissions and nightly summit incandescence were observed in the NSEC (figure 300). By 30 April there were no longer any active lava flows; the entire flow field had begun cooling. The mass of the SO2 emissions varied in April from 5,000-15,000 tons per day.

Figure (see Caption) Figure 298. Photos of Strombolian explosions at Etna in the Voragine Crater (top left), strong degassing at the Northeast Crater (NEC) (top right), and incandescent flashes and Strombolian activity in the New Southeast Crater (NSEC) seen from Tremestieri Etneo (bottom row) on 10 April 2020. Photos by Francesco Ciancitto (top row) and Boris Behncke (bottom row), courtesy of INGV.
Figure (see Caption) Figure 299. Strombolian activity at Etna’s “cono della sella” of the NSEC crater on 19 April 2020 included (a-b) lava fountaining that rose 3 km altitude, ejecting bomb-sized material and a spatter deposit captured by the Montagnola (EMOV) thermal camera. (c-d) An eruptive column and increased white gas-and-steam and ash emissions were captured by the Montagnola (EMOV) visible camera and (e-f) were also seen from Tremestieri Etneo captured by Boris Behncke. Courtesy of INGV (Report 17/2020, ETNA, Bollettino Settimanale, 13/04/2020 – 19/04/2020, data emissione 21/04/2020).
Figure (see Caption) Figure 300. Webcam images showing intra-crater explosive activity at Etna in the Voragine (VOR) and New Southeast Crater (NSEC) on 24 April 2020 captured by the (a-b) Montagnola and (c) Monte Cagliato cameras. At night, summit incandescence was visible and accompanied by strong degassing. Courtesy of INGV (Report 18/2020, ETNA, Bollettino Settimanale, 20/04/2020 – 26/04/2020, data emissione 28/04/2020).

Strombolian explosions produced periodic ash emissions and ejected mild, discontinuous incandescent material in the VOR Crater; the coarse material was deposited onto the S flank of BN (figure 301). Pulsating degassing continued from the summit craters, some of which were accompanied by incandescent flashes at night. The Strombolian activity in the cono della sella occasionally produced reddish ash during 3-4 May. During 5 and 8 May, there was an increase in ash emissions at the NSEC that drifted SSE. A strong explosive event in the VOR Crater located E of the main cone produced a significant amount of ash and ejected coarse material, which included blocks and bombs measuring 15-20 cm, that fell on the W edge of the crater, as well as on the S terrace of the BN Crater (figure 302).

Figure (see Caption) Figure 301. Photos of Strombolian explosions and summit incandescence at Etna on 4 May (left) and during the night of 11-12 May. Photos by Gianni Pennisi (left) and Boris Behncke (right, seen from Tremestieri Etneo). Courtesy of INGV.
Figure (see Caption) Figure 302. A photo on 5 May (left) and thermal image on 8 May (right) of Strombolian explosions at Etna in the Voragine Crater accompanied by a dense, gray ash plume. Photo by Daniele Andronico. Courtesy of INGV (Report 20/2020, ETNA, Bollettino Settimanale, 04/05/2020 – 10/05/2020, data emissione 12/05/2020).

On 10 May degassing continued in the NSEC while Strombolian activity fluctuated in both the VOR and NSEC Craters, ejecting ballistics beyond the crater rim; in the latter, some of the blocks fell back in, accumulated on the edge, and rolled down the slopes (figure 303). During the week of 11-17 May, eruptive activity at the VOR Crater was the lowest observed since early March; there were 4-5 weak, low intensity pulses not accompanied by bombs or ashfall in the VOR Crater. Degassing continued in the BN Crater. The crater of the cono della sella had widened further N following collapses due to the Strombolian activity, which exposed the internal wall.

Figure (see Caption) Figure 303. Map of the summit craters of Etna showing the active vents, the area of cooled lava flows (light green), and the location of the widening pit crater in the Bocca Nuova (BN) Crater (light blue circle) updated on 9 May 2020. The base is modified from a 2014 DEM created by Laboratorio di Aerogeofisica-Sezione Roma 2. Black hatch marks indicate the crater rims: BN = Bocca Nuova, with NW BN-1 and SE BN-2; VOR = Voragine; NEC = North East Crater; SEC = South East Crater; NSEC = New South East Crater. Red circles indicate areas with ash emissions and/or Strombolian activity, yellow circles indicate steam and/or gas emissions only. Courtesy of INGV (Report 29/2020, ETNA, Bollettino Settimanale, 06/07/2020 – 12/07/2020, data emissione 14/07/2020).

On 18 May an ash plume from the NSEC rose 4.5 km altitude and drifted NE. Strombolian explosions on 22 May at the NSEC produced multiple ash plumes that rose 4.5 km altitude and drifted S and SW (figure 304), depositing a thin layer of ash on the S slope, and resulting in ashfall in Catania (27 km S). Explosions from the VOR Crater had ejected a deposit of large clasts (greater than 30 cm) on the NE flank, between the VOR Crater and NEC on 23 May. INGV reported that the pit crater in the BN continued to widen and degassing was observed in the NSEC, VOR Crater, and NEC. During the week of 25-31 May persistent visible flashes of incandescence at night were observed, which suggested there was intra-crater Strombolian activity in the SEC and NSEC. The mass of the SO2 plumes varied between 5,000-9,000 tons per day.

Figure (see Caption) Figure 304. Photo of repeated Strombolian activity and ash emissions rising from Etna above the New Southeast Crater (NSEC) on 22 May 2020 seen from Zafferana Etnea on the SE flank at 0955 local time. Photo by Boris Behncke, INGV.

Activity during June-July 2020. During June, moderate intra-crater Strombolian activity with intermittent ash emissions continued in the NSEC and occurred more sporadically in the VOR Crater; at night, incandescence of variable intensity was observed at the summit. During the week of 8-14 June, Strombolian explosions in the cono della sella generated some incandescence and rare jets of incandescent material above the crater rim, though no ash emissions were reported. On the morning of 14 June a sequence of ten small explosions in the VOR Crater ejected incandescent material just above the crater rim and produced small ash emissions. On 25 June an overflight showed the developing pit crater in the center of the BN, accompanied by degassing along the S edge of the wall; degassing continued from the NEC, VOR Crater, SEC, and NSEC (figure 305). The mass of the SO2 plumes measured 5,000-7,000 tons per day, according to INGV.

Figure (see Caption) Figure 305. Aerial photo of Etna from the NE during an overflight on 25 June 2020 by the Catania Coast Guard (2 Nucleo Aereo della Guardia Costiera di Catania) showing degassing of the summit craters. Photo captured from the Aw139 helicopter by Stefano Branca. Courtesy of INGV (Report 27/2020, ETNA, Bollettino Settimanale, 22/06/2020 – 28/06/2020, data emissione 30/06/2020).

Similar modest, intra-crater Strombolian explosions in the NSEC, sporadic explosions in the VOR Crater, and degassing in the BN, VOR Crater, and NEC persisted into July. On 2 July degassing in the NEC was accompanied by weak intra-crater Strombolian activity. Intermittent weak ash emissions and ejecta from the NSEC and VOR Crater were observed during the month. During the week of 6-12 July INGV reported gas-and-steam emissions continued to rise from the vent in the pit crater at the bottom of BN (figure 306). On 11 July mild Strombolian activity, nighttime incandescence, and degassing was visible in the SEC (figure 307). By 15 July there was a modest increase in activity in the NSEC and VOR Craters, generating ash emissions and ejecting material over the crater rims while the other summit craters were dominantly characterized by degassing. On 31 July an explosion in the NSEC produced an ash plume that rose 4.5 km altitude.

Figure (see Caption) Figure 306. Photos of the bottom of the Bocca Nuova (BN) crater at Etna on 8 July 2020 showing the developing pit crater (left) and degassing. Minor ash emissions were visible in the background at the Voragine Crater (right). Both photos by Daniele Andronico. Courtesy of INGV (Report 29/2020, ETNA, Bollettino Settimanale, 06/07/2020 – 12/07/2020, data emissione 14/07/2020).
Figure (see Caption) Figure 307. Mild Strombolian activity and summit incandescence in the “cono della sella” (saddle vent) at the Southeast crater (SEC) of Etna on 11 July 2020, seen from Piano del Vescovo (left) and Piano Vetore (right). Photo by Boris Behncke, INGV.

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

Information Contacts: Sezione di Catania - Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/it/); 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/); Boris Behncke, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy.

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Bulletin of the Global Volcanism Network - Volume 43, Number 07 (July 2018)

Managing Editor: Edward Venzke

Aira (Japan)

Activity resumed in March 2017 and remained relatively low through the year

Ambae (Vanuatu)

Major explosions during March-April 2018 cause heavy ashfall on island; significant lahar damages to infrastructure

Ambrym (Vanuatu)

Benbow and Marum lava lake activity continues with steam and gas emissions through June 2018

Bezymianny (Russia)

Ongoing low-level thermal anomalies during January-June 2018

Cleveland (United States)

Ongoing episodes of lava effusion in the crater and explosions through July 2018

Copahue (Chile-Argentina)

Phreatic explosion in March; possible ash emissions June 2018

Kerinci (Indonesia)

Small ash plumes observed in August 2017, April 2018, and June 2018

Kilauea (United States)

Overflows of lava lake in Halema'uma'u crater; Pu'u 'O'o crater floor collapses 30 April 2018; inflation and increased seismicity

Kirishimayama (Japan)

No further activity from Shinmoedake after 27 June 2018

Merapi (Indonesia)

Lahar in October 2016; phreatic explosions May-June 2018



Aira (Japan) — July 2018 Citation iconCite this Report

Aira

Japan

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

All times are local (unless otherwise noted)


Activity resumed in March 2017 and remained relatively low through the year

Aira caldera encompasses the northern half of Kagoshima Bay in Kyushu, Japan. During the Holocene activity has been focused at Sakurajima volcano along the southern rim of the caldera, and more recent activity has occurred at the Minamidake and Showa summit craters (figure 59). Minamidake crater has been persistently active since 1955, and activity at Showa crater resumed in 2006. Sakurajima is one of Japan's most active volcanoes and frequently deposits ash over the nearby Kagoshima city. This report covers activity that occurred through 2017 and is based on reports issued by the Japan Meteorological Agency (JMA).

Figure (see Caption) Figure 59. The active Minamidake and Showa craters of Sakurajima volcano at Aira. Three incandescent vents within the craters are visible in this Sentinel-2 false color thermal image (bands 12, 11, 4) that was acquired on 13 December 2017. Courtesy of Sentinel Hub Playground.

Typical activity largely consists of Vulcanian explosions that produce ash plumes and small pyroclastic flows. Prior to a decrease in activity in August 2016, the volcano typically produced tens of explosions per month. The last recorded explosion in 2016 was a low-level ash plume on 22 August at 1.2 km altitude, reported by the Tokyo Volcanic Ash Advisory Center (VAAC). Sakurajima has remained on Activity Alert Level 3 (do not approach) on an alert level scale of 1 (little to no activity) to 5 (eruption or imminent eruption causing significant damage to residential areas).

Activity has been low since August 2016. No eruptions were observed through January and February 2017, and both seismicity and SO2 emission levels remained low.

Eruptive activity resumed on 25 March 2017 at 1803 local time, when the Minamidake crater produced an ash plume to 500 m above the crater and a pyroclastic flow travelled approximately 1,100 m to the south (figure 60). Several additional small ash emission events were noted after this event.

Figure (see Caption) Figure 60. Eruption at the Minamidake crater of Sakurajima (Aira caldera) on 25 March 2017 at 1803 local time. The ash plume reached 500 m above the crater and a pyroclastic flow traveled 1,100 m to the south. Image taken by the Kaigata surveillance camera, courtesy of JMA (March 2017 Monthly Sakurajima report).

Showa crater resumed activity at 0511 on 26 April 2017; 19 more events occurred through the month, including two larger explosive events. One explosive event produced an ash plume to 3,200 m above the crater on 28 April at 1101 local time. Two events occurred at the Minamidake crater through April.

Activity continued at the Showa crater in May, with 47 ash emission events, with nine of these being explosive events. One event on 2 May produced a 4,000-m-high plume that deposited ash on nearby communities (figure 61). Several larger explosions ejected blocks out to 500-800 m from the Showa crater. Activity continued at Minamidake crater, with ash reaching 2,500 m above the crater during an event on 5 May.

Figure (see Caption) Figure 61. Eruption of Sakurajima in the Aira caldera on 2 May 2017 at 0320 local time. The ash plume reached 4,000 m above the crater. Image taken by the Tarumi Ararazaki surveillance camera, courtesy of JMA (May 2017 Monthly Sakurajima report).

Through June, the Showa crater produced 14 events, including two explosive events. An explosion on 6 June produced an ash plume up to 3,200 m above the crater and blocks were deposited out to 800 m from the crater. One small event occurred at Minamidake. Activity was reduced in July, with seven events at Showa crater and none at Minamidake.

During August no events took place at Minamidake. However, Showa crater remained active with 98 events, including 20 that were explosive. Activity through September was similar with no activity in Minamidake crater and 170 events at Showa, including 38 explosive events.

Activity declined again from October through December. During October there were 37 events from Showa crater, with five being explosive (figure 62). One event at Minamidake crater on 31 October produced an ash plume up to 1,000 m above the crater. During November, five events occurred at Minamidake crater, and one at Showa crater that produced an ash plume to 1,300 m above the crater. In December, one event occurred at the Showa crater and Minamidake produced one small event.

Figure (see Caption) Figure 62. An explosive event is seen in this webcam image from the Sakurajima volcano Showa crater (Aira caldera) on 1 October, 2135 local time. Incandescent blocks were deposited out to 1,300 m from the crater. Image taken by the Tarumi Arasaki surveillance camera, courtesy of JMA (October 2017 Monthly Sakurajima report).

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


Ambae (Vanuatu) — July 2018 Citation iconCite this Report

Ambae

Vanuatu

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

All times are local (unless otherwise noted)


Major explosions during March-April 2018 cause heavy ashfall on island; significant lahar damages to infrastructure

Ambae (Aoba) is a large basaltic shield volcano in the New Hebrides arc that has generated periodic phreatic and pyroclastic explosions originating in the summit crater lakes Manaro Lakua and Voui during the last 25 years; the central edifice with the active summit craters is often referred to as Manaro Voui. A pyroclastic cone appeared in Lake Voui during November 2005-February 2006 (figure 30, BGVN 31:12). The volcano remained mostly quiet until an explosive eruption from a new pyroclastic cone in the lake began in mid-September 2017 and lasted through mid-November (BGVN 43:02). Activity included high-altitude ash emissions (9.1 km), lava flows, and Strombolian activity. After a quieter December, ash emissions resumed during January-April 2018. This report summarizes activity from January to June 2018, with information provided by the Vanuatu Geohazards Observatory of the Vanuatu Meteorology and Geo-Hazards Department (VMGD), the Wellington Volcanic Ash Advisory Center (VAAC), satellite data from several sources, and social media photographs.

Ongoing steam and intermittent ash emissions were observed during January and February 2018; incandescent ejecta continued from the pyroclastic cone at the summit. An increase in the frequency and volume of ash emissions in March led VMGD to raise the Alert Level to 3 (on a 0-5 level scale) by the middle of the month. Ash plume heights ranged from 3-5 km altitude. Heavy rains on 30 March caused a large lahar that significantly damaged a village on the N side of the island. A high-altitude plume on 31 March was measured at 13.7 km altitude. Significant ashfall around the island caused infrastructure damage and health hazards to humans, livestock, and plants. An explosion in early April produced another high-altitude ash plume observed in satellite imagery at 12.2 km altitude and one of the largest SO2 plumes measured in several years. A major ash plume on 11 April rose to 9.1 km altitude and enveloped much of the island in ash-laden meteoric clouds. The pyroclastic cone growing in Lake Voui had bisected the lake by March, and continued to fill it in. By late May, only two remnants of the lake remained, and a nearby smaller lake was dry. A low-level ash emission in late June signaled the beginning of a new, larger eruptive episode that began on 1 July 2018.

Activity during January-February 2018. The Wellington VAAC reported an ash plume at Ambae on 2 January 2018 drifting E at 3.1 km altitude that dissipated after a few hours. A plume on 8 January estimated at the same altitude resulted in reports of ashfall on the N and NE areas of the island; meteoric clouds prevented observations of the plume. Ongoing steam emissions were reported for the rest of January. On 7 February a continuous ash plume was observed in satellite data at 2.7 km altitude moving N. The following day, it was visible spreading E from the summit. A pilot confirmed observation of the plume continuing to spread to the E at 3.1 km altitude late on 8 February. Another low-level emission on 10 February extended NE at 2.1 km for a few hours. An ash plume on 13 February was clearly visible drifting N in satellite imagery; its altitude was estimated at 3.1 km.

A larger eruption on 16 February generated an ash plume that rose to 4.6 km altitude and initially drifted NE. Continuous ash emission extended as high as 5.5 km through 17 February and drifted SE and then S. By the next day, the constant emissions were still visible in satellite imagery, estimated at 4.6 km altitude; the main plume was drifting E with a remnant moving to the SW, finally dissipating on 19 February (figure 54). Ash emissions were visible in infrared imagery at about 3.9 km altitude on 23 February. Ongoing explosions were observed in the webcam on 23 and 24 February; ash was visible in satellite imagery until the end of the day on 24 February. A brief explosion observed in the webcam around sunrise on 27 February generated a small ash plume that rose to 3.1 km altitude and drifted SE. Moderate sulfur dioxide emissions were recorded a number of times during January and February (figure 55).

Figure (see Caption) Figure 54. On 18 February 2018, the pyroclastic cone at Ambae had grown significantly since 1 October 2017 (see figure 46 BGVN 43:02) (upper image) and actively ejected pyroclastic material along with magmatic gas and steam (lower image). Courtesy of pilot David Sarginson, Facebook.
Figure (see Caption) Figure 55. SO2 plumes from Vanuatu's Ambae, Ambrym, and Gaua volcanoes were all substantial enough sometime during January and February 2018 to be recorded by the OMI instrument on NASA's Aura satellite. Emissions on 2 January 2018 (top left) were drifting slowly SW from Ambae (upper plume) and Ambrym (lower plume); only Ambae had a plume drifting W on 11 January (top right); both Ambae and Ambrym SO2 plumes drifted NE on 17 February (bottom left); on 19 February (bottom right) Gaua (top plume) produced an emission that drifted E while Ambae and Ambrym generated SO2 that drifted SW. Courtesy of NASA Goddard Space Flight Center.

Activity during March 2018. The frequency and volume of ash emissions increased significantly during March 2018. Ash plumes were visible in satellite imagery during 3-6 March 2018. The initial plume rose to 3.7 km altitude and drifted NE, rising to 3.9 on 4 March and drifting N. The following day plumes rose to 4.6 km. By 6 March the plume was lower, drifting NW at 2.4 km altitude. A series of continuous low-level ash emissions were visible in satellite and webcam imagery every day from 11-19 March (figure 56). They initially drifted SE and SW and then moved to the W on 15 March at altitudes of generally 2.4-3.1 km, occasionally higher. The plumes drifted N and W during 17-19 March. This increase in ash emissions affecting local villages led VMGD to raise the alert level from 2 to 3 on 18 March 2018. They noted that activity was similar to the previous October but with more sustained ash emissions.

Figure (see Caption) Figure 56. Continuous ash emissions from Ambae beginning on 11 March 2018 (10 March UTC shown here) were visible in satellite imagery for over a week. Courtesy of European Space Agency, Copernicus EMS.

Local observers reported an explosion on 21 March that rose to 3.4 km altitude and drifted SW (figures 57-59). Continuous emissions through the end of the month were discernible in either satellite imagery or the webcam each day. Plume altitudes ranged from 3.1 to 4.9 km altitude, drifting in several directions. Significant ashfall began affecting local villages, destroying crops and livestock, and collapsing structures during the second half of March.

Figure (see Caption) Figure 57. A strong explosion on 21 March 2018 at Ambae produced an ash plume that rose several kilometers above the crater. Ashfall affected villagers in many communities on the island. Image courtesy VMGD Saratamata webcam located 22 km NE on the NE tip of Ambae Island, annotations by Cultur Volcan.
Figure (see Caption) Figure 58. A major ash plume rose from the crater of the pyroclastic cone in Lake Voui on Ambae on 21 March 2018. Photo courtesy of Robson S Tigona (VMGD), posted on Facebook.
Figure (see Caption) Figure 59. The dense ash plume from the explosion on 21 March 2018 at Ambae caused significant localized ashfall on the SW of the island as seen from Nduidui wharf in W Ambae. Courtesy of Dan McGarry, Vanuatu Daily Post.

Local news reports on 25 March noted that ejecta from the previous evening was visible over 70 km away to the SW by residents on Espiritu Santo Island, and small amounts of ash fell on Pentecost Island, 60 km SE (figure 60). According to the Vanuatu Independent, Virgin Australia cancelled flights to Vanuatu on 25 March. The New Zealand Defence Force did an aerial survey on 26 March and observed a large ash plume rising several kilometers (figure 61). Radio New Zealand reported on 30 March that large amounts of ashfall and acid rain had damaged crops, water supplies and buildings on Ambae (figures 62). A New Zealand GNS Science volcanologist reported that gardens were covered by ash and limbs on trees were broken. Some of the roofs over buildings and water supplies had collapsed due to the weight of the volcanic ash. Heavy ashfall in the S and NW parts of the island at the end of the month resulted in evacuations of several villages in the affected areas.

Figure (see Caption) Figure 60. Ashfall was observed on Pentecost Island, 60 km SE of Ambae after significant explosions overnight during 24-25 March 2018. Courtesy of Dan McGarry, Vanuatu Daily Post via twitter.
Figure (see Caption) Figure 61. The New Zealand Defence Force photographed this large ash plume rising from the summit of Ambae during an aerial survey on 26 March 2018. Courtesy of the New Zealand Defence Force (NZDF).
Figure (see Caption) Figure 62. Dense volcanic ash fell at the Penama Adventist College (PAC) in Red Cliff on Ambae in late March 2018. The upper image was taken on 14 April 2017, the lower image on 27 March 2018. Photos by John Metojoe, Vanuatu Police Force, and PAC. Courtesy of Philipson Bani (IRD/LMV).

The village of Waluebue on the N side of Ambae was badly damaged by a lahar during the night of 30-31 March. Homes and churches were destroyed from the mud and large boulders in the debris flow. All residents were safely evacuated (figures 63-67).

Figure (see Caption) Figure 63. A large lahar deposited boulders and damaged many buildings in the village of Waluebue on the N side of Ambae during the night of 30-31 March 2018. Photo courtesy of Clifford Tarisimbi.
Figure (see Caption) Figure 64. As seen in this example of a building undercut on one side and partially buried on the other, a large lahar damaged many buildings in the village of Waluebue on the N side of Ambae during the night of 30-31 March 2018. Photos courtesy of Clifford Tarisimbi.
Figure (see Caption) Figure 65. Mud and boulders buried some buildings to the roofline when a large lahar damaged passed through the village of Waluebue on the N side of Ambae during the night of 30-31 March 2018. Photos courtesy of Clifford Tarisimbi.
Figure (see Caption) Figure 66. Boulders a meter or more in diameter destroyed buildings when large lahar traveled through the village of Waluebue on the N side of Ambae during the night of 30-31 March 2018. Photo courtesy of Clifford Tarisimbi.
Figure (see Caption) Figure 67. Boulders a meter or more in diameter destroyed buildings when large lahar traveled through the village of Waluebue on the N side of Ambae during the night of 30-31 March 2018. Photo courtesy of Clifford Tarisimbi.

A new series of high-altitude ash emissions were reported by the Washington VAAC beginning on 30 March (figure 68). Early reports from satellite images and webcams indicated an ash plume at 6.1 km altitude. This was followed within the hour of confirmation from satellite imagery of the plume at 13.7 km altitude moving NW. By the following morning, two plumes were visible, one drifting S at 6.1 km and a second drifting NW at 13.7 km altitude. Meteoric clouds prevented observations later that day, but by 1 April, intermittent explosions were producing plumes moving E at an estimated altitude of 3.0 km, and SE estimated at 6.1 km altitude.

Figure (see Caption) Figure 68. A 13.7-km-high ash plume was visible from the VMGD Webcam at Ambae on 31 March 2018. Satellite imagery showed plumes drifting in multiple directions. Courtesy of VMGD.

Activity during April-June 2018. New eruptions occurred overnight during 5-6 April 2018 that generated an ash plume and a large distinct SO2 plume. Meteoric clouds and darkness prevented observation of the ash plume, but the SO2 signal was clearly visible on false-color satellite imagery. The plume initially rose to 7.3 km altitude and drifted W; a few hours later, it rose to 12.2 km. With a Dobson Unit measurement of 52.55 units, it was one of the strongest SO2 plumes measured on the planet since 2015, according to Simon Carn of Michigan Technological University (figure 69). An ongoing eruption was visible in the webcam on 6 April, but meteoric clouds again prevented observation in satellite data. A cluster of lightning strikes was detected by the World Wide Lightning Location Network (WWLLN) around the reported time of the eruption, according to Simon Carn. Intermittent low-level ash emissions were confirmed in the webcam on 8 April, estimated to be moving NE and E at 3.0-4.9 km altitude.

Figure (see Caption) Figure 69. The largest SO2 plume recorded since 2015 erupted from Ambae during 5-6 April 2018. Courtesy of NASA Goddard Space Flight Center.

Ash from a continuous low-level eruption during 9-10 April 2018 was clearly visible in the webcam and partly visible in satellite imagery drifting E and NE at 4.3-4.9 km altitude. The SO2 plume from the eruption stretched across most of the South Pacific (figure 70). Ashfall from the plume spread across a large area of the island causing substantial damage in local communities (figures 71 and 72).

Figure (see Caption) Figure 70. A sulfur dioxide plume from Ambae in Vanuatu stretched across the South Pacific in this 9 April 2018 image from the OMI instrument on the Aura satellite. Courtesy of NASA Goddard Space Science Center and Simon Carn.
Figure (see Caption) Figure 71. Ashfall from continuous emissions at Ambae during 9-10 April 2018 spread across much of the island, damaging local communities. Image posted on 10 April 2018. Courtesy of Wilfred Woodrow, Facebook.
Figure (see Caption) Figure 72. Ashfall from continuous emissions during 9-10 April 2018 at Ambae spread across much of the island, damaging local communities. Photo from Ghevin Banga, posted by Bani Philipson (IRD/LMV).

The ash plume height increased significantly on 11 April to 9.1 km altitude and drifted SE according to the Wellington VAAC. Planet Lab images showed the plume covering the N half of the island a short time later (figure 73). The following day, the plume altitude gradually lowered from 4.6 to 1.8 km and drifted N, then NW. Local communities reported intermittent low-level ash emissions and localized ashfall late on 12 April; this was the last report of ash emissions for April. Thick meteoric and ash clouds enveloped much of the island as seen in social media video on 12 April.

Figure (see Caption) Figure 73. Three satellite images from Planet Labs Inc. show the changes at Ambae between September 2017 and April 2018. On 30 September 2017 (top), the pyroclastic cone in Lake Voui was still an island within the lake. By 10 March 2018 (middle), the lake had been divided in two by the growth of the cone, the lake was discolored, and ashfall covered a large area several kilometers in diameter around the lake. A major ash emission on 11 April 2018 (bottom) rose to 9.1 km altitude and covered the N half of the island. Courtesy of Planet Labs Inc. posted on Twitter at Planet@planetlabs.

According to the Vanuatu Daily Post on 16 April 2018, the Council of Ministers for Vanuatu declared their intent to seek help from International Relief Organizations to evacuate the island's population after the latest episodes of extensive ashfall destroyed much of the infrastructure. Photographs from an overflight by VGMD on 21 April 2018 showed the increased size of the pyroclastic cone inside Lake Voui dividing the lake into two segments, one nearly consumed by the cone (figure 74). They reported small eruptions on 23 and 27 April; these were the last ash emissions until the end of June 2018.

Figure (see Caption) Figure 74. Aerial images of the active pyroclastic cone at Ambae were captured by VMGD during an overflight on 21 April 2018. Only dense steam emissions were observed in the view to the E across the summit, and the original Lake Voui was in two segments split by the pyroclastic cone. Courtesy of VMGD.

The thermal activity recorded by the MODVOLC and MIROVA systems corresponded with the observations of explosions and ash emissions. There were MODVOLC thermal alerts issued each month from January through 10 April 2018, with strong, multi-alert periods in February and March; these data were similar to the MIROVA signal for the period, which also showed increased activity during the same time (figure 75).

Figure (see Caption) Figure 75. Data from the MIROVA project show significant pulses of heat flow from Ambae during February-April 2018. Inset photo shows the large ash plume of 9 April as viewed from the VMGD webcam, which corresponds to the largest heat flow in April shown on the graph. Courtesy of MIROVA and VMGD.

By the end of May 2018, Manaro Ngoru, the small water body on the W side of the summit was dry; Lake Voui, divided into two segments by the pyroclastic cone, had a small amount of orange-brown water in the W half, and muddy brown water in the E half (figures 76 and 77). Steam plumes rose continuously from the cone, but no ash emissions were observed.

Figure (see Caption) Figure 76. The summit of Ambae on 22 May 2018 was covered with ash over a large area; former Lake Voui was divided in two by the pyroclastic cone, and only a modest steam plume rose from the top of the cone. Manaro Ngoru, the former lake on the W side of the summit, was completely dry. Courtesy of Planet Labs.
Figure (see Caption) Figure 77. The W side of Lake Voui on Ambae on 29 May 2018 was a small area of dark reddish brown water around the pyroclastic cone. View is to the S. Courtesy of Bani Philipson (IRD/LMV). =

VMGB issued a volcano alert on 7 June 2018, announcing that they had lowered the Alert Level from 3 to 2, due to the reduced activity at Ambae during late April and May. Radio New Zealand reported that on 9 June, the Vanuatu government announced plans to move its Penama Province capital due to the ongoing eruption. The Penama Council agreed to relocate its headquarters from Saatamaa in Eastern Ambae to Loltong in North Pentacost. The Penama Province is one of six in Vanuatu and includes the three islands of Ambae, Maewo, and Pentecost.

The Wellington VAAC issued an ash advisory from a low-level ash emission on 21 June 2018. It was clearly visible in satellite imagery, and rose to 3 km altitude, drifting SE. That was the last activity reported until a large new ash plume was recorded in the webcam on 1 July 2018.

Geologic Background. The island of Ambae, also known as Aoba, is a massive 2,500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Information Contacts: Geo-Hazards Division, Vanuatu Meteorology and Geo-Hazards Department (VMGD), Ministry of Climate Change Adaptation, Meteorology, Geo-Hazards, Energy, Environment and Disaster Management, Private Mail Bag 9054, Lini Highway, Port Vila, Vanuatu (URL: http://www.vmgd.gov.vu/, https://www.facebook.com/VanuatuGeohazardsObservatory/); Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html); 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/); European Space Agency (ESA), Copernicus (URL: http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus; 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/); New Zealand Defence Force (NZDF), Wellington, New Zealand (URL: http://www.nzdf.mil.nz/, Twitter: @NZDefenceForce); Vanuatu Daily Post (URL: http://dailypost.vu/news/flash-appeal/article_7c929c1e-dda3-5eab-925b-c814e04eeacb.html); Dan McGarry, Vanuatu Daily Post (Twitter: @dailypostdan); Vanuatu Independent News Magazine, Port Vila, Vanuatu (URL: https://vanuatuindependent.com/2018/03/26/flight-cancelled-due-to-volcanic-ash/); Simon Carn, Dept of Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, USA (URL: http://www.volcarno.com/, http://so2.umbc.edu/omi/); Radio New Zealand, 155 The Terrace, Wellington 6011, New Zealand (URL: https://www.radionz.co.nz/international/pacific-news/359231/vanuatu-provincial-capital-moves-due-to-volcano); Bani Philipson, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC) and Institut de Recherche pour le Developpement (IRD), Laboratoire Magmas et Volcans (LMV), University Campus of Cézeaux, 6 Blaise Pascal Avenue, TSA 60026 - CS 60026, 63178 AUBIERE Cedex, France (URL: http://lmv.univ-bpclermont.fr/bani-philipson/, Twitter: @philipsonbani); David Sarginson (Facebook: URL: https://www.facebook.com/david.sarginson.16); Clifford Tarisimbi (Facebook: https://www.facebook.com/profile.php?id=100009930510696); Wilfred Woodrow (Facebook: https://www.facebook.com/groups/558036627684741/permalink/974980079323725); Planet Labs Inc. (URL: http://www.planet.com/).


Ambrym (Vanuatu) — July 2018 Citation iconCite this Report

Ambrym

Vanuatu

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

All times are local (unless otherwise noted)


Benbow and Marum lava lake activity continues with steam and gas emissions through June 2018

Ambrym volcano, located in Vanuatu along the New Hebrides Island Arc, consists of a large 12-km-diameter caldera with two active craters, Marum and Benbow. Historical activity has occurred at summit and flank vents, producing moderate explosive eruptions and lava flows that reach the coast. Historically important eruptions date back two centuries, including extra-caldera W-flank lava flows that caused destruction in coastal areas in 1820, 1894, 1913, and 1929. Since then, there have not been extra-caldera lava eruptions, although the areas around Marum and Benbow craters remain hazardous. The Vanuatu Meteorology and Geo-Hazards Department (VMGD) located in Port Vila, Vanuatu, is responsible for monitoring ongoing activity at Ambrym.

During January through June 2018, volcanic activity was confined to the eruptive vents of Benbow and Marum craters, including ongoing lava lake activity inside the active vents, substantial degassing, and emission of steam clouds. The Volcanic Alert Level remained at Level 2 on a scale from 0 to 5 with five being the highest (figure 30). At Level 2 ('Major Unrest') the danger is restricted to the active craters and the Permanent Exclusion Zones, which are located within a 1 km radius around Benbow crater and about a 2.7 km radius around Marum crater (figure 38).

Figure (see Caption) Figure 38. A "Safety Map" showing Benbow and Marum craters at Ambrym with the locations of both designated permanent exclusion zones and danger zones. Courtesy of Vanuatu Meteorology and Geo-Hazards Department.

VMGD reported that the lava lakes in Benbow and Marum craters continued to be active and produced gas and steam emissions on 30 January, 19 March, and 25 April 2018. More sustained and substantial emissions were reported on 7 June.

During the reporting period, numerous thermal anomalies were detected by the MODIS satellite instruments and subsequently analyzed using the MODVOLC algorithm, possibly reflecting lava lake activity in Benbow and Marum craters (figures 39 and 40). The MIROVA (Middle InfraRed Observation of Volcanic Activity) system also detected numerous hotspots almost every day (figure 41).

Figure (see Caption) Figure 39. Showing two active craters of Ambrym, Benbow and Marum. Red areas indicate approximate locations of Thermal Anomaly detections with the number of detections from MODVOLC Thermal Alert System from the period January through June 2018. Courtesy of HIGP - MODVOLC Thermal Alerts System.
Figure (see Caption) Figure 40. MODVOLC thermal alerts detected during the reporting period from January to June 2018 showing hot spots located at Benbow and Marum craters. Courtesy of HIGP - MODVOLC Thermal Alerts System.
Figure (see Caption) Figure 41. Plot of MODIS thermal infrared data analyzed by MIROVA showing the log radiative power of thermal anomalies at Ambrym for the year ending on 29 August 2018. Courtesy of MIROVA.

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/).


Bezymianny (Russia) — July 2018 Citation iconCite this Report

Bezymianny

Russia

55.972°N, 160.595°E; summit elev. 2882 m

All times are local (unless otherwise noted)


Ongoing low-level thermal anomalies during January-June 2018

Activity at Bezymianny has been frequent over the past 60 years, and almost continuous since May 2010. The Kamchatka Volcanic Eruptions Response Team (KVERT) reported that ash plumes from the 20 December 2017 explosive eruption (BGVN 43:01) rose as high as 15 km and drifted 320 km NE (figure 24). On 29 December activity included moderate gas-and-steam emissions; a lava flow likely continued to effuse onto the N flank of the lava dome. A thermal anomaly over the volcano was identified in satellite images in late December 2017.

Figure (see Caption) Figure 24. Explosions from Bezymianny sent ash plumes up to 15 km altitude on 20 December 2017. Photo by Yu. Demyanchuk; courtesy of IVS FEB RAS, KVERT.

KVERT reported on 5 April 2018 that moderate gas-and-steam activity was continuing. Satellite data showed a thermal anomaly over the volcano on 29-30 March and 2-3 April, but the volcano was obscured by clouds in the other days of week. Fumarolic plumes were also seen on 13 April (figure 25). No MODVOLC thermal alerts were measured during the first half of 2018, and MIROVA analysis shows only low level radiative power anomalies for the same period (figure 26).

Figure (see Caption) Figure 25. Thermal anomalies at Bezymianny recorded by the MIROVA system (log radiative power) for the year ending 2 February 2018 (top) and 28 June 2018 (bottom). Courtesy of MIROVA.
Figure (see Caption) Figure 26. Thermal anomalies at Bezymianny recorded by the MIROVA system (log radiative power) for the year ending 28 June 2018. Courtesy of MIROVA.

Geologic Background. Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 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/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); 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/).


Cleveland (United States) — July 2018 Citation iconCite this Report

Cleveland

United States

52.825°N, 169.944°W; summit elev. 1730 m

All times are local (unless otherwise noted)


Ongoing episodes of lava effusion in the crater and explosions through July 2018

Cleveland, at the western end of the isolated Chuginadak Island in the Aleutian Islands, is characterized by frequent small explosions that are monitored using local seismic and infrasound sensors, and by elevated surface temperatures that are monitored by satellite-based infrared sensors. The current eruptive period began in April 2016 and has continued through at least July 2018. The Alaska Volcano Observatory (AVO) is responsible for monitoring, and issues regular reports describing activity.

Small explosions in mid-December 2017 were followed by elevated surface temperatures later in the month and a lava flow in the summit crater that began effusing on 5 January 2018 (table 9). Thermal anomalies and other signs of unrest continued through 24 February, when a small explosion was detected. Another explosion was reported on 2 March with a plume rising to 4.6 km altitude and drifting ENE. Satellite data continued to identify elevated temperatures in early March. Small explosions were identified using seismic and infrasound data on 14 March and 4 April. The ash cloud on 4 April rose to 4.6 km altitude and drifted SW; hot material was ejected onto the W flank.

Thermal anomalies were ongoing in June. A small circular lava flow (~80 m in diameter) in the summit crater was reported on 25 June; a thermal anomaly noted during 29 June-2 July extending SW downslope within the crater was consistent with a lava flow, according to AVO. Weakly elevated surface temperatures were reported on many days during 7-23 July, along with some small steam plumes (figure 25). A small deposit of blocks, within the summit crater and just below the E crater rim, seen using satellite imagery during 18-23 July suggested to AVO that there had been a very small explosion not recorded using seismic or pressure sensor monitors.

Table 9. Observations of dome growth and other crater activity at Cleveland, December 2017-July 2018. Note that the absence of observable activity from satellites is often due to cloud cover. Data courtesy of Alaska Volcano Observatory (AVO).

Date Observation
13 Dec 2017 Small explosion (0420); plume rising to 6.1 km and drifting E
17 Dec 2017 Small explosion (1817)
27 Dec-01 Jan 2018 Elevated surface temperatures
19 Jan 2018 New lava flow within summit crater since 5 January
19-22 Jan 2018 Elevated surface temperatures
24-30 Jan 2018 Unrest; possible cold vapor plume drifted S on 24 Jan; some slightly elevated surface temperatures during 26-30 Jan
31 Jan-06 Feb 2018 Unrest, moderately elevated surface temperatures
07-13 Feb 2018 Low-level unrest
14-20 Feb 2018 Low-level unrest; thermal anomalies during 15-17 Feb
24 Feb 2018 Small explosion (2154); several hours later satellite showed moderately elevated surface temperatures extending ~2 km from summit
28 Feb-03 Mar 2018 Elevated surface temperatures
02 Mar 2018 Small explosion (0557); plume rose to 4.6 km, drifted ENE
07 Mar 2018 Elevated surface temperatures on satellite images
08 Mar 2018 Seismicity slightly increased
14 Mar 2018 Small explosion in seismic and infrasound (2219), no visible ash plume
04 Apr 2018 Small explosion in seismic and infrasound (0355), hot material ejected on W flank and small ash cloud to 4.6 km drift SW
04 Apr 2018 Small, short-duration seismic event (~0600) coupled with small ash emission
13 Apr 2018 Small explosion (0759) in seismic and infrasound
04 May 2018 Small explosion (2149) in seismic and infrasound; small ash cloud to 6.7 km, drift SE
6-12 Jun 2018 Elevated surface temperatures
11-12 Jun 2018 Steam emissions
13-19 Jun 2018 Elevated surface temperatures
25 Jun 2018 Small, circular lava flow (~80 m in diameter) in summit crater
29 Jun-02 Jul 2018 Elevated surface temperatures; thermal anomaly extended SW
07, 09-10 Jul 2018 Weakly elevated surface temperatures; small steam cloud on 7 July
11 Jul 2018 Weakly elevated surface temperatures
18-23 Jul 2018 Weakly elevated surface temperatures; small deposit of blocks within the summit crater and just below the E crater rim
Figure (see Caption) Figure 25. Worldwide-3 satellite image of the summit crater of Cleveland volcano on 10 July 2018. The 80-m-diameter circular lava flow extruded in late June 2018 can be seen as well as minor steam emissions. Courtesy of Alaska Volcano Observatory / U.S. Geological Survey (Image 117311, color adjusted).

Geologic Background. The beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Joined to the rest of Chuginadak Island by a low isthmus, Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 it produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

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://www.dggs.alaska.gov/); Anchorage Volcanic Ash Advisory Center (VAAC), Alaska Aviation Weather Unit, NWS NOAA US Dept of Commerce, 6930 Sand Lake Road, Anchorage, AK 99502-1845 USA (URL: http://vaac.arh.noaa.gov/).


Copahue (Chile-Argentina) — July 2018 Citation iconCite this Report

Copahue

Chile-Argentina

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

All times are local (unless otherwise noted)


Phreatic explosion in March; possible ash emissions June 2018

The most recent activity from Copahue originates in the El Agrio crater, which has permanent fumarolic activity and an acidic lake. During 2017, ash emissions began in early June, but decreased after July, although tremor and degassing with occasional ash continued for the remainder of the year (BGVN 43:01). The volcano is monitored by the Servicio Nacional de Geología y Minería (SERNAGEOMIN). This report discusses activity during January-June 2018.

According to the Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI), SERNAGEOMIN reported that a hydrothermal explosion was recorded on 24 March 2018, along with increased tremor. The Alert Level was raised to Yellow (second highest level on a four-color scale); SERNAGEOMIN recommended no entry into a restricted area within 1 km of the crater. ONEMI maintained its own Alert Level of Yellow (the middle level on a three-color scale) for the municipality of Alto Biobío (25 km SW).

Based on SERNAGEOMIN information, ONEMI reported that during 1-31 March 2018 there were 83 volcano-tectonic events recorded and 204 earthquakes indicting fluid movement. Tremor levels increased on 24 March, the same day as a phreatic explosion, though by the next day it had decreased to baseline levels. Webcams recorded gas plumes rising from El Agrio crater as high as 1 km. During an overflight on 3 April, scientists observed continuous white gas plumes rising almost 400 m.

The Buenos Aires Volcanic Ash Advisory Center (VAAC) reported that on 24 June diffuse steam emissions possibly containing ash were visible in webcam views rising to an altitude of 3.6 km.

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: Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI), Beaucheff 1637/1671, Santiago, Chile (URL: http://www.onemi.cl/); Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php).


Kerinci (Indonesia) — July 2018 Citation iconCite this Report

Kerinci

Indonesia

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

All times are local (unless otherwise noted)


Small ash plumes observed in August 2017, April 2018, and June 2018

Kerinci has produced intermittent ash explosions in recent years, including December 2011, June 2013, March-June 2016, and November 2016 (BGVN 42:04). The Darwin Volcanic Ash Advisory Centre (VAAC) has issued the only reports on activity between December 2016 and July 2018, and these have been based on satellite data. The Indonesia volcano monitoring agency, Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), has kept the Alert Level at 2 (on a scale of 1-4) since 9 September 2007.

According to the Darwin VAAC, on 13 August 2017, an ash plume rose to an altitude of 4.3 km and drifted WSW.

Sentinel-2 satellite imagery showed what appeared to be a small ash plume rising from the crater on 21 April 2018 (figure 4). The Darwin VAAC also reported that on 5 June 2018 a minor ash emission rose to an altitude of 4.3 km and drifted W (figure 5). On 10 June an ash plume rose to an altitude of 4 km and drifted W.

Figure (see Caption) Figure 4. Natural color satellite image from Sentinel-2 on 21 April 2018 showing a small light-brown ash plume rising from the Kerinci summit crater. Courtesy of Sentinel Hub.
Figure (see Caption) Figure 5. A brown ash plume is visible in this natural color Sentinel-2 satellite image of the Kerinci crater on 5 June 2018. Courtesy of Sentinel Hub.

During the reporting period, no significant sulfur dioxide levels near the volcano were recorded by NASA's satellite-borne ozone instruments, and no thermal anomalies were detected.

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

Information Contacts: 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/); 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/); 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/); 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/).


Kilauea (United States) — July 2018 Citation iconCite this Report

Kilauea

United States

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

All times are local (unless otherwise noted)


Overflows of lava lake in Halema'uma'u crater; Pu'u 'O'o crater floor collapses 30 April 2018; inflation and increased seismicity

Open lava lakes at the Kilauea summit caldera along with a lava lake and flows from the East Rift Zone (ERZ) have been almost continuous since the current eruption began in 1983, and the rift zone has been intermittently active for at least two thousand years. The period from January-April 2018 included the ending of activity in one part of the ERZ and the beginning of a new episode. March 2018 marked the tenth year of the active lava lake inside the Overlook vent at Halema'uma'u. Information for this report comes primarily from the US Geological Survey's (USGS) Hawaii Volcano Observatory (HVO) which provides daily reports, volcanic activity notices, and photo and video data.

At the end of 2017, the lava lake inside the Overlook vent at Halema'uma'u crater maintained the typical activity it had exhibited throughout the year, with a consistent lava circulation pattern, and occasional spattering events from hardened lava falling into the lake from the pit walls. The lake level rose and fell by a few meters over periods of hours to days, ending the year about 30 m below its level at the beginning of the year. Longer-term subsidence of the Pu'u 'O'o cone on the East Rift Zone was also apparent during 2017, although there was little change in the elevation of the lava pond inside the west pit area of the crater; occasional rockfalls triggered minor spattering. At the end of 2017 the East Rift Zone episode 61g surface lava flow activity persisted on the upper portions of the flow field near Pu'u 'O'o, on the pali, and in scattered areas along the coastal plain. Changes in the subsurface flow in lava tubes contributed to frequent changes to surface breakout locations. The lava flowing into the ocean at Kamokuna slowed and finally ended in November 2017.

During January-April 2018, the lava lake level inside the Overlook vent of Halema'uma'u crater rose and fell daily with alternating periods of inflation and deflation, with a gradual overall inflationary trend. Inflation intensified at the end of April, and the lake overflowed onto the floor of the crater during 21-27 April. The lake level had dropped several meters below the rim of the vent by the last day of the month. Activity of the episode 61g lava flow decreased gradually throughout the period. The flow remained active at the base of the pali and on the upper flow field through February, but activity tapered off on the coastal plain. By the end of March, only the upper flow field was still active. Notable inflationary tilt began at Pu'u 'O'o on 12 March 2018. Lava flowed out of vents on the main crater floor and also created a perched lava pond in the west pit. In mid-April HVO noted that the inflation resulted from increased pressurization of the magma under Pu'u 'O'o and in the past this had led to the formation of new vents and lava flows along the East Rift Zone. A marked increase in seismicity and ground deformation at Pu'u 'O'o on the afternoon of 30 April was followed by the collapse of the crater floor, dispersing red ash a significant distance around the cone. Following the collapse, HVO seismometers and tiltmeters recorded a substantial increase in seismic activity and deformation from Kilauea's summit to an area about 10-16 km downrift (east) of Pu'u 'O'o which propagated eastward overnight along the Lower East Rift Zone (LERZ), marking the beginning of a major new eruptive phase.

Activity during January 2018. Consistent activity continued into January 2018 with few notable changes. The lava lake inside the Overlook vent at Halema'uma'u crater rose and fell by a few meters over hours and days; on the East Rift Zone the lava pond persisted at Pu'u 'O'o cone, and scattered breakouts from the episode 61g lava flow continued. Early on 19 January two earthquakes of magnitude 2.4 and 2.5 occurred on the lower East Rift Zone near Leilani Estates. Also on 19 January, a rockfall from the wall of Halema?uma?u crater plunged into the lava lake producing a short-lived explosion of spatter and wallrock that blanketed an area around the former visitor overlook. Debris fell as far as the Halema'uma'u parking lot (figure 312).

Figure (see Caption) Figure 312. Spatter up to about 30 cm in size was thrown onto the rim of Halema'uma'u crater at Kilauea during explosive events on 19 January 2018. Some fragments were thrown or blown farther downwind, reaching as far as the closed section of Crater Rim Drive in Hawai'i Volcanoes National Park. The boot of an HVO scientist, who entered the area to check on HVO's webcameras, is shown here for scale. Courtesy of HVO.

HVO noted that spattering from the lava lake at Halema'uma'u was visible from the visitor overlook overnight during 25-26 January. Spatter appeared again briefly the next day, and overnight during 29-30 January. Four spattering sites were visible on a clear 30 January day (figure 313). Webcam views overnight on 30-31 January showed that incandescence persisted from the small lava pond on the W side of the Pu'u 'O'o crater. On the morning of 26 January a new breakout from the episode 61g flow appeared on the pali. By the end of January, most of the breakouts from the episode 61g flow field were concentrated at the base of the pali and on the upper flow field, with little activity on the coastal plain.

Figure (see Caption) Figure 313. Clear views at the summit of Kilauea on 30 January 2018 revealed four spattering sites visible on the surface of the Halema'uma'u lava lake inside the Overlook vent. Through the gas plume, a visible scar (light-colored wall rock) from the 19 January rockfall that triggered an explosive event, could be seen on the southern Overlook vent wall. Another, smaller scar on the northeastern lake wall (left), resulted from two small rock falls on 24 January. Courtesy of HVO.

Activity during February 2018. The lake level inside the Overlook vent continued with daily fluctuations of several meters, between 31 and 42 m below the Halema'uma'u crater floor, during February 2018. A small veneer collapse (rockfall) into the lava lake on 23 February was visible in lava lake webcam images. Throughout the month, persistent incandescence was observed in the webcam at the Pu'u 'O'o west pit lava pond (figure 314). On 10 February a large portion of the NE rim of the west pit collapsed. Prior to and during the rim collapse, the adjacent ground also subsided. The episode 61g flow remained active at the base of the pali (figure 315) and in the upper flow field. A new breakout on the upper flow field, 1-2 km from the vent, appeared early on 26 February. A small swarm of earthquakes occurred in the upper East Rift Zone on 21 February; the largest event was a M 2.3. Seismicity throughout the volcano was otherwise at normal rates throughout the month.

Figure (see Caption) Figure 314. Incandescence from the west pit at Kilauea's Pu'u 'O'o cone on 19 February 2018 was typical of that observed during clear weather throughout the month. Courtesy of HVO.
Figure (see Caption) Figure 315. 'A'a flows at the base of Pulama pali at Kilauea on 20 February 2018 produced shimmers of heat (top center) and incandescent fragments. Rubble from the flow rolled downhill, as the molten center slowly pushed forward. Courtesy of HVO.

Activity during March 2018. A brief swarm of small earthquakes occurred in the upper East Rift Zone on 2 March 2018. An ongoing long-period earthquake swarm at 5-10 km depth beneath the caldera began late on 6 March and continued into the next day. At the Halema'uma'u crater, the lava lake fluctuated daily, with levels ranging from a low of 40.5 m below the crater floor to a high of 20 m below it. Changes in levels of up to 10 m in a 24-hour period were common. Vigorous spattering was observed on 6 March (figure 316). On 16 March, the lava lake rose high enough (26 m below the crater floor) for active spattering to be visible in webcams mounted in the HVO tower, located across the crater from the vent. The 10th anniversary of the eruption within Halema'uma'u crater was marked on 19 March. When the vent first opened on 19 March 2008, it formed a small pit about 35 m wide. Over the following decade, the pit (informally called the "Overlook crater") grew to about 280 x 200 m in size (see figure 313).

Figure (see Caption) Figure 316. Within Kilauea volcano's summit lava lake at the Halema'uma'u crater, vigorous spattering on 6 March 2018 was occurring on the southern margin where a ledge of solidified lava had built out from the vent wall. Courtesy of HVO.

Notable inflationary tilt at Pu'u 'O'o cone began on 12 March 2018; GPS stations also started recording extension across the cone on that date. A small increase in seismic events was observed at Pu'u 'O'o on the evening of 21 March. Increased views of spattering from the west pit lava pond were visible beginning the following day, likely due to subsidence over the previous months as reported by HVO. During the evening of 25 March lava flowed out of a vent in the SE part of the crater floor and continued to expand for the rest of the month (figure 317). Inflationary tilt slowed significantly on 27 March. Cracks along the ridge between the main crater and the west pit continued to grow throughout the month as the ridge continued to subside (figure 318).

Figure (see Caption) Figure 317. On 25 March 2018 a small lava flow began erupting onto the Pu'u 'O'o crater floor at Kilauea for the first time since May 2016. In this thermal image, taken by the PTcam on 26 March 2018 at 1318, the flow (bright color) appears to be supplied by one of the small spatter cones in the crater's south embayment. The lava flow did not extend beyond the crater. This type of activity is not unusual for Pu'u 'O'o. Courtesy of HVO.
Figure (see Caption) Figure 318. At Pu'u 'O'o on Kilauea's East Rift Zone, the ridge separating the main crater (top) from the west pit (bottom) had been subsiding over the previous several months due to small rockfalls and unstable ground when this image was taken on 27 March 2018. As the ground shifted, cracks along the ridge and on both sides of it continued to open. The lava pond within the west pit rose several meters during March and produced overflows (darker lava) onto the floor of the pit as it rose. A small lava flow also erupted onto the floor of the main crater on 25 March and remained active through 27 March, visible as the lava darker in color in the foreground of the main crater floor. Courtesy of HVO.

By 20 March surface lava flow activity from the episode 61g flow near the base of the pali appeared to have diminished, and only sparse lava flow activity on the coastal plains was noted after 23 March. Activity on the upper flow field, closer to Pu'u 'O'o, continued (figure 319). A 30 March overflight by HVO confirmed no flow activity on the coastal plain or the pali.

Figure (see Caption) Figure 319. Active lava breakouts were scarce across the episode 61g flow field on Kilauea's East Rift Zone, with active flows confined to an area approximately 1-2 km from Pu'u 'O'o during March 2018. This breakout from the lava tube consisted of fluid pahoehoe and was photographed on 27 March 2018 during an overflight. The incandescent area is several meters across. Courtesy of HVO.

Activity during 1-16 April 2018. Constant spattering at the Overlook vent lava lake (figure 320) was intermittently visible from HVO and the Jagger Museum during April 2018 as the lake level rose and fell several meters on a daily basis. Its lowest level of the month was 32 m below the crater floor, and a general inflationary trend throughout the month resulted in significant overflows onto the floor of Halema'uma'u crater at the end of the month. A rockfall in the morning of 6 April triggered an explosion at the summit lava lake that damaged the power system to the Halema'uma'u crater rim webcams (figure 321). A moderate swarm of over 200 earthquakes occurred on 11 April at depths of 7-9 km below the summit; the largest event in the sequence was M 2.4. Seismicity returned to its background rate in the early morning of 12 April. Three minor ledge collapses, common while the lava lake level is lowering, occurred on 12 April.

Figure (see Caption) Figure 320. A clear view of Kilauea's summit lava lake in the Overlook vent on 4 April 2018 revealed spattering on the N side and center of the lake surface, a departure from its more common location on the SE side of the lake; this occasionally happened when the surface flow direction reversed. Spattering is caused by gas bubbles bursting within the lava lake. Courtesy of HVO.
Figure (see Caption) Figure 321. On 6 April 2018 at 1028 HST a partial collapse of the southern Overlook crater wall triggered an explosive event at Kilauea's summit lava lake. A large plume of gas, ash, and lava fragments rose from the lava lake and was visible from the Jaggar overlook. The explosion threw debris onto the Halema'uma'u crater rim at the old visitor overlook, which has been closed due to ongoing volcanic hazards such as this explosive event. Courtesy of HVO.

For the first half of April 2018, steady minor inflation continued at Pu'u 'O'o, interrupted by brief episodes of sharp deflation that appeared related to small lava flows on the crater floor. During an overflight on 13 April HVO geologists viewed a perched lava pond inside the west pit (figure 322). A slight increase in seismicity in the Upper East Rift Zone began overnight during 15-16 April; the largest event was a M 2.9 earthquake.

Figure (see Caption) Figure 322. During an overflight of Kilauea on 13 April 2018 geologists from HVO observed that lava within the west pit at Pu'u 'O'o had formed a perched lava pond (center) contained within a levee. This levee, formed by an accumulation of hardened lava, confined molten lava to the perched pond, which allowed the lava surface to rise higher than the west pit floor. If the pond rises high enough, lava can spill over the levee, forming small flows around the margin of the perched pond. Courtesy of HVO.

At the beginning of April 2018 the episode 61g lava flow was active only above the Pulama pali. The areas of the upper flow field with active lava flows were located within the Kahauale'a Natural Area Reserve, which has been closed to the public since 2007 due to volcanic hazards. On 13 April 2018, geologists observed scattered breakouts from the 61g flow within about 2.2 km from Pu'u 'O'o and another sluggish breakout about 5 km from Pu'u 'O'o (figure 323).

Figure (see Caption) Figure 323. An HVO geologist photographed an active pahoehoe breakout on 13 April 2018 at Kilauea after taking a lava sample nearby. This breakout was located approximately 0.4 km from the episode 61g vent. As the flow inflated, internal pressure cracked the rigid crust of the flow allowing molten lava to ooze out. Courtesy of HVO.

Activity during 17-30 April 2018. Beginning in mid-April 2018 seismometers recorded an increase in the number of small earthquakes beneath the summit and upper East Rift Zone reflecting increased pressurization. Kilauea's summit and East Rift Zone magma systems are connected, with changes at one sometimes leading to changes at the other. Tiltmeters, GPS, web cameras, and field observations, continued to record inflation at the Halema'uma'u crater, at Pu'u 'O'o, and at the upper portion of the episode 61g lava tube system. HVO noted that this inflation could lead to the opening of a new vent on or near Pu'u 'O'o that could cause a significant drop in the summit lake level.

At the Halema'uma'u crater, inflation significantly outpaced deflation for the second half of April. In the afternoon of 18 April the lake level was at 25 m below the crater floor. A lengthy episode of inflation brought the lava to within 6 m of the floor on the afternoon of 21 April. As the level continued to rise, a small overflow along the S crater rim occurred about midnight overnight on 21-22 April (figure 324). The lava lake was below the rim again the next morning but spilled out several times over the next several days to the N, S, and SW. The flows, similar to those produced during the last significant overflow event in April-May 2015, consisted of lobate sheets of shelly pahoehoe traveling as far as 375 m across the floor of Halema'uma'u. A small overflow had also occurred in October 2016.

Figure (see Caption) Figure 324. The rising summit lava lake levels first peaked overnight on 21-22 April 2018, producing small overflows onto the floor of Halema'uma'u Crater at Kilauea. The largest overflow, on the N side of the Overlook vent (shown here), reached about 80 m from the lake margin. Image taken on 22 April 2018, courtesy of HVO.

The summit lava lake spilled out of the Overlook crater rim multiple times during 22-27 April, caused by repeated inflation-deflation cycles (figures 325-327). Between overflows, the lava column receded below the crater rim. An overflight during the afternoon of 23 April showed that the overflows covered about 30% of the Halema'uma'u crater floor, approximately 16 ha. The height of the lava lake, on the floor of Halema'uma'u crater, was 79 m below the rim of the crater on 25 April. HVO estimated that only about one quarter of the floor of the crater remained uncovered by new flows as of 26 April. Summit tiltmeters continued to record an overall inflationary trend with brief periods of deflation until turning to more sustained deflation around midnight overnight on 26-27 April. A magnitude 3.2 earthquake occurred around 1308 HST on 26 April but did not cause any eruptive changes. Seismometers recorded a few small earthquakes in the upper East Rift Zone and south part of the caldera during 25-29 April.

Figure (see Caption) Figure 325. On 24 April 2018 between around 2030 and 2300, Kilauea's summit lava lake overflowed again. The large overflow spread W (to the right) from the lava lake onto the floor of Halema'uma'u around 2230 in this image. The bright (yellow-white) spot is spattering along the S margin of the lava lake. USGS photo by M. Patrick, courtesy of HVO.
Figure (see Caption) Figure 326. Beginning at approximately 0615 on 26 April 2018 a new overflow began covering about 36 hectares (90 acres) of Kilauea's Halema'uma'u crater floor with lava, continuing for about four hours and covering about two-thirds of crater floor. This was the largest overflow since the summit eruption began in 2008. In this view to the S taken later in the day, the gas plume was being produced by the lava lake in the SE crater floor (upper left). Courtesy of HVO.
Figure (see Caption) Figure 327. This thermal image (looking S) taken on 26 April 2018 at Kilauea shows the active overflows from the lava lake (upper left) onto the Halema'uma'u crater floor. View is toward the south. Courtesy of HVO.

The summit lake level dropped 16 m during 27-28 April, ending the period of inflation that produced the overflows onto the crater floor. The lake level remained about 15 m below the floor when skies cleared on 30 April and permitted a view from the webcam (figure 328). Slight inflation returned later in the day and the lake level rose to just beneath the vent rim.

Figure (see Caption) Figure 328. A break in the weather on the morning of 30 April 2018 allowed HVO's webcam to capture this image of the lava lake within Halema'uma'u at the summit of Kilauea. Following multiple overflows of the lava lake the previous week, the lake level dropped after summit deflation. Early that morning, the lava lake level was estimated to be about 15 m below the vent rim, but shortly thereafter, the summit switched to inflation, and the lake level rose to just below the vent rim. Courtesy of HVO.

HVO released a Volcanic Activity Notice, in addition to their regular daily report, midday on 17 April 2018. They noted that observations and measurements at Pu'u 'O'o during the previous month suggested that the magma system had become increasingly pressurized, raising the possibility that a new vent could form at any time, either on the Pu'u 'O'o cone or along adjacent areas. Since mid-March there had been uplift of the Pu'u 'O'o crater floor by several meters. Similar episodes of inflation and uplift at Pu'u 'O'o occurred in May-June 2014, prior to the start of the June 27th flow (active 2014-2016) and May 2016 before the start of the ongoing episode 61g flow.

When measured during a site visit on 18 April the pond level in the west pit at Pu'u 'O'o was 7 m higher than it had been in late March as a result of lava overflows building up the surrounding levee. An overflight on 23 April showed the perched lava pond with overflows slowly filling the pit (figure 329), and significant cracks on the NE part of the crater rim (figure 330). The pond had another overflow that remained in the pit on 24 April, and the floor continued to rise. Inflationary tilt continued at Pu'u 'O'o until it leveled off around midnight during 26-27 April, but the crater floor continued to rise for the next four days.

Figure (see Caption) Figure 329. On the East Rift Zone of Kilauea, the perched lava pond in Pu'u 'O'o's west pit persisted during the second half of April, seen here on 23 April 2018. Overflows of the pond levees were slowly filling the bottom of the west pit and raising the floor. Courtesy of HVO.
Figure (see Caption) Figure 330. Ongoing uplift of the crater floor of Pu'u 'O'o at Kilauea beginning in mid-March 2018 generated numerous cracks on the crater floor and around the rim. These cracks cut through both recent lava flows (darker color) and older flows on the crater floor. Image taken on 23 April 2018, courtesy of HVO.

Just after 1400 on 30 April 2018, a marked increase in seismicity and ground deformation began at Pu'u 'O'o. A few minutes later, a thermal webcam (PTcam) located on the crater rim showed the first of two episodes of floor collapse; the second collapse began at 1520 and lasted about an hour. Webcam views into the crater and surrounding area were frequently obscured by poor weather conditions. However, shortly after 1600 the PTcam recorded images that were likely the signature of small explosions from the western side of the crater as the floor collapsed.

Following the collapse there was an increase in seismicity and deformation from the summit to an area about 10-16 km downrift (east) of Pu'u 'O'o. Overnight, this activity continued to propagate eastward along the rift zone. The largest earthquake of this sequence was a magnitude 4.0 just offshore south of Pu'u 'O'o at 0239 on the morning of 1 May. HVO field crews were turned back the next morning by ash in the air above Pu'u 'O'o, likely due to continuing collapse within the crater and vigorous gas emissions. Reddish ash was also noted in abundance on the ground around Pu'u 'O'o.

Lava flow activity in the episode 61g flow continued on the upper flow field through the end of April 2018. Activity was focused above the pali and closer to Pu'u 'O'o, within 2 km of the vent. After the explosion and collapse of the crater floor at Pu'u 'O'o on 30 April, a large amount of red ash was deposited around the cone and covered over some of the active breakouts of the 61g flow (figure 331).

Figure (see Caption) Figure 331. The collapse of the Pu'u 'O'o crater floor at Kilauea on 30 April 2018 produced a large amount of red ash that was deposited around Pu'u 'O'o, as well as blown farther downwind, with a thin dusting of ash reaching uprift (west) as far as Mauna Ulu. On 1 May 2018, a layer of red ash covered active 61g lava flow surface breakouts in an area between 1-2 km from the 61g vent. 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/).


Kirishimayama (Japan) — July 2018 Citation iconCite this Report

Kirishimayama

Japan

31.934°N, 130.862°E; summit elev. 1700 m

All times are local (unless otherwise noted)


No further activity from Shinmoedake after 27 June 2018

Three volcanoes in the Kirishimayama volcanic complex experienced heightened activity during late 2017 and early 2018. There were explosions at Shinmoedake during September-October 2017 and March-May 2018, an explosion at Iwo-yama in April 2018, and heightened seismicity at Ohachi in February 2018 (BGVN 43:06). Activity weakened afterwards, and by the beginning of July the three volcanoes were relatively quiet except for some fumarolic activity and seismic activity. This report documents activity between June and November 2018. Most of the information was provided in Japan Meteorological Agency (JMA) monthly reports.

Activity at Shinmoedake during June 2018. JMA reported that an explosion at 0909 on 22 June generated an ash plume that rose 2.6 km above the crater rim and drifted E. Tephra was ejected 1.1 km away, and shock waves were felt in the Miyazaki region. Minor amounts of ash fell in Kirishima prefecture and Kagoshima prefecture to the S, Miyakonojo city (Miyazaki prefecture) to the E, and Takahara Town. Another explosion at 1534 on 27 June generated a plume that rose 2.2 km above the crater rim.

According to JMA, since the beginning of May the rate of deformation had slowed, and tiltmeter data showed no change. In addition, sulfur dioxide emissions had decreased from 1,000 tons/day on mid-March to 80 tons/day on 1 June. Based on the data, JMA believed the magma supply had declined, decreasing the possibility of an eruption affecting an area outside a radius of 2 km. Thus, on 28 June, JMA lowered the Alert Level from 3 to 2.

Activity at Iwo-yama during June-July 2018. Activity weakened in May, and no volcanic explosions occurred after 27 April. However, active fumarolic activity and ejection of mud continued through November from the vent on the S side. During 23-30 July, white plumes rose 300-500 m above the vent. Also on the S side, the hot lake, which was muddy in May, became transparent in June, but was cloudy again in July. Fumarolic activity also occurred at a vent 500 W of the crater.

Volcanic earthquakes slightly increased in late May. According to measurements by the Global Navigation Satellite System (GNSS), the volcano, which had been contracting, began to expand slowly at the beginning of June. The Alert Level remained at 2.

Geologic Background. Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located Karakunidake being the highest. Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.

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).


Merapi (Indonesia) — July 2018 Citation iconCite this Report

Merapi

Indonesia

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

All times are local (unless otherwise noted)


Lahar in October 2016; phreatic explosions May-June 2018

After a major eruption on 26 October 2010 that subsided in early December of that year, Merapi erupted regularly amid elevated seismicity between 13 June 2011 and April 2014; seismicity returned to normal levels in May 2014 (BGVN 39:10). Renewed activity in the form of phreatic explosions took place during May-June 2018.

Lahar in October 2016. According to the Badan Nasional Penanggulangan Bencana (BNPB) (National Disaster Management Agency), a lahar on 27 October 2016 induced by moderate to heavy rain swept nine sand mining trucks down the Bebeng River on the SW flank; at least one truck was buried and six were severely damaged. There were no fatalities as the miners and other people at the scene escaped. Material at the summit and on the flanks produced during the October-November 2010 eruption was an estimated 20-25 million cubic meters, contributing to the continuing high potential of lahars during heavy rain. BNPB recommended that the public remain vigilant during rainy weather because a lahar formed on the upper flanks of Merapi can reach the bottom in less than 30 minutes. The Alert Level remained at 1 (on a scale of 1-4).

Phreatic explosions during May-June 2018. The volcano was apparently quiet between November 2016 and April 2018. According to the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), an explosion occurred at 0740 on 11 May 2018. The eruption began with a small roar and vibrations that were felt at the observation post for 10 minutes. A plume rose to 5.5 km above the summit. There was no seismic precursor and no subsequent seismic activity. According to a news account (The Jakarta Post) on 11 May, the increased activity caused Yogyakarta's Adisutjipto International Airport (27 km S) to close, resulting in the cancellation of eight Garuda Indonesia flights. PVMBG did not increase the alert level from Green/Normal; they interpreted the explosion as being a minor event triggered by the accumulation of volcanic gases, and unlikely to result in subsequent explosions. High levels of sulfur dioxide in the vicinity of the volcano were detected by the satellite-based Ozone Monitoring Instrument (OMI) on 11 May; concentrations reached as high as 2.0 Dobson Units.

On 21 May a phreatic explosion began at 0125 and lasted for 19 minutes, generating an ash plume that rose 700 m above the crater and drifted W. At 0938, another phreatic explosion began that lasted six minutes and produced an ash plume that rose 1.2 km above the crater. Ashfall from both events was reported in areas 15 km downwind. A third event, detected at 1750, lasted three minutes and produced a plume of unknown height. After these events, one volcano-tectonic (VT) earthquake and one tremor event were recorded. The seismicity along with increased phreatic events prompted PVMBG to raise the Alert Level to 2.

According to PVMBG, on 23 May, at 1349 the Babadan observation post heard a two-minute-long phreatic explosion. A plume was not visible due to inclement weather, though minor ashfall was reported at the Ngepos observation post. On 24 May an event at 0256 generated an ash plume that rose 6 km above the crater rim and drifted W. Roaring was heard at all the Merapi observation posts. A two-minute-long event at 1048 produced an ash plume that rose 1.5 km and drifted W. PVMBG recommended the evacuation of everyone within 3 km of the summit.

PVMBG reported that on 1 June, at 0820, an event generated an ash plume that rose at least 6 km above the crater rim and drifted NW, then SW (figure 68). Ashfall was reported at the Selo observation post. Observers noted white smoke rising from a forested area 1.5 km NW, possibly indicating burning vegetation. PVMBG indicated that VT events were occurring at about 3 km below the crater. Later that day at 2024, an ash plume from a 1.5-minute-long event rose 2.5 km above the crater rim and drifted NE and W. At 2100, an ash plume rose 1 km and drifted NW. The Alert Level remained at 2.

Figure (see Caption) Figure 68. Photo of an explosion at Merapi on 1 June 2018. Courtesy of Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency.

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities.

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/); The Jakarta Post (URL: http://www.thejakartapost.com/); 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/).

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