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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

Klyuchevskoy (Russia) Strombolian activity November 2019 through May 2020; lava flow down the SE flank in April

Nyamuragira (DR Congo) Intermittent thermal anomalies within the summit crater during December 2019-May 2020

Nyiragongo (DR Congo) Activity in the lava lake and small eruptive cone persists during December 2019-May 2020

Kavachi (Solomon Islands) Discolored water plumes seen using satellite imagery in 2018 and 2020

Kuchinoerabujima (Japan) Eruption and ash plumes begin on 11 January 2020 and continue through April 2020

Soputan (Indonesia) Minor ash emissions during 23 March and 2 April 2020

Heard (Australia) Eruptive activity including a lava flow during October 2019-April 2020

Kikai (Japan) Ash explosion on 29 April 2020

Fuego (Guatemala) Ongoing ash explosions, block avalanches, and intermittent lava flows

Ebeko (Russia) Frequent moderate explosions, ash plumes, and ashfall continue, December 2019-May 2020

Piton de la Fournaise (France) Fissure eruptions in February and April 2020 included lava fountains and flows

Sabancaya (Peru) Daily explosions with ash emissions, large SO2 flux, ongoing thermal anomalies, December 2019-May 2020



Klyuchevskoy (Russia) — June 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 November 2019 through May 2020; lava flow down the SE flank in April

Klyuchevskoy is part of the Klyuchevskaya volcanic group in northern Kamchatka and is one of the most frequently active volcanoes of the region. Eruptions produce lava flows, ashfall, and lahars originating from summit and flank activity. This report summarizes activity during October 2019 through May 2020, and is based on reports by the Kamchatkan Volcanic Eruption Response Team (KVERT) and satellite data.

There were no activity reports from 1 to 22 October, but gas emissions were visible in satellite images. At 1020 on 24 October (2220 on 23 October UTC) KVERT noted that there was a small ash component in the ash plume from erosion of the conduit, with the plume reaching 130 km ENE. The Aviation Colour Code was raised from Green to Yellow, then to Orange the following day. An ash plume continued on the 25th to 5-7 km altitude and extending 15 km SE and 70 km SW and reached 30 km ESE on the 26th. Similar activity continued through to the end of the month.

Moderate gas emissions continued during 1-19 November, but the summit was obscured by clouds. Strong nighttime incandescence was visible at the crater during the 10-11 November and thermal anomalies were detected on 8 and 10-13 November. Explosions produced ash plumes up to 6 km altitude on the 20-21st and Strombolian activity was reported during 20-22 November. Degassing continued from 23 November through 12 December, and a thermal anomaly was visible on the days when the summit was not covered by clouds. An ash plume was reported moving to the NW on the 13th, and degassing with a thermal anomaly and intermittent Strombolian activity then resumed, continuing through to the end of December with an ash plume reported on the 30th.

Gas-and-steam plumes continued into January 2020 with incandescence noted when the summit was clear (figure 33). Strombolian activity was reported again starting on the 3rd. A weak ash plume produced on the 6th extended 55 km E, and on the 21st an ash plume reached 5-5.5 km altitude and extended 190 km NE (figure 34). Another ash plume the next day rose to the same altitude and extended 388 km NE. During 23-29 Strombolian activity continued, and Vulcanian activity produced ash plumes up to 5.5 altitude, extending to 282 km E on the 30th, and 145 km E on the 31st.

Figure (see Caption) Figure 33. Incandescence and degassing were visible at Klyuchevskoy through January 2020, seen here on the 11th. Courtesy of KVERT.
Figure (see Caption) Figure 34. A low ash plume at Klyuchevskoy on 21 January 2020 extended 190 km NE. Courtesy of KVERT.

Strombolian activity continued throughout February with occasional explosions producing ash plumes up to 5.5 km altitude, as well as gas-and-steam plumes and a persistent thermal anomaly with incandescence visible at night. Starting in late February thermal anomalies were detected much more frequently, and with higher energy output compared to the previous year (figure 35). A lava fountain was reported on 1 March with the material falling back into the summit crater. Strombolian activity continued through early March. Lava fountaining was reported again on the 8th with ejecta landing in the crater and down the flanks (figure 36). A strong persistent gas-and-steam plume containing some ash continued along with Strombolian activity through 25 March (figure 37), with Vulcanian activity noted on the 20th and 25th. Strombolian and Vulcanian activity was reported through the end of March.

Figure (see Caption) Figure 35. This MIROVA thermal energy plot for Klyuchevskoy for the year ending 29 April 2020 (log radiative power) shows intermittent thermal anomalies leading up to more sustained energy detected from February through March, then steadily increasing energy through April 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 36. Strombolian explosions at Klyuchevskoy eject incandescent ash and gas, and blocks and bombs onto the upper flanks on 8 and 10 March 2020. Courtesy of IVS FEB RAS, KVERT.
Figure (see Caption) Figure 37. Weak ash emission from the Klyuchevskoy summit crater are dispersed by wind on 19 and 29 March 2020, with ash depositing on the flanks. Courtesy of IVS FEB RAS, KVERT.

Activity was dominantly Strombolian during 1-5 April and included intermittent Vulcanian explosions from the 6th onwards, with ash plumes reaching 6 km altitude. On 18 April a lava flow began moving down the SE flank (figures 38). A report on the 26th reported explosions from lava-water interactions with avalanches from the active lava flow, which continued to move down the SE flank and into the Apakhonchich chute (figures 39 and 40). This continued throughout April and May with sustained Strombolian and intermittent Vulcanian activity at the summit (figures 41 and 42).

Figure (see Caption) Figure 38. Strombolian activity produced ash plumes and a lava flow down the SE flank of Klyuchevskoy on 18 April 2020. Courtesy of IVS FEB RAS, KVERT.
Figure (see Caption) Figure 39. A lava flow descends the SW flank of Klyuchevskoy and a gas plume is dispersed by winds on 21 April 2020. Courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.
Figure (see Caption) Figure 40. Sentinel-2 thermal satellite images show the progression of the Klyuchevskoy lava flow from the summit crater down the SE flank from 19-29 April 2020. Associated gas plumes are dispersed in various directions. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 41. Strombolian activity at Klyuchevskoy ejects incandescent ejecta, gas, and ash above the summit on 27 April 2020. Courtesy of D. Bud'kov, IVS FEB RAS, KVERT.
Figure (see Caption) Figure 42. Sentinel-2 thermal satellite images of Klyuchevskoy show the progression of the SE flank lava flow through May 2020, with associated gas plumes being dispersed in multiple directions. Courtesy of Sentinel Hub Playground.

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/); 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).


Nyamuragira (DR Congo) — June 2020 Citation iconCite this Report

Nyamuragira

DR Congo

1.408°S, 29.2°E; summit elev. 3058 m

All times are local (unless otherwise noted)


Intermittent thermal anomalies within the summit crater during December 2019-May 2020

Nyamuragira (also known as Nyamulagira) is located in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo and consists of a lava lake that reappeared in the summit crater in mid-April 2018. Volcanism has been characterized by lava emissions, thermal anomalies, seismicity, and gas-and-steam emissions. This report summarizes activity during December 2019 through May 2020 using information from monthly reports by the Observatoire Volcanologique de Goma (OVG) and satellite data.

According to OVG, intermittent eruptive activity was detected in the lava lake of the central crater during December 2019 and January-April 2020, which also resulted in few seismic events. MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows thermal anomalies within the summit crater that varied in both frequency and power between August 2019 and mid-March 2020, but very few were recorded afterward through late May (figure 88). Thermal hotspots identified by MODVOLC from 15 December 2019 through March 2020 were mainly located in the active central crater, with only three hotspots just outside the SW crater rim (figure 89). Sentinel-2 thermal satellite imagery also showed activity within the summit crater during January-May 2020, but by mid-March the thermal anomaly had visibly decreased in power (figure 90).

Figure (see Caption) Figure 88. The MIROVA graph of thermal activity (log radiative power) at Nyamuragira during 27 July through May 2020 shows variably strong, intermittent thermal anomalies with a variation in power and frequency from August 2019 to mid-March 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 89. Map showing the number of MODVOLC hotspot pixels at Nyamuragira from 1 December 2019 t0 31 May 2020. 37 pixels were registered within the summit crater while 3 were detected just outside the SW crater rim. Courtesy of HIGP-MODVOLC Thermal Alerts System.
Figure (see Caption) Figure 90. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) confirmed ongoing thermal activity (bright yellow-orange) at Nyamuragira from February into April 2020. The strength of the thermal anomaly in the summit crater decreased by late March 2020, but was still visible. Courtesy of Sentinel Hub Playground.

Geologic Background. Africa's most active volcano, Nyamuragira, is a massive high-potassium basaltic shield about 25 km N of Lake Kivu. Also known as Nyamulagira, it has generated extensive lava flows that cover 1500 km2 of the western branch of the East African Rift. The broad low-angle shield volcano contrasts dramatically with the adjacent steep-sided Nyiragongo to the SW. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Historical eruptions have occurred within the summit caldera, as well as from the numerous fissures and cinder cones on the flanks. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Historical lava flows extend down the flanks more than 30 km from the summit, reaching as far as Lake Kivu.

Information Contacts: Information contacts: Observatoire Volcanologique de Goma (OVG), Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo; MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/exp.


Nyiragongo (DR Congo) — June 2020 Citation iconCite this Report

Nyiragongo

DR Congo

1.52°S, 29.25°E; summit elev. 3470 m

All times are local (unless otherwise noted)


Activity in the lava lake and small eruptive cone persists during December 2019-May 2020

Nyiragongo is located in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo, part of the western branch of the East African Rift System and contains a 1.2 km-wide summit crater with a lava lake that has been active since at least 1971. Volcanism has been characterized by strong and frequent thermal anomalies, incandescence, gas-and-steam emissions, and seismicity. This report summarizes activity during December 2019 through May 2020 using information from monthly reports by the Observatoire Volcanologique de Goma (OVG) and satellite data.

In the December 2019 monthly report, OVG stated that the level of the lava lake had increased. This level of the lava lake was maintained for the duration of the reporting period, according to later OVG monthly reports. Seismicity increased starting in November 2019 and was detected in the NE part of the crater, but it decreased by mid-April 2020. SO2 emissions increased in January 2020 to roughly 7,000 tons/day but decreased again near the end of the month. OVG reported that SO2 emissions rose again in February to roughly 8,500 tons/day before declining to about 6,000 tons/day. Unlike in the previous report (BGVN 44:12), incandescence was visible during the day in the active lava lake and activity at the small eruptive cone within the 1.2-km-wide summit crater has since increased, consisting of incandescence and some lava fountaining (figure 72). A field survey was conducted on 3-4 March where an OVG team observed active lava fountains and ejecta that produced Pele’s hair from the small eruptive cone (figure 73). During this survey, OVG reported that the level of the lava lake had reached the second terrace, which was formed on 17 January 2002 and represents remnants of the lava lake at different eruption stages. There, the open surface lava lake was observed; gas-and-steam emissions accompanied both the active lava lake and the small eruptive cone (figures 72 and 73).

Figure (see Caption) Figure 72. Webcam image of Nyiragongo in February 2020 showing an open lava lake surface and incandescence from the active crater cone within the 1.2 km-wide summit crater visible during the day, accompanied by white gas-and-steam emissions. Courtesy of OVG (Rapport OVG February 2020).
Figure (see Caption) Figure 73. Webcam image of Nyiragongo on 4 March 2020 showing an open lava lake surface and incandescence from the active crater cone within the 1.2 km-wide summit crater visible during the day, accompanied by white gas-and-steam emissions. Courtesy of OVG (Rapport OVG Mars 2020).

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data continued to show frequent strong thermal anomalies within 5 km of the summit crater through May 2020 (figure 74). Similarly, the MODVOLC algorithm reported multiple thermal hotspots almost daily within the summit crater between December 2019 and May 2020. These thermal signatures were also observed in Sentinel-2 thermal satellite imagery within the summit crater (figure 75).

Figure (see Caption) Figure 74. Thermal anomalies at Nyiragongo from 27 July through May 2020 as recorded by the MIROVA system (Log Radiative Power) were frequent and strong. Courtesy of MIROVA.
Figure (see Caption) Figure 75. Sentinel-2 thermal satellite imagery (bands 12, 11, 8A) showed ongoing thermal activity (bright yellow-orange) in the summit crater at Nyiragongo during January through April 2020. Courtesy of Sentinel Hub Playground.

Geologic Background. One of Africa's most notable volcanoes, Nyiragongo contained a lava lake in its deep summit crater that was active for half a century before draining catastrophically through its outer flanks in 1977. The steep slopes of a stratovolcano contrast to the low profile of its neighboring shield volcano, Nyamuragira. Benches in the steep-walled, 1.2-km-wide summit crater mark levels of former lava lakes, which have been observed since the late-19th century. Two older stratovolcanoes, Baruta and Shaheru, are partially overlapped by Nyiragongo on the north and south. About 100 parasitic cones are located primarily along radial fissures south of Shaheru, east of the summit, and along a NE-SW zone extending as far as Lake Kivu. Many cones are buried by voluminous lava flows that extend long distances down the flanks, which is characterized by the eruption of foiditic rocks. The extremely fluid 1977 lava flows caused many fatalities, as did lava flows that inundated portions of the major city of Goma in January 2002.

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


Kavachi (Solomon Islands) — May 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 seen using satellite imagery in 2018 and 2020

Kavachi is a submarine volcano located in the Solomon Islands south of Gatokae and Vangunu islands. Volcanism is frequently active, but rarely observed. The most recent eruptions took place during 2014, which consisted of an ash eruption, and during 2016, which included phreatomagmatic explosions (BGVN 42:03). This reporting period covers December 2016-April 2020 primarily using satellite data.

Activity at Kavachi is often only observed through satellite images, and frequently consists of discolored submarine plumes for which the cause is uncertain. On 1 January 2018 a slight yellow discoloration in the water is seen extending to the E from a specific point (figure 20). Similar faint plumes were observed on 16 January, 25 February, 2 March, 26 April, 6 May, and 25 June 2018. No similar water discoloration was noted during 2019, though clouds may have obscured views.

Figure (see Caption) Figure 20. Satellite images from Sentinel-2 revealed intermittent faint water discoloration (yellow) at Kavachi during the first half of 2018, as seen here on 1 January (top left), 25 February (top right), 26 April (bottom left), and 25 June (bottom right). Images with “Natural color” rendering (bands 4, 3, 2); courtesy of Sentinel Hub Playground.

Activity resumed in 2020, showing more discolored water in satellite imagery. The first instance occurred on 16 March, where a distinct plume extended from a specific point to the SE. On 25 April a satellite image showed a larger discolored plume in the water that spread over about 30 km2, encompassing the area around Kavachi (figure 21). Another image on 30 April showed a thin ribbon of discolored water extending about 50 km W of the vent.

Figure (see Caption) Figure 21. Sentinel-2 satellite images of a discolored plume (yellow) at Kavachi beginning on 16 March (top left) with a significant large plume on 25 April (right), which remained until 30 April (bottom left). 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 about 30 km N of the site of subduction of the Indo-Australian plate beneath the Pacific plate. 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).


Kuchinoerabujima (Japan) — May 2020 Citation iconCite this Report

Kuchinoerabujima

Japan

30.443°N, 130.217°E; summit elev. 657 m

All times are local (unless otherwise noted)


Eruption and ash plumes begin on 11 January 2020 and continue through April 2020

Kuchinoerabujima encompasses a group of young stratovolcanoes located in the northern Ryukyu Islands. All historical eruptions have originated from the Shindake cone, with the exception of a lava flow that originated from the S flank of the Furudake cone. The most recent previous eruptive period took place during October 2018-February 2019 and primarily consisted of weak explosions, ash plumes, and ashfall. The current eruption began on 11 January 2020 after nearly a year of dominantly gas-and-steam emissions. Volcanism for this reporting period from March 2019 to April 2020 included explosions, ash plumes, SO2 emissions, and ashfall. The primary source of information for this report comes from monthly and annual reports from the Japan Meteorological Agency (JMA) and advisories from the Tokyo Volcanic Ash Advisory Center (VAAC). Activity has been limited to Kuchinoerabujima's Shindake Crater.

Volcanism at Kuchinoerabujima was relatively low during March through December 2019, according to JMA. During this time, SO2 emissions ranged from 100 to 1,000 tons/day. Gas-and-steam emissions were frequently observed throughout the entire reporting period, rising to a maximum height of 1.1 km above the crater on 13 December 2019. Satellite imagery from Sentinel-2 showed gas-and-steam and occasional ash emissions rising from the Shindake crater throughout the reporting period (figure 7). Though JMA reported thermal anomalies occurring on 29 January and continuing through late April 2020, Sentinel-2 imagery shows the first thermal signature appearing on 26 April.

Figure (see Caption) Figure 7. Sentinel-2 thermal satellite images showed gas-and-steam and ash emissions rising from Kuchinoerabujima. Some ash deposits can be seen on 6 February 2020 (top right). A thermal anomaly appeared on 26 April 2020 (bottom right). Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.

An eruption on 11 January 2020 at 1505 ejected material 300 m from the crater and produced ash plumes that rose 2 km above the crater rim, extending E, according to JMA. The eruption continued through 12 January until 0730. The resulting ash plumes rose 400 m above the crater, drifting SW while the SO2 emissions measured 1,300 tons/day. Ashfall was reported on Yakushima Island (15 km E). Minor eruptive activity was reported during 17-20 January which produced gray-white plumes that rose 300-500 m above the crater. On 23 January, seismicity increased, and an eruption produced an ash plume that rose 1.2 km altitude, according to a Tokyo VAAC report, resulting in ashfall 2 km NE of the crater. A small explosion was detected on 24 January, followed by an increase in the number of earthquakes during 25-26 January (65-71 earthquakes per day were registered). Another small eruptive event detected on 27 January at 0148 was accompanied by a volcanic tremor and a change in tilt data. During the month of January, some inflation was detected at the base on the volcano and a total of 347 earthquakes were recorded. The SO2 emissions ranged from 200-1,600 tons/day.

An eruption on 1 February 2020 produced an eruption column that rose less than 1 km altitude and extended SE and SW (figure 8), according to the Tokyo VAAC report. On 3 February, an eruption from the Shindake crater at 0521 produced an ash plume that rose 7 km above the crater and ejected material as far as 600 m away. As a result, a pyroclastic flow formed, traveling 900-1,500 m SW. The previous pyroclastic flow that was recorded occurred on 29 January 2019. Ashfall was confirmed in the N part of Yakushima Island with a large amount in Miyanoura (32 km ESE) and southern Tanegashima. The SO2 emissions measured 1,700 tons/day during this event.

Figure (see Caption) Figure 8. Webcam images from the Honmura west surveillance camera of an ash plume rising from Kuchinoerabujima on 1 February 2020. Courtesy of JMA (Weekly bulletin report 509, February 2020).

Intermittent small eruptive events occurred during 5-9 February; field observations showed a large amount of ashfall on the SE flank which included lapilli that measured up to 2 cm in diameter. Additionally, thermal images showed 5-km-long pyroclastic flow deposits on the SW flank. An eruption on 9 February produced an ash plume that rose 1.2 km altitude, drifting SE. On 13 February a small eruption was detected in the Shindake crater at 1211, producing gray-white plumes that rose 300 m above the crater, drifting NE. Small eruptive events also occurred during 20-21 February, resulting in gas-and-steam emissions that rose 200 m above the crater. During the month of February, some horizontal extension was observed since January 2020 using GNSS data. The total number of earthquakes during this month drastically increased to 1225 compared to January. The SO2 emissions ranged from 300-1,700 tons/day.

By 2 March 2020, seismicity decreased, and activity declined. Gas-and-steam emissions continued infrequently for the duration of the reporting period. The SO2 emissions during March ranged from 700-2,100 tons/day, the latter of which occurred on 15 March. Seismicity increased again on 27 March. During 5-8 April 2020, small eruptive events were detected, generating ash plumes that rose 900 m above the crater (figure 9). The SO2 emissions on 6 April reached 3,200 tons/day, the maximum measurement for this reporting period. These small eruptive events continued from 13-20 and 23-25 April within the Shindake crater, producing gray-white plumes that rose 300-800 m above the crater.

Figure (see Caption) Figure 9. Webcam images from the Honmura Nishi (top) and Honmura west (bottom) surveillance cameras of ash plumes rising from Kuchinoerabujima on 6 March and 5 April 2020. Courtesy of JMA (Weekly bulletin report 509, March and April 2020).

Geologic Background. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. The youngest cone, centrally-located Shindake, formed after the NW side of Furudake was breached by an explosion. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

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


Soputan (Indonesia) — May 2020 Citation iconCite this Report

Soputan

Indonesia

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

All times are local (unless otherwise noted)


Minor ash emissions during 23 March and 2 April 2020

Soputan is a stratovolcano located in the northern arm of Sulawesi Island, Indonesia. Previous eruptive periods were characterized by ash explosions, lava flows, and Strombolian eruptions. The most recent eruption occurred during October-December 2018, which consisted mostly of ash plumes and some summit incandescence (BGVN 44:01). This report updates information for January 2019-April 2020 characterized by two ash plumes and gas-and-steam emissions. The primary source of information come from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and the Darwin Volcanic Ash Advisory Center (VAAC).

Activity during January 2019-April 2020 was relatively low; three faint thermal anomalies were observed at the summit at Soputan in satellite imagery for a total of three days on 2 and 4 January, and 1 October 2019 (figure 17). The MIROVA (Middle InfraRed Observation of Volcanic Activity) based on analysis of MODIS data detected 12 distal hotspots and six low-power hotspots within 5 km of the summit during August to early October 2019. A single distal thermal hotspot was detected in early March 2020. In March, activity primarily consisted of white to gray gas-and-steam plumes that rose 20-100 m above the crater, according to PVMBG. The Darwin VAAC issued a notice on 23 March 2020 that reported an ash plume rose to 4.3 km altitude; minor ash emissions had been visible in a webcam image the previous day (figure 18). A second notice was issued on 2 April, where an ash plume was observed rising 2.1 km altitude and drifting W.

Figure (see Caption) Figure 17. Sentinel-2 thermal satellite imagery detected a total of three thermal hotspots (bright yellow-orange) at the summit of Soputan on 2 and 4 January and 1 October 2019. Sentinel-2 atmospheric penetration (bands 12, 11, 8A) images courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 18. Minor ash emissions were seen rising from Soputan on 22 March 2020. Courtesy of MAGMA Indonesia.

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); 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/); 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).


Heard (Australia) — May 2020 Citation iconCite this Report

Heard

Australia

53.106°S, 73.513°E; summit elev. 2745 m

All times are local (unless otherwise noted)


Eruptive activity including a lava flow during October 2019-April 2020

Heard Island is located on the Kerguelen Plateau in the southern Indian Ocean and contains Big Ben, a snow-covered stratovolcano with intermittent volcanism reported since 1910. Due to its remote location, visual observations are rare; therefore, thermal anomalies and hotspots detected by satellite-based instruments are the primary source of information. This report updates activity from October 2019 to April 2020.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed three prominent periods of strong thermal anomaly activity during this reporting period: late October 2019, December 2019, and the end of April 2020 (figure 41). These thermal anomalies were relatively strong and occurred within 5 km of the summit. Similarly, the MODVOLC algorithm reported a total of six thermal hotspots during 28 October, 1 November 2019, and 26 April 2020.

Figure (see Caption) Figure 41. Thermal anomalies at Heard from 29 April 2019 through April 2020 as recorded by the MIROVA system (Log Radiative Power) were strong and frequent in late October, during December 2019, and at the end of April 2020. Courtesy of MIROVA.

Six thermal satellite images ranging from late October 2019 to late March showed evidence of active lava at the summit (figure 42). These images show hot material, possibly a lava flow, extending SW from the summit; a hotspot also remained at the summit. Cloud cover was pervasive during the majority of this reporting period, especially in April 2020, though gas-and-steam emissions were visible on 25 April through the clouds.

Figure (see Caption) Figure 42. Thermal satellite images of Heard Island’s Big Ben showing strong thermal signatures representing a lava flow in the SW direction from 28 October to 17 December 2019. These thermal anomalies are located NE from Mawson Peak. A faint thermal anomaly is also captured on 26 March 2020. Satellite images with atmospheric penetration (bands 12, 11, and 8A), courtesy of Sentinel Hub Playground.

Geologic Background. Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben because of its extensive ice cover. The historically active Mawson Peak forms the island's high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported at this isolated volcano, but observations are infrequent and additional activity may have occurred.

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


Kikai (Japan) — May 2020 Citation iconCite this Report

Kikai

Japan

30.793°N, 130.305°E; summit elev. 704 m

All times are local (unless otherwise noted)


Ash explosion on 29 April 2020

The Kikai caldera is located at the N end of Japan’s Ryukyu Islands and has been recently characterized by intermittent ash emissions and limited ashfall in nearby communities. On Satsuma Iwo Jima island, the larger subaerial fragment of the Kikai caldera, there was a single explosion with gas-and-steam and ash emissions on 2 November 2019, accompanied by nighttime incandescence (BGVN 45:02). This report covers volcanism from January 2020 through April 2020 with a single-day eruption occurring on 29 April based on reports from the Japan Meteorological Agency (JMA).

Since the last one-day eruption on 2 November 2019, volcanism at Kikai has been relatively low and primarily consisted of 107-170 earthquakes per month and intermittent white gas-and-steam emissions rising up to 1.3 km above the crater summit. Intermittent weak hotspots were observed at night in the summit in Sentinel-2 thermal satellite imagery and webcams, according to JMA (figures 14 and 15).

Figure (see Caption) Figure 14. Weak thermal hotspots (bright yellow-orange) were observed on 7 January (top) and 6 April 2020 (bottom) at Satsuma Iwo Jima (Kikai). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 15. Incandescence at night on 10 January 2020 was observed at Satsuma Iwo Jima (Kikai) in the Iodake crater with the Iwanogami webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, January 2nd year of Reiwa [2020]).

Weak incandescence continued in April 2020. JMA reported SO2 measurements during April were 400-2000 tons/day. A brief eruption in the Iodake crater on 29 April 2020 at 0609 generated a gray-white ash plume that rose 1 km above the crater (figure 16). No ashfall or ejecta was observed after the eruption on 29 April.

Figure (see Caption) Figure 16. The Iwanogami webcam captured a brief gray-white ash and steam plume rising above the Iodake crater rim on Satsuma Iwo Jima (Kikai) on 29 April 2020 at 0609 local time. The plume rose 1 km above the crater summit. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, April 2nd year of Reiwa [2020]).

Geologic Background. Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world's largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Fuego (Guatemala) — April 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 ash explosions, block avalanches, and intermittent lava flows

Fuego is a stratovolcano in Guatemala that has been erupting since 2002 with historical eruptions that date back to 1531. Volcanism is characterized by major ashfalls, pyroclastic flows, lava flows, and lahars. The previous report (BGVN 44:10) detailed activity that included multiple ash explosions, ash plumes, ashfall, active lava flows, and block avalanches. This report covers this continuing activity from October 2019 through March 2020 and consists of ash plumes, ashfall, incandescent ejecta, block avalanches, and lava flows. 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 October 2019-March 2020. Daily activity persisted throughout October 2019-March 2020 (table 20) with multiple ash explosions recorded every hour, ash plumes that rose to a maximum of 4.8 km altitude each month drifting in multiple directions, incandescent ejecta reaching a 500 m above the crater resulting in block avalanches traveling down multiple drainages, and ashfall affecting communities in multiple directions. The highest rate of explosions occurred on 7 November with up to 25 per hour. Dominantly white fumaroles occurred frequently throughout this reporting period, rising to a maximum altitude of 4.5 km and drifting in multiple directions. Intermittent lava flows that reached a maximum length of 1.2 km were observed each month in the Seca (Santa Teresa) and Ceniza drainages (figure 128), but rarely in the Trinidad drainage. Thermal activity increased slightly in frequency and strength in late October and remained relatively consistent through mid-March as seen in the MIROVA analysis of MODIS satellite data (figure 129).

Table 20. Activity summary by month for Fuego with information compiled from INSIVUMEH daily reports.

Month Ash plume heights (km) Ash plume distance (km) and direction Drainages affected by avalanche blocks Villages reporting ashfall
Oct 2019 4.3-4.8 km 10-25 km, W-SW-S-NW Seca, Taniluyá, Ceniza, Trinidad, El Jute, Honda, and Las Lajas Panimaché I and II, Morelia, Santa Sofía, Porvenir, Finca Palo Verde, La Rochela, San Andrés Osuna, Sangre de Cristo, and San Pedro Yepocapa
Nov 2019 4.0-4.8 km 10-20 km, W-SW-S-NW Seca, Taniluyá, Trinidad, Las Lajas, Honda, and Ceniza Panimaché I and II, Morelia, Santa Sofía, Porvenir, Sangre de Cristo, Finca Palo Verde, and San Pedro Yepocapa
Dec 2019 4.2-4.8 km 10-25 km, W-SW-S-SE-N-NE Seca, Taniluya, Ceniza, Trinidad, and Las Lajas Morelia, Santa Sofía, Finca Palo Verde, El Porvenir, Sangre de Cristo, San Pedro Yepocapa, Panimaché I and II, La Rochela, and San Andrés Osuna
Jan 2020 4.3-4.8 km 10-25 km, W-SW-S-N-NE-E Seca, Ceniza, Taniluyá, Trinidad, Honda, and Las Lajas Morelia, Santa Sofía, Sangre de Cristo, San Pedro Yepocapa, Panimaché I and II, El Porvenir, Finca Palo Verde, Rodeo, La Rochela, Alotenango, El Zapote, Trinidad, La Reina, Ceilán
Feb 2020 4.3-4.8 km 8-25 km, W-SW-S-SE-E-NE-N-NW Seca, Ceniza, Taniluya, Trinidad, Las Lajas, Honda, La Rochela, El Zapote, and San Andrés Osuna Panimache I and II, Morelia, Santa Sofia, Sangre de Cristo, San Pedro Yepocapa, Rodeo, La Reina, Alotenango, Yucales, Siquinalá, Santa Lucia, El Porvenir, Finca Los Tarros, La Soledad, Buena Vista, La Cruz, Pajales, San Miguel Dueñas, Ciudad Vieja, San Miguel Escobar, San Pedro las Huertas, Antigua, La Rochela, and San Andrés Osuna
Mar 2020 4.3-4.8 km 10-23 km, W-SW-S-SE-N-NW Seca, Ceniza, Trinidad, Taniluyá, Las Lajas, Honda, La Rochela, El Zapote, San Andrés Osuna, Morelia, Panimache, and Santa Sofia San Andrés Osuna, La Rochela, El Rodeo, Chuchu, Panimache I and II, Santa Sofia, Morelia, Finca Palo Verde, El Porvenir, Sangre de Cristo, La Cruz, San Pedro Yepocapa, La Conchita, La Soledad, Alotenango, Aldea la Cruz, Acatenango, Ceilan, Taniluyá, Ceniza, Las Lajas, Trinidad, Seca, and Honda
Figure (see Caption) Figure 128. Sentinel-2 thermal satellite images of Fuego between 21 November 2019 and 20 March 2020 showing lava flows (bright yellow-orange) traveling generally S and W from the crater summit. An ash plume can also be seen on 21 November 2019, accompanying the lava flow. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 129. Thermal activity at Fuego increased in frequency and strength (log radiative power) in late October 2019 and remained relatively consistent through February 2020. In early March, there is a small decrease in thermal power, followed by a short pulse of activity and another decline. Courtesy of MIROVA.

Activity during October-December 2019. Activity in October 2019 consisted of 6-20 ash explosions per hour; ash plumes rose to 4.8 km altitude, drifting up to 25 km in multiple directions, resulting in ashfall in Panimaché I and II (8 km SW), Morelia (9 km SW), San Pedro Yepocapa (8 km NW), Sangre de Cristo (8 km WSW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Finca Palo Verde, La Rochela and San Andrés Osuna. The Washington VAAC issued multiple aviation advisories for a total of nine days in October. Continuous white gas-and-steam plumes reached 4.1-4.4 km altitude drifting generally W. Weak SO2 emissions were infrequently observed in satellite imagery during October and January 2020 (figure 130) Incandescent ejecta was frequently observed rising 200-400 m above the summit, which generated block avalanches that traveled down the Seca (W), Taniluyá (SW), Ceniza (SSW), Trinidad (S), El Jute, Honda, and Las Lajas (SE) drainages. During 3-7 October lahars descended the Ceniza, El Mineral, and Seca drainages, carrying tree branches, tree trunks, and blocks 1-3 m in diameter. During 6-8 and 13 October, active lava flows traveled up to 200 m down the Seca drainage.

Figure (see Caption) Figure 130. Weak SO2 emissions were observed rising from Fuego using the TROPOMI instrument on the Sentinel-5P satellite. Top left: 17 October 2019. Top right: 17 November 2019. Bottom left: 20 January 2020. Bottom right: 22 January 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

During November 2019, the rate of explosions increased to 5-25 per hour, the latter of which occurred on 7 November. The explosions resulted in ash plumes that rose 4-4.8 km altitude, drifting 10-20 km in the W direction. Ashfall was observed in Panimaché I and II, Morelia, Santa Sofía, Porvenir, Sangre de Cristo, Finca Palo Verde, and San Pedro Yepocapa. Multiple Washington VAAC notices were issued for 11 days in November. Continuous white gas-and-steam plumes rose up to 4.5 km altitude drifting generally W. Incandescent ejecta rose 100-500 m above the crater, generating block avalanches in Seca, Taniluyá, Trinidad, Las Lajas, Honda, and Ceniza drainages. Lava flows were observed for a majority of the month into early December measuring 100-900 m long in the Seca and Ceniza drainages.

The number of explosions in December 2019 decreased compared to November, recording 8-19 per hour with incandescent ejecta rising 100-400 m above the crater. The explosions generated block avalanches that traveled in the Seca, Taniluya, Ceniza, Trinidad, and Las Lajas drainages throughout the month. Ash plumes continued to rise above the summit crater to 4.8 km drifting up to 25 km in multiple directions. The Washington VAAC issued multiple daily notices almost daily in December. A continuous lava flow observed during 6-15, 21-22, 24, and 26 November through 9 December measured 100-800 m long in the Seca and Ceniza drainages.

Activity during January-March 2020. Incandescent Strombolian explosions continued daily during January 2020, ejecting material up to 100-500 m above the crater. Ash plumes continued to rise to a maximum altitude of 4.8 km, resulting in ashfall in all directions affecting Morelia, Santa Sofía, Sangre de Cristo, San Pedro Yepocapa, Panimaché I and II, El Porvenir, Finca Palo Verde, Rodeo, La Rochela, Alotenango, El Zapote, Trinidad, La Reina, and Ceilán. The Washington VAAC issued multiple notices for a total of 12 days during January. Block avalanches resulting from the Strombolian explosions traveled down the Seca, Ceniza, Taniluyá, Trinidad, Honda, and Las Lajas drainages. An active lava flow in the Ceniza drainage measured 150-600 m long during 6-10 January.

During February 2020, INSIVUMEH reported a range of 4-16 explosions per hour, accompanied by incandescent material that rose 100-500 m above the crater (figure 131). Block avalanches traveled in the Santa Teresa, Seca, Ceniza, Taniluya, Trinidad, Las Lajas, Honda, La Rochela, El Zapote, and San Andrés Osuna drainages. Ash emissions from the explosions continued to rise 4.8 km altitude, drifting in multiple directions as far as 25 km and resulting in ashfall in the communities of Panimache I and II, Morelia, Santa Sofia, Sangre de Cristo, San Pedro Yepocapa, Rodeo, La Reina, Alotenango, Yucales, Siquinalá, Santa Lucia, El Porvenir, Finca Los Tarros, La Soledad, Buena Vista, La Cruz, Pajales, San Miguel Dueñas, Ciudad Vieja, San Miguel Escobar, San Pedro las Huertas, Antigua, La Rochela, and San Andrés Osuna. Washington VAAC notices were issued almost daily during the month. Lava flows were active in the Ceniza drainage during 13-20, 23-24, and 26-27 February measuring as long as 1.2 km.

Figure (see Caption) Figure 131. Incandescent ejecta rose several hundred meters above the crater of Fuego on 6 February 2020, resulting in block avalanches down multiple drainages. Courtesy of Crelosa.

Daily explosions and incandescent ejecta continued through March 2020, with 8-17 explosions per hour that rose up to 500 m above the crater. Block avalanches from the explosions were observed in the Seca, Ceniza, Trinidad, Taniluyá, Las Lajas, Honda, Santa Teresa, La Rochela, El Zapote, San Andrés Osuna, Morelia, Panimache, and Santa Sofia drainages. Accompanying ash plumes rose 4.8 km altitude, drifting in multiple directions mostly to the W as far as 23 km and resulting in ashfall in San Andrés Osuna, La Rochela, El Rodeo, Chuchu, Panimache I and II, Santa Sofia, Morelia, Finca Palo Verde, El Porvenir, Sangre de Cristo, La Cruz, San Pedro Yepocapa, La Conchita, La Soledad, Alotenango, Aldea la Cruz, Acatenango, Ceilan, Taniluyá, Ceniza, Las Lajas, Trinidad, Seca, and Honda. Multiple Washington VAAC notices were issued for a total of 15 days during March. Active lava flows were observed from 16-21 March in the Trinidad and Ceniza drainages measuring 400-1,200 m long and were accompanied by weak to moderate explosions. By 23 March, active lava flows were no longer observed.

Geologic Background. Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); Crelosa, 3ra. avenida. 8-66, Zona 14. Colonia El Campo, Guatemala Ciudad de Guatemala (URL: http://crelosa.com/, post at https://www.youtube.com/watch?v=1P4kWqxU2m0&feature=youtu.be).


Ebeko (Russia) — June 2020 Citation iconCite this Report

Ebeko

Russia

50.686°N, 156.014°E; summit elev. 1103 m

All times are local (unless otherwise noted)


Frequent moderate explosions, ash plumes, and ashfall continue, December 2019-May 2020

The current moderate explosive eruption of Ebeko has been ongoing since October 2016, with frequent ash explosions that have reached altitudes of 1.3-6 km (BGVN 42:08, 43:03, 43:06, 43:12, 44:12). Ashfall is common in Severo-Kurilsk, a town of about 2,500 residents 7 km ESE, where the Kamchatka Volcanic Eruptions Response Team (KVERT) monitor the volcano. During the reporting period, December 2019-May 2020, the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

During December 2019-May 2020, frequent explosions generated ash plumes that reached altitudes of 1.5-4.6 km (table 9); reports of ashfall in Severo-Kurilsk were common. Ash explosions in late April caused ashfall in Severo-Kurilsk during 25-30 April (figure 24), and the plume drifted 180 km SE on the 29th. There was also a higher level of activity during the second half of May (figure 25), when plumes drifted up to 80 km downwind.

Table 9. Summary of activity at Ebeko, December 2019-May 2020. S-K is Severo-Kurilsk (7 km ESE of the volcano). TA is thermal anomaly in satellite images. In the plume distance column, only plumes that drifted more than 10 km are indicated. Dates based on UTC times. Data courtesy of KVERT.

Date Plume Altitude (km) Plume Distance Plume Directions Other Observations
30 Nov-05 Dec 2019 3 -- NE, E Intermittent explosions.
06-13 Dec 2019 4 -- E Explosions all week. Ashfall in S-K on 10-12 Dec.
15-17 Dec 2019 3 -- E Explosions. Ashfall in S-K on 16-17 Dec.
22-24 Dec 2019 3 -- NE Explosions.
01-02 Jan 2020 3 30 km N N Explosions. TA over dome on 1 Jan.
03, 05, 09 Jan 2020 2.9 -- NE, SE Explosions. Ashfall in S-K on 8 Jan.
11, 13-14 Jan 2020 3 -- E Explosions. Ashfall in S-K.
19-20 Jan 2020 3 -- E Ashfall in S-K on 19 Jan.
24-31 Jan 2020 4 -- E Explosions.
01-07 Feb 2020 3 -- E, S Explosions all week.
12-13 Feb 2020 1.5 -- E Explosions. Ashfall in S-K.
18-19 Feb 2020 2.3 -- SE Explosions.
21, 25, 27 Feb 2020 2.9 -- S, SE, NE Explosions. Ashfall in S-K on 22 Feb.
01-02, 05 Mar 2020 2 -- S, E Explosions.
08 Mar 2020 2.5 -- NE Explosions.
13, 17 Mar 2020 2.5 -- NE, SE Bursts of gas, steam, and small amount of ash.
24-25 Mar 2020 2.5 -- NE, W Explosions.
29 Mar-02 Apr 2020 2.2 -- NE, E Explosions. Ashfall in S-K on 1 Apr. TA on 30-31 Mar.
04-05, 09 Apr 2020 1.5 -- NE Explosions. TA on 5 Apr.
13 Apr 2020 2.5 -- SE Explosions.
18, 20 Apr 2020 -- -- -- TA on 18, 20 Apr.
24 Apr-01 May 2020 3.5 180 km SE on 29 Apr E, SE Explosions all week. Ashfall in S-K on 25-30 Apr.
01-08 May 2020 2.6 -- E Explosions all week. Ashfall in S-K on 3-5 May. TA on 3 May.
08-15 May 2020 4 -- E Explosions. Ashfall in S-K on 8-12 May. TA during 12-14 May.
14-15, 19-21 May 2020 3.6 80 km SW, S, SE during 14, 20-21 May -- Explosions. TA on same days.
22-29 May 2020 4.6 60 km SE E, SE Explosions all week. Ashfall in S-K on 22, 24 May.
29-31 May 2020 4.5 -- E, S Explosions. TA on 30 May.
Figure (see Caption) Figure 24. Photo of ash explosion at Ebeko at 2110 UTC on 28 April 2020, as viewed from Severo-Kurilsk. Courtesy of KVERT (L. Kotenko).
Figure (see Caption) Figure 25. Satellite image of Ebeko from Sentinel-2 on 27 May 2020, showing a plume drifting SE. Image using natural color rendering (bands 4, 3, 2) courtesy of Sentinel Hub Playground.

Geologic Background. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Piton de la Fournaise (France) — May 2020 Citation iconCite this Report

Piton de la Fournaise

France

21.244°S, 55.708°E; summit elev. 2632 m

All times are local (unless otherwise noted)


Fissure eruptions in February and April 2020 included lava fountains and flows

Piton de la Fournaise is a massive basaltic shield volcano on the French island of Réunion in the western Indian Ocean. Recent volcanism is characterized by multiple fissure eruptions, lava fountains, and lava flows (BGVN 44:11). The activity during this reporting period of November 2019-April 2020 is consistent with the previous eruption, including lava fountaining and lava flows. Information for this report comes from the Observatoire Volcanologique du Piton de la Fournaise (OVPF) and various satellite data.

Activity during November 2019-January 2020 was relatively low; no eruptive events were detected, according to OVPF. Edifice deformation resumed during the last week in December and continued through January. Seismicity significantly increased in early January, registering 258 shallow earthquakes from 1-16 January. During 17-31 January, the seismicity declined, averaging one earthquake per day.

Two eruptive events took place during February-April 2020. OVPF reported that the first occurred from 10 to 16 February on the E and SE flanks of the Dolomieu Crater. The second took place during 2-6 April. Both eruptive events began with a sharp increase in seismicity accompanied by edifice inflation, followed by a fissure eruption that resulted in lava fountains and lava flows (figure 193). MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed the two eruptive events occurring during February-April 2020 (figure 194). Similarly, the MODVOLC algorithm reported 72 thermal signatures proximal to the summit crater from 12 February to 6 April. Both of these eruptive events were accompanied by SO2 emissions that were detected by the Sentinel-5P/TROPOMI instrument (figures 195 and 196).

Figure (see Caption) Figure 193. Location maps of the lava flows on the E flank at Piton de la Fournaise on 10-16 February 2020 (left) and 2-6 April 2020 (right) as derived from SAR satellite data. Courtesy of OVPF-IPGP, OPGC, LMV (Monthly bulletins of the Piton de la Fournaise Volcanological Observatory, February and April 2020).
Figure (see Caption) Figure 194. Two significant eruptive events at Piton de la Fournaise took place during February-April 2020 as recorded by the MIROVA system (Log Radiative Power). Courtesy of MIROVA.
Figure (see Caption) Figure 195. Images of the SO2 emissions during the February 2020 eruptive event at Piton de la Fournaise detected by the Sentinel-5P/TROPOMI satellite. Top left: 10 February 2020. Top right: 11 February 2020. Bottom left: 13 February 2020. Bottom right: 14 February 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 196. Images of the SO2 emissions during the April 2020 eruptive event at Piton de la Fournaise detected by the Sentinel-5P/TROPOMI satellite. Left: 4 April 2020. Middle: 5 April 2020. Right: 6 April 2020. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

On 10 February 2020 a seismic swarm was detected at 1027, followed by rapid deformation. At 1050, volcanic tremors were recorded, signaling the start of the eruption. Several fissures opened on the E flank of the Dolomieu Crater between the crater rim and at 2,000 m elevation, as observed by an overflight during 1300 and 1330. These fissures were at least 1 km long and produced lava fountains that rose up to 10 m high. Lava flows were also observed traveling E and S to 1,700 m elevation by 1315 (figures 197 and 198). The farthest flow traveled E to an elevation of 1,400 m. Satellite data from HOTVOLC platform (OPGC - University of Auvergne) was used to estimate the peak lava flow rate on 11 February at 10 m3/s. By 13 February only one lava flow that was traveling E below the Marco Crater remained active. OVPF also reported the formation of a cone, measuring 30 m tall, surrounded by three additional vents that produced lava fountains up to 15 m high. On 15 February the volcanic tremors began to decrease at 1400; by 16 February at 1412 the tremors stopped, indicating the end of the eruptive event.

Figure (see Caption) Figure 197. Photo of a lava flow and degassing at Piton de la Fournaise on 10 February 2020. Courtesy of OVPF-IPGP.
Figure (see Caption) Figure 198. Photos of the lava flows at Piton de la Fournaise taken during the February 2020 eruption by Richard Bouchet courtesy of AFP News Service.

Volcanism during the month of March 2020 consisted of low seismicity, including 21 shallow volcanic tremors and near the end of the month, edifice inflation was detected. A second eruptive event began on 2 April 2020, starting with an increase in seismicity during 0815-0851. Much of this seismicity was located on the SE part of the Dolomieu Crater. A fissure opened on the E flank, consistent with the fissures that were active during the February 2020 event. Seismicity continued to increase in intensity through 6 April located dominantly in the SE part of the Dolomieu Crater. An overflight on 5 April at 1030 showed lava fountains rising more than 50 m high accompanied by gas-and-steam plumes rising to 3-3.5 km altitude (figures 199 and 200). A lava flow advanced to an elevation of 360 m, roughly 2 km from the RN2 national road (figure 199). A significant amount of Pele’s hair and clusters of fine volcanic products were produced during the more intense phase of the eruption (5-6 April) and deposited at distances more than 10 km from the eruptive site (figure 201). It was also during this period that the SO2 emissions peaked (figure 196). The eruption stopped at 1330 after a sharp decrease in volcanic tremors.

Figure (see Caption) Figure 199. Photos of a lava flow (left) and lava fountains (right) at Piton de la Fournaise during the April 2020 eruption. Left: photo taken on 2 April 2020 at 1500. Right: photo taken on 5 April 2020 at 1030. Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, April 2020).
Figure (see Caption) Figure 200. Photo of the lava fountains erupting from Piton de la Fournaise on 4 April 2020. Photo taken by Richard Bouchet courtesy of Geo Magazine via Jeannie Curtis.
Figure (see Caption) Figure 201. Photos of Pele’s hair deposited due to the April 2020 eruption at Piton de la Fournaise. Samples collected near the Gîte du volcan on 7 April 2020 (left) and a cluster of Pele’s hair found near the Foc-Foc car park on 9 April 2020 (right). Courtesy of OVPF-IPGP (Monthly bulletin of the Piton de la Fournaise Volcanological Observatory, April 2020).

Geologic Background. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano.

Information Contacts: Observatoire Volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, 14 route nationale 3, 27 ème km, 97418 La Plaine des Cafres, La Réunion, France (URL: http://www.ipgp.fr/fr); 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); GEO Magazine (AFP story at URL: https://www.geo.fr/environnement/la-reunion-fin-deruption-au-piton-de-la-fournaise-200397); AFP (URL: https://twitter.com/AFP/status/1227140765106622464, Twitter: @AFP, https://twitter.com/AFP); Jeannie Curtis (Twitter: @VolcanoJeannie, https://twitter.com/VolcanoJeannie).


Sabancaya (Peru) — June 2020 Citation iconCite this Report

Sabancaya

Peru

15.787°S, 71.857°W; summit elev. 5960 m

All times are local (unless otherwise noted)


Daily explosions with ash emissions, large SO2 flux, ongoing thermal anomalies, December 2019-May 2020

Although tephrochronology has dated activity at Sabancaya back several thousand years, renewed activity that began in 1986 was the first recorded in over 200 years. Intermittent activity since then has produced significant ashfall deposits, seismic unrest, and fumarolic emissions. A new period of explosive activity that began in November 2016 has been characterized by pulses of ash emissions with some plumes exceeding 10 km altitude, thermal anomalies, and significant SO2 plumes. Ash emissions and high levels of SO2 continued each week during December 2019-May 2020. The Observatorio Vulcanologico INGEMMET (OVI) reports weekly on numbers of daily explosions, ash plume heights and directions of drift, seismicity, and other activity. The Buenos Aires Volcanic Ash Advisory Center (VAAC) issued three or four daily reports of ongoing ash emissions at Sabancaya throughout the period.

The dome inside the summit crater continued to grow throughout this period, along with nearly constant ash, gas, and steam emissions; the average number of daily explosions ranged from 4 to 29. Ash and gas plume heights rose 1,800-3,800 m above the summit crater, and multiple communities around the volcano reported ashfall every month (table 6). Sulfur dioxide emissions were notably high and recorded daily with the TROPOMI satellite instrument (figure 75). Thermal activity declined during December 2019 from levels earlier in the year but remained steady and increased in both frequency and intensity during April and May 2020 (figure 76). Infrared satellite images indicated that the primary heat source throughout the period was from the dome inside the summit crater (figure 77).

Table 6. Persistent activity at Sabancaya during December 2019-May 2020 included multiple daily explosions with ash plumes that rose several kilometers above the summit and drifted in many directions; this resulted in ashfall in communities within 30 km of the volcano. Satellite instruments recorded SO2 emissions daily. Data courtesy of OVI-INGEMMET.

Month Avg. Daily Explosions by week Max plume Heights (m above crater) Plume drift (km) and direction Communities reporting ashfall Min Days with SO2 over 2 DU
Dec 2019 16, 13, 5, 5 2,600-3,800 20-30 NW Pinchollo, Madrigal, Lari, Maca, Achoma, Coporaque, Yanque, Chivay, Huambo, Cabanaconde 27
Jan 2020 10, 8, 11, 14, 4 1,800-3,400 30 km W, NW, SE, S Chivay, Yanque, Achoma 29
Feb 2020 8, 11, 20, 19 2,000-2,200 30 km SE, E, NE, W Huambo 29
Mar 2020 14, 22, 29, 18 2,000-3,000 30 km NE, W, NW, SW Madrigal, Lari, Pinchollo 30
Apr 2020 12, 12, 16, 13, 8 2,000-3,000 30 km SE, NW, E, S Pinchollo, Madrigal, Lari, Maca, Ichupampa, Yanque, Chivay, Coporaque, Achoma 27
May 2020 15, 14, 6, 16 1,800-2,400 30 km SW, SE, E, NE, W Chivay, Achoma, Maca, Lari, Madrigal, Pinchollo 27
Figure (see Caption) Figure 75. Sulfur dioxide anomalies were captured daily from Sabancaya during December 2019-May 2020 by the TROPOMI instrument on the Sentinel-5P satellite. Some of the largest SO2 plumes are shown here with dates listed in the information at the top of each image. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 76. Thermal activity at Sabancaya declined during December 2019 from levels earlier in the year but remained steady and increased slightly in frequency and intensity during April and May 2020, according to the MIROVA graph of Log Radiative Power from 23 June 2019 through May 2020. Courtesy of MIROVA.
Figure (see Caption) Figure 77. Sentinel-2 satellite imagery of Sabancaya confirmed the frequent ash emissions and ongoing thermal activity from the dome inside the summit crater during December 2019-May 2020. Top row (left to right): On 6 December 2019 a large plume of steam and ash drifted N from the summit. On 16 December 2019 a thermal anomaly encircled the dome inside the summit caldera while gas and possible ash drifted NW. On 14 April 2020 a very similar pattern persisted inside the crater. Bottom row (left to right): On 19 April an ash plume was clearly visible above dense cloud cover. On 24 May the infrared glow around the dome remained strong; a diffuse plume drifted W. A large plume of ash and steam drifted SE from the summit on 29 May. Infrared images use Atmospheric penetration rendering (bands 12, 11, 8a), other images use Natural Color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

The average number of daily explosions during December 2019 decreased from a high of 16 the first week of the month to a low of five during the last week. Six pyroclastic flows occurred on 10 December (figure 78). Tremors were associated with gas-and-ash emissions for most of the month. Ashfall was reported in Pinchollo, Madrigal, Lari, Maca, Achoma, Coporaque, Yanque, and Chivay during the first week of the month, and in Huambo and Cabanaconde during the second week (figure 79). Inflation of the volcano was measured throughout the month. SO2 flux was measured by OVI as ranging from 2,500 to 4,300 tons per day.

Figure (see Caption) Figure 78. Multiple daily explosions at Sabancaya produced ash plumes that rose several kilometers above the summit. Left image is from 5 December and right image is from 11 December 2019. Note pyroclastic flows to the right of the crater on 11 December. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-49-2019/INGEMMET Semana del 2 al 8 de diciembre de 2019 and RSSAB-50-2019/INGEMMET Semana del 9 al 15 de diciembre de 2019).
Figure (see Caption) Figure 79. Communities to the N and W of Sabancaya recorded ashfall from the volcano the first week of December and also every month during December 2019-May 2020. The red zone is the area where access is prohibited (about a 12-km radius from the crater). Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-22-2020/INGEMMET Semana del 25 al 31 de mayo del 2020).

During January and February 2020 the number of daily explosions averaged 4-20. Ash plumes rose as high as 3.4 km above the summit (figure 80) and drifted up to 30 km in multiple directions. Ashfall was reported in Chivay, Yanque, and Achoma on 8 January, and in Huambo on 25 February. Sulfur dioxide flux ranged from a low of 1,200 t/d on 29 February to a high of 8,200 t/d on 28 January. Inflation of the edifice was measured during January; deformation changed to deflation in early February but then returned to inflation by the end of the month.

Figure (see Caption) Figure 80. Ash plumes rose from Sabancaya every day during January and February 2020. Left: 11 January. Right: 28 February. Courtesy of OVI (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-02-2020/INGEMMET Semana del 06 al 12 de enero del 2020 and RSSAB-09-2020/INGEMMET Semana del 24 de febrero al 01 de marzo del 2020).

Explosions continued during March and April 2020, averaging 8-29 per day. Explosions appeared to come from multiple vents on 11 March (figure 81). Ash plumes rose 3 km above the summit during the first week of March and again the first week of April; they were lower during the other weeks. Ashfall was reported in Madrigal, Lari, and Pinchollo on 27 March and 5 April. On 17 April ashfall was reported in Maca, Ichupampa, Yanque, Chivay, Coporaque, and Achoma. Sulfur dioxide flux ranged from 1,900 t/d on 5 March to 10,700 t/d on 30 March. Inflation at depth continued throughout March and April with 10 +/- 4 mm recorded between 21 and 26 April. Similar activity continued during May 2020; explosions averaged 6-16 per day (figure 82). Ashfall was reported on 6 May in Chivay, Achoma, Maca, Lari, Madrigal, and Pinchollo; heavy ashfall was reported in Achoma on 12 May. Additional ashfall was reported in Achoma, Maca, Madrigal, and Lari on 23 May.

Figure (see Caption) Figure 81. Explosions at Sabancaya on 11 March 2020 appeared to originate simultaneously from two different vents (left). The plume on 12 April was measured at about 2,500 m above the summit. Courtesy of OVI-INGEMMET (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya, RSSAB-11-2020/INGEMMET Semana del 9 al 15 de marzo del 2020 and RSSAB-15-2020/INGEMMET Semana del 6 al 12 de abril del 2020).
Figure (see Caption) Figure 82. Explosions dense with ash continued during May 2020 at Sabancaya. On 11 and 29 May 2020 ash plumes rose from the summit and drifted as far as 30 km before dissipating. Courtesy of OVI-INGEMMET (Reporte Semanal de Monitorio de la Actividad de la Volcan Sabancaya , RSSAB-20-2020/INGEMMET Semana del 11 al 17 de mayo del 2020 and RSSAB-22-2020/INGEMMET Semana del 25 al 31 de mayo del 2020).

Geologic Background. Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

Information Contacts: Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa, Peru (URL: http://ovi.ingemmet.gob.pe); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

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Bulletin of the Global Volcanism Network - Volume 31, Number 04 (April 2006)

Managing Editor: Richard Wunderman

Augustine (United States)

Dome building eruptions continuing through late March 2006 and later

Bezymianny (Russia)

Pyroclastic flows on 9 May extend 7-8 km; plumes over 500 km long

Bulusan (Philippines)

Eruptions and earthquakes in March and April 2006 after years of little activity

Karymsky (Russia)

During April 2006, emerging ash plumes remained visible for up to 145 km

Kilauea (United States)

Maps of past year's surface lava flows and photos of lava entering the sea

Lascar (Chile)

Five-day eruption sequence in April 2006; plume seen 220 km away

Masaya (Nicaragua)

Intermittent ash eruptions November 2003-March 2005; continuing incandescence

Sangay (Ecuador)

Some conspicuous plumes during 2004-2005; climber's photos from January 2006

Santa Maria (Guatemala)

During October 2005 to January 2006, occasional ash plumes

Saunders (United Kingdom)

Lack of new thermal signals suggesting any eruption since October 2005

Soputan (Indonesia)

Late 2005 phreatic and Strombolian eruptions; ash plume to ~ 5.8 km altitude



Augustine (United States) — April 2006 Citation iconCite this Report

Augustine

United States

59.363°N, 153.43°W; summit elev. 1252 m

All times are local (unless otherwise noted)


Dome building eruptions continuing through late March 2006 and later

Although the previous report (BGVN 31:01) noted Augustine's events through 22 February 2006, this one overlaps and further discusses some aspects of behavior during late January through 1 February 2006. This report then continues with summaries of Alaska Volcano Observatory (AVO) reports during 24 February to 26 March 2006.

After eight months of increasing seismicity, gas-and-steam emissions, and phreatic eruptions in December 2005, Augustine began magmatic eruptions on 11 January 2006 (BGVN 30:12). Eruptions continued throughout January, producing ash clouds up to ~ 9 km altitude. The eruption was described by Jon Dehn (University of Alaska Fairbanks, personal communication) as occurring in the following three phases: I) 11-28 January; II) 29 January-4 February; and III) 5 February and into at least late March.

During 11 January to 21 March 2006 (70 days), the Anchorage Volcanic Ash Advisory Center (VAAC) issued text reports (Volcanic Activity Advisories) on Augustine 567 times (averaging 8.1 reports per day). These alerted the aviation community to the ongoing airborne-ash hazards.

Augustine lies ~ 277 km SW of Anchorage's airport, a key hub for flights across the North Pacific. According to the US Department of Transportation, during 2003 Anchorage's airport supported the largest tonnage of any in the US, and functioned as the 8th busiest in the US by value of shipments. Augustine's eruptions can potentially impact aviation and operations at the airport, and more generally, they complicate North Pacific air travel.

Plumes, 28 January-1 February. AIRS SO2 retrievals for Augustine plumes on 28 and 29 January were provided by Fred Prata (figure 27). He commented that the SO2 "blobs" seem to spread out rather than elongate into a plume shape, possibly because of calm winds or intermittent ejections.

Figure (see Caption) Figure 27. Atmospheric SO2 from the AIRS instrument for Augustine plumes on 28 and 29 January 2006. Details of the processing and resulting analysis are included on the four panels, which correspond to these dates and times (UTC): a) 12:11:25 on 28 January, b) 21:47:25 on 28 January, c) 23:29:25 on 28 January, and d) 12:53:25 on 29 January. All images provided courtesy of Fred Prata (Norwegian Institute for Air Research).

Shortly after the 28-29 January plumes mentioned above, on 30 January, an overflight by AVO confirmed a ~ 5-km-tall volcanic cloud and small explosions and associated pyroclastic flows. The airborne observations indicated that a considerable amount of ash was being produced during this time period from small explosions and associated pyroclastic flows. Figures 28 and 29 show images from 30 January. AVO also presented 31 January thermal infrared images similarly indicative of vigorous eruptions and fresh pyroclastic flows (figure 30).

Figure (see Caption) Figure 28. Aerial view of Augustine during an eruption on 30 January 2006. The volcano was shrouded in ash cloud. The plume blew NE. Courtesy of Pavel Izbekov, AVO/UAF-GI.
Figure (see Caption) Figure 29. A MODIS satellite image for 30 January at 12:30:00 showing an Augustine ash and steam plume. This image was collected at approximately the same time as an AVO overflight, and shows the volcanic cloud moving NE at ~ 4.8 km altitude. Processing and interpretation courtesy of Dave Schneider, USGS-AVO. Image courtesy of MODIS Rapid Response Project at NASA/GSFC.
Figure (see Caption) Figure 30. Two 31 January 2006 (at 22:50:44 AST; 1 February 2006 UTC) night-time ASTER thermal infrared (TIR) images showing hot pyroclastic flow deposits on Augustine's N flank. The image on the left also shows a broad ash and SO2 plume extending ENE. Image processing and interpretation courtesy of Rick Wessels (AVO-USGS); ASTER data courtesy of NASA/GSFC/METI/ERSDAC/JAROS, and US/Japan ASTER Science Team.

René Servranckx looked at several images from 1 February 2006 and sent associated messages and links to the Volcanicclouds listserv. He found a hotspot at Augustine and identified various cloud features from plumes. Using a NOAA-12 IR image taken at 1542 UTC, Servranckx could not detect an ash signature in the split window.

On 4 February, Ken Dean (UAF) posted a message on the Volcanicclouds listserv discussing Augustine for 28 January-1 February. He noted that, regarding SO2 detection in northern Alaska, they had been monitoring the atmospheric transport direction using Puff, a modeling routine for predicting the atmospheric dispersal of ash clouds. Generally speaking, trajectories were to the N and over Fairbanks. Accordingly, lidar systems at both the UAF's Geophysical Institute and ~ 50 km N of Fairbanks at the Poker Flat Rocket Range were turned on to see if they could detect volcanic aerosols from the eruption. Lidar uses laser energy to probe the atmosphere, where it can detect suspended material such as volcanic aerosols in identifiable regions. Preliminary results indicated volcanic aerosols at 4.6-6.6 km altitude in the atmosphere above both Fairbanks and Poker Flats. There could also have been volcanic aerosols at lower altitudes in the weather clouds.

Dean also noted that ground-based event-monitoring collectors set out by Cathy Cahill (UAF) sampled volcanic aerosols and possible traces of ash at Fairbanks. He noted that these observations and trajectories were consistent with Prata's SO2 observations and Servranckx's back trajectories.

24 February-26 March 2006. On 24 February, AVO noted repeated and ongoing unrest during the past week. This included relatively low but above-background seismicity that indicated small, intermittent rockfalls and avalanches from the lava dome. Satellites detected a persisting thermal anomaly in the summit area. These data, along with a 20 February visit to the island, indicated continued slow growth at the summit lava dome. A veil of fresh, light ash dressed Augustine's flanks. The ongoing AVO reports into March noted similar processes and observations, and soon included mention of ash plumes, a lava flow, and a pyroclastic flow.

An overflight of the volcano on 1 March revealed a short, stubby lava flow that extended NE from the dome, terminating at ~ 1 km elevation. AVO noted a small dilute ash plume as well as a 20-minute interval of elevated seismicity at 1010 on 5 March, interpreted as a small explosion with associated ash emission, although low clouds obscured web-camera views. On 6 March AVO reported seismic signals and the low-light camera in Homer suggested rockfalls and avalanches. Although Augustine's plumes in this time frame were generally characterized as local, dilute, and under ~ 1 km above the summit, pyroclastic flows were also seen on 6 March.

Early on the morning of 8 March, AVO's seismometers began recording periods of discrete, repetitive, small events. These signals were taken to indicate ongoing dome growth, observations consistent with those from web cameras, which revealed minor ash emissions and mass wasting. Reports on 8 and 9 March discussed seismicity sufficiently elevated as to sometimes saturate several instruments. In addition, cameras portrayed two areas of high thermal flux. AVO initially interpreted these observations as including elevated rates of lava extruding into the dome, possibly with vigorous lava movement, and block-and-ash flows.

Later reports disclosed further details from around 9 March. AVO's 8-10 March reports noted that the summit was steaming more vigorously than the previous 3-4 weeks. A brownish-orange plume rose from the top of the summit lava dome. Fumaroles on the S and W side of the dome were the source of the most vigorous steaming. Areas of bare ground on the upper W and S flanks had substantially enlarged since 1 March. The greatest amounts of steam came from bare areas on the upper NW flank. Web-camera images and observations from overflights on 8 and 9 March indicated regular small-scale collapses of the summit lava dome. Usually these collapse events produce block-and-ash flows and small diffuse ash clouds. Block-and-ash flows to the E to NE sectors extended to within about 1 km of the coastline. Dilute ash clouds were observed rising from the block-and-ash flows to about the level of the summit and drifting away with the wind.

10 March seismicity included prolonged volcanic tremor and an increase in the frequency of small volcano-tectonic earthquakes. Block-and-ash flows, rock avalanches, and rockfalls originating from the summit lava dome continue to be recorded by the seismic network, particularly at the E flank station.

The 10 March report stated that "Satellite and low-light camera images obtained intermittently throughout the week show that thermal anomalies in the summit area and on the upper NE flank persist. On several evenings this past week, a low-light camera at the AVO site in Homer captured hot avalanches in progress and prolonged periods of incandescence. AVO also received several reports from observers in Homer and Nanwalek of summit glow in the evening hours. Airborne measurements of gas emissions made on March 9 indicate both SO2 and CO2 gas in the plume. This is the first time since the fall of 2005 that CO2 has been a component of the gas plume and likely indicates the presence of new magma entering the volcanic system."

The AVO report for 17 March chronicled low-level eruptive activity. It said that the past week's seismicity changed from periods of prolonged tremor and closely spaced discreet events to episodic short-duration events. Observers interpreted the change as indicating that steady effusion of lava and dome growth had given way to slower effusion of lava and intermittent block-and-ash flows, rock avalanches, and rock-falls from the summit lava dome. On several evenings during the week, clear atmospheric conditions enabled low-light cameras at the AVO site in Homer to capture hot avalanches and prolonged periods of incandescence in both the summit area and on the upper NE flank. Satellite images also showed thermal anomalies.

The 17 March report said that overflights indicated two lava flows were seen on the N and NE flanks. They advanced slowly. Occasional collapses of the lava flow fronts shed hot blocks and produce minor ash emissions. Estimates using photographs indicated that the new lava dome stood ~ 70 m higher than the one formed in 1986.

Little new information was discussed in AVO reports issued on 20-26 March. The 26 March report included the remark that satellite views were then obscured by cloud cover; however, vigorous steaming from the summit was visible with the on-island web camera.

Correction. A previous Augustine report (BGVN 30:12; issued in early 2006) had a typographic error in the title: "Eruptions begin 11 January 2005 and eight outbursts occur by late January)." The year has since been changed on our website to 11 January 2006.

Geologic Background. Augustine volcano, rising above Kamishak Bay in the southern Cook Inlet about 290 km SW of Anchorage, is the most active volcano of the eastern Aleutian arc. It consists of a complex of overlapping summit lava domes surrounded by an apron of volcaniclastic debris that descends to the sea on all sides. Few lava flows are exposed; the flanks consist mainly of debris-avalanche and pyroclastic-flow deposits formed by repeated collapse and regrowth of the volcano's summit. The latest episode of edifice collapse occurred during Augustine's largest historical eruption in 1883; subsequent dome growth has restored the volcano to a height comparable to that prior to 1883. The oldest dated volcanic rocks on Augustine are more than 40,000 years old. At least 11 large debris avalanches have reached the sea during the past 1800-2000 years, and five major pumiceous tephras have been erupted during this interval. Historical eruptions have typically consisted of explosive activity with emplacement of pumiceous pyroclastic-flow deposits followed by lava dome extrusion with associated block-and-ash flows.

Information Contacts: Jon Dehn, Cathy Cahill, Ken Dean, and Pavel E. Izbekov, Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, PO Box 757320 Fairbanks, AK 99775-7320, USA; Anchorage VAAC, Alaska Aviation Weather Unit, National Weather Service, 6930 Sand Lake Road, Anchorage, AK 99502, USA (URL: http://aawu.arh.noaa.gov/vaac.php); Fred Prata, Norwegian Institute for Air Research, P.O. Box 100, 2027 Kjeller, Norway; René Servranckx, Montreal Volcanic Ash Advisory Centre, Canadian Meteorological Centre, Meteorological Service of Canada, 2121 North Service Road, Trans-Canada Highway, Dorval, Quebec, H9P 1J3 Canada; Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.


Bezymianny (Russia) — April 2006 Citation iconCite this Report

Bezymianny

Russia

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

All times are local (unless otherwise noted)


Pyroclastic flows on 9 May extend 7-8 km; plumes over 500 km long

This report describes a substantial eruption on 9 May 2006, and events before and shortly afterwards. Bezymianny was last reported on in BGVN 30:11, covering a series of events during mid-January through late December 2005.

An explosive eruption occurred on 30 November 2005. Seismicity decreased subsequently and from January to the end of April 2006, Bezymianny remained comparatively calm; fumarolic activity and a small thermal anomaly were observed during periods of good visibility. A 1 April aerial photo of the summit area appears as figure 6.

Figure (see Caption) Figure 6. Bezymianny aerial photo taken on 1 April 2006, showing the large dome within the breached summit crater. Labels indicate both a fissure on the dome's flank and a large extrusive block (or spine) on the dome's top. Considerable areas discharged light steam. Photo by Yu. Demyanchuk and provided courtesy of KVERT.

During 28 April to 5 May, Bezymianny's lava dome continued to grow. Seismicity was above background levels during 30 April to 3 May. Incandescent avalanches were visible on 4 May. At the lava dome, fumarolic activity occurred and thermal anomalies were visible on satellite imagery. Bezymianny was at Yellow on the four stage Concern Color Code (low to high–Green, Yellow, Orange, Red).

On 7 May the Concern Color Code was raised to Orange due to an increase in seismicity and the number of incandescent avalanches (14 occurred on 6 May in comparison to 4-6 during the previous 2 days). Intense fumarolic activity occurred, with occasional small amounts of ash. KVERT reported that an explosive eruption was possible in the next 1 or 2 weeks.

9 May eruption. On 9 May around 1935, the Concern Color Code was raised to Red, the highest level, due to increased seismicity and incandescent avalanches. A gas plume rose higher than 7 km altitude and a strong thermal anomaly was visible on satellite imagery.

An explosive eruption occurred on 9 May during 2121 to 2145. The explosion produced an ash column that rose to a height of ~ 15 km altitude. A co-ignimbrite ash plume was about 40 km in diameter and mainly extended NE of the volcano. Ash plumes extended more than 500 km ENE from the volcano. Pyroclastic flows deposits extended 7-8 km from the volcano.

On 10 May around 0100, seismicity returned to background levels and the Concern Color Code was reduced to Orange. Small fumarolic plumes were observed during the early morning of the 10th and lava probably began to flow at the lava dome.

By 11 May seismic activity was still at background levels. Gas and steam plumes were visible above the volcano. A thermal anomaly was noted at the volcano on 10-11 May. Lava effusion was probably occurring at the lava dome. This was interpreted to mean that the likelihood of a large, ash-producing eruption had diminished.

Geologic Background. Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), a cooperative program of the Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia, the Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.


Bulusan (Philippines) — April 2006 Citation iconCite this Report

Bulusan

Philippines

12.769°N, 124.056°E; summit elev. 1535 m

All times are local (unless otherwise noted)


Eruptions and earthquakes in March and April 2006 after years of little activity

Bulusan, after remaining relatively quiet since 1995, erupted multiple times during March and April 2006. There were no casualties or damage from these eruptions. On 21 March at 1044 the summit crater erupted, sending a column of ash 1.5 km into the sky accompanied by lightning and rumbling noises. Ash drifted N, W, and SW of the volcano and an hour after the event light ash fell on neighborhoods such as Barangays Cogon, Tinampo, Gulang-Gulang, and Bolos in the town of Irosin, as well as Barangays Puting Sapa and Bura-Buran in the town of Juban.

Ash ejected at 1058 on 22 March coincided with an explosion-type earthquake. Three other earthquakes were recorded at 2330, 2332, and 2337. The hazard status had been raised to Alert Level 1; the area within a 4 km radius of the summit is a Permanent Danger Zone.

On 29 April the volcano erupted in a similar fashion, emitting ash nearly 1.6 km into the air. There was no sign of lava and no reports of rumbling noises. It was reported that ash rained on nearby communities.

Geologic Background. Luzon's southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 36,000 years ago. It lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon. A broad, flat moat is located below the topographically prominent SW rim of Irosin caldera; the NE rim is buried by the andesitic complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded since the mid-19th century.

Information Contacts: R.U. Solidum and E. Corpuz, Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P. Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Inq7.net, a venture between The Philippine Daily Inquirer Inc., and GMANetwork Inc. (URL: http://news.inq7.net/).


Karymsky (Russia) — April 2006 Citation iconCite this Report

Karymsky

Russia

54.049°N, 159.443°E; summit elev. 1513 m

All times are local (unless otherwise noted)


During April 2006, emerging ash plumes remained visible for up to 145 km

Karymsky was last reported on in BGVN 30:11. After frequent explosions from December 2004 to June 2005 (BGVN 30:06) a brief decrease in seismic and volcanic activity took place but this ended in late June when ash and gas plumes rose to 3 km above the crater. Seismicity remained above background levels throughout August-December 2005. During this period, ash and gas plumes and thermal anomalies were observed at the volcano.

Seismic activity indicated that ash explosions from the summit crater of Karymsky continued during 14-20 January 2006. Ash plumes extending 6-9 km S from the volcano were observed on 12 January and a thermal anomaly over the dome was observed during 13-15 January. According to seismic data, two possible ash plumes rose to 3.0-3.4 km altitude on 14-15 January.

According to reports from pilots of local airlines, ash emissions from Karymsky rose to 4-5 km altitude during 30-31 January. The ash plumes extended 13-29 km to the SW and SE, respectively. A thermal anomaly was visible at the lava dome during 27 January to 3 February, except when the volcano was obscured by clouds on 28 January. KVERT warned that activity from the volcano could affect nearby low-flying aircraft.

Strombolian activity continued through April 2006. During 10 February to 10 March, a large thermal anomaly was visible at the crater and numerous ash plumes were visible on satellite imagery extending as far as 140 km. On 9 March, a pilot reported an ash plume at a height of ~ 3 km altitude.

During 17-24 March, several ash plumes were visible on satellite imagery at a height of ~ 4 km altitude and extending SE and E. A thermal anomaly was seen at the volcano during periods of visibility. About 40-450 small earthquakes occurred daily.

During 7-14 April satellite imagery showed ash plumes extending ~ 40-145 km E and SE of the volcano, and a large thermal anomaly at the crater. Karymsky remained at Concern Color Code Orange from January to April 2006.

Geologic Background. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian with moderate explosive activity and occasional lava flows from the summit crater.

Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), a cooperative program of the Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia, the Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA; Tokyo Volcanic Ash Advisory Center (VAAC) (URL: https://ds.data.jma.go.jp/svd/vaac/data/).


Kilauea (United States) — April 2006 Citation iconCite this Report

Kilauea

United States

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

All times are local (unless otherwise noted)


Maps of past year's surface lava flows and photos of lava entering the sea

This report covers the interval 31 January 2005 to 7 February 2006 and is drawn exclusively from U.S. Geological Survey Hawaiian Volcanic Observatory (USGS HVO) sources. During this interval, active lava flows during tended to remain along the W to central portions of the existing field (figures 173 and 174). On 31 January 2005, lava from Kilauea began pouring into the ocean at two entry points. The Ka`ili`ili entry to the E of the flow field was the largest and was fed by the large W arm of the Prince Kuhio Kalaniana (PKK) lava flow. The West Highcastle ocean entry was supplied by the W branch of the W arm of the PKK lava flow.

Figure (see Caption) Figure 173. A series of maps portraying Kilauea's surface lava flows at various times during 31 January 2005 to 7 February 2006. New vents opened at the southern base of Pu`u `O`o on 19 January 2004. Map panels are as follows: a) A map with features as of February 2005, b) as of April 2005, c) as of May 2005, d) as of 31 July 2005, and e) as of 30 September 2005. Courtesy of Christina Heliker, USGS HVO.
Figure (see Caption) Figure 174. Map portraying Kilauea's near-shore and coastal lava flows areas in the vicinity of East Lae'apuki and East Kamoamoa as of 23 September 2005. Courtesy of Christina Heliker, USGS HVO.

From 7 February 2005 to 20 February 2005, lava flows were visible on the Pulama pali fault scarp and on the coastal flat. Instruments recorded a few small earthquakes and no tremor at Kilauea's summit. At Pu`u `O`o, volcanic tremor remained moderate. Small amounts of deformation were recorded.

On 21 February 2005 a new ocean entry formed, named E Lae`apuki. The entry was located between the other two ocean entries (Ka`ili`ili and West Highcastle) that had been active since 31 January 2005. This was the first time there had been three ocean entries active since early 2003 (figures 173-175).

Figure (see Caption) Figure 175. Photos of Kilauea activity taken along the coast on 21 February 2005. (A) A photo showing the walls of a large crack into which lava pours at E Lae`apuki. Sea cliff is to the right, at shelf's edge beyond the glow. (B and C, respectively) The top and bottom of lava falls at E Lae`apuki ocean entry looking W. (D) A closer view focused on showing the base of the lava falls. The sea cliff's height is ~ 12 m. Courtesy of HVO.

During 23-26 February 2005, lava from Pu`u `O`o entered the sea at three ocean entries–West Highcastle, East Lae'apuki, and Ka`ili`ili–spots along 4.7 km of the island's SE coast (figure 176). Lava may have stopped flowing into the sea at the W entry (West Highcastle) on 26 February 2005. The number of surface lava flows diminished in comparison to the previous weeks, and small earthquakes continued to occur at Kilauea's summit without accompanying tremor. Tremor remained at moderate levels at Pu`u `O`o, and as of 28 February 2005, deflation had occurred at Pu`u `O`o for more than a week and at the summit since 24 February 2005.

Figure (see Caption) Figure 176. A Kilauea photograph taken on 23 February 2005 depicting active lava delta construction at E Lae`apuki ocean entry. Note the fan building outward from the sea cliff and the person (upper right) for scale. Courtesy of USGS HVO.

During the month of March 2005, lava from Kilauea continued to enter the ocean at the Ka`ili`ili and E Lae`apuki, but there were no signs of activity at the West Highcastle entry. Surface lava flowed down the Pulami pali fault scarp and the coastal flat. Small earthquakes occurred at Kilauea's summit, and no tremor was recorded. Tremor remained at moderate levels at Pu`u `O`o.

On 29 March 2005, lava from Kilauea entered the ocean at five areas. The largest, named Kamoamoa, consisted of six or more places where lava entered the water along the front of a growing lava delta (figure 177). At one of the two Highcastle entries, a cascade of lava streamed down the old sea cliff. A bright glow came from Ka`ili`ili entry, and a weak glow from E Highcastle entry. Seismicity remained above background levels at Kilauea's summit, consisting mainly of tremor and some long-period earthquakes. Surface waves from an M 8.7 earthquake on 28 March 2005 off Sumatra, Indonesia disturbed tilt measurements at Kilauea but otherwise the tilt change was small.

Figure (see Caption) Figure 177. A photo taken 25 March 2005 showing Kilauea's new Kamoamoa ocean entry, located just NE of East Lae'apuki. Descending lava poured over an old sea cliff to land upon, and flow across, an old delta; it then dropped into the sea, forming a new delta. Courtesy of USGS HVO.

Lava from Kilauea continued to flow into the ocean at several points during 1-13 April 2005. Seismicity remained above background levels at Kilauea's summit, consisting mainly of tremor and some long-period earthquakes. Volcanic tremor was at moderate levels at Pu`u `O`o. During 14-19 April, surface lava flows from Kilauea were visible on the Pulama pali fault scarp but lava was not seen entering the ocean.

Seismicity remained above background levels at Kilauea's summit during 14-19 April 2005, consisting mainly of tremor and some long-period earthquakes. Volcanic tremor was at moderate levels at Pu`u `O`o. Episodes of inflation and deflation occurred during the week.

During 21-25 April, there were fewer surface lava flows visible at Kilauea than during the previous week. On 24 April a small amount of lava again began to enter the sea. Seismicity remained above background levels at Kilauea's summit, consisting mainly of tremor and some long-period earthquakes.

During 27 April-3 May 2005, lava entered the ocean at the Kamoamoa entry. Numerous surface lava flows were visible on the coastal flat. Seismicity remained above background levels at Kilauea's summit, consisting of both tremor and long-period earthquakes.

A third ocean entry, in the E Lae`apuki area, became active on 5 May 2005. That entry and the Far E Lae`apuki entry were both being fed by lava falls down the old sea cliff and were relatively small. Based on the brighter glow, the Kamoamoa entry was thought to be more substantial. By the morning of 9 May lava was streaming over the old sea cliff in four locations: two falls went into the sea and two other falls landed on an old delta. The branch of the PKK flow feeding E Lae`apuki sprung numerous new lava flows on 9 May. The next day, the middle branch of the PKK flow developed an open-channel stream on the Pulama pali; it was 10-20 m wide, 500-600 m long, and moving rapidly.

Ocean entries remained active during 11-17 May 2005 in the E Lae`apuki and Kamoamoa areas. By 16 May the E Lae`apuki and E Kamoamoa entries both had benches ~ 350 m long and up to 75 m wide. A large plume from West Highcastle on 10 May probably recorded a collapse of part of that lava delta, which has been inactive for the past several weeks following growth in March and April. The middle branch of the PKK flow remained active and extended down Pulama Pali. The E branch reached out farther but was narrower and contained fewer breakouts. The W branch was reduced to a cluster of breakouts about halfway down the pali. Glow was seen from all of the Pu`u `O`o crater vents, as well as the MLK vent at the SW foot of the cone.

During 18-31 May 2005, lava from Kilauea continued to enter the sea at three areas. Surface lava flows were visible on the coastal plain and on the Pulama pali fault scarp. During 1-4 June 2005 lava entered the sea at three points along the S flank of Kilauea, and then at only two points through 7 June. Small surface lava flows were visible on the Pulama pali fault scarp and the coastal flat.

Lava again entered the sea at three points on 13 June. During the 14-21 June lava continued to enter the sea and there was a small number of lava flows on the Pulama pali fault scarp. On 22 June lava in the W branch of the current flow descended onto the coastal flat for the first time in several months. On 24 June it was noted that Kilauea's summit continued its inflation, while Pu`u `O`o was deflating during the same period.

On 27 June part of the active E Lae`apuki lava delta collapsed. Lava stored within the delta gushed out onto the surface and into the water. Fountains of lava reported to be about 25 m high spurted from the central part of the delta soon afterward. Lava also entered the sea during 4-5 July and a few surface flows were on Pulama pali.

During 6-19 July 2005, lava continued to enter the sea at E Kamoamoa and E Lae`apuki. The latter entry was much larger, with several entry points. E Kamoamoa barely glowed. Surface lava was visible along the PKK lava flow throughout the month of July. Background volcanic tremor remained above normal levels at Kilauea's summit and at moderate levels at Pu`u `O`o. Slight inflation and deflation occurred at the volcano. An M 4.5 earthquake occurred on 25 July at 2209 along the SE edge of Kilauea's SW rift zone at a depth of ~ 30 km.

Up to seven ocean-entry points were visible off the W-facing front of the E Lae`apuki lava delta during 3-9 August; still others were hidden from view off the E-facing front. On Pulama pali, the W branch of the PKK flow reached its greatest extent of the week on 5 August, when it broadened to include hundreds of meters of scattered breakouts and reached from 460 m down to 260 m elevation. During 15-16 August 2005, surface lava at Kilauea was again visible on the W and E branches of the PKK lava flow. Lava continued to enter the sea at the E Lae`apuki entry through 5 September. Background volcanic tremor was near normal levels at Kilauea's summit and at moderate levels at Pu`u `O`o cone. There were small periods of inflation and deflation at Kilauea's summit and Pu`u `O`o. By 22 August, surface lava on the W branch of the PKK lava flow was no longer visible. On 27 August, part of a lava-bench collapsed.

Throughout September, lava entered the sea at the E Lae`apuki area with surface lava flows visible on the Pulama Pali fault scarp. Lava filled a scar left by the lava-bench collapse on 27 August. Background volcanic tremor continued to remain around normal levels at the summit. Volcanic tremor was at moderate levels at Pu`u `O`o. On 11 September, substantial deflation at the volcano was followed by sharp inflation. On 19 September, several small shallow earthquakes occurred along the Kao`iki fault system with small amounts of inflation and deflation.

In October 2005, lava from Kilauea continued to enter the sea at the E Lae`apuki area, and surface lava flows were visible along the PKK lava flow. Lava flows continued to enter the sea at E Lae`apuki area, mostly NE of the point of the lava delta. On 18 October, weak surface lava flows were visible at Kilauea and one cascade of lava flowed off of the western front of the E Lae`apuki delta.

Activity during November 2005 was similar to the previous month. Lava continued to enter the sea at the E Lae`apuki area and surface lava flows were visible on the Pulama pali fault scarp. Background volcanic tremor was near normal levels at Kilauea's summit.

A lava-bench collapse in the E Lae`apuki area on 29 November 2005 was the largest bench collapse of the current eruption, which began in January 1983. The collapse lasted several hours, sending the 137,588 m2 of bench and an additional 40,467 m2 of adjacent cliff, into the sea. The collapse left a 20-m-high cliff, from which a 2 m thick stream of lava was emitted from an open lava tube. Cracks had been observed on the inland portion of the bench several months earlier; visitors were not allowed near the bench, but a viewing area was provided ~ 3 km away. Growth of the new delta at E Lae`apuki was continuing as of 6 December 2005. At that time breakouts were also active on Pulama Pali.

During December, lava from Kilauea continued to enter the sea at the E Lae`apuki area and surface lava flows were visible on the Pulama pali fault scarp.

From 28 December 2005 to 9 January 2006, lava from Kilauea continued to enter the sea at the E Lae`apuki area building a new lava delta with surface lava flows visible on the Pulama pali fault scarp. Background volcanic tremor was near normal levels at Kilauea's summit. Volcanic tremor reached moderate levels at Pu`u `O`o. Small amounts of deformation occurred. On 10 January, the summit deflation switched abruptly to inflation after a loss of 5.2 µrad. Relatively high tremor occurred at this time. The tremor quickly dropped, becoming weak to moderate when deflation ended, with seismicity punctuated by a few small earthquakes. By 13 January, background volcanic tremor was near normal levels at Kilauea's summit and reached moderate levels at Pu`u `O`o. On 14 January, the lava delta was about 500 m long (parallel to shore) and still 140 m wide. By the end of the month the lava delta was 615 m long and 140 m wide. Background volcanic tremor was near normal levels at Kilauea's summit, with numerous shallow earthquakes occurring at the summit and upper E rift zone during several days.

During 2-7 February 2006, lava from Kilauea continued to enter the sea at the E Lae`apuki area and surface lava flows were visible on the Pulama pali fault scarp. Background volcanic tremor was near normal levels at Kilauea's summit, with numerous shallow earthquakes continuing to occur at the summit and upper E rift zone. Volcanic tremor reached moderate levels at Pu`u `O`o. Small amounts of inflation and deflation were reported. From mid-to-late February, surface lava flows were not visible on Kilauea's Pulama pali fault scarp due to lava traveling underground through the PKK lava tube until reaching E Lae`apuki lava delta and flowing into the sea. Observations on 7 February 2006 revealed that the lava delta had broadened 120 m W since 30 January 2006.

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

Information Contacts: Hawaiian Volcano Observatory (HVO), U.S. Geological Survey, PO Box 51, Hawaii National Park, HI 96718, USA (URL: https://volcanoes.usgs.gov/observatories/hvo/).


Lascar (Chile) — April 2006 Citation iconCite this Report

Lascar

Chile

23.37°S, 67.73°W; summit elev. 5592 m

All times are local (unless otherwise noted)


Five-day eruption sequence in April 2006; plume seen 220 km away

Lascar's eruption on 4 May 2005 (BGVN 30:05) was followed by a new eruptive cycle, which began on 18 April 2006 and lasted 5 days. Observers familiar with Lascar judged this eruptive episode unusual compared to those observed previously in terms of eruptive character, frequency, and duration time. The Volcanic Ash Advisory Center (VAAC) in Buenos Aires and Servicio Metererológico Nacional of Argentina detected the eruption from satellite images, and aircraft warnings were posted. All of the times cited are in UTC (local time = UTC - 4 hours).

Eruptions start, 18 April. Four explosions registered (at 1520, 1722, 1900, and 2100 hours UTC). The first explosion, the largest of four, was visible from El Abra cooper mine (220 km NW) and reached ~ 10 km above the summit crater (figure 33). The shape of the eruptive column suggested that it reached the tropopause (~ 15 km altitude in this region). The white to gray plume, containing little ash but a large amount of water, dispersed to the NNE.

Figure (see Caption) Figure 33. Lascar's first explosion of 18 April 2006 as photographed from El Abra copper mine, 220 km NW from volcano. Courtesy of personnel at the El Abra copper mine.

The second explosion reached 3 km above the summit crater, while the third and fourth explosions reached 800 m. These latter eruptive plumes were gray colored, had higher contents of ash than the first explosion, and were dispersed NNE. Only slight ash fall was registered on the N side of the volcano. No seismic activity or eruption noises were registered. Analysis of GOES satellite images (figure 34) indicated that for the first and second eruptive plumes the mean horizontal velocities were 70 and 85 km/hour, respectively, while the maximum plume areas were ~ 8,240 and 1,074 km2, respectively. Minimum volumes erupted were ~ 4.1 x 106 and ~ 0.54 x 106 m3 assuming a hypothetical ash fall deposit of 0.5 mm over the stated areas. The third and fourth explosions were not detected by satellite.

Figure (see Caption) Figure 34. GOES satellite image capturing Lascar's first and second eruptive plumes. Rivers and international borders are also shown. Image is for 1829 UTC on the 18 April 2006. The first plume (oblong black area labeled 'cloud' in Spanish?'nube') stretched over N Argentina and S Bolivia. A second plume appears as a much smaller dark area between Lascar and the first plume. It lay over the NE Chilean border. Courtesy of Comisión Nacional de Asuntos Espaciales (CONAE), Argentina.

19-22 April eruptions and comparative calm that followed. On 19 April 2006 at 1504 hours (UTC) an explosion generated a gray-colored eruptive column that reached 3 km above the summit crater and was dispersed NNE. Slight ash fall was noted on the N side of the volcano. Neither seismic activity nor eruption noises were reported. Two explosions were recorded 20 April at 1505 and 1739 hours (UTC). The first eruptive plume reached 2.5 km above the summit crater and contained a small amount of ash. The plume from the second explosion, the larger of the pair, reached 7 km above the crater. The eruption lasted 1 hour and 50 min. Both plumes were dispersed N and slight ash fall was registered on the N side of the volcano. No seismic activity or eruption noises were registered.

Analysis of satellite data from the sequence of GOES images (figure 35) indicated that the first and second eruptive plumes had mean horizontal velocities of 40 km/h, while the maximum areas were ~ 430 and ~ 800 km2, respectively. Minimal volumes erupted were ~ 0.4 x 106 and ~ 0.2 x 106 m3, again assuming a hypothetical 0.5 mm ash-fall deposit.

Figure (see Caption) Figure 35. GOES satellite image of Lascar showing the second eruptive plume (black circle) at 1807 hours (UTC) of 20 April eruption dispersed to NE. Courtesy of Servicio Meteorológico Nacional and Comisión Nacional de Asuntos Espaciales (CONAE), Argentina.

Two explosions were recorded on 21 April 2006 at 1248 and 1547 UTC, each lasting ~ 15 minutes. Their eruptive columns reached 3 km above the summit crater and rapidly dispersed ESE. Seismic activity and eruption noises were not noted.

On 22 April at 1518 UTC an explosion generated an eruptive column that reached 3 km above the summit crater; it was blown SE. Local inhabitants heard subterranean noises. On 23 April at 1600 UTC an explosion generated a gray-colored eruptive column that reached 2.5 km above the summit crater and dispersed NNW (figure 36). Seismic activity and eruption noises were not registered. During the following 2 days, the color of the plume was white and it's top remained ~ 1.5 km above the crater.

Figure (see Caption) Figure 36. Photograph of Lascar taken 23 April 2006 from the SW border of the Atacama salar (salt pan), ~ 40 km SW of the volcano. Courtesy of Gabriel González.

Other studies. After the 4 May 2005 eruption (BGVN 30:05), a team of scientists from Universidad Católica del Norte (UCN) carried out a gas sampling campaign on new fumaroles around the S edge of the central active crater. They used the direct sampling of fumaroles technique described by Giggenbach (1975) and Giggenbach and Goguel (1989). Gas data showed increasing amounts of H2O, H2S, and CH4 with respect to samples taken in 2002 from inside the active crater (Tassi et al., 2004). However, acid gases also displayed very high values. During December 2005 a team of scientists from UCN and Universidad Autónoma de México (UNAM) carried out field investigations to generate hazard maps.

Scientists from Università degli Studi di Firenze (Italy) and Universidad Católica del Norte (Chile) are conducting a systematic gas sample campaign at Lascar and other active volcanoes in the Central Volcanic Zone (e.g. Putana, Lastarria, and Isluga). Finally, scientists from the Universidad Católica del Norte, the Universidad Nacional de Salta and SEGEMAR (Argentina) are processing data from Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images, with the objective of understanding the behavior of Lascar volcano during the 1998-2004 period.

References. Giggenbach, W., 1975, A simple method for the collection and analysis of volcanic gas sample: Bulletin of Volcanology, 39, 132?145.

Giggenbach, W., and Goguel, R., 1989, Collection and analysis of geothermal and volcanic water and gas discharges: DSIR Chemistry, Rept. No. 2401.

Matthews, S., Gardeweg, M., and Sparks, R., 1997, The 1984 to 1996 cyclic activity of Lascar volcano, northern Chile: cycles of dome growth, dome subsidence, degassing and explosive eruptions: Bulletin of Volcanology, v. 59, p. 72-82.

Tassi, F., Viramonte, J., Vaselli, O., Poodts, M., Aguilera, F., Martínez, C., Rodríguez, L., and Watson, I., 2004, First geochemical data from fumarolic gases at Lascar volcano, Chile: 32nd International Geological Congress, Florence, August 20-28, 2004.

Viramonte, J., Aguilera, F., Delgado, H., Rodríguez, L., Guzman, K., Jiménez, J., and Becchio, R., 2006, A new eruptive cycle of Lascar Volcano (Chile): The risk for the aeronavigation in northern Argentina. Garavolcan 2006, Tenerife, Spain.

Geologic Background. Láscar is the most active volcano of the northern Chilean Andes. The andesitic-to-dacitic stratovolcano contains six overlapping summit craters. Prominent lava flows descend its NW flanks. An older, higher stratovolcano 5 km E, Volcán Aguas Calientes, displays a well-developed summit crater and a probable Holocene lava flow near its summit (de Silva and Francis, 1991). Láscar consists of two major edifices; activity began at the eastern volcano and then shifted to the western cone. The largest eruption took place about 26,500 years ago, and following the eruption of the Tumbres scoria flow about 9000 years ago, activity shifted back to the eastern edifice, where three overlapping craters were formed. Frequent small-to-moderate explosive eruptions have been recorded since the mid-19th century, along with periodic larger eruptions that produced ashfall hundreds of kilometers away. The largest historical eruption took place in 1993, producing pyroclastic flows to 8.5 km NW of the summit and ashfall in Buenos Aires.

Information Contacts: Felipe Aguilera, Eduardo Medina, and Karen Guzmán, Programa de Doctorado en Ciencias mención Geología and Departamento de Ciencias Geológicas, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile (URL: http://www.geodoctorado.cl, http://www.ucn.cl/); José G. Viramonte, Raúl Becchio, and Marcelo J. Arnosio, Instituto GEONORTE and CONICET, Universidad Nacional de Salta, Buenos Aires 177, Salta 4400, Argentina (URL: http://www.unsa.edu.ar/); Ricardo Valenti and Sergio Haspert, Servicio Metereológico Nacional, Argentina; Hugo G. Delgado, Instituto de Geofísica, Universidad Nacional Autónoma de México (UNAM), Coyoacán 04510, México, D.F.; Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/productos.php).


Masaya (Nicaragua) — April 2006 Citation iconCite this Report

Masaya

Nicaragua

11.985°N, 86.165°W; summit elev. 594 m

All times are local (unless otherwise noted)


Intermittent ash eruptions November 2003-March 2005; continuing incandescence

Previously reported behavior at Masaya through 22 September 2003 consisted primarily of incandescence from Santiago crater (BGVN 28:10). Monthly reports prepared by the Instituto Nicarag?ense de Estudios Territoriales (INETER) since that time noted continuing seismicity and incandescence through March 2005. A small explosions was reported on 29 November 2003. Masaya Volcano National Park workers also reported two ash-and-gas explosions at 0121 on 12 December 2003. A collapse event within the crater was noted on 22 June 2004. A report from the Washington Volcanic Ash Advisory Center (VAAC) noted that on 4 July 2004 at 0015 local time, a narrow plume of steam and/or ash from Masaya was visible on satellite imagery extending to the SW. An hour later the plume had extended ~ 12 km from the summit. The report below notes changes induced in Santiago crater after a landslide in early March 2005. A magnitude 1.9 earthquake at a depth of 2.2 km below Masaya on 30 March 2005 was followed by rumbling noises and gas-and-ash emissions.

Field work during February-March 2005. Patricia Nadeau and Glyn Williams-Jones sent us a report of an intensive, multi-component field campaign conducted at Masaya from 16 February 2005 to 12 March 2005. Two FLYSPEC ultraviolet spectrometers were used in tandem with two Microtops sun photometers to constrain passive SO2 and aerosol fluxes and also to evaluate potential downwind loss of SO2 by conversion to aerosols. Additionally, self-potential geophysical measurements were performed at Masaya's summit in a preliminary attempt to delineate the hydrothermal system of the volcano.

On the morning of 3 March, Park workers reported that a landslide had occurred within Santiago crater the previous night. A visibly diminished plume from the crater's active vent suggested that the landslide may have caused a blockage that reduced the escape of SO2 (figures 20 and 21).

Figure (see Caption) Figure 20. A photo taken from the tourist parking lot on 1 March 2005 showing the inner crater at Masaya emitting a large plume prior to the 2-3 March 2005 landslide. The diameter of the crater in this view is estimated to be 150-200 m. Courtesy of Patricia Nadeau and Glyn Williams-Jones.
Figure (see Caption) Figure 21. A view into the Santiago Crater at Masaya and its diminished plume rising from the inner crater, as taken from the tourist parking lot on 3 March 2005. The diameter of the outer crater is approximately 500 m; the inner crater is about 200 m across. Courtesy of Patricia Nadeau and Glyn Williams-Jones.

The visual observations were supported by subsequent SO2-flux measurements, which confirmed a significant drop in SO2 emissions from an average of ~ 300 tons/day prior to the landslide to an average of ~ 80 tons/day following the landslide (figure 22). This decrease in emissions led to concerns over the possibility of a small vent-clearing explosion such as the one that occurred on 23 April 2001 (BGVN 26:04). That explosion was preceded by a similar drop in SO2 emissions for several weeks due to a blockage of the vent that was active at the time. The 2001 explosion resulted in the opening of a new vent, which has since been the site of Masaya's degassing. After the 2001 explosion, the previously active vent no longer degassed and was assumed to be completely inactive.

Figure (see Caption) Figure 22. Graph showing Masaya's daily SO2 fluxes during 25 February 2005-17 April 2005 (normalized to a wind speed of 1 m/s) before and after the landslide during the night of 2-3 March 2005. Courtesy of Patricia Nadeau and Glyn Williams-Jones.

In the days following the 2 March 2005 landslide, gas output was monitored closely, both visually and with the FLYSPEC, for any further decreases, which could have been indicative of further blockage and possible pressurization. Visual observations of the crater on the nights of 4 March and 11 March revealed that while the currently degassing vent was not incandescent, the older vent (believed to be inactive after the April 2001 explosion) was indeed incandescent, though not degassing (figure 23).

Figure (see Caption) Figure 23. A photo taken from the second parking lot overlooking Masaya's Santiago Crater captured the scene at two vents within the inner crater on 10 March 2005. The younger, actively degassing vent and plume are in the foreground; the older, non-degassing vent is in the background. The latter vent was incandescent at night. The diameter of the active vent in this view is estimated to be 30-40 m. Courtesy of Patricia Nadeau and Glyn Williams-Jones.

As of 10 March, the visible gas emissions were the lowest seen, despite the apparent open conduit, as indicated by incandescence in the old vent. Rumbling and sloshing sounds from within the crater had increased from sporadic to nearly constant. However, the days following were marked by a decrease in acoustical noise, as well as the apparent beginning of a climb back to higher SO2 emission rates (~ 120 tons/day on 16 March). These observations were consistent with devlopments in the upper conduit.

References. Williams-Jones, G., Horton, K. A., Elias, T., Garbeil, H., Mouginis-Mark, P. J., Sutton, A. J., and Harris, A. J. L., Accurately measuring volcanic plume velocity with multiple UV spectrometers: Bulletin of Volcanology, in press.

Williams-Jones, G., Delmelle, P., Baxter, P., Beaulieu, A., Burton, M., Garcia-Alvarez, J., Gaonac'h, H., Horrocks, L., Oppenheimer, C., Rymer, H., Rothery, D., St-Amand, K., Stix, J., Strauch, W., and van Wyk de Vries, B., (2001?), Projecto Laboratorio Geofisico-Geoquimico Volcán Masaya, Geochemical, geophysical, and petrological studies at Masaya volcano (1997-2000), on INETER website at.

Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras caldera and is itself a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The Nindirí and Masaya cones, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6,500 years ago. Historical lava flows cover much of the caldera floor and there is a lake at the far eastern end. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals have caused health hazards and crop damage.

Information Contacts: Patricia Nadeau and Glyn Williams-Jones, Department of Earth Sciences, Simon Fraser University, Burnaby, Canada; Kirstie Simpson, Geological Survey of Canada, Vancouver, Canada; 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/); Wilfried Strauch and Martha Navarro, Instituto Nicaraguense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua.


Sangay (Ecuador) — April 2006 Citation iconCite this Report

Sangay

Ecuador

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

All times are local (unless otherwise noted)


Some conspicuous plumes during 2004-2005; climber's photos from January 2006

Our previous report was in 1996 (BGVN 21:03); this report covers the time interval January 2004 to January 2006. According to a 2004 annual summary on the Instituto Geofísico (IG) website, Sangay was one of the most active volcanoes in Ecuador, and has been in eruption for ~ 80 years. Its isolated location (figure 6) has meant it has been thought of as a relatively small hazard risk. For this reason, monitoring has been less than for other Ecuadorian volcanoes. Thermal, visual, and satellite monitoring during 2002-2004 confirmed the central crater as the source of frequent explosions and continuing steam-and-gas emissions.

Figure (see Caption) Figure 6. Satellite imagery showing the region around the city of Riobamba (center) in Ecuador), including Sangay (lower right), Chimborazo (upper left), Tungurahua (upper right), and Licto (center) volcanoes. An eruption plume can be discerned coming from Tungurahua, but the date of the image is unknown. The city of Riobamba is about 50 km NW of Sangay. Courtesy of Google Earth.

During 2004 observers did not see lava flows or pyroclastic flows. An abnormally large eruption cloud was detected on 14 January 2004; it contained dominantly steam and gases, with minor ash content. Although only clearly detected and reported then, such events are thought to occur with considerable frequency.

Ramon and others (2006) summarized Sangay's activity as continuously erupting since 1934. Thermal images taken during the last three years showed that only one of the three summit craters was active and documented a lack of new, visible lava flows.

On 14 January 2004 a plume from Sangay was observed around 0500. The plume extended about 45 km E and most likely contained ash. During this time a hotspot was also visible on the satellite imagery. On 27 January 2004 a narrow ash plume emitted by Sangay rose to 6 km altitude and drifted SW.

On 1 May 2004, based on a pilot's report, the Washington VAAC noted that ash from an eruption at Sangay produced a plume to a height of ~ 6 km altitude at 1750. Ash was not visible on satellite imagery.

On 28 December 2004 around 0715 a plume from Sangay, most likely composed of steam with little ash, was detected. The plume was E of the volcano's summit at a height of ~ 6.4 km altitude. A hotspot was prominent on satellite imagery, but ash was more difficult to distinguish.

On 16 October 2005 around 0645 Sangay emitted an ash plume. The plume moved SSW very slowly, corresponding to a possible height of ~ 6.7 km altitude. By 0900 the plume was too thin to be visible on satellite imagery and thunderstorms developed in the area, further obscuring the ash cloud. Based on information from the IG, on 26 October 2005 the Washington VAAC noted that ash was seen over Sangay at 0758. No ash was visible on satellite imagery.

Climber's photo journal. Climbers Thorsten Boeckel and Martin Rietze created a website briefly describing a trek to Sangay's summit during 4-12 January 2006. Several of their posted photos from that trip appear here (figures 7-10; unfortunately, the photos, which are strikingly beautiful, were generally presented without much geographic context). The team included at least one local guide and was aided by horses. Settlements on the approach and return included the mountain village St. Eduardo, which they described as ~ 50 km S of Riobamba.

Figure (see Caption) Figure 7. A vista of Sangay at nightfall in early January 2006. Direction of view is approximately WNW. Photo credit to Boeckel and Rietze.
Figure (see Caption) Figure 8. Photograph documenting the climbers tent camp high on the snowbound slopes of Sangay during their descent. Exact location on Sangay unknown; this was labeled "day 4/5," and should correspond to 7 or 8 January 2006. Photo credit to Boeckel and Rietze.
Figure (see Caption) Figure 9. A topographic high forming part of the Sangay structure, gently steaming, apparently seen from the summit. This corresponds to 7 or 8 January 2006. Photo credit to Boeckel and Rietze.
Figure (see Caption) Figure 10. A crater on Sangay as seen by the climbers from the summit or upper flanks, described by them as the "snow covered east crater." This photo corresponds to 7 or 8 January 2006. Photo credit to Boeckel and Rietze.

Except for some degassing, the group saw no other activity. Although local residents indicated that the last eruption had occurred about 2 months prior to their visit, intermittent eruptions pose hazards to climbers; in 1976 two climbers were killed by explosions from Sangay (SEAN 01:10).

Reference. Ramón, P., Rivero, D., Böker, F., and Yepes, H., 2006, Thermal monitoring using a portable IR camera: results on Ecuadorian volcanoes in "Cities on Volcanoes IV"; 23-27 January 2006.

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: P. Ramón, Instituto Geofísico-Departamento de Geofísica (IG), Escuela Politécnica Nacional, Casilla 17-01-2759, Quito, Ecuador; 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/); Thorsten Boeckel and Martin Rietze, c/o Kermarstr.10, Germerswang, D-82216, Germany (URL: http://www.tboeckel.de/).


Santa Maria (Guatemala) — April 2006 Citation iconCite this Report

Santa Maria

Guatemala

14.757°N, 91.552°W; summit elev. 3745 m

All times are local (unless otherwise noted)


During October 2005 to January 2006, occasional ash plumes

This summary of activity at Santa María's Santiaguito lava-dome complex, taken largely from Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH) reported for October 2005 to January 2006. During this interval Santa María continued to emit occasional ash plumes.

During 26-31 October 2005, several explosions took place and plumes rose to a maximum of ~ 5 km altitude on 28 October. In early November, several explosions occurred producing ash plumes to an altitude of ~ 5 km. A few weak avalanches of volcanic material were observed SW of the lava dome.

Explosions produced several ash plumes to ~ 5 km altitude during 11-14 November 2005. Several small pyroclastic flows traveled down the SW, NE, and S flanks of Caliente dome. Frequent avalanches of volcanic material occurred off of the fronts of active lava flows mostly to the W of Caliente dome, and less frequently to the S and NE. An ash-and-gas emission on 14 November produced a cloud that was visible on satellite imagery.

During 17-21 November, Santa María produced weak-to-moderate explosions, sending ash plumes to an altitude of ~ 4.6 km. Several small pyroclastic flows traveled down the SW and NE flanks of Caliente dome, stopping at the base of the dome. Avalanches spalled off of the fronts of active lava flows and traveled SW.

On 24 November at 0955, an eruption produced an ash cloud to an altitude of ~ 4 km accompanied by a pyroclastic flow to the S. Fine ash fell 6-7 km S of the volcano, impacting properties in the area.

Moderate-to-strong explosions in December produced ash plumes that rose ~ 1.5-2.5 km. Pyroclastic flows occasionally accompanied explosions and traveled towards the SW. Several avalanches of volcanic material also occurred during the report period.

Throughout January 2006, explosions continued to occur sending resultant ash emissions to the SW. Lava avalanches originated from the SW edge of the Caliente dome and from the fronts of active lava flows on the SW flank. An explosion on the morning of 11 January 2006 generated a small pyroclastic flow that traveled down Caliente dome to the NE. INSIVUMEH reported on 16 January that a slight decrease in explosive activity was observed during the previous month. On 16 January there were reports of a small amount of ashfall 25 km SW in the urban area of San Felipe Retalhuleu.

During 1-3 February, weak-to-moderate explosions took place at Santiaguito's lava-dome complex, producing plumes that rose to a maximum height of 1 km above the volcano. On 1 February at 0657 and 0708, moderate explosions were accompanied by pyroclastic flows. Lava extrusion at Caliente dome produced block-and-ash flows that descended the dome's S, E, and W sides. Several explosions on 9 February also produced small pyroclastic flows that traveled down the SW and SE sides of Caliente dome. On 15-17 February, pyroclastic flows traveled SW and NE, associated with avalanches of incandescent volcanic material spalled off of active lava-flow fronts.

On 4, 6, and 7 March, satellite imagery showed small ash plumes emitted from the lava-dome complex. The plumes reached ~ 3 km above the volcano. On 6 March around 0733, a moderate explosion produced an ash plume and pyroclastic flows. A strong explosion later that day, at 1025, sent an ash plume ~ 3 km above the volcano that deposited ash throughout the volcanic complex. The explosion was accompanied by pyroclastic flows down the NE and SW flanks. Fine ash drifted S falling on properties in that area. On 12 March, there were avalanches of volcanic blocks and ash. On 13 March, a pyroclastic flow traveled down the S flank of Caliente dome.

Geologic Background. Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing W towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (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/).


Saunders (United Kingdom) — April 2006 Citation iconCite this Report

Saunders

United Kingdom

57.8°S, 26.483°W; summit elev. 843 m

All times are local (unless otherwise noted)


Lack of new thermal signals suggesting any eruption since October 2005

The last reported activity of Mount Michael was noted in the SI/USGS Weekly Report of 12-18 October 2005. At that time the first MODVOLC alerts for the volcano since May 2003 indicated an increased level of activity in the island's summit crater and a presumed semi-permanent lava lake that appeared confined to the summit crater. Those alerts occurred on 3, 5, and 6 October 2005. Since that time there has been no additional information concerning Mount Michael and presumably little to no activity.

Geologic Background. Saunders Island is a volcanic structure consisting of a large central edifice intersected by two seamount chains, as shown by bathymetric mapping (Leat et al., 2013). The young constructional Mount Michael stratovolcano dominates the glacier-covered island, while two submarine plateaus, Harpers Bank and Saunders Bank, extend north. The symmetrical Michael has a 500-m-wide summit crater and a remnant of a somma rim to the SE. Tephra layers visible in ice cliffs surrounding the island are evidence of recent eruptions. Ash clouds were reported from the summit crater in 1819, and an effusive eruption was inferred to have occurred from a N-flank fissure around the end of the 19th century and beginning of the 20th century. A low ice-free lava platform, Blackstone Plain, is located on the north coast, surrounding a group of former sea stacks. A cluster of parasitic cones on the SE flank, the Ashen Hills, appear to have been modified since 1820 (LeMasurier and Thomson, 1990). Analysis of satellite imagery available since 1989 (Gray et al., 2019; MODVOLC) suggests frequent eruptive activity (when weatehr conditions allow), volcanic clouds, steam plumes, and thermal anomalies indicative of a persistent, or at least frequently active, lava lake in the summit crater. Due to this observational bias, there has been a presumption when defining eruptive periods that activity has been ongoing unless there is no evidence for at least 10 months.

Information Contacts: Matt Patrick, Luke Flynn, Harold Garbeil, Andy Harris, Eric Pilger, Glyn Williams-Jones, and Rob Wright, HIGP Thermal Alerts Team, Hawai'i Institute of Geophysics and Planetology (HIGP) / School of Ocean and Earth Science and Technology (SOEST), University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); John Smellie, British Antarctic Survey, Natural Environment Research Council, High Cross, Madingly Road, Cambridge CB3 0ET, United Kingdom (URL: https://www.bas.ac.uk/).


Soputan (Indonesia) — April 2006 Citation iconCite this Report

Soputan

Indonesia

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

All times are local (unless otherwise noted)


Late 2005 phreatic and Strombolian eruptions; ash plume to ~ 5.8 km altitude

Our last report covered events through July 2005 (BGVN 30:08); this report includes activity that took place in late December 2005 and also presents a discussion of the wide discrepancy of cloud-height estimates between ground, aircraft, and satellite remote-sensing observations.

Activity during 21-27 December 2005. A phreatic eruption began at Soputan on 26 December 2005 around 1230 following heavy rain. Observers concluded that rainwater contacted lava at the volcano's summit. On 27 December at 0400, a Strombolian eruption began that lasted about 50 minutes. Incandescent material was ejected ~ 35 m, and avalanches spalling off the margins of the summit traveled as far as 750 m E. Booming noises were heard 5 km from the summit. The Darwin VAAC reported that an ash plume reached a height of ~ 5.8 km altitude and drifted SE.

As of 28 December, eruptive activity continued, producing ash plumes to a height of ~ 1 km above the volcano. Strombolian eruptions ejected incandescent material up to 200 m above the summit. Pyroclastic avalanches traveled ~ 500 m E and SW. This was Soputan's fourth event in 2005, with previous activity on 14 and 20 April, and on 12 September. The Alert Level remained at 2, since the volcano is about 11 km from the nearest settlement. Visitors were prohibited from climbing Soputan's summit and from camping around Kawah Masem.

October 2005 eruption plume height discussion. The Darwin Volcanic Ash Advisory Centre and the Cooperative Institute for Meteorological Satellite Studies (CIMSS) at the University of Wisconsin – Madison collaborated to compare various estimates for the height of the 27 December cloud (BGVN 30:08). The eruption height had been initially reported at less than 6 km altitude on the 27th by an airline pilot, and 1 km above the summit (~ 2.8 km altitude) by ground observers on the 28th. Darwin VAAC, on reviewing hourly MTSAT imagery on the 27th, estimated the plume top at 15 km altitude operationally and then 12.5 km altitude in post-analysis studies.

Michael Richards of CIMSS used an established remote-sensing technique known as "CO2 slicing" (Menzel et al., 1983, Richards et al., 2006), to obtain heights of the cloudscape around Soputan after the eruption. The technique takes advantage of the fact that the emissive infrared CO2 bands available on the MODIS satellite become more transmissive with decreasing wavelength, as the bands move away from the peak wavelength of CO2 absorption at 15 µm. There were two good MODIS images obtained over the eruption on the 27th, with the first, at 0210 UTC or 1010 local time. These images were taken at close to the time of the peak cloud height observed on MTSAT imagery, and the CO2 slicing technique appears to validate the post-analyzed VAAC height of ~ 12.5 km altitude.

The different results for the height of the eruption cloud illustrate the difficulty that observers would have had viewing the cloud from any angle. Weather clouds in the tropics typically extend up to 16 km or more altitude. Cirrus cloud from a storm complex can obscure the view of a satellite for hours. On the other hand, middle-level clouds, such as altostratus, will typically lie between aircraft cruising altitudes and the ground, meaning that pilots at cruising altitude may not associate any eruption cloud with a volcano on the ground, unless the cloud is obviously volcanic. Ground observers are completely unable to view the full height of the cloud if it is penetrating through the middle-level clouds.

The appearance of the cloud on true-color, near-infrared and infrared imagery is consistent with an ice-rich (glaciated) volcanic cloud, in-line with the CVGHM account of water interactions at the ground, and also with a high water loading in the atmosphere. The extensive areas of cloud in the area hindered satellite detection of the eruption until after the pilot report of the eruption had been received.

References. Menzel, W. P., Smith, W. L., and Stewart, T. R., 1983, Improved cloud motion wind vector and altitude assignment using VAS: Journal of Applied Meteorology, v. 22, p. 377-384.

Richards, M. S., Ackerman, S. A., Pavolonis, M. J., Feltz, W. F., and Tupper, A.C., 2006, Volcanic ash cloud heights using the MODIS CO2-slicing algorithm: AMS 12th, conference on aerospace and range meteorology, Atlanta, Georgia, USA (http://ams.confex.com/ams/pdfpapers/104055.pdf).

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

Information Contacts: Center of Volcanology and Geological Hazard Mitigation, Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Andrew Tupper and Rebecca Patrick, Darwin Volcanic Ash Advisory Centre (VAAC), Australian Bureau of Meteorology (URL: http://www.bom.gov.au/info/vaac/soputan.shtml); Michael Richards and Wayne Feltz, Cooperative Institute for Meteorological Satellite Studies (CIMSS), University of Wisconsin, 1225 West Dayton Street, Madison, WI 53706, USA.

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