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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 39, Number 02 (February 2014)

Managing Editor: Richard Wunderman

Ahyi (United States)

Seismic/acoustic signals and bathymetric data validate April-May 2014 eruption

Kelut (Indonesia)

Big 2014 eruption; plume over 26 km a.s.l.; ~7 deaths and over 100,000 refugees

Ritter Island (Papua New Guinea)

Report includes past geothermal activity observations

Sangay (Ecuador)

Absence of evidence for ongoing eruption; new hazard maps

Sangeang Api (Indonesia)

Ashfall from 30 May 2014 eruption causes evacuations, airline delays

Telica (Nicaragua)

Small explosions in September 2013; a new intracrater vent

Whakaari/White Island (New Zealand)

Dome extrusion in late 2012 and further eruptions in 2012-2013



Ahyi (United States) — February 2014 Citation iconCite this Report

Ahyi

United States

20.42°N, 145.03°E; summit elev. -75 m

All times are local (unless otherwise noted)


Seismic/acoustic signals and bathymetric data validate April-May 2014 eruption

Ahyi seamount is located ~20 km SE of Farallon de Pajaros and was discussed in the Bulletin associated with volcanic unrest in 1979 (SEAN 04:01) and in 2001 (BGVN 26:05). The evidence for a 2014 eruption at Ahyi seamount includes seismicity, noises heard by divers and felt aboard a vessel in the area, and a follow-up research cruise to Ahyi that measured a hydrothermal plume and significant bathymetric changes since the last survey in 2003. This report is revised from an earlier version.

The U.S. Geological Survey (USGS) reported that, beginning about 0635 local time on 24 April 2014 (2035 on 23 April 2014, UTC), seismometers in various locations in the Mariana Islands began recording T-phase signals interpreted as stemming from an undersea eruption in an area to the N of Pagan island near the island of Uracas (also known as Farallon de Pajaros). Note that throughout this report, at the suggestion of William Chadwick of NOAA, 'T-phase signals' have been used in lieu of 'earthquakes' since all the eruption-related signals were hydroacoustic (from underwater explosions) rather than seismic body-waves. See the final section of this report for a brief definition of T-phase waves. The eruption was ultimately tracked to Ahyi seamount (figures 2 and 3).

Figure (see Caption) Figure 2. Map of the western Pacific margin showing the Northern Mariana Islands with the location of Ahyi volcano added. Original map from Magellan Graphix (1957).
Figure (see Caption) Figure 3. (left) A bathymetric map showing the islands and seamounts making up the Mariana island arc. The rectangular box on that map delineates the N part of the arc that is shown on the map at right. (right) A larger scale bathymetric map that highlights features in the vicinity of Ahyi seamount; within the yellow-lined box is the islands unit of the Mariana Trench Marine National Monument. Maps courtesy of Susan Merle, Oregon State University and NOAA-PMEL.

Seismometers that recorded the 2014 T-phase signals included those on Saipan, Pagan, Sarigan, and Anatahan islands (figure 2). The USGS reported recording T-phases during 24 April through 8 May 2014. During this same period, hydroacoustic sensors on Wake Island (~2,300 km ENE from Ahyi) also received signals. The recorded events all indicated that the source of the hydroacoustic signals was at or near Ahyi seamount, but the accuracy of the initially determined locations remained uncertain because there are other active volcanic seamounts in the area.

On 25 April 2014 the Aviation Color Code was raised by the USGS from Unassigned (Volcanic Alert Level: Unassigned) to Yellow (Volcanic Alert Level: Advisory). As of 29 May, USGS had received no reports of an eruption plume or any evidence that eruptive products had reached the surface. Satellite images showed nothing indicative of a volcanic eruption. On 29 May the Aviation Color Code was lowered by the USGS to Unassigned (Volcanic Alert Level: Unassigned).

At the time of the T-phase signals in April 2014, submarine explosions were heard and felt by scuba divers conducting coral reef research in the area. Chip Young, leader of the Hi'ialakai expedition working in the area as part of a coral reef survey by the NOAA Pacific Islands Fisheries Science Center (PIFSC), provided the following information on 28-29 April 2014. At this stage, the source of the signals was still a mystery.

"While we were diving [on 26 April at Farallon de Pajaros (FDP)] we could hear eruptions underwater. It wasn't casual, in fact, it sounded like bombs exploding with the concussion felt through your body. I don't know how close we were to the event, none of the…divers saw volcanic activity, but at least one explosion was so powerful, that it reverberated through the hull of the ship and the crew onboard thought that something had happened to the ship (at the time they didn't realized we too were hearing these explosions under water)."

"The first divers' comments about hearing something underwater started at Asuncion (4/24-4/25). We were at FDP on [26 April] and to my best guess, the massive explosion that I previously wrote about occurred 0100-0230 26 APR 14 UTC on the SE side of FDP. There were plenty of other explosions throughout the day, but that was the largest one I experienced. There were conglomerates/mats of orange+yellow bubbles on the surface of the water on the SE coastline of FDP as well. We had a very calm day at FDP, so the mats/sludge stretched on for 20-30 ft [~7-9 m] or more. These could have been from Ahyi, but visual disturbances near Ahyi weren't specifically made because we passed there in the early [morning] on the way to FDP and then in the evening on the way to Maug. We did hear explosions underwater at Maug too. I heard distant explosions, which I assumed were from FDP, but there were closer ones too. Not as violent as the sounds we heard at FDP, but 'cracks' for sure."

During the height of the T-phase swarm, explosive signals from the underwater eruption source in the vicinity of Ahyi were occurring at a rate of ~20 per hour. On 16 May 2014, the USGS reported that over the preceding week, T-phase signals had greatly diminished.

Verification of 2014 Ahyi eruption. A subsequent expedition took place during 12-18 May, after the eruption T-phases had stopped. This expedition, led by Chip Young and Dave Butterfield aboard the R/V Hi'ialakai, was working at Maug island (~50 km SSE of Ahyi) and conducted several water-column CTD (conductivity-temperature-depth) casts in the area. They found a hydrothermal plume coming from Ahyi. In addition, they collected new bathymetric data over the summit of Ahyi, which showed the depth changes that confirmed that Ahyi was indeed the source of the 2014 eruption.

According to William Chadwick, NOAA surveyed Ahyi in 2003, measuring a summit depth of 60 m. After the T-phase signals declined in mid-May 2014, the NOAA ship Hi'ialakai went over the summit and the new minimum depth was found to be 75 m. In addition, a new summit crater is evident in the 2014 bathymetry that is ~95 m deep. Bloomer and others (1989) noted a value of 137 m as Ahyi's summit depth, based on U.S. Navy Sonar Array Sounding System (SASS), an early form of multibeam sonar. This pre-2003 summit depth value is probably less accurate and therefore does not necessarily represent a true depth change between the SASS survey and 2003.

Figure 4B shows the results of multibeam sonar bathymetry over Ahyi's summit collected by the Hi'ialakai in 2014. This map was compared to their previous survey in 2003 (figure 4A) and used to compose a third map (figure 4C) showing depth differences between the two surveys. In essence, the summit elevation dropped by 25 m; a crater had developed with a floor at a depth of 195 m; and a conspicuous landslide chute descended to at least 2,300 m depth along the SE slope. Up to 125 m of material was removed from the head of the landslide chute, and constructional deposits downslope were up to 40 m thick. The map analysts noted that even though the 2014 re-survey was limited and produced an incomplete look at the entire Ahyi edifice, the changes were very clear and indicated recent eruptive activity at Ahyi.

Figure (see Caption) Figure 4. Three maps (frames A, B, C) showing multibeam bathymetry and analyses of bathymetric changes between surveys of 2003 and May 2014 of Ahyi volcano (white areas signify lack of data). (A) Bathymetry of Ahyi volcano conducted 2003 showing a cone with summit at a depth of 65 m (Merle and others, 2003). (B) Ahyi map from survey conducted May 2014. The cone was gone and was replaced by a new crater with a rim at 90 m depth and a floor at 195 m depth. The current minimum summit depth for the volcano at 75 m resides near the location on figure 4B labeled "crater rim ~90 m." Extending SSE from the new crater, the research disclosed a new landslide chute descending to at least 2,300 m depth. (C) Depth changes comparing 2003 and 2014 maps. As defined on key at lower left, the cool colors signify material removed; green, no change; and warm colors, material added. Labels indicate elevation changes disclosed in the comparison (e.g. -20 m means this area is 20 m lower on the 2014 map than on the 2003 map). Map courtesy of Susan Merle, Oregon State University and NOAA/PMEL.

T-phase waves: According to Okal (2011) "T phases are defined as seismic recordings of signals having traveled an extended path as acoustic waves in the water body of the oceans. This is made possible by the 'Sound Fixing and Ranging' (SOFAR) channel, a layer of minimum sound velocity acting as a wave guide at average depths of 1,000 m. It allows the efficient propagation of extremely small signals over extremely long distances, in practice limited only by the finite size of the ocean basins."

The use of T-waves has led to much improved diagnosis of submarine vent locations. For example, Fox and Dziak (1998) described the detection of intense seismicity the NE Pacific Ocean using the T-phase Monitoring System developed by NOAA/PMEL to access the U.S. Navy's SOund SUrveillance System (SOSUS) in the North Pacific. Dziak and Fox (2002) discussed monitoring of hydroacoustic signals from the Volcano Islands arc, S of Japan (just N of the N Mariana Islands shown in figure 2), a region with frequent submarine eruptions. The signals are characterized by a narrowband, long-duration, high-amplitude fundamental centered at 10 Hz with three harmonics at 20, 30, and 40 Hz. The hydroacoustic (T-wave) signals are consistent with harmonic tremor signals observed using traditional seismic methods at active subaerial volcanoes throughout the world.

References. Bloomer, S.H., Stern, R.J., and Smoot, N.C., 1989, Physical volcanology of the submarine Mariana and Volcano Arcs, Bulletin of Volcanology, v. 51, pp. 210-224.

Bloomer, S.H., Stern, R.J., Fisk, E., and Geschwind, C.H., 1989, Shoshonitic Volcanism in the Northern Mariana Arc 1. Mineralogic and Major and Trace Element Characteristics, Journal of Geophysical Research, v. 94, no. B4, pp. 4469-4496.

Dziak, R.P., and Fox, C.G., 2002, Evidence of harmonic tremor from a submarine volcano detected across the Pacific Ocean basin, Journal of Geophysical Research, v. 107, no. B5, p. 2085.

Fox, C.G., and Dziak, R.P., 1998 (December), Hydroacoustic detection of volcanic activity on the Gorda Ridge, February-March 1996, Deep Sea Research Part II: Topical Studies in Oceanography, v. 45, no. 12, pp. 2513-2530 (DOI: 10.1016/S0967-0645(98)00081-2).

Magellan Graphix, 1997, Map: Northern Mariana Islands (territory of US) (URL: http://www.infoplease.com/atlas/state/northernmarianaislands.html).

Merle, S., Embley, R., Baker, E., and Chadwick, B., 2003, Submarine Ring of Fire 2003 - Mariana Arc R/V T.G. Thompson Cruise TN-153, February 9-March 5, 2003, Guam to Guam, Cruise Report, NOAA-PMEL (URL: http://www.pmel.noaa.gov/eoi/marianas/marianas-crrpt-03.pdf).

Okal, E.A., 2011, T Waves, in Gupta, H.K. (ed), Encyclopedia of Solid Earth Geophysics, pp. 1421-1423, Springer Netherlands (DOI: 10.1007/978-90-481-8702-7_165).

USGS, 2014 (30 April), Northern Mariana Islands Information Statement, Wednesday, April 30, 2014 5:36 AM ChST (Tuesday, April 29, 2014 19:36 UTC) (URL: http://volcanoes.usgs.gov/activity/archiveupdate.php?noticeid=10031).

USGS, 2014 (1 May), A new submarine eruption in the Northern Mariana Islands: could it happen here?, Hawaii Volcano Observatory (URL: http://hvo.wr.usgs.gov/volcanowatch/view.php?id=226).

USGS, 2014 (16 May), Current Alerts for U.S. Volcanoes, Northern Mariana Islands Weekly Update, 16 May (URL: http://volcanoes.usgs.gov/nmi/activity//status.php).

USGS, 2014 (23 May), Northern Mariana islands Weekly Update, 23 May 2014 (URL: http://volcanoes.usgs.gov/nmi/activity/index.php).

Geologic Background. Ahyi seamount is a large conical submarine volcano that rises to within 75 m of the sea surface about 18 km SE of the island of Farallon de Pajaros (Uracas) in the northern Marianas. Water discoloration has been observed there, and in 1979 the crew of a fishing boat felt shocks over the summit area of the seamount, followed by upwelling of sulfur-bearing water. On 24-25 April 2001 an explosive eruption was detected seismically by a station on Rangiroa Atoll, Tuamotu Archipelago. The event was well constrained (+/- 15 km) at a location near the southern base of Ahyi. An eruption in April-May 2014 was detected by NOAA divers, hydroacoustic sensors, and seismic stations.

Information Contacts: NOAA Pacific Marine Environmental Laboratory (NOAA-PMEL), 7600 Sand Point Way NE, Bldg #3, Seattle, WA 98115 (URL: http://www.pmel.noaa.gov/); William W. Chadwick and Susan Merle, NOAA-PMEL Earth-Ocean Interactions Program and Oregon State University; David A. Butterfield, University of Washington and NOAA-PMEL; Charles (Chip) Young, NOAA Fisheries, Pacific Islands Fisheries Science Center (PIFSC); Matt Haney, U.S. Geological Survey (USGS), Alaska Volcano Observatory (AVO), Anchorage, AK 99508; USGS Volcano Hazards Program (URL: http://volcanoes.usgs.gov/nmi/activity/); and CNMI Emergency Management Office (URL: http://www.cnmihomelandsecurity.gov.mp/).


Kelut (Indonesia) — February 2014 Citation iconCite this Report

Kelut

Indonesia

7.93°S, 112.308°E; summit elev. 1731 m

All times are local (unless otherwise noted)


Big 2014 eruption; plume over 26 km a.s.l.; ~7 deaths and over 100,000 refugees

Synopsis. On 13 February 2014, the Indonesian National Board for Disaster Management (Badan Nasional Penanggulangan Bencana-BNPB) reported that a major eruption occurred at Kelut (also known as Kelud) volcano in East Java, Indonesia. Ground-based observers had little insight about the ash plume height, but a number of satellite observations helped to constrain the height and other eruption parameters such the direction of plume movement. CALIPSO satellite data revealed that a rapidly rising portion of the plume ejected material up to an altitude exceeding ~26 km, well into the tropical stratosphere. Most of the less rapidly rising portions of the plume remained lower, at 19-20 km altitude. The 2014 eruption destroyed a dome emplaced in the volcano's caldera during the previous eruption in 2007 (BGVN 33:03 and 33:07). According to BNPB in a report issued on 18 February 2014, ~7 people were killed and ~100,000 evacuated. At least one commercial aircraft flew into the plume, later landing successfully but incurring costly engine damage.

This report discusses the pre- and syn-eruption observations from the early January through 25 February 2014. Much of the detailed reporting used here describing Kelut's behavior came from the Indonesian Centre for Volcanology and Geological Hazard Mitigation (CVGHM; also known as Pusat Vulkanologi dan Mitigasi Bencana Geologi, PVMBG). Kelut is located just S of Surabaya (Surabaja), Indonesia's second largest city (see a map, figure 8 in BGVN 33:03).

Pre-eruption. According to CVGHM, the lake-water temperature in the crater increased 5.5°C during 10 September 2013 to 2 February 2014. During 1 January-2 February 2014 the number of shallow volcanic earthquakes at Kelut volcano increased. During 3-10 February 2014, seismic activity at Kelut was dominated by both shallow and deep volcanic earthquakes; some hypocenters were 3 km below the summit. Real-time Seismic-Amplitude Measurement (RSAM, a gauge of volcanic seismicity) values increased on 6 and 9 February 2014. Inflation was detected at one station.

Peaks of pre-eruptive seismicity occurred during 15-16 and 28 January, and 2-13 February. Table 3 also portrays the available early 2014 seismic data from CVGHM, but it can be hard to see the aforementioned detail because the various entries on table's rows generally summarize multiple days and some of the time intervals differ. The number of deep volcanic earthquakes fluctuated but generally increased overall. Earthquakes often occurred at 2-8 km depth. Based on these observations, on 2 February the Alert Level was raised to from 1 to 2 (on a scale with increasing severity in the range 1-4). Tiltmeter data on 10 February indicated inflation.

Table 3. Seismicity at Kelut volcano during January and into 13 February 2014. Note that the data stream changed abruptly on 13 February when four of Kelut's 5 seismic stations were destroyed by eruptive material. Courtesy of CVGHM.

Time period 2014 (no. of days) Shallow/deep volcanic earthquakes (VB / VA) Deep/local tectonic earthquakes (TJ) (nr-none reported) Low frequency earthquakes (LF)
1-7 Jan (7) 14 / 1 44 / -- 4
8-14 Jan (7) 18 / 4 32 / -- 2
15-21 Jan (7) 38 / 34 27 / -- 0
22-31 Jan (10) 234 / 74 79 / 2 1
1-3 Feb (3) 111 / 30 3 / -- 0
3-10 Feb (8) 693 / 297 50 / -- 0
13 Feb (1) 440 / 1,135 1 / 3 198

Crater lake water temperatures continued to increase after September 2013, particularly during 23 January-9 February. Temperatures decreased slightly when measured on 10 February.

On 10 February, based on the factors noted above, CVGHM increased the Alert Level to 3. This excluded visitors and residents from within a 5-km radius of the crater.

Eruption on 13 February. At 2115 on 13 February the Alert Level for Kelut was raised to 4, extending the exclusionary zone to a 10-km radius. As noted above, BNPB reported that a major eruption occurred less than two hours later at 2250, followed by another large explosion at 2330. NASA reported that satellite images showed the Kelut eruption about 2 hours later on 13 February 2014 at ~2315 local time (1615 UTC).

According to a Darwin VAAC (2014) weekly activity report, the eruption was seen on the hourly MTSAT-2 IR satellite for 1632 UTC (2332 local time) on 13 February, where it appeared as a rapidly expanding cloud. More details came from 10-minute IR data being used on a special basis in the High Ice Project in Darwin, which captured the eruption clearly as a small cluster of cold pixels on a 1610 UTC (2310 local time) IR image. Later analysis found a small low altitude plume as early as 1540 UTC (2240 local time) at Kelut on the MTSAT-1R satellite; this is the earliest reported start time for the eruption.

According to CVGHM, ash plumes rose to an altitude of 17 km and caused ashfall in areas NE, NW, W, and elsewhere as far as Pacitan (133 km WSW), Kulon Progo (236 km W), Temanggung (240 km WNW), and Banyuwangi (228 km E). As ash began to blanket parts of the region, 40 airline flights were cancelled; impacted airports included Juanda (81 km NE), Adi Sucipto Yogya (208 km W), and Adi Sumarmo Solo (175 km WNW). News articles reported that flights in and out of seven airports were cancelled or rerouted.

Figures 15 and 16 show satellite images of the plume taken on 13 February 2014. The image at the top of figure 15 portrays the scene at 0030 local time and the trace of the path across it taken by the satellite. At ~1813 UTC on 13 February. CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation). CALIPSO flew over the plume deploying CALIOP (a lidar instrument, essentially a laser range finder that creates a profile of clouds and particles in the atmosphere). This is one of the favored instruments for cloud height measurement. It is part of the A-Train, a constellation of multiple satellites and instruments that follow the same track on polar orbits and cross the equator within seconds to minutes of each other. This allows near-simultaneous observations. CALIOP data revealed that the Kelut ash cloud was generally at an altitude of 18-19 km, with some cloud/ash material reaching a maximum height of ~26 km. This is sufficiently high, and the A-Train data capabilities are sufficiently large to cause great interest, and more refined estimates of height and other parameters are likely to follow.

Figure (see Caption) Figure 15. Figure 15 (top and bottom). At 0030 local time (1730 UTC 13 February) on 14 February, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite acquired the top image as the gray circular ash plume over Kelut reached above a lighter-colored weather-cloud deck. Forty minutes later, at 0110 local time (1810 UTC 13 February), the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite flew over the plume with its lidar instrument. The instrument recorded the ash cloud at nearly 20 km altitude, with sections of the plume reaching to nearly 26 km. Courtesy of NASA Earth Observatory; image by Jesse Allen, using data provided by the CALIPSO team; caption by Holli Riebeek.
Figure (see Caption) Figure 16. A cross-section through the Kelut volcanic plume from data acquired on 14 February 2014. The image zooms in on CALIPSO data for the tallest parts of the volcanic cloud (using the CALIOP data). The white line shows the approximate troposphere-stratosphere boundary. Some wave structure (small white oscillations) is apparent in the umbrella region. The vertical scale on the left shows computed altitude, and on the lower right shows the color scale for intensity of the 532 nm wavelength backscatter. The horizontal scale and labels at the bottom of the figure shows the latitude, longitude, and time in UTC for the vertical sounding across the transect. The red trace across the bottom of the figure shows land topography, with the volcano at the center. The AIRS (atmospheric infrared sounder) determined SO2 brightness temperature differences (BTD-scale at upper right) referring to features such as the red stars, where AIRS detected SO2 towards the edge of the cloud. Courtesy of Carn and Telling (2014).

Figure 17 shows a view of an eruption at 0030 local time on 14 February. In Figure 18, a plane, service vehicle, and boarding area are shown covered by ash at Yogyakarta airport, 215 km E of Kelut. Closer to the volcano, ashfall and tephra blocks 5-8 cm in diameter caused structures to collapse, including schools, homes, and businesses.

Figure (see Caption) Figure 17. A photo of the eruption of Kelut at 0030 on 14 February 2014, with lightning being generated in the ash plume. Courtesy of Volcano Discovery web site (URL: http:pic.twitter.com/ypy7kx9615 / @hilmi_dzi).
Figure (see Caption) Figure 18. Image of a tan-colored ash blanket covering the landscape, including a parked jet liner and service vehicle, at Yogyakarta airport, 215 km W of Kelut, taken 14 February 2014. Image from NBC News web site (BIMO SATRIO / EPA).

As a result of this eruption, four of the five Kelut seismic stations were destroyed, after which, volcanic and low-frequency earthquakes were not recorded. Subsequently, available seismicity recorded at the one remaining station, 5 km away, was dominated by continuous tremor with amplitudes ranging from 0.5 to 15 mm. That station later recorded declining seismicity during 14-20 February. Two more seismic stations were installed on 16 February, 2-3 km from the crater.

On 14 February, gray-to-black plumes rose 400-600 m above the crater, and on 15 February grayish white plumes rose as high as 3 km (figure 19).

Figure (see Caption) Figure 19. The eruption of Kelut (labeled just to the right of the image's center) on 13 February 2014 sent a large plume of ash drifting W across Java and over the Indian Ocean. This satellite image, acquired 14 February, shows widespread tan atmospheric discoloration from the ash plume. According to an advisory issued by the Australian Bureau of Meteorology, ash had reached 13 km in altitude, prompting the closure of several airports. Three people were killed, and Indonesian authorities have evacuated more than 75,000 people from their homes. NASA Earth Observatory, image by Jesse Allen and caption by Adam Voiland, using data from the Land Atmosphere Near real-time Capability for EOS (LANCE).

On 14 February BNPB reported that the eruption had killed four people (but later estimates were higher): one died due to a collapsing wall, one from ash inhalation, and two from "shortness of breath." All four victims lived within 7 km of Kelut in the regency of Malang, an area that received ashfall up to 20 cm thick.

By 0600 on 14 February, BNPB reported that the number of displaced people reached 100,248, but the report also noted that volcanic activity had declined. Later that day BNPB noted that 76,388 people remained evacuated. Seismicity continued to decline and was at moderate levels during 15-17 February. During 16-20 February white plumes rose as high as 1 km and drifted N, NE, and E.

Heavy rain on 18 February caused lahars in Ngobo, Mangli (Kediri, 35 km WNW), Bladak (Blitar, 20 km SW), and Konto (Malang, 35 km E). BNPB noted that the lahars flooded five houses and one mosque, and destroyed two homes and one bridge.

An 18 February BNPB report noted that a total of 7 people in Malang regency had died, and that the ashfall had affected farms, including cattle health and dairy production, and the water supply. Damage to infrastructure in Malang included 3,782 houses, 20 government buildings, 251 schools, 9 hospitals, and 36 churches.

Data from satellite instruments provided a 14 February 2014 image on sulfur dioxide (SO2) from Kelut (figure 20). The plume had spread primarily W of the volcano.

Figure (see Caption) Figure 20. Sulfur dioxide burdens measured from Kelut (red triangle) over the Indonesian island of Java and Indian Ocean in the early morning of 14 February 2014 following the Kelut eruption. This image is based on data from the IASI instrument on the MetOp mission. Courtesy of European Space Agency (2014).

The Alert Level for Kelut was lowered by CVGHM from 4 to 3 on 20 February and to 2 on 28 February based on decreased amplitude of tremors and thick clouds of white smoke continuously emitted from the crater instead of dark grey. At this point, visitors and residents were prohibited from approaching the crater within a radius of 5 km, but residents outside of this zone were permitted to return home.

Associated with the Kelut eruption, only a single pixel MODVOLC satellite thermal alert was measured during the interval from 13 February through March 2014. The alert occurred at 1515 hours UTC on 20 February 2014, the first alert measured since nearly daily alerts from Kelut's last eruption, 18 November 2007-23 January 2008. During the February 2014 eruption, cloudy weather over Kelut was a major factor that precluded some alerts from being measured, but those visualized suggest that the recent Kelut eruption continued until at least 20 February 2014.

A satellite image made available thanks to the International Charter Space and Major Disasters (2014) was acquired on 18 February and interpreted by the U.S. Geological Survey. The image reveals the impact of the eruption on the summit area and regions peripheral to it (figure 21).

Figure (see Caption) Figure 21. Satellite image of the crater area of Kelud, acquired on 18 February 2014. The former dome was destroyed during the 14 February eruption and significant ash and debris were deposited on the volcano slopes and in the river channels from lahars and pyroclastic flows around the volcano. Steam can be seen rising from the central crater. Courtesy of International Charter Space and Major Disasters (2014); source was WorldView, acquired 18/02/2014 by DigitalGlobe Inc.; map produced by USGS, and found online at Klemetti (2014c).

Later visits disclosed that the 2014 eruption had left a large crater 400 m in diameter and destroyed the 2007 dome, parking area, and access stairs in the crater (see figures 22 and 23).

Figure (see Caption) Figure 22. Photograph of the inner dome in Kelut volcano taken in 2010, showing the then- existing lava dome from the 2007 eruption and the access stairs to the crater, both of which were destroyed by the February 2014 eruption. Image courtesy of Zahidayat / Flickr, from Klemetti (2014b).
Figure (see Caption) Figure 23. (Left) The Kelut lava dome that grew in the crater in 2007, photographed 30 October 2011 by Andersen (2011). In front of the dome was the small portion of what was left of the volcanic lake that used to fill the crater. (Right) The crater of Kelut seen on the morning of 18 February 2014 (photo by Suwarno, a local photographer, via Andersen), showing that the 2014 eruption forcefully removed the dome. Comparison figure came from Andersen (2014).

A group of photographs taken by Oystein Lund Andersen (2014) during a visit from 22 to 23 February show after-eruption images, including steam rising from the crater area, ash and volcanic bombs deposited 2-5 km from Kelut's crater, and damage to trees and other vegetation by pyroclastic flows (for example, Figures 24 and 25). In addition, photographs showed that steam continued to rise from the crater through 25 February 2014. Andersen observed that activity at the volcano has decreased, but it was still unknown what exactly the situation at the vent is, whether or not a new lava dome is forming there.

Figure (see Caption) Figure 24. Steaming pyroclastic flow deposits in one of the valleys below the crater, a once forested area ~1 km SW of the crater .Photo taken at 1157 on 22 February 2014. Courtesy of Andersen (2014).
Figure (see Caption) Figure 25. A lush green forest once stood here, now covered by deposits from a pyroclastic flow and scattered remains of large felled trees. Photo taken at 1205 on 22 February 2014. Courtesy of Andersen (2014).

Airliner encounters plume. A commercial A320 airliner carrying passengers from Perth, Australia, to Jakarta, Indonesia, encountered an ash plume from Kelut near Indonesia on 14 February 2014. The incident was reported by the West Australian (Perth) newspaper and the Sydney Morning Herald (14 February). The reports noted that the airliner left Perth on 14 February 2014 at 0225 local time and flew through the ash cloud before arriving safely in Jakarta at 0550 local time. The estimated cost to replace the two engines of the Airbus aircraft was reported to be $20 million (US dollars). The A320 was grounded after the flight.

Morning Herald reporter Amanda Hoh (2014) reported that a "flight from Perth to Jakarta on Friday morning was filled with smoke after the plane flew into Indonesia's volcanic ash cloud … Richard Craig, from Perth, was on a flight to Jakarta at about 5am on Friday [14 February] when he said the plane suddenly flew into the ash cloud about 30 minutes before landing" Passenger Craig was quoted to have said "It was just starting to get light then it suddenly went quite dark and what I thought was smoke appeared in the cabin out the front, started coming out of the air vent and alarm went off and beeped a few times," he said. "There was an unusual smell. It wasn't like smoke, a slightly sweet smell. More like a very fine smoke…" The smoke cleared within a few minutes and Craig noted that the pilot announced that "it was a volcanic ash cloud and that 'no one was aware of it in the area.'" The plane landed safely.

Summary of damage. According to the International Federation of Red Cross and Red Crescent Societies (IFRC) (2014), "over the first few days the eruption affected 201,228 people (58,341 families) from 35 villages in three districts: Blitar, Kediri, and Malang. . . As of 14 February 2014, there had been seven fatalities and 70 people in hospitals in serious condition suffering from ash inhalation. Around this time the number of internally displaced persons (IDPs) had reduced to 100,248 people who had evacuated and camped across the province in 172 IDP camps set up to cater for their basic needs."

"In addition to the volcanic ash, heavy rain fell and produced cold lahar flooding in Malang, Kediri and Blitar districts. This caused further damage to buildings, farm lands, and roads."

Table 4 gives data on damage to structures in the 3 affected districts surrounding Kelut through February 2014. The figures are expected to increase once a more thorough assessment is made.

Table 4. An initial assessment of the damage to housing and other buildings as a result of Kelut eruption volcanic ash. Courtesy of IFRC (2014).

District Totally damaged Moderately damaged Minor damaged
Kediri 8,622 5,426 5,088
Malang 1,514 1,066 1,378
Bitar 957 878 1,578
Totals 11,093 7,370 8,044

As reported on 24 February 2014 in the Jakarta Globe (Pitaloka, 2014), "torrential rain in East Java on 23 February 2014 prompted local officials to impose a safety curfew over some areas affected by the eruption of Mount Kelud for fear that rainwater could mix with volcanic dust, triggering mud flows." The Head of the Malang Disaster Mitigation Agency, Hafi Lutfi, said rain had triggered landslides that damaged several sections of mountain road. "A mud flow in Padansari village on Thursday [13 February] washed away two houses and two bridges, although no casualties were reported . . . Volcanic mud was carried down the mountain's slopes by the river, which flows through Kasembon, Ngantang and Pujon subdistricts" (figure 26).

Figure (see Caption) Figure 26. Villagers stand on the remains of a bridge washed out in Malang district near Pandansari village. The bridge succumbed to water mixed with volcanic material from Mount Kelut's eruption on 19 February 2014. From Pitaloka (2014); EPA photo by Fully Handoko.

Lutfi was reported to have stated further that the "impact of Mount Kelud's eruption will extend far beyond the initial cleanup efforts. Fruit farmers reportedly lost more than Rp 24 billion ($2 million) in revenue as ash and debris destroyed whole fields of apples, durian and rambutan that were ready for harvest. The trees, covered in a thick coating of ash, had withered from lack of sunlight."

Background. The CVGHM reported that activity at Kelut last occurred in 2007, beginning with an increase in seismic activity and an eruption in October 2007. The activity ended with an effusive eruption on 3-4 November 2007 resulting with a crater lake surrounding a central lava dome (BGVN 33:03, 33:07, and 37:03).

References. Andersen, O.L., 2014 (22 February), Kelud Volcano, East-Java, Indonesia (URL: http://www.oysteinlundandersen.com/Volcanoes/Kelud/Kelud-Volcano-Indonesia-February-2014.html)

Andersen, O.L., 2011 (30 October), Mt. Kelud Volcano, Indonesia, 30 October 2011(URL: http://www.oysteinlundandersen.com/Volcanoes/Kelud/Kelud-Volcano-Indonesia-October-2011.html).

Carn, S., and Telling, J., 2014, Kelut 2014, IAVCEI (International Association of Volcanology and Chemistry of the Earth's Interior) Remote Sensing Commission (RSC) (URL: https://sites.google.com/site/iavceirscweb/eruptions/kelut-2014)

CIMSS Satellite Blog, 2014 (13 February), Eruption of the Kelut volcano in Java, Indonesia (URL: http://cimss.ssec.wisc.edu/goes/blog/archives/14910 ).

European Space Agency (ESA), 2014 (14 February), Kelut volcano grounds air travel, ESA Observing the Earth web site (URL: http://www.esa.int/Our_Activities/Observing_the_Earth/Kelut_volcano_grounds_air_travel).

Hoh, A., 2014 (14 February), Volcano eruption cancels Bali, Phuket flights and closes Indonesian airports, The Sydney Morning Herald (URL: 14http://www.smh.com.au/travel/travel-incidents/volcano-eruption-cancels-bali-phuket-flights-and-closes-indonesian-airports-20140214-32qd8.html)

International Charter Space and Major Disasters, (2014), Mount Kelud volcanic eruption in Indonesia (URL: http://www.disasterscharter.org/web/charter/activation_details?p_r_p_1415474252_assetId=ACT-481)

International Federation of Red Cross and Red Crescent Societies, 2014 (3 March), Emergency plans of action (EPofA), Indonesia: Volcanic eruption - Mt. Kelud (URL: http://reliefweb.int/sites/reliefweb.int/files/resources/MDRID009dref.pdf).

Klemetti, E., 2014a (11 February), Indonesian Eruption Update for February 11, 2014: Kelut and Sinabung (URL: http://www.wired.com/wiredscience/2014/02/indonesias-kelut-placed-highest-alert/)

Klemetti, E., 2014b (13 February), Significant Eruption Started at Indonesia's Kelut (URL: http://www.wired.com/wiredscience/2014/02/significant-eruption-started-indonesias-kelut/).

Klemetti, E., 2014c (24 February), Kelud, Before and After the Eruption (URL: http://www.wired.com/wiredscience/2014/02/kelud-eruption/).

National Aeronautics and Space Administration (NASA) Goddard Space Flight Center, 2014 (13 February), Kelut (Kelud) Eruption- February 13, 2014 (URL: http://so2.gsfc.nasa.gov/pix/special/2014/kelut/Kelut_summary_Feb14_2014.html)

Pitaloka, D.A., 2014 (24 February), Torrential Rain Worsens Kelud Misery, Jakarta Globe (URL: http://www.thejakartaglobe.com/news/torrential-rain-worsens-kelud-misery).

Volcano Discovery, 2014 (2 March), Kelut volcano news (URL: http://www.volcanodiscovery.Kelut volcano news & eruption updates _ 27 Sep 2007 - 2 Mar 2014.htm).

Geologic Background. The relatively inconspicuous Kelut stratovolcano contains a summit crater lake that has been the source of some of Indonesia's most deadly eruptions. A cluster of summit lava domes cut by numerous craters has given the summit a very irregular profile. Satellitic cones and lava domes are also located low on the E, W, and SSW flanks. Eruptive activity has in general migrated in a clockwise direction around the summit vent complex. More than 30 eruptions have been recorded from Gunung Kelut since 1000 CE. The ejection of water from the crater lake during the typically short but violent eruptions has created pyroclastic flows and lahars that have caused widespread fatalities and destruction. After more than 5000 people were killed during an eruption in 1919, an ambitious engineering project sought to drain the crater lake. This initial effort lowered the lake by more than 50 m, but the 1951 eruption deepened the crater by 70 m, leaving 50 million cubic meters of water after repair of the damaged drainage tunnels. After more than 200 deaths in the 1966 eruption, a new deeper tunnel was constructed, and the lake's volume before the 1990 eruption was only about 1 million cubic meters.

Information Contacts: Indonesian Centre for Volcanology and Geological Hazard Mitigation – CVGHM (also known as Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG)), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Australian Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Badan Nasional Penanggulangan Bencana (BNPB – Indonesian National Board for Disaster Management), Jl. Ir.H.Juanda No. 36 Jakarta Pusat, Indonesia (URL: http://www.bnpb.go.id); CIMSS (NOAA's Cooperative Institute for Meteorological Satellite Studies), University of Wisconsin – Madison's Space Science and Engineering Center (SSEC) (URL: http://cimss.ssec.wisc.edu/goes/blog/about); NOAA Satellite and Information Service, Automated OMI SO2 Alert System, High SO2 Concentration Areas (URL: http://satepsanone.nesdis.noaa.gov/pub/OMI/OMISO2/Alert/alert.html); National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (URL: http://so2.gsfc.nasa.gov); European Space Agency (URL: http://www.esa.int); West Australian (Perth) news (URL: http://au.news.yahoo.com/a/21467336/); Sydney Morning Herald (URL: http://www.smh.com.au); Andersen, Oystein Lund (URL: http://www.oysteinlundandersen.com/); IAVCEI Remote Sensing Commission website (URL: https://sites.google.com/site/iavceirscweb/eruptions/kelut-2014); and Simon Carn, Department of Geological and Mining Engineering and Sciences, Michigan Technical University, Houghton, MI.


Ritter Island (Papua New Guinea) — February 2014 Citation iconCite this Report

Ritter Island

Papua New Guinea

5.519°S, 148.115°E; summit elev. 75 m

All times are local (unless otherwise noted)


Report includes past geothermal activity observations

According to the Rabaul Volcanological Observatory, a "small (probably submarine) eruption was reported to have taken place at Ritter Island on 18 April 2014 (figures 2 and 3). At about 1700 hours, an earthquake was felt at Kampalap village on Umboi Island. At the same time the level of sea rose a little over normal but was confined to the beach at Kampalap. At around 0000 hours on 19 April, another felt earthquake occurred. The earthquakes were estimated to have an intensity at Kampalap of between II to III. No floating debris where seen, and no ash or damage was reported."

Figure (see Caption) Figure 2. Location maps for Ritter Island. The upper map shows the region of Papua New Guinea containing Ritter Island and other volcanoes, and the lower map is enlargement of the center of the upper map focused on Ritter Island. From of Saunders and Kuduon (2009).
Figure (see Caption) Figure 3. Oblique aerial view of Ritter Island photographed in 2006 by John Holder (the originator of Oceanic Expeditions) from SW looking NE, with some of the location names used in the report by Saunders and Kuduon (2009). From of Saunders and Kuduon (2009).

A Rabaul Volcanological Observatory (RVO) report by Saunder and Kuduon (2009) noted past possible geothermal activity on Ritter Island that had not been previously reported. According to their report, "In 1997 a patrol officer (Hita Mesere) in a media release relayed reports from Councilor Nalong (Kampalap Village?) of an explosive eruption and large waves reaching nearby villages. In the preparation of this report Mr. Mesere was contacted and he confirmed that he and officers from the Morobe PDO flew over Ritter after this event and saw white smoke coming from 'boiling' in the sea, close to land in the South Bay (Mesere, 2009 Pers. Comm.)."

The report concluded that "Ritter is active, both volcanically and geomorphologically. More volcanic activity can be expected. Seismically this will probably not be as intense as in the early 1970's, as the conduit seems now to be open. Volcanic phenomena may however increase in importance if the cone continues to grow towards the surface and magma is erupted into an environment of lower hydrostatic pressures. There seems to be two causes of eruptive activity, one is the rise of fresh magma at the site of the submarine cone and the other is slope instability causing water to come into contact with residual hot rocks leading to small hydrovolcanian events close inshore of Ritter."

The RVO report also included the following table (table 1) showing past observations of possible geothermal activity on Ritter Island.

Table 1. Dates and details of reported post-collapse activity at Ritter. From of Saunders and Kuduon (2009).

Date Seismic Intensity Explosions reported White steam reported Dust/Dark material reported Sound reported Location of emission
9 Oct. 1972 Felt 35 km away; regionally recorded Multiple Y Y Strong rumbling Inshore W (S Cove) & off terminal cusps
17 Oct. 1974 Felt 30 km away: recorded in PNG Multiple Y Y N Offshore ~1 km W
19 Oct. 1996? (Pilot report only) None reported N Y N N ?
1997 None reported Single or few Y N N Inshore W (S Cove)
17 Oct. 2006 Few small, locally felt N Y Y N Offshore ~1 km W
19 May 2007 None reported Several Y Y (and flames) Rumbling & 3 explosions Offshore ~1 km W

Tsunami of 1888. Several recent papers have revisited the 13 March 1888 collapse of Ritter Island volcano that generated a catastrophic tsunami. According to Ward and Day (2003), "In the early morning of 1888 March 13, roughly 5 km3 of Ritter Island Volcano fell violently into the sea northeast of New Guinea. This event, the largest lateral collapse of an island volcano to be recorded in historical time, flung devastating tsunami tens of meters high on to adjacent shores. Several hundred kilometers away, observers on New Guinea chronicled 3 min period waves up to 8 m high, that lasted for as long as 3 h. These accounts represent the best available first-hand information on tsunami generated by a major volcano lateral collapse." Eyewitness accounts noted the lack of explosive activity accompanying the collapse. In this paper, the authors simulated the Ritter Island landslide as constrained by a 1985 sonar survey of its debris field and compare predicted tsunami with historical observations.

Ray and others (2014) reported that, based on primary and secondary eyewitness accounts on the morning of 13 March 1888 "there is no clear evidence for a coincident [to the collapse] or causal magmatic explosive eruption. One report suggests that there was activity (perhaps phreatic or phreatomagmatic explosions?) prior to the collapse that lead some of the resident local communities to seek higher ground, but evidence for precursory flank movements or changes in eruptive style have not been found in the historical accounts."

References. Ray, M.J., Day, S., and Downes, H., 2014, The growth of Ritter Island volcano, Papua New Guinea, and the lateral collapse landslide and tsunami of 1888: new insights from eyewitness accounts, EGU General Assembly 2014, Geophysical Research Abstracts, v. 16, EGU2014-1305.

Saunders, S., and Kuduon, J., 2009, The June 2009 Investigation Of Ritter Volcano, With A Brief Discussion On Its Current Nature, Rabaul Volcanological Observatory Open File Report OFP 003/2009, 25 pp.

Ward, S.N., and Day, S. 2003. Ritter Island—lateral collapse and the tsunami of 1888. Geophysics Journal International, v. 154, pp. 891-902.

Geologic Background. Prior to 1888, Ritter Island was a steep-sided, nearly circular island about 780 m high between Umboi and Sakar Islands. Several historical explosive eruptions had been recorded prior to 1888, when large-scale slope failure destroyed the summit of the conical basaltic-andesitic volcano, leaving the arcuate 140-m-high island with a steep west-facing scarp. Devastating tsunamis were produced by the collapse and swept the coast of Papua New Guinea and offshore islands. Two minor post-collapse explosive eruptions, during 1972 and 1974, occurred offshore within the largely submarine 3.5 x 4.5 km breached depression formed by the collapse.

Information Contacts: Rabaul Volcanological Observatory, P.O. Box 386, Rabaul, Papua New Guinea.


Sangay (Ecuador) — February 2014 Citation iconCite this Report

Sangay

Ecuador

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

All times are local (unless otherwise noted)


Absence of evidence for ongoing eruption; new hazard maps

Previously reported activity from Sangay volcano (figure 14) included ash plumes as late as 23 May 2013 and satellite infrared thermal alerts ending in early May 2013 (BGVN 36:01). In that previous report, satellite thermal alerts from the MODVOLC system were noted to have persisted and as late as 4 May 2013. That lack of alerts continued as late as 16 July 2013 when the MODVOLC website was last checked. Since that reporting, there have been no new updates regarding Sangay on the website of the Instituto Geofisico (IG), the aviation reports have not mentioned Sangay, and other news of Sangay behavior has also been generally lacking.

Figure (see Caption) Figure 14. (Inset at bottom) A regional map showing Sangay with respect to large rivers and other features surrounding Sangay. Orange line is the PanAmerican highway, which passes near Río Bamba on the map's N. Major rivers (blue) are primary routes of lahars. (Main map) A hazards map for Sangay made with hazards focus and compiling the results of multiple kinds of modeling. Key (in Spanish) notes that the upper three colors were based on slope angle (H/L) with text noting gradation of hazards in those regions from pyroclastic flows, lava flows, ash falls, volcanic bombs, rock falls, and proximal lahars. The lower three colors on the key represent inferred gradations of lahar hazard at distance from the volcano. Dashed envelopes in red refer to boundaries for small and moderate sizes of ash falls. White line shows inferred boundary for an E directed debris avalanche. Base map is from the Instituto Geografico Militar (IGM). Taken from an online poster by Ordóñez and others, 2014).

Absence of MODVOLC and aviation alerts does not necessarily translate to a lack of eruptions. The MODVOLC system imposes a reasonably high threshold to the infrared data acquired from space. Factors such as weather conditions, snow pack, and geometry of the vent area may play a role. Emissions of spatter, ash fall, and small pyroclastic flows could easily be missed. Assessments are generally best made in conjunction with information at the volcano. The current eruption began on 8 August 1934 and is thus far confirmed only through 23 May 2013.

Hazard modeling and products. In late 2013 to early 2014 IG released a poster discussing Sangay hazards (Ordóñez and others, 2014), some of the results of which we reprint here (figures 14, 15, and 16). Figure 14 contains IGEPN's recently published a map of volcanic hazards associated with Sangay, which resides in the Cordillera Real between the cities of Río Bamba and Macas. The IG and others have generally considered Sangay one of the most active volcanoes in South America. The poster noted historical records of its eruptive activity dating back to 1628 (Hall, 1977) and in the last century some important periods of activity were recorded during 1903, 1934-1937, 1941-1942, 1975-1976, and 1995 to the present (Monzier et al.. 1999). Observations of surface activity carried out in the past 40 years allowed scientists to recognize some important morphological changes at the summit of the volcano, including the emergence of new craters, dome growth, extrusion of lava flows, local explosions and ash emissions, and relatively small pyroclastic flows.

Figure (see Caption) Figure 15. Modeled ash fall blanket from a hypothetical eruption at Sangay of moderate size. The key (in Spanish) refers to the colors in the key and on the isopach map, with thicknesses in millimeters. Taken from an online poster by Ordóñez and others (2014).
Figure (see Caption) Figure 16. Modeled ash fall blanket from a hypothetical eruption at Sangay of large size. The key (in Spanish) refers to the colors in the key and on the isopach map, with thicknesses in millimeters. Taken from an online poster by Ordóñez and others (2014).

A larger suite of volcanic hazards models is not shown here but includes results VolcFlow. Ash3D, Tephra2, and LAHARZ. The data used for the simulations were obtained from the few geological studies in this volcano (Hall, 1977; Monzier et al, 1999; Johnson et al, 2003). Sangay is judged in some ways analogous to Tungurahua volcano, because of its chemical composition, and it similar lava rheology and eruptive style of volcanic flows.

During August-September 2013, IG installed seismic monitoring instruments (broad band and infrasound ) and for the measurement of sulfur dioxide (SO2) in the southwestern flank of the volcano Sangay. These tools facilitate the monitoring of internal and surface activity of the volcano which will give an early warning of a potential hazards.

With regard to monitoring, during August-September 2013 IG personnel installed ~4 km southwest of Sangay volcano, permanent telemetered monitoring system consisting of a broadband seismic sensor, infrasound, and gas monitoring.

Figures 15 and 16 show the respective modeled results for a moderate and large eruption. To define the zones affected by ash fall, the modeling used the following computer routines based on assumptions and approaches discussed in the literature: Ash3d (Mastin and others, 2012) and Tephra2 (Banadonna and others, 2005). Some input data came from inferences and interpretations of descriptions by Monzier and others (1999) and from analogy with recent eruptions at Tungurahua. Plume heights were assumed to reach 10-15 km in altitude and the magma volumes in the plumes were assumed to be on the order of 0.001-0.005 km3 (dense-rock equivalent, DRE). Wind field data came from the Global Forecast System (NOAA, US National Weather Service, Environment Modeling Center). LAHARZ (Schilling, 1998), a modeling approach, was also taken to estimate the extent and coverage of lahars seen in figure 14. (The poster includes other maps on this topic as well.)

References. Bonadonna, C, Connor CB, Houghton BF, Byrne M, Laing A, Hincks T., 2005, Probabilistic modeling of tephra dispersal: Hazard assessment of a multi-phase eruption at Tarawera, New Zealand; J. Geophys. Res., 110, B03203.

Hall M. (1977). El Volcanismo en Ecuador. Publicación del Instituto Panamericano de Geografía e Historia, Sección nacional del Ecuador, Quito. 120pp.

Mastin, L, Schwaiger H, Denlinger R., 2012, User's Guide to Ash3d: A 3-D Eulerian Atmospheric Tephra Transportation and Dispersion Model, U.S. Geological Survey Open File Report.

Monzier M, Robin C, Samaniego P, Hall M, Cotten J, Mothes P, Arnaud N., 1999, J. Volcanol. Geotherm. Res. 90, 49-79.

Ordóñez J., Vallejo S., Bustillos J., Hall M., Andrade D., Hidalgo S., and Samaniego P., (Document created, December 2013; Accessed online July 2014), Volcan Sangay---Peligros Volcanicos Potenciales, Instituto Geofísico, Escuela Politécnica Nacional (IG-ESPN) (URL: http://www.igepn.edu.ec/volcan-sangay/mapa-de-peligros.html ).

Schilling S. (1998). LAHARZ: GIS programs for automated mapping of lahar-inundation hazard zones. US Geological Survey Open-File Report 98-638; 79 pp.

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

Information Contacts: Instituto Geofísico-Escuela Politécnica Nacional (IG), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); and 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/).


Sangeang Api (Indonesia) — February 2014 Citation iconCite this Report

Sangeang Api

Indonesia

8.2°S, 119.07°E; summit elev. 1912 m

All times are local (unless otherwise noted)


Ashfall from 30 May 2014 eruption causes evacuations, airline delays

Due to elevated seismic activity, the Indonesian Center for Volcanology and Geologic Hazard Mitigation (CVGHM) issued an alert for Sangeang Api volcano on 21 May 2014. On 30 May 2014 at 1555, CVGHM reported an eruption of the island volcano that generated an explosive eruption column of ash and sulfur dioxide into the atmosphere, extending >3 km above the summit (figure 8). While the 13-km-wide island of Sangeang has no permanent settlements or residents, dozens of farmers cultivate land on the island during the growing and harvest seasons. Photographs of the eruption showed several pyroclastic flows coming down the volcano summit to the S and E that may be hazardous to anyone of the island. On 30 May, the Alert Level was raised from 2 to 3 (on a scale of 1-4). Civil authorities evacuated 135 people from within 1.5 km of the volcano to the mainland (nearby Sumbawa Island), with the result that no one was reported to have been killed or injured during the eruption.

Figure (see Caption) Figure 8. Eruption plume rising from Sangeang Api volcano on 30 May 2014, photographed to the N from Sambawa Island. Note the distinctive lenticular white cloud condensed from uplifted moist air carried by the rising plume. Pyroclastic flows can also be seen moving down along the S and E sides of the volcano. Courtesy of Anonymous (2014).

Based on satellite images, pilot observations, and the Indonesian Meteorological Office, the Darwin VAAC reported that on 30 May an ash plume rose to an maximum altitude of 15.2 km and drifted 440 km E and 750 km SE (figure 9).

Figure (see Caption) Figure 9. After erupting, the Sangeang Api volcano sent an ash plume to the E, along with a distinctive lenticular white cloud condensed from uplifted moist air. Pilots in the area reported seeing the cloud rising to 19.8 km, spreading over a 40 km area. Photograph taken on 30 May 2014 by Sofyan Efendi looking N during a commercial flight from Bali to the fishing town of Labuan Bajo; from Hall (2014).

The Indonesian Regional Disaster Management Agency (BNPB) reported that on 31 May two larger explosions occurred at 1330 and 2242 hrs. According to the VAAC, ash plumes from these two explosions rose to altitudes of 13.7-15.2 km and drifted 280 km NW (and other various directions, including S). Later in the day the ash plumes, including one from the previous day, eventually became detached. Ashfall affected many areas in the Bima Regency on the mainland, including Wera, and prompted the evacuation of 7,328 people from four villages within a radius of 8 km from Sangeang Api. The Bima and Tambolaka airports were temporarily closed. According to a news article, all flights to and from the Darwin International Airport in Australia on 31 May were canceled (figure 10). The VAAC noted that ash plumes rose to an altitude of 4.3 km on 1 June and drifted W and SW (figure 11). During 2-3 June ash plumes rose to altitudes of 3-4.3 km and drifted 45 km W. Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 14 June an ash plume from Sangeang Api rose to an altitude of 2.1 km and drifted 55 km NW.

Figure (see Caption) Figure 10. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite captured imagery of the eruption plume from Sangeang Api (dark brown line on the image extending from the volcanic island to the SE) at 0235 UTC (1035 local time) on 31 May 2014. Ash drifted SE, shutting down airports in Bima, Indonesia, and Darwin, Australia. Service to Darwin resumed by 1 June, but Bima remained shut down as of 2 June, according to the Jakarta Globe. Other satellites have observed the ash plume as well. A near real-time tool developed by University of Wisconsin and NOAA scientists estimated that the plume reached an altitude of at least 12 to 14 km based on observations from multiple weather satellites. The Ozone Mapping & Profiler Suite on Suomi NPP also observed ash drifting toward Australia on 31 May. NASA image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC; Caption by Adam Voiland. From NASA Earth Observatory (2014, 3 June).
Figure (see Caption) Figure 11. Landsat 8 satellite collected this true-color image of an ash plume rising from the Sangeang Api, an island volcano just of the coast of Sumbawa Island, Indonesia, on 1 June 2014. Note that on this day the plume is being blown W and then SW as compared with the previous day shown in figure 8. NASA Earth Observatory images by Robert Simmon, using Landsat 8 data from the USGS Earth Explorer. From NASA Earth Observatory (2014, 1 June).

During the period from 2-17 June, thin to thick white smoke was ejected as high as 200-500 m. Seismic activity during the major part of the eruption is shown on Table 4; as of 17 June, seismicity continued to decline. The Alert Level was reduced from 3 to 2 (on a scale of 1-4) on 17 June.

Table 4. Numbers of daily earthquakes measured for 3 days during and after the eruption of Sangeang Api, as reported by CVGHM. 'VB' represents shallow volcanic earthquakes; 'VA' represents deep volcanic earthquakes; 'TL' represents local earthquake tectonics; 'X' indicates activity present; 'nr' is not reported .

Date, 2014 30 May 31 May 1 June
VB 88 143 35
VA 270 157 62
TL nr nr 5
Volcanic swarm X nr nr
Continuous tremor X X X
Tremor eruption X X X
Blowing earthquake nr nr 36

MODVOLC and other satellite imaging. Satellite infrared measurements of thermal alerts over this Sangeang Api volcano eruption first appeared as 2 pixels (an area of thermal anomaly of ≥2 km2) at 1405 UTC on 30 May 2014. These were the first thermal alerts measured over Sangeang Api since 20 October 2013. From 30 May 2014 through 7 July, satellite crossings measured alerts of between 1 and 9 pixels (areas of ≥1 to ≥9 km2, respectively) daily until 1500 UTC on 30 June; the 9-pixel thermal alert was measured 20 June 2014 at 1425 UTC (figure 12). (Note: As an explanation for this technique, the MODVOLC web site states that "Using infrared satellite data provided by the Moderate Resolution Imaging Spectroradiometer (MODIS), scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, have developed an automated system [MODVOLC] which maps the global distribution of thermal hot-spots in near-real-time, and displays the results on this web-site." A paper by Wright and others (2004) states that "Although MODIS pixels are nominally 1 km, pixel size increases with distance from nadir and at the edges of the MODIS swath (where the scan angle reaches ±55°) MODIS pixels measure ~2.08 km in the along-track, and ~4.83 km in the across-track direction.")

Figure (see Caption) Figure 12. MODVOLC image for the period 30 May to 7 July 2014 of thermal alerts measured on Sangeang Api volcano. The volcano lies on the island of Sangeang just off the Indonesian island of Sumbawa. The central array of pixels trending E-W are for those alerts measured for the period 30 May - 30 June 2014. Courtesy of MODVOLC.

Figures 13 and 14 show satellite images of ash plume temperature and SO2 plume from Sangeang Api volcano on 30 and 31 May 2014, respectively. The plume is obviously drifting to the E and S toward Australia.

Figure (see Caption) Figure 13. Composite of the Day-Night Band (DNB, red-to-yellow) at 750m resolution and the IR11.45 (I5, color scale at the top) channel at 375m resolution, image made 30 May 2014 at 1745 UTC. The DNB shows two craters at Sangeang Api volcano, Doro Api and Doro Mantoi. The brighter one was emanating the big plume with temperature values down to -196.5 K (76.6 °C) at the top. The secondary crater was emanating some material, but at much lower level so could hardly be seen. Courtesy of EUMETSAT (2014).
Figure (see Caption) Figure 14. SO2 measured from the Sangeang Api volcano plume on 31 May 2014 at 0535 UTC. The volcano is located at the W end of the measured area. Courtesy of NOAA.

References. Anonymous, 2014 (30 May), Massive volcano eruption: Sangeang Api volcano - Sunda Islands, Indonesia, Before Its News web site (http://beforeitsnews.com/environment/2014/05/massive-volcano-eruption-sangeang-api-volcano-sunda-islands-indonesia-2502094.html).

EUMETSAT, 2014, Eruption of Sangeang Api volcano: There were a series of spectacular eruptions from the Indonesian volcano Sangeang Api at the end of the May. URL: http://www.eumetsat.int/website/home/Images/ImageLibrary/DAT_2235292.html

NASA Earth Observatory, 2014 (3 June), Sangeang Api Erupts (URL: http://earthobservatory.nasa.gov/IOTD/view.php?id=83799).

NASA Earth Observatory, 2014 (1 June), Sangeang Api Eruption (URL: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=83887&eocn=image&eoci=nh_viewall)

Wright, R., Flynn, L.P, Garbeil, H., Harris, A.J.L., and Pilger, E., 2004, MODVOLC: near-real-time thermal monitoring of global volcanism, Journal of Volcanology and Geothermal Research, v. 135, pp. 29-49.

Hall, J., 2014 (30 May), Pictured from a passenger plane: Menacing 12-mile-high ash cloud looms over Indonesia's 'Mountain of Spirits' after volcano erupts, Daily Mail (URL: http://www.dailymail.co.uk/news/article-2644253/Incredible-moment-huge-volcano-erupts-Indonesia-sending-ash-spewing-thousands-feet-sky.html).

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

Information Contacts: Indonesian Centre for Volcanology and Geological Hazard Mitigation – CVGHM (also known as Pusat Vulkanologi dan Mitigasi Bencana Geologi - PVMBG)), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); DARWIN VAAC (Darwin Volcanic Ash Advisory Centre), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Badan Penanggulangan Bencana Daerah (BPBD), Indonesian Regional Disaster Management Agency (URL: http://bpbd.malangkab.go.id/); and Badan Nasional Penanggulangan Bencana (BNPB), Indonesian National Disaster Management Agency (URL: http://www.bnpb.go.id/).


Telica (Nicaragua) — February 2014 Citation iconCite this Report

Telica

Nicaragua

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

All times are local (unless otherwise noted)


Small explosions in September 2013; a new intracrater vent

INETER reported that during 2013, Telica was one of the main contributors to Nicaragua's volcanic seismicity (along with Momotombo, San Cristóbal, Cerro Negro, and Concepción). Of the total seismicity detected in Nicaragua, 28% was associated with the volcanic chain.

Throughout 2013, white, low-level gas plumes rose over 200 m above the crater. Field observers saw incandescence from the crater floor and heard jetting sounds. This activity was slightly diminished in May and peaked in late September.

In March 2013, a group of students from Chalmers University of Technology, Switzerland, surveyed the crater with an FTIR spectrometer to determine SO2 flux (figure 34). Overall, during 5-21 March, SO2 flux averaged 175 tons/day with the maximum value of 250 tons/day recorded on 17 March. The group returned to Telica in March 2014 and found fluxes of similar levels (figure 34).

Figure (see Caption) Figure 34. SO2 flux measured from Telica during 5-22 March 2013 by students from the Chalmers University of Technology, Switzerland. Courtesy of Vladimir Conde, Chalmers University of Technology.

On 25 September 2013, small explosions were detected from the crater that released gas and ash. There were four explosions during 0725-1605; the largest occurred at 0725 and generated a plume 50 m above the crater rim. The other three explosions were less energetic and did not eject material beyond the crater. During a field visit that day, INETER scientists observed incandescence from a new vent within the crater as well as small fractures crossing the crater floor. An infrared thermometer measured a maximum of 505°C from the active vent.

A field survey team observed strong degassing from the crater on 8 October. The main source of the gas was the SW wall and jetting sounds were also noted.

2014. Low-level degassing continued during January-June 2014. Jetting sounds and incandescence from the crater occurred less frequently based on field visits by INETER scientists. Seismicity in January and February was elevated; 11,182 and 26,355 volcano-tectonic (VT) earthquakes were detected respectively. In April 2014, seismicity was greatly reduced (2,454 earthquakes) and was dominated by paired earthquakes known as doublets (also detected in January 2014).

During a field visit on 22 May 2014, INETER scientists noted that, while incandescence was still visible, gas emissions were greatly reduced and the jetting sounds were absent. The active vent within the crater appeared to be covered and possibly blocked by rockfalls originating from the crater walls. Emissions, jetting sounds, and incandescence were also reduced in June 2014.

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

Information Contacts: Virginia Tenorio, Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni).


Whakaari/White Island (New Zealand) — February 2014 Citation iconCite this Report

Whakaari/White Island

New Zealand

37.52°S, 177.18°E; summit elev. 294 m

All times are local (unless otherwise noted)


Dome extrusion in late 2012 and further eruptions in 2012-2013

On 5 August 2012, White Island erupted, following rapid water level rises in the crater lake. Minor ash emission continued to as late as 17 August (BGVN 37:06). This report describes activity during September 2012-January 2014. Unless otherwise stated, information was compiled from GeoNet reports. Major events during the reporting interval include a spiny dome first viewed in December 2012, several months of explosive phreatic activity in early 2013, and discrete explosive eruptions during the latter half of 2013. Magma last surfaced at White Island in 2000 in an explosive eruption that ejected molten lava (BGVN 25:08). GeoNet, a monitoring project funded by the Earthquake Commission, is operated by New Zealand's GNS Science which produces an on-line Volcanic Alert Bulletin. It monitors volcano events by webcam, and acoustic and seismic instruments. Periodically, in situ temperature, fumarole and spring chemical sampling, deformation, gas data, and visual narratives were also recorded. Surveillance includes a mini DOAS network and may also airborne visual observations, photos, and IR images.

GeoNet currently describes White Island as the most active of New Zealand's volcanoes. During 2012 and 2013 normal seismic activity was interspersed with periods of heightened activity. GeoNet reported minor ash, seismicity, gas emissions, dome building, and changes at the crater and crater lakes. Two significant eruptions occurred after a period of reduced activity in 2013: one in August and the other in October. In January 2014, GeoNet volcanologists reported low seismicity. During a single year, tour companies estimated that over 10,000 tourists visited White Island from NZ's North Island ~45 km to the S. Safety of visitors to the island and surrounding waters depends on Volcanic Alert Bulletins. The NZ volcano alert levels ranged from 0 (low risk) to 5 (high risk); Aviation Alert colors ranged from Green (low risk), to Yellow, to Orange and then to Red (high risk). These two alert types were frequently updated, based on spikes in activity. For example in August 2013, Alert Levels ranged from 1 to 2 and Aviation Colour Codes shifted from Yellow to Green to Red to Orange and back to Yellow.

Ashfall in 2012 and a spiny lava dome. In a Volcanic Alert Bulletin issued on 12 December 2012, GNS reported that after the 5 August eruption, a spiny done was formed. In the 26 July 2013 report, phreatic and steam driven activity was observed beginning in December with minor ash emissions interspersed and continuing into the following year. Degassing and tremors were frequent with varying intensities (figure 55). The figure records seismicity as root square amplitude mean (RSAM) on the ordinate plotted along the time line abscissa from June 2007 to December 2013. The tremors were generally attributed to fluid movement (magma, geothermal water, and steam) at an undetermined depth in the crust.

Figure (see Caption) Figure 55. White Island seismicity as root square amplitude mean (RSAM) on the ordinate plotted along the time line abscissa from June 2007 to December 2013. Figure by Brad Scott; courtesy New Zealand's Geological and Nuclear Sciences (GNS Science).

In December 2012, two airborne observations were conducted. GNS volcanologists on 10 December viewed for the first time a small spiny lava dome in the crater active during August 2012. The dome emerged in the vent active in a spot adjacent to two other venting areas (figure 56). GNS reporting attributed the dome morphology to a cooled carapace thrust upward by injection of magma deeper in the dome. Several spines protruded from the roughly 20-30 m diameter dome base (figure 57). Tour operators to the island commented that the dome was visible weeks before the volcanologists viewed it. The actual date of formation remained unstated and possibly unknown.

Figure (see Caption) Figure 56. Aerial view of White Island's active crater. A lava dome juts up adjacent to the front edge of an active oval vent near the prominent lake in the center of the image. The image was taken from a helicopter on 10 December 2012 looking W at ~600 m from the active vents. Photo by Brad Scott; courtesy GNS Science.
Figure (see Caption) Figure 57. Magnified view of the 10 December 2012 image showing the spiny lava dome (about 20-30 m diameter). The hot lake in the foreground sits adjacent to the active vent. Courtesy of GeoNet. Image by B. J. Scott, GNS Science.

Airborne observations on 20 December 2012 found the lava dome unchanged. Several small lakes occupied parts of the area formally covered by a large lake viewed before the August eruption. Infrared temperatures taken during the flight found the dome to be 187°C, the actively upwelling hot lake S of the dome to be 71°C, and the cool lake on the N side of the dome to be 35°C. 20 December airborne measurements resulted in a gas flux rate for SO2 of 400 metric tons/day (t/d), for CO2: 1,300 t/d, and for H2S2; 10 t/d.

Ashfall after the August 2012 eruption to the end of 2012 was unreported in the 2012 Volcanic Alert Bulletin archive. However, in the 26 July 2013 report, GeoNet summarized the December 2012-February 2013 activity as an eruption sequence interspersed with phreatic, steam driven activity and very minor ash emissions. Ashfall in December 2012 and January-February 2013 are reported in table 12. Exact ashfall dates were unreported due to the minor nature of ashfall events and irregular visits. Table 12 summarizes eruptive activity at White Island during this report period.

Table 12. December 2012-11 October 2013 eruptive activity at White Island. Column headings are eruptions, seismicity, and a brief eruptive narrative. Dates in the second column from the right came from Volcanic Alert Bulletin reports. Notes refer to image and video records found in the Reference section under GNS. Courtesy of GNS.

Date Emissions Seismicity noted Eruptive narrative GeoNet report Notes
1 Dec 2012 Small phreatic explosions, minor ash Elevated RSAM levels Intermittent eruptions 26 Jul 2013 --
Jan-Feb 2013 Phreatic explosions, minor ash Elevated RSAM levels Intermittent emissions 26 Jul 2013 --
23-24 Feb 2013 Phreatic explosions, minor ash Increased tremor Intermittent emissions 25 Feb 2013 --
Early Apr 2013 Mud and ash eruption Tremor, outgassing Crater lake starts to form 29 Apr 2013 --
20 Aug 2013 Small explosive eruption Tremor White plume ~4 km 20 Aug 2013 1,2
4,8,11 Oct 2013 Small explosive eruptions -- Minor ash columns 12 Oct 2013 3

Ashfall in 2013, 20 August eruption, and 11 October eruption. On 1 January 2013, GNS volcanologists reported the spiny lava dome (figure 58) remained unchanged from December 2012. The lava dome temperature was 200-240°C, up from 187°C in December, and the nearby 'hot lake' was 70-80°C, unchanged from December.

GNS volcanologist Brad Scott, who visited the island, commented in the 22 January Volcano Alert Bulletin "the hydrothermal activity is some of the most vigorous I have seen at White Island for many years." Scott also reported the hot lake had disappeared, replaced by a small tuff cone. That cone was the main point of emission for steam and gas. On 30 January 2013, the active vent continued to produce intermittent vigorous bursts of mud, rock, steam, and gas rising 50-100 m high without detectable ash in the plume. On 31 January, gas fluxes were 2,000 metric tons per day (t/d) for carbon dioxide (CO2), 600 t/d for sulfur dioxide (SO2), and 19 t/d for hydrogen sulfide (H2S).

Figure (see Caption) Figure 58. This is the same photo seen in figure 56, but in this case it shows infrared temperatures of White Island's dome and lakes taken on 7 January 2013. The active vent continued to produce vigorous bursts of mud, rock, steam, and gas reaching 50-100 m high. Ash was not carried into the plume at the time of this photo. The small lake to the left is the cool lake (35°C) and the lava-dome crater is partially hidden under the steam plume. Courtesy of GeoNet. Image by Brad Scott, GNS Science.

On 7 February, SO2 and CO2 rates were similar to measurements in January: SO2 was 560 t/d and CO2 was 1,800 t/d. The main steam and gas plume came from the ash cone occupying the previous hot lake crater. Small explosive eruptions in the active crater and seismicity, which had been occurring for three weeks prior to the week of 11 February, became less intense.

During 23-24 February 2013 minor ash erupted from the active vent. Tremor was consistent with the level of unrest seen over the past month. On 25 February, the ash emissions had ceased and had been replaced by steam-and-gas explosions from the active vent. The level of volcanic tremor increased, associated with the reappearance of fluids in the vent area (figure 55). The unrest was among the most vigorous that Scott had observed during visits to White Island. He was quoted in the 25 February report to say "the unrest continues and we continue to see small scale explosive events. Larger explosive eruptions can occur at any time with little or no warning. As always a high level of caution should be taken if visiting the island."

The crater on 4 March 2013 contained an ash cone surrounded by water (figure 59), which replaced the previous hot lake as the primary source of steam in the crater. On 29 April 2013, GNS reported that ash had ceased being emitted at an undisclosed date during the first part of the month. In April, low to moderate seismic tremor was detected, while degassing continued. Rainfall during April caused the two lakes to combine. The maximum lake temperature was ~ 62°C. The lava dome temperature was ~200°C.

Figure (see Caption) Figure 59. A 4 March 2013 image looking W ~600 m from the crater. A new ash cone formed at the hot lake emitted gas and steam. N of the ash cone sits the cool lake. Image by B. J. Scott, GNS Science.

During April, May, and June 2013 the crater lake reformed. On 9 July 2013 GNS reported small volcanic earthquakes occurred approximately every 70 seconds, with changing amplitude and frequency. GNS volcanologists visiting on 26 July observed gas venting through the small lake with debris ejected 20-30 m vertically. By 5 August this minor venting had declined and tremor had decreased to near-background levels (see figure 55).

A small eruption took place in August 2013 detected by a constellation of instruments on White Island which included audio receivers, seismometers, temperature sensors, and IR sensors. The eruption was captured on video media by several cameras near the crater rim and a camera stationed ~45 km S at NZ's North Island (figure 60). The eruption occurred at 1023 on 20 August 2013 (NZ local time) and continued for about 10 minutes. As seen from the mainland, it mainly produced a steam plume rising to ~4 km, and slowly trending W before dispersing (figure 61). The eruption originated from a vent in the active crater that had been experiencing very small mud eruptions in early to mid-August 2013. This eruption was preceded by strong tremor.

Figure (see Caption) Figure 60. Map locating GNS video camera which resides at Whakatane on NZ's North Island ~50 km S of White Island. It recorded the 20 August 2013 eruption seen in the next figure. Map courtesy of 100% New Zealand (2014) and revised by GVP.
Figure (see Caption) Figure 61. Image of White Island taken from Whakatane WebCam video of the 20 August 2013 eruption. The image was in the GNS 22 August 2013 report. Courtesy of Geonet.

The N rim webcam captured visual and thermal infrared images of the eruption. Both the N Island camera and the N rim camera video links were included in the GNS 22 August report. The 20 August eruption ejected mud and rocks a short distance from the vent and produced large volumes of white steam. Weather radar observations suggested that the steam also contained a small proportion of volcanic ash. The hazards posed by the eruption were restricted to the island or possibly vessels anchored nearby. By 21 August 2013, White Island activity had diminished. Volcanologists flying over the island on 23 August observed the return of a small lake. Steam emissions chiefly emerged from the cone area, but their intensity dropped as the small lake reformed. SO2, CO2, and H2S gases recorded during the flight had diminished to pre-eruption levels.

The 7 October GNS report described the changes associated with the August 2013 eruption. A new basin further to the NE of the previous lake filled with water. The lava dome area appeared unchanged while nearby a small pond had formed. Landslides had altered several of the main crater walls, the result of processes most likely related to weather events. Daily SO2 gas flux measured the previous month ranged from 117 to 662 t/d, typical of the last 12-18 months but higher than before July 2012. In early October it remained elevated.

A moderate but potentially dangerous eruption emerged on 11 October 2013. The eruption sequence began 4 October, with a small energetic steam emission followed by intensified tremor. On 8 October, a period of strong seismicity prevailed accompanied by acoustic signals, and a minor steam and mud eruption that produced a steam plume. During the evening of 11 October, a moderate explosive eruption lasted ~1 minute based on data from acoustic and seismic sensors. The N rim camera images showed that the eruption emerged from the crater's central vent. The explosive eruption produced an ash cloud that expanded across the main crater floor. New mud deposited on the crater floor was evident in the web camera images taken the following day (figure 63). The deposit was thick enough to bury much of the small scale topography on parts of the crater floor. This image and the muddy stratigraphic layer established the baseline for subsequent changes created by volcanism and erosion.

Figure (see Caption) Figure 62. On 12 October 2013 at 0650, the crater floor and walls lie draped beneath fresh deposits of dark gray mud from the eruption the night before. Courtesy of Geonet.

The October 2013 mud eruption was the largest of recent events. GNS volcanologists estimated it would have been life threatening to people on the island. Volcanic tremor gradually decreased after 11 October returning to levels equivalent to the middle of the prior week (see figure 55). The mud deposited on 11 October 2013 had clearly begun to erode by early December 2013. Around this time a new camera on the W rim captured active steam-and-gas plumes from several vents and the large lake seen in 2012 (figure 63). On 23 December 2013 GNS reported an absence of eruptive activity since the 11 October eruption. Seismicity remained low; gas flux, variable. Average daily SO2 flux ranged from 300 to over 1,000 t/d. Prior to 2012, daily averages were generally less than 300 t/d.

Figure (see Caption) Figure 63. An 11 December 2013 image showing gullies and rills as erosion set in on the fresh mud coating within the crater formed by the 11 October 2013 eruption. Several vents produced active steam plumes and the lake had returned. Courtesy of GNS.

January 2014 changes to the crater and rate of gas emitted. During several January visits, GNS Science staff observed a continued rise in water level of the crater lake, reaching ~5 m higher than in late 2013. The average daily SO2 flux ranged from 133 to 924 t/d. GNS volcanologists reported an absence of further eruptive activity since the 11 October 2013 eruption.

On 15 January 2014, a thermal infrared image was taken by a portable infrared sensor pointed W from the western crater rim (figure 64). The image shows part of the Crater Lake (oval labeled El1), the area of the 2012 lava extrusion below the lake (large rectangular box labeled Ar1), and a hot fumarole on the S edge of the Crater Lake (small rectangle in the center labeled Ar2). Maximum temperatures were 58°C at the lake, 285°C forAr1, and 297°C for Ar2. These observations confirmed that hot volcanic gases were still passing through these vents.

Figure (see Caption) Figure 64. Thermal infrared image taken on 15 January 2014, with scale at right and areas with analysis at upper left. The oval area (El12) includes part of the Crater Lake, and the area of the 2012 lava extrusion (in rectangular Ar1). The smaller rectangle, Ar2, includes a hot fumarole on the southern edge of the Crater Lake. Courtesy of GeoNet.

Historical background. White Island was named by Captain Cook on 1 October 1769 while on his third and last circumnavigation renowned for two outstanding accomplishments. First, he was equipped with a Kendall 1 chronometer, a copy of the Harrison chronometer that the navy found accurate to ~3 seconds per day, a key requirement for determining longitude and the most precise measure to that time. Second, a new diet enriched with vitamin C prevented scurvy, a killer on most long voyages of the period (Sobel, 1995). White Island, privately owned, became a scenic reserve in 1953. Over 10,000 people visit annually to view the crater and the remains of a sulfur mine complex. Tour boats depart from North Island (figure 60). Tourists can also view the island by helicopter. (Wikipedia, White Island History)

References. 100% New Zealand, accessed 5 May 2014, New Zealand Map (URL: http://www.newzealand.com/int/map/)

GNS (22 August 2013), White Island eruption 20 August 2013 - 5x speed, (URL: http://info.geonet.org.nz/display/volc/2013/08/20/White+Island+Eruption)

GNS (22 August 2013), White Island eruption 20 August 2013 Crater rim - 5x speed, (URL: http://info.geonet.org.nz/display/volc/2013/08/20/White+Island+Eruption)

GNS (14 October 2012), Un-named video clip URL reference in body of GNS report (URL: http://info.geonet.org.nz/pages/viewpage.action?pageId=7241739)

Sobel, D. (1995). Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. New York: Walker.

Wikipedia, accessed April 2014, White Island history (URL: http://en.wikipedia.org/wiki/Whakaari_/_White_Island#History).

Geologic Background. The uninhabited Whakaari/White Island is the 2 x 2.4 km emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater is open at sea level, with the recent activity centered about 1 km from the shore close to the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. The formation of many new vents during the 19th and 20th centuries caused rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project. Explosive activity in December 2019 took place while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Maori name of Te Puia o Whakaari ("The Dramatic Volcano") and White Island (referencing the constant steam plume) given by Captain James Cook in 1769.

Information Contacts: GeoNet, a collaboration between the Earthquake Commission and GNS Science (URL: http://www.GeoNet.org.nz/); and GNS Science, Wairakei Research Center, Private Bag 2000, Taupo 3352, New Zealand (URL: http://www.gns.cri.nz/).

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