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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

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

Sheveluch (Russia) Lava dome growth and thermal anomalies continue through April 2020, but few ash explosions



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).


Sheveluch (Russia) — May 2020 Citation iconCite this Report

Sheveluch

Russia

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

All times are local (unless otherwise noted)


Lava dome growth and thermal anomalies continue through April 2020, but few ash explosions

The eruption at Sheveluch has continued for more than 20 years, with strong explosions that have produced ash plumes, lava dome growth, hot avalanches, numerous thermal anomalies, and strong fumarolic activity (BGVN 44:05). During this time, there have been periods of greater or lesser activity. The most recent period of increased activity began in December 2018 and continued through October 2019 (BGVN 44:11). This report covers activity between November 2019 to April 2020, a period during which activity waned. The volcano is monitored by the Kamchatka Volcanic Eruptions Response Team (KVERT) and Tokyo Volcanic Ash Advisory Center (VAAC).

During the reporting period, KVERT noted that lava dome growth continued, accompanied by incandescence of the dome blocks and hot avalanches. Strong fumarolic activity was also present (figure 53). However, the overall eruption intensity waned. Ash plumes sometimes rose to 10 km altitude and drifted downwind over 600 km (table 14). The Aviation Color Code (ACC) remained at Orange (the second highest level on a four-color scale), except for 3 November when it was raised briefly to Red (the highest level).

Figure (see Caption) Figure 53. Fumarolic activity of Sheveluch’s lava dome on 24 January 2020. Photo by Y. Demyanchuk; courtesy of KVERT.

Table 14. Explosions and ash plumes at Sheveluch during November 2019-April 2020. Dates and times are UTC, not local. Data courtesy of KVERT and the Tokyo VAAC.

Dates Plume Altitude (km) Drift Distance and Direction Remarks
01-08 Nov 2019 -- 640 km NW 3 November: ACC raised to Red from 0546-0718 UTC before returning to Orange.
08-15 Nov 2019 9-10 1,300 km ESE
17-27 Dec 2019 6.0-6.5 25 km E Explosions at about 23:50 UTC on 21 Dec.
20-27 Mar 2020 -- 45 km N 25 March: Gas-and-steam plume containing some ash.
03-10 Apr 2020 10 km 526 km SE 8 April: Strong explosion at 1910 UTC.
17-24 Apr 2020 -- 140 km NE Re-suspended ash plume.

KVERT reported thermal anomalies over the volcano every day, except for 25-26 January, when clouds obscured observations. During the reporting period, thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm recorded hotspots on 10 days in November, 13 days in December, nine days in January, eight days in both February and March, and five days in April. The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, detected numerous hotspots every month, almost all of which were of moderate radiative power (figure 54).

Figure (see Caption) Figure 54. Thermal anomalies at Sheveluch continued at elevated levels during November 2019-April 2020, as seen on this MIROVA Log Radiative Power graph for July 2019-April 2020. Courtesy of MIROVA.

High sulfur dioxide levels were occasionally recorded just above or in the close vicinity of Sheveluch by the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Copernicus Sentinel-5 Precursor satellite, but very little drift was observed.

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

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); 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/).

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Bulletin of the Global Volcanism Network - Volume 31, Number 05 (May 2006)

Managing Editor: Richard Wunderman

Ambae (Vanuatu)

During May-June 2006, Lake Voui's water rapidly turns from blue to red

Anatahan (United States)

Eruptions restarted in 2005 and continued until at least June 2006

Bagana (Papua New Guinea)

Lava flows and ash emission throughout March 2006

Bulusan (Philippines)

Explosive activity continues

Daikoku (United States)

Discovery of agitated pool of molten sulfur at 420 m ocean depth

Heard (Australia)

2006 imagery indicates renewed volcanism

Krummel-Garbuna-Welcker (Papua New Guinea)

Earthquakes continue while vents remain calm through April 2006

Lamington (Papua New Guinea)

Mild vapor emission and earthquakes through March 2006

Langila (Papua New Guinea)

Moderate activity steady through March 2006

Merapi (Indonesia)

Mid-2006 brings multiple pyroclastic flows that kill two, and travel up to 7 km

NW Rota-1 (United States)

Views of submarine volcano ejecting lava and bombs

Popocatepetl (Mexico)

During first half of 2006, several ash plumes rose to ~ 7-8 km altitude

Rabaul (Papua New Guinea)

Gas emissions and earthquakes during March-April 2006

Soufriere Hills (United Kingdom)

Big dome collapse and tall plume on 20 May 2006 leave a W-leaning crater

St. Helens (United States)

Intracrater lava dome continues to grow through at least May 2006

Ubinas (Peru)

Ash and steam emissions stir hazard and environmental concerns

Villarrica (Chile)

Unusual seismicity, minor pyroclastic, and gas explosions, January-April 2005



Ambae (Vanuatu) — May 2006 Citation iconCite this Report

Ambae

Vanuatu

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

All times are local (unless otherwise noted)


During May-June 2006, Lake Voui's water rapidly turns from blue to red

Alain Bernard reported that Lake Voui in Aoba-Ambae volcano (BGVN 31:01) was undergoing a spectacular change in its color?the previously aqua-colored lake was turning red (figure 27).

Figure (see Caption) Figure 27. Lake Voui at Aoba as seen from the air on 28 May (top) and 3 June 2006 (bottom). Images courtesy of Esline Garaebiti (top) and Philippe Métois (bottom).

Images of a pale reddish Lake Voui were obtained by Esline Garaebiti, who flew over the volcano 28 May 2006. Philippe Métois, who flew over on 3 June 2006, photographed a blood-red lake. These photos were are posted on the CVL website along with recent ASTER temperature data. This color change was tentatively attributed to a rapid shift in the lake water's redox state. The change might be linked to the ratio of SO2/H2S in the hydrothermal fluids.

Geologic Background. The island of Ambae, also known as Aoba, is a massive 2500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Information Contacts: Alain Bernard, IAVCEI Commission on Volcanic Lakes (CVL), Université Libre de Bruxelles (ULB), CP160/02, avenue F.D. Roosevelt 50, Brussels, Belgium (URL: http://www.ulb.ac.be/sciences/cvl/aoba/Ambae1.html, http://www.ulb.ac.be/sciences/cvl/multispectral/multispectral2.htm); Esline Garaebiti, Department of Geology, Mines, and Water Resources (DGMWR), Port-Vila, Vanuatu; Philippe Métois, World of Wonders.


Anatahan (United States) — May 2006 Citation iconCite this Report

Anatahan

United States

16.35°N, 145.67°E; summit elev. 790 m

All times are local (unless otherwise noted)


Eruptions restarted in 2005 and continued until at least June 2006

Anatahan erupted almost continuously from 5 January 2005 until 3 September 2005 when eruptions suddenly ceased (BGVN 30:07, 30:08). Observations through 16 September indicated relative quiet. Indications from later reports (discussed below) are that this lull continued through at least mid- to late-February 2006. Eruptions resumed after that, although the observations suggest chiefly or entirely gas-rich plumes. Jenifer Piatt suggested that plumes after early September 2005 and through May 2006 rose only to low altitude, perhaps 2,500 m.

This report covers the period through early June 2006 and includes both field observations as well as several satellite-based SO2 measurements, and extensive satellite images of thin plumes assessed as vog (volcanic smog; table 5). Some of those plumes extended W to SW from Anatahan and had overall atmospheric SO2 masses on the order of up to 4 kilotons (kt).

Table 5. AURA/OMI SO2 from Anatahan plumes at stated dates in 2006 (the two indicated with asterisks ("**") shown as figures). The last column displays the plume's overall estimated SO2 mass. The second and third columns indicate, respectively, the area of the sulfurous plume, and the estimated maximum SO2 concentration (in DU) and its latitude and longitude. Courtesy of Simon Carn.

Date Time (UTC) Orbit Area of plume (km2) Highest concentration in Dobson Units (DU) Coordinates Atmospheric SO2 (kilotons)
15 Mar 2006 0400-0420** 08852 -- -- -- 1-2
12 Apr 2006 0249-0428** -- 9.1 x 104 1.9 DU 13.16°N, 137.26°E 2.2
16 Apr 2006 0401-0404 09318 9.8 x 104 6.7 DU 16.28°N, 145.39°E 3.9
23 Apr 2006 0407-0410 09420 11.0 x 104 4.6 DU 17.42°N, 143.06°E 3.5
31 May 2006 0331-0334 09979 4.8 x 104 3.0 DU 16.07°N, 145.24°E 1.4

During the week ending 19 September 2005, there were three periods of elevated tremor. On 13 September, technicians from the Emergency Management Office of the Commonwealth of the Northern Mariana Islands (EMO-CNMI) who were reinstalling seismic station ANA2 on Anatahan reported that the plume was gray, small, and moving to the NW. They heard no explosions and saw no craters or large ballistics in vicinity of ANA2.

CMNI-USGS reports for 3 September until at least 26 December 2005 noted an absence of erupted ash. At least as late as 27 February 2006, Anatahan lacked reported ash emissions. Also as late as the 27th, seismicity was at background levels, amounting to a few percent of the late June 2005 maximum, with occasional long-period earthquakes. On 27 February 2006, the Alert level was reduced to Normal and the Aviation Color Code to Green because of the continuing low levels of activity.

By the date of the next USGS update, on 20 March 2006, activity had increased somewhat and the Alert level was raised to Advisory and the Aviation Color Code to Yellow. A faint, thin plume of gas that was occasionally observable during January and February became continuous and slightly more dense on satellite imagery during the first three weeks of March.

Using the Ozone Monitoring Instrument (OMI) on NASA's EOS/Aura satellite, Simon Carn imaged Anatahan's plume of 15 March 2006 (figure 27). Anatahan lies at the solid triangle; the plume blew largely SW. Carn found that the atmospheric SO2 mass was 1-2 kilotons. He noted that there had been an upsurge in satellite-detected SO2 output that began in mid-February 2006. The highest concentrations of several OMI analyses (table 6 and figure 28) were measured on 16 and 23 April (3.9 and 3.5 kilotons of SO2, respectively).

Table 6. A summary of Anatahan plume data based on US AFWA satellite observations during 15 March to 31 May 2006. DMSP stands for Defense Meteorological Satellite Program. Courtesy of Charles Holliday and Jenifer E. Piatt, AFWA.

Date Time (UTC) Satellite (resolution or wavelength) Observation
15 Mar 2006 0354 Aqua Modis (500 m res.) Faint vog plume seen drifting generally SSW
16 Mar 2006 0125 Terra Modis (500 m res.) Vog seen drifting generally to the SW
17 Mar 2006 0330 Aqua Modis (1 km res.) Cloud cover obscured visibility
18 Mar 2006 0415 Aqua Modis (500 m res.) Vog plume appears longer and more dense, drifting generally SW
19 Mar 2006 0320 Aqua Modis (500 m res.) Moderately dense vog plume, extending over 370 km SW. No signature has been visible on MTSAT split window IR imagery nor NOAA channel differencing images, suggesting minimal ash content in the plume.
19 Mar 2006 1606 NOAA-18 Shortwave IR (3.55-3.93 µm) Hot spot visible at island
19 Mar 2006 2221 DMSP F-16 Visible (566 m res.) A very faint plume discernable out to 230 km SW from source
20 Mar 2006 0400 Aqua Modis (500 m res.) Vog plume drifting S and SW
20 Mar 2006 2209 DMSP F-16 Visible (556 m res.) Very light vog drifting SSW
21 Mar 2006 0305 Aqua Modis (500 m res.) Distinct vog plume drifting SSW
21 Mar 2006 1546 NOAA-18 Shortwave IR (3.55-3.93 µm) Hot spot indicated at island
24 Mar 2006 0035 Terra Modis (500 m res.) Vog plume drifting W then NW
24 Mar 2006 0804 DMSP F-13 Visible (1.11 km res.) Plume extended at least 833 km W before curling N. Using shadows, the plume is estimated at below ~1.2 km (4,000 ft).
29 Mar 2006 1604 NOAA - 18 Shortwave IR (3.55-3.93 µm) Hot spot indicated at island
29 Mar 2006 2110 DMSP F-13 Visual (1.11 km res.) Steam measures 37 km W and vog measures ~320 km SW and ~670 km NNE of the summit. Tops are estimated below ~1.5 km (5,000 ft).
29 Mar 2006 2110 DSMP F-13 Visual (556 m res.) Steam and vog visible at island; greater detail of vog trending ~320 km to SW
30 Mar 2006 0820 DMSP F-13 Visual (1.11 km res.) Steam measured 56 km NW; vog measured ~600 km SW and ~670 km NNE of the summit. Tops are estimated below ~1.5 km (5,000 ft).
30 Mar 2006 1554 NOAA 18 Shortwave IR (3.55-3.93 µm) Hot spot detected at the island
02 Apr 2006 1953 NOAA18 Shortwaave IR (3.55-3.93 µm) Hot spot detected
04 Apr 2006 0320 Aqua Modis (500 m res.) Cloud formation along the vog plume with tops estimated at below ~3 km (10,000 ft)
04 Apr 2006 0559 DMSP-F-12 Visual (556 m res.) Vog measures 210 km SSW of the summit
14 Apr 2006 0355 Aqua Modis (500 m res.) Vog drifting over ~390 km SW
14 Apr 2006 0808 DMSP F-13 Visual (556 m res.) Vog seen drifting over ~ 500 km SW, expanding extensively as it spreads
17 Apr 2006 0125 Terra Modis (500 m res.) Light vog plume blown over 400 km WSW to W
17 Apr 2006 1612 NOAA-18 Shortwave IR (3.55-3.93 µm) Hot spot visible
17 Apr 2006 2143 DMSP F-13 Visual (556 m res.) Vog measures over 490 km WSW
22 Apr 2006 2153 DMSP F-16 Visual (556 m res.) Faint vog plume trended ~40 km NW
23 Apr 2006 0045 Terra Modis (250 m res.) Possible gray steam/ash plume extending under 28 km NW and vog extending over 155 km NW
23 Apr 2006 1954 NOAA-17 Shortwave IR (3.55-3.93 µm) Hot spot detected at island
24 Apr 2006 0130 Terra Modis (500 m res.) Visible vog trended ~325 km W then curved ~130 km NE and dissipated
23 May 2006 0430 Aqua Modis (500 m res.) Vog seen drifting generally W, then curving S and SW
23 May 2006 0710 NOAA 15 Visual (1.85 km res.) Vog trending generally SW then W for ~390 km
26 May 2006 0130 Terra Modis (500 m res.) Vog trending WNW(?)
26 May 2006 0800 DMSP F-16 Visual (2.78 km res.) Vog seen drifting WSW for up to 1,250 km
26 May 2006 1234 NOAA 17 Shortwave IR (3.55-3.93 µm) Hot spot detected at the island
30 May 2006 2120 DMSP F-14 Visible (2.77 km res.) Plume extends over 1,480 km to the WSW
30 May 2006 2120 DMSP F-14 Visible (556 m res.) Plume extends over 1,480 to the WSW. NASA Aura/OMI estimated the columnar SO2 concentration associated with the plume.
31 May 2006 0315 Aqua Modis (500 m res.) Vog seen drifting generally to the SW, with great dispersion
Figure (see Caption) Figure 27. AURA/OMI image of SO2 from Anatahan at 0400-0420 UTC on 15 March 2006 (orbit 08852). The overall estimated SO2 mass in the 15 March plume was 1-2 kilotons. Concentration path-lengths for the atmospheric column are scaled in Dobson Units (DU). This is an example of a comparatively short plume, with greatest SO2 concentrations nearest the source, and blown somewhat more southerly than some of the later ones. Courtesy of Simon Carn.
Figure (see Caption) Figure 28. AURA/OMI image of SO2 from Anatahan at 0249-0428 UTC on 12 April 2006. The overall estimated SO2 mass in the 12 April plume was 2.2 kilotons (for other parameters and comparisons, see table 6). This is an example of a comparatively elongate plume, with highest SO2 registered in areas ~1,000 km ESE of the source. Courtesy of Simon Carn.

OMI is a Dutch-Finnish imaging spectrometer that measures ozone and other atmospheric trace gases such as SO2. OMI is a nadir-viewing imaging spectrometer that covers the ultraviolet and visible spectral range (270-500 nm). Its high spatial resolution increases the chance of observing cloud-free pixels, thereby enhancing the accuracy of the data products. OMI observes a strip of the Earth's surface about 2,600-2,800 km wide in one shot. The satellite's own movement along with Earth's rotation enables OMI to scan the entire globe. A two-dimensional CCD detector records both the complete swath and the spectrum of every ground pixel in the swath. The spatial information is imaged on one dimension of the CCD detector while the spectrum is projected along the other dimension of the CCD detector. OMI detects the total column amount of SO2 between the sensor and the Earth's surface and maps this quantity as it orbits.

On 17 March around 2200 UTC, the level of seismicity nearly doubled and continued at that level for 2 hours. On the 18th around 1400 UTC, the level of seismicity again nearly doubled and continued at that level for about 8 hours before returning to the baseline level prior to 17 March. The increased seismicity consisted of small (M 0-1) long-period earthquakes occurring approximately every minute, sometimes reaching two per minute. A total of about 600 such events were detected during 17 and 18 March. Volcanic Ash Advisories were issued by the Washington VAAC; plumes appeared to contain gas and only insignificant amounts of ash.

According to the Air Force Weather Agency (AFWA), on 19 March a hot spot at Anatahan was visible on satellite imagery. Vog (volcanic smog) extended 200 km from the island (figure 29).

Figure (see Caption) Figure 29. Anatahan's SW-drifting plume at 0320 UTC on 19 March as seen in a satellite image (AQUA MODIS, 500 m resolution) The US Air Force Weather Agency (AFWA) analysts interpreted this plume as vog. Courtesy of AFWA and NASA.

On 24 March around 1330, seismicity at Anatahan abruptly increased to about twice the background level. The seismicity consisted of low-amplitude tremor and small, long-period earthquakes, similar to the seismicity on 17 and 18 March. On 24 March, vog from Anatahan was visible on satellite imagery extending W, then curling N. The plume was estimated to be below 1.2 km altitude, and no ash or hot spots were visible. Anatahan remained at Alert level Advisory; Aviation Color Code Yellow (Volcanic activity has increased somewhat, but remains fairly low and is being closely monitored).

From 28 March to 4 April, seismic levels fluctuated. Seismicity again jumped up to about double the background level for a few hours on 29 and 31 March and 2 April. Anatahan continued to produce a gas-and-steam plume visible in satellite imagery. On 4 April, Saipan residents reported smog and the smell of sulphur.

On 8 April a team from EMO-CNMI visited Anatahan and found steam and gas discharging from the E crater along the SW crater wall above a discolored lake. Testing confirmed the presence of SO2 and H2S in the plume. The plume rose to an altitude of less than 2 km and drifted to the NW as brownish vog. No ash fell from the plume onto the island. Based on these results and satellite surveillance, Anatahan was inferred to be emitting steam, gas, and vog.

Three long-period earthquakes occurred on 14 and 15 April. Each was preceded by several minutes of significantly reduced seismicity. AFWA reported that a hot spot was visible on NOAA shortwave IR imagery on 17 April at 1612 UTC, and vog extended over 490 km WSW in F-13 imagery on 17 April at 2143 UTC. SO2 mass values for 23 April were the second highest in this reporting interval. On 24 April 2006 AFWA reported that hot spots were occasionally visible and that vog was nearly always visible in satellite images.

Throughout May 2006, Anatahan's E crater continued to emit vog that was visible in MODIS imagery. Seismicity levels were low throughout April and May. A few to several microearthquakes occurred each day, all with magnitudes M 1 or smaller.

Ash may have erupted in late May. Although ash was indicated on radar on 27 May, and in a pilot's report for 29 May, those events took place during intervals of such low seismicity that people watching that data felt eruptions were unlikely to have occurred then.

On the other hand, based on a pilot report, the Washington VAAC declared that an ash plume from Anatahan reached an altitude of 3 km on 29 May and drifted W. Vog issuing from the E crater was visible on satellite imagery at about 1333 on 29 May 2006, and increased prior to emission of an ash plume. A report issued from the Washington VAAC on 30 May at 0535 indicated a faint, low-level gas-and-ash plume extending from the summit. At 2120 UTC on 30 May the plume extended over 1,480 km WSW.

By 19 June continued gas and steam emissions remained visible in satellite imagery. Seismicity dropped from recent levels and occasional microearthquakes were recorded locally.

Geologic Background. The elongate, 9-km-long island of Anatahan in the central Mariana Islands consists of a large stratovolcano with a 2.3 x 5 km compound summit caldera. The larger western portion of the caldera is 2.3 x 3 km wide, and its western rim forms the island's high point. Ponded lava flows overlain by pyroclastic deposits fill the floor of the western caldera, whose SW side is cut by a fresh-looking smaller crater. The 2-km-wide eastern portion of the caldera contained a steep-walled inner crater whose floor prior to the 2003 eruption was only 68 m above sea level. A submarine cone, named NE Anatahan, rises to within 460 m of the sea surface on the NE flank, and numerous other submarine vents are found on the NE-to-SE flanks. Sparseness of vegetation on the most recent lava flows had indicated that they were of Holocene age, but the first historical eruption did not occur until May 2003, when a large explosive eruption took place forming a new crater inside the eastern caldera.

Information Contacts: Juan Takai Camacho and Ramon Chong, Emergency Management Office of the Commonwealth of the Northern Mariana Islands (EMO-CNMI), PO Box 100007, Saipan, MP 96950, USA (URL: http://www.cnmihsem.gov.mp/); Simon Carn, Joint Center for Earth Systems Technology (JCET), University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA; Charles Holliday and Jenifer E. Piatt, U.S. Air Force Weather Agency (AFWA)/XOGM, Offutt Air Force Base, NE 68113, USA.


Bagana (Papua New Guinea) — May 2006 Citation iconCite this Report

Bagana

Papua New Guinea

6.137°S, 155.196°E; summit elev. 1855 m

All times are local (unless otherwise noted)


Lava flows and ash emission throughout March 2006

Little activity had been recorded at Bagana since 18 September 2005, when forceful emissions of whitish-brown ash occurred, accompanied by ash fall in downwind areas and large booming noises. From the end of January to mid-April 2006 there were brief periods of effusive activity. The summit crater released moderate to dense white vapor throughout this time.

Emissions were forceful on 27 February, and on 3, 5, 7, 13, 22, 24, and 29 March. Denser emissions of pale gray ash clouds were reported on 27 March. Rumbling and roaring noises were heard on 15-16, 22, and 26-28 March. Moderate to bright glow was accompanied by projections of lava fragments and the advance of a lava flow down the S-SW flank, which was visible from 15 March until the end of the month. During April, the summit crater continued to release white vapor. A forceful emission was recorded on 8 April. A weak glow was visible on 9 April. Occasional weak rumbling noises were heard on 12-13 and 15 April. On 4 May, there was an ash plume visible on satellite imagery at a height of ~ 3 km (10,000 ft) altitude that extended 4 km W. On 18 June there was an ash-and-steam plume drifting SW; the height of the plume was not recorded.

Geologic Background. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.


Bulusan (Philippines) — May 2006 Citation iconCite this Report

Bulusan

Philippines

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

All times are local (unless otherwise noted)


Explosive activity continues

Bulusan erupted at 2258 on 21 March 2006, continuing into April 2006 (BGVN 31:04). Figure 2 shows the location of Bulusan volcano on the SE tip of Luzon. Figure 3 gives satellite measurements of SO2 one day after the eruption.

Figure (see Caption) Figure 2. Map of the Philippines showing the PHIVOLCS earthquake and volcano monitoring network, and Bulusan's location. Smaller inset focuses on the Bulusan region and indicates some settlements. The smaller map is from Encarta Maps; the larger map, courtesy of PHIVOLCS.
Figure (see Caption) Figure 3. Sulfur dioxide (SO2) emissions at 1345-1347 (local) on 22 March 2006 from Bulusan. The eruption was measured by the Ozone Monitoring Instrument (OMI) on NASA's EOS/Aura satellite [OMI detects the total column amount of SO2 between the sensor and the Earth's surface]. This cloud appeared quite significant (estimated total mass ~ 1,000 metric tons) considering that the event was reported as phreatic and that the image was collected about 15 hours after the eruption. Courtesy of Simon Carn.

An ash eruption on 29 April did not cause any damage, but authorities asked people to avoid the region near the crater (figure 4). The current report stems in large part from information coming from The Philippine Institute of Volcanology and Seismology (PHIVOLCS). Table 2 provides a brief summary of 2006 activity and resulting plumes.

Figure (see Caption) Figure 4. Image of a light ash plume snaking W from Bulusan acquired at 1250 on 29 April 2006. The image was made by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the U.S. National Aeronautics and Space Administration (NASA) Terra satellite. Courtesy of NASA Earth Observatory.

Table 2. Bulusan explosive plumes recorded during 2006. Courtesy of PHIVOLCS.

Date Local Time Plume character Plume height above summit Direction(s) of plume drift
21 Mar 2006 2258 ash 1.5 km N, W, SW
29 Apr 2006 1044 ash 1.5 km WSW, NW
25 May 2006 2117 ash -- W, SW
31 May 2006 1617 ash/steam 1.5 km W, WNW
07 Jun 2006 2017 ash/steam 2.0 km N, W, SW
10 Jun 2006 0018 ash/steam 1.0 km N, NE
13 Jun 2006 1904 ash/steam 1.5 km NW
18 Jun 2006 1556 ash/steam 1.5 km W
20 Jun 2006 2013 cloud-covered summit -- --
28 Jun 2006 0206 cloud-covered summit -- --

A phreatic ash explosion was recorded by the seismograph network at Bulusan between 2117 and 2130 on 25 May 2006. Light ashfall ranging from trace amounts to deposits 2 mm thick was reported from the W and SW villages of Bacolod, Sankayon, Puting Sapa, Rangas, Mapili, Caladgao, and Buraburan in the municipality of Juban, and Bolos in the municipality of Irosin, province of Sorsogon. PHIVOLCS reported that the ash explosion was more-or-less typical of activity at Bulusan during its current eruptive phase, and they expect more explosions to occur. Bulusan was at Alert Level 1, with a Permanent Danger Zone of 4 kilometers around the summit. The PHIVOLCS volcano alert signals range from Alert Level 1 (low-level unrest, no eruption imminent) through Alert Level 5 (hazardous explosive eruption in progress).

An ash-and-steam cloud emitted from the volcano on 31 May 2006 (figure 5) resulted in light ashfall, from trace amounts to 1.5 mm thickness, in areas W and NW of the volcano. An ash-and-steam cloud from Bulusan on 7 June 2006 resulted in light ashfall 5 km N and trace amounts as far as 20 km N. The Alert Level was raised to 2, which means restricted entry within 4 km of the summit. On 10 June, an ash-and-steam cloud reached a height of ~ 1 km above the summit and drifted N and NE. The Manila Standard Today reported one death caused by an asthma condition aggravated by exposure to ash.

Figure (see Caption) Figure 5. A Bulusan ash explosion seen at 1617 on 31 May 2006. The event was photographed from the foot of the volcano, 5- 6 km from the summit, in the town of Irosin. Courtesy of PHIVOLCS.

On 13 June 2006 at 1904, an explosion lasting ~13 minutes issued from a fissure W of the summit vent of Bulusan. It produced an ash-and-steam cloud (table 2). Ashfall up to 7 mm thick accumulated at the foot of the volcano in neighborhoods in the municipality of Juban.

On 18 June at 1556 , an explosion lasted ~11 minutes; it produced an ash-and-steam cloud (figure 6). This was the 8th explosion since Bulusan reactivated in March. Ash up to 5 mm thick fell on a W-flank village.

Figure (see Caption) Figure 6. Mount Bulusan spews ash on 18 June 2006. Courtesy of Associated Press.

On 20 June, a mild ash-and-steam explosion lasted approximately 17 minutes. The seismic network around the volcano recorded only one high frequency volcanic earthquake prior to the explosion. The ash and steam emission coincided with heavy rains that generated some lahars and torrential flows. The sulfur dioxide (SO2) emission rate that morning was 469 tons per day (t/d).

At 0800 on 26 June 2006, PHIVOLCS reported that the Bulusan seismic network had recorded four volcanic earthquakes during the past 24 hours. Steaming activity was wispy to moderate and reached an approximate height of 50 m above the summit before drifting WNW. On 28 June 2006, PHIVOLCS reported at 0800 that continuous seismic observation at Bulusan disclosed one small explosion-type earthquake and two volcanic earthquakes for the past 24 hours. The explosion occurred at 0206 on 28 June and lasted for about 4 minutes. However, the event was not observed because the summit was cloud covered all of 27 June until early in the morning of 28 June. No ashfall was reported following the explosion, and no lahar occurred at Gulang-gulang River in Cogon, Irosin. Sulfur dioxide (SO2) emission rates of the volcanic plume measured on 27 June decreased slightly, to 597 tons per day (t/d) in comparison to the 26 June 2006 rate of 942 t/d.

PHIVOLCS summarized the current 2006 activity as follows. In general, the character of explosions evolved only slightly, apparently becoming a little stronger later. The explosions in June were also somewhat longer in duration than earlier ash ejections, based on instrumental records and general visual monitoring. However, the absence of earthquakes, tremor, and generally low SO2 emission rates prior to each explosion suggested an absence of a large or active magmatic intrusion into shallow depths. Instead, they interpreted the sequence of explosions since March 2006 as pointing to interaction of small volumes of magma with an overlying water-saturated zone beneath the summit. These were thought to develop overpressures released during each explosion. It remains to be seen if the recent explosions would provide an "uncorking effect" and induce a major hazardous eruption. The very low earthquake activity was taken to suggests otherwise.

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: Philippine Institute of Volcanology and Seismology (PHIVOLCS), PHIVOLCS Building, C.P. Garcia Avenue, U.P. Campus, Diliman, Quezon City, PHILIPPINES (URL: http://www.phivolcs.dost.gov.ph/); Earth Observatory, National Aeronautics and Space Administration (NASA) (URL: http://earthobservatory.nasa.gov/NaturalHarards/); The Manila Standard Today (URL: http://manilastandard.net/); Simon Carn, Joint Center for Earth Systems Technology (JCET), University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250.


Daikoku (United States) — May 2006 Citation iconCite this Report

Daikoku

United States

21.324°N, 144.194°E; summit elev. -323 m

All times are local (unless otherwise noted)


Discovery of agitated pool of molten sulfur at 420 m ocean depth

Submarine exploration at Daikoku seamount has discovered a small pit or cauldron containing a pool of molten sulfur. During the period of 18 April-13 May 2006, scientists from the National Oceanic and Atmospheric Agency (NOAA), aboard the research vessel Melville completed the 2006 Submarine Ring of Fire Expedition. This expedition was the third in a series exploring of the submarine volcanoes lying along the Mariana arc (figure 1). The arc extends from S of the island of Guam northward more than 1,450 km. Daily logs of the 2006 expedition, including photographs and video clips, can be viewed on the NOAA Ocean Explorer website (see Information Contacts below).

Figure (see Caption) Figure 1. Bathymetric tectonic map of the Marianas arc showing islands and seamounts (with respective labels on backgrounds of dark and white). Reports in this issue discuss (from N to S), Diakoku, Anatahan, and NW Rotoa-1. Courtesy of Submarine Ring of Fire 2006 Expedition, NOAA Vents Program.

William Chadwick reported on the 2006 expedition (Oregon State University press release, 25 May 2006) that ". . . on another volcano called Daikoku, in the northern part of the Mariana volcanic arc, the researchers discovered a pool of molten sulfur at a depth of 420 m. It was measured at 187°C. It was a sulfur pond with a flexible 'crust' that was moving in a wavelike motion. The movement was triggered by continuous gases being emitted from beneath the pool and passing through the sulfur." (figure 2).

Figure (see Caption) Figure 2. On 4 May 2006 scientists piloting the submersible Remotely Operated Vehicle (ROV) Jason at Daikoku observed and photographed a convecting, black pool of liquid sulfur (inset, and upper image) with a partly solidified sulfur crust (bottom image). Gases, particulate with the appearance of smoke, and liquid sulfur were bubbling up from the back edge of the sulfur pool. The top image shows a zoomed-in view of the liquid sulfur extruding from a fracture in the solid crust. Image courtesy of Submarine Ring of Fire 2006 Expedition, NOAA Vents Program.

In another pit on the summit of Daikoku, over 100 m deep and ~ 80 m in diameter, the scientists observed a large plume of slowly rising white fluid.

References. Embley, R.W., Baker, E.T., Chadwick, W.W., Jr., Lipton, J.E., Resing, J.A., Massoth, G.J., and Nakamura, K., 2004, Explorations of Mariana Arc volcanoes reveal new hydrothermal systems: EOS, Transactions, American Geophysical Union, v. 85, no. 2, p. 37, 40.

Embley, R.W., Chadwick, W.W., Jr, Baker, E.T., Butterfield, D.A., Resing, J.A., de Ronde, C. E.J., Tunnicliffe, V., Lupton, J.E., Juniper, S.K., Rubin, K.H., Stern, R.J., Lebon, G.T., Nakamura, K., Merle, S.G., Hein, J.R., Wiens, D.A., and Tamura, Y., 2006, Long-term eruptive activity at a submarine arc volcano: Nature, v. 441, no. 7092, p. 494-497.

Oregon State University, 25 May 2006, Press Release: Nature paper details eruption activity at submarine volcano: College of Oceanic and Atmospheric Science (COAS), 104 COAS Admininstration Building, Corvallis, OR 97331.

Geologic Background. The conical summit of Daikoku seamount lies along an elongated E-W ridge SE of Eifuku submarine volcano and rises to within 323 m of the sea surface. It is one of about a dozen displaying hydrothermal activity in the southern part of the Izu-Marianas chain. A steep-walled, 50-m-wide cylindrical crater on the north flank, about 75 m below the summit, is at least 135 m deep and was observed to emit cloudy hydrothermal fluid. During a NOAA expedition in 2006, scientists observed a convecting, black pool of liquid sulfur with a partly solidified, undulating sulfur crust at a depth of 420 m below the summit. Gases, particulate with the appearance of smoke, and liquid sulfur were bubbling up from the back edge of the sulfur pool.

Information Contacts: William W. Chadwick, Jr., Cooperative Institute for Marine Resources Studies (CIMRS), NOAA Pacific Marine Environmental Laboratory (PMEL), 2115 SE OSU Drive, Newport, OR 97365 USA; NOAA Ocean Explorer (URL: http://oceanexplorer.noaa.gov/explorations/06fire/welcome.html).


Heard (Australia) — May 2006 Citation iconCite this Report

Heard

Australia

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

All times are local (unless otherwise noted)


2006 imagery indicates renewed volcanism

Matt Patrick observed from MODIS (Moderate Resolution Imaging Spectroradiometer) images analyzed by the HIGP MODVOLC algorithm that relatively new activity began in March 2006 at Heard Island. Two isolated alerts occurred on 11-12 March 2006, and sustained alerts occurred from 7-18 May, 28 May-5 June, and 13-20 June (table 1). Alerts were 1-3 pixels in size. The pixel locations all appeared to be clustered generally near the summit of Big Ben, suggesting central vent (lava lake?) activity rather than lava flows. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images over the last several months have all been cloudy and therefore unable to reinforce or support the MODVOLC results. However, a nighttime ASTER image on 29 May 2006 at 0110 showed the new activity (figure 9).

Table 1. MODVOLC alerts for 2006 through 21 June. Courtesy of Hawai'i Institute of Geophysical and Planetology (HIGP) Thermal Alerts Team.

Date Time (local) Pixels Satellite
11 Mar 2006 2315 1 Terra
12 Mar 2006 0100 2 Aqua
07 May 2006 0100 1 Terra
07 May 2006 2305 1 Terra
08 May 2006 0150 1 Aqua
09 May 2006 2255 1 Terra
10 May 2006 0140 1 Aqua
11 May 2006 2335 1 Terra
18 May 2006 2250 2 Terra
28 May 2006 2325 1 Terra
29 May 2006 0110 2 Aqua
02 Jun 2006 2345 3 Terra
03 Jun 2006 0130 2 Aqua
05 Jun 2006 0115 1 Aqua
13 Jun 2006 2325 2 Terra
14 Jun 2006 0110 4 Aqua
15 Jun 2006 0010 2 Terra
16 Jun 2006 0100 1 Aqua
20 Jun 2006 2330 1 Terra
Figure (see Caption) Figure 9. ASTER image of Heard Island taken at 0110 on 29 May 2006. The main image is the thermal infrared Band 14 (90 m pixel size), with the inserts showing the shortwave infrared (SWIR Band 9; 30 m pixel size) and thermal infrared (TIR Band 14) closeups. This a nighttime image with no visible bands with 15 m pixel size was difficult to interpret. The N-most segment of the summit anomaly, seen clearly in the Band 9 image, may be the vent, with the remainder of the anomaly possibly representing a ~ 900-m-long lava flow to the S. Alternatively, the segmentation of the anomaly may reflect different vents. Courtesy Matt Patrick, HIGP Thermal Alert Team.

The previous phases of activity spanned May 2000-February 2001 and June 2003-June 2004 (BGVN 29:12).

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: Matt Patrick, 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/); Andrew Tupper, Darwin Volcanic Ash Advisory Centre, Bureau of Meteorology, Australia.


Krummel-Garbuna-Welcker (Papua New Guinea) — May 2006 Citation iconCite this Report

Krummel-Garbuna-Welcker

Papua New Guinea

5.416°S, 150.027°E; summit elev. 564 m

All times are local (unless otherwise noted)


Earthquakes continue while vents remain calm through April 2006

Garbuna remained relatively quiet between mid-February and mid-April 2006. The two vents at the summit released weak to moderate volumes of white vapor during this time, but no glow was observed. There was a weak rumbling noise on 14 April. Seismic activity remained at a low level. Few earthquakes were recorded during February and March; the daily average number of high-frequency events was 3 and of low-frequency events between 0 and 5. In April, a few earthquake swarms were recorded with individual events every 1-2 minutes. These episodes lasted less than 20 minutes. Low-frequency earthquakes occurred at the rate of 3-5 times per day and the Real-time Seismic Amplitude Measurement (RSAM) data was at background level fluctuating between 8 and 51 units.

Geologic Background. The basaltic-to-dacitic Krummel-Garbuna-Welcker Volcanic Complex consists of three volcanic peaks located along a 7-km N-S line above a shield-like foundation at the southern end of the Willaumez Peninsula. The central and lower peaks of the centrally located Garbuna contain a large vegetation-free area that is probably the most extensive thermal field in Papua New Guinea. A prominent lava dome and blocky lava flow in the center of thermal area have resisted destruction by thermal activity, and may be of Holocene age. Krummel volcano at the south end of the group contains a summit crater, breached to the NW. The highest peak of the group is Welcker volcano, which has fed blocky lava flows that extend to the eastern coast of the peninsula. The last major eruption from both it and Garbuna volcanoes took place about 1800 years ago. The first historical eruption took place at Garbuna in October 2005.

Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.


Lamington (Papua New Guinea) — May 2006 Citation iconCite this Report

Lamington

Papua New Guinea

8.95°S, 148.15°E; summit elev. 1680 m

All times are local (unless otherwise noted)


Mild vapor emission and earthquakes through March 2006

Lamington has continued the trend of relative quiet during mid-January to the end of March 2006. Consistent reporting has been difficult due to overcast weather. Small volumes of thin white vapor were released during this time. No audible noises or glow were recorded. High frequency earthquakes continued to be recorded. The highest total was 25 recorded on 18 February.

Geologic Background. Lamington is an andesitic stratovolcano with a 1.3-km-wide breached summit crater containing a lava dome. Prior to its renowned devastating eruption in 1951, the forested peak had not been recognized as a volcano. Mount Lamington rises above the coastal plain north of the Owen Stanley Range. A summit complex of lava domes and crater remnants tops a low-angle base of volcaniclastic deposits dissected by radial valleys. A prominent broad "avalanche valley" extends northward from the breached crater. Ash layers from two early Holocene eruptions have been identified. After a long quiescent period, the volcano suddenly became active in 1951, producing a powerful explosive eruption during which devastating pyroclastic flows and surges swept all sides of the volcano, killing nearly 3000 people. The eruption concluded with growth of a 560-m-high lava dome in the summit crater.

Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.


Langila (Papua New Guinea) — May 2006 Citation iconCite this Report

Langila

Papua New Guinea

5.525°S, 148.42°E; summit elev. 1330 m

All times are local (unless otherwise noted)


Moderate activity steady through March 2006

Moderate activity took place at Langila during January 2006, including continuous ash fall, rumbling, and weak emissions of lava fragments. During 20 January to 7 February eruptive activity was characterized by thin, pale gray ash clouds. Minimal noises were heard on 26-27 February. A changing weak-to-bright glow accompanied by projections of glowing lava fragments were visible on the nights of 22-23 and 28 February, and 1-2, and 6 March. Moderate-to-thick dark gray ash clouds were reported on 1-2, 6-7, and 9 March. Ash plumes rose less than 2 km above the summit crater before drifting SW-W of the volcano. Crater 3 remained quiet.

Geologic Background. Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite basaltic-andesitic cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the north and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m.

Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.


Merapi (Indonesia) — May 2006 Citation iconCite this Report

Merapi

Indonesia

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

All times are local (unless otherwise noted)


Mid-2006 brings multiple pyroclastic flows that kill two, and travel up to 7 km

Seismic activity at Merapi began to increase on 19 March 2006, leading the Center of Volcanology and Geological Hazard Mitigation (CVGHM) to raise the Alert Level from 1 to 2 (on a scale of 1-4). Ten thousand residents were warned to prepare for possible evacuation.

On 10 April, authorities banned mountain climbing due to reports of increased tremor. Unverified preliminary reports indicated "lava" reportedly flowing near Pasar Bubar village, ~ 350 m from the volcano's crater. At 1500 on 12 April, CVGHM raised the Alert Level from 2 to 3. No one was permitted within 8 km of the summit.

During 21-25 April, seismicity remained elevated; several seismic signals associated with rockfalls were recorded. The SO2 flux measured from Merapi was 175 metric tons on 22 April. On 22 and 23 April, fumarolic emissions rose 400 m above the summit. On 25 April, two rockslides from lava-flow fronts were heard from nearby observatories. According to news reports, about 600 of the approximately 14,000 people living near the volcano had been evacuated by 24 April.

According to news reports, on 27 April nearly 2,000 villagers were evacuated from Sidorejo and Tegalmulyo villages. That day, small amounts of ash fell in Gemer village about 5 km from the summit.

On 28 April, CVGHM reported volcanic material traveling ~ 1.5 km SW to the Lamat River. Seismicity that day was dominated by multi-phase earthquakes; but signals from landslides, rockfalls, and low-frequency events were also recorded.

On 6 May, gas plumes rose to 800 m above the summit and eighteen incandescent avalanches of volcanic material were observed. On 7 May, 26 incandescent avalanches that extended ~ 100 m were seen during the morning. On 6 and 7 May, the lava dome continued to grow and seismicity was dominated by multi-phase earthquakes. Shallow volcanic earthquakes and signals from landslides and rockfalls were also recorded. On 8 May, the Darwin VAAC reported that CVGHM warned of a plume rising to ~ 3.7 km, but no ash was visible on satellite imagery.

According to the Darwin VAAC, gas plumes that rose ~ 600 m above the summit were visible on satellite imagery on 11 May. Avalanches of incandescent material extended 200 m SE towards the Gendol River, and 1.5 km SW towards the Krasak River. Several small incandescent avalanches of volcanic material were visible from observatory posts. The new lava dome at the volcano's summit had grown to fill the gap between the 1997 and 2001 lava flows on the W side of the summit, and had reached a height about the same as the 1997 lava flows. Seismicity was dominated by multi-phase earthquakes and signals associated with avalanches.

At 0940 on 13 May, the Alert Level was raised from 3 to 4, the highest level, and ~ 4,500 people living near the volcano were evacuated.

On 15 May pyroclastic flows traveled as far as 4 km to the W. By 16 May, more than 22,000 people had been evacuated, according to figures posted at the district disaster center; about 16,870 people were evacuated from three districts in Central Java Province, and more than 5,600 others were evacuated from the Slemen district. On 17 May, pyroclastic flows traveled as far as 3 km. Local volcanologists reported that the lava dome continued to grow, but at a slower rate than during previous days.

Pyroclastic flows to the SW and SE reached 4 km on 19 May and 3 km on 20 May. On 22 May, the lava dome volume was estimated at ~ 2.3 million cubic meters. The Darwin VAAC reported that low-level emissions continued during 18-19 and 23 May. CVGHM recommended that residents who lived in valleys on the NNW flanks near Sat, Lamat, Senowo, Trising, and Apu Rivers and on the SE flank near Woro River be allowed to return to their homes. Residents remained evacuated from villages within a 7 km radius from the volcano's summit and within 300 m of the banks of the Krasak/Bebeng, Bedog, and Boyong Rivers to the SW, and the Gendol River to the SE.

According to news reports, an eruption produced a cloud of hot gas and ash on 17 May. Witnesses said the size of the plume was smaller than ash-and-gas plumes seen on 15 May. On 18 May, a representative for Merapi from the Center for Volcanological Research and Technology Development (part of CVGHM), reported new ashfall.

On 24-25 May, lava flows were observed moving SW towards the Krasak River and SE towards the Gendol River. News reports indicated that on 27 May a M 6.3 earthquake that killed about 5,400 people resulted in a three-fold increase in activity at Merapi. A M 5.9 earthquake coincided with pyroclastic flows of unknown origin that extended 3.8 km SW. During 28-30 May, multiple pyroclastic flows reached 3 km SE and 4 km SW. Gas plumes reached 500 m above the summit on 25 May, 1,200 m on 26 May, 100 m on 29 May, and 900 m on 30 May.

From 31 May to 6 June, SO2-bearing plumes were observed daily; on 1 June they reached 1.3 km above the summit. According to the Darwin VAAC, low-level emissions were visible on satellite imagery on 1 and 6 June. Multiple pyroclastic flows reached ~ 4 km SE toward the Gendol River and 3.5 km SW toward the Krasak and Boyong Rivers. CVGHM reported on 31 May that lava avalanches moved W for the first time during the recent eruption.

According to a volcanologist in Yogyakarta, lava-flow distances and dome volume had both approximately doubled since the 27 May M 6.2 earthquake. On 6 June, people living near the base of the volcano began to move into temporary shelters. Activities remain restricted within a 7 km radius from the volcano's summit and within 300 m of the banks of Krasak/Bebeng, Bedog, and Boyong Rivers to the SW, and Gendol River to the SE.

On 8 June, the lava-dome growth rate at Merapi was an estimated 100,000 cubic meters per day and the estimated volume was then ~ 4 million cubic meters. An estimated volume loss of 400,000 cubic meters on 4 June had been due to a partial collapse of the S part of the Geger Buaya crater wall, which was constructed from 1910 lava flows.

On 8 June, a pyroclastic flow, lasting 12 minutes, reached a distance of ~ 5 km SE toward the Gendol River, the predominant travel direction since the M 6.2 earthquake on 27 May. According to a news report, this event prompted approximately 15,500 people to evacuate from the Sleman district to the S and the Magelang district to the W. On 13 June, the Alert Level was lowered from 4 to 3 but renewed pyroclastic-flow activity the next day prompted a return to Alert Level 4.

Gas plumes were observed almost daily during 7-13 June and reached ~ 1.2 km above the summit on 10 June. The Darwin VAAC reported small ash plumes visible on satellite imagery; minor ashfall was reported to the S at an observatory outpost, and in Yogyakarta, about 32 km away.

Gas plumes emitted on 14 and 15 June reached 900 m above the summit. On 14 June a dome collapse lasting ~ 3.5 hours produced pyroclastic flows that reached 7 km SE. Two volunteers on a search-and-rescue team assisting with evacuation efforts were trapped in an underground refuge in Kaliadem village and died, the first fatalities of the current eruption. Stone (2006) wrote that the volunteers had ". . . sought refuge in a bunker, one of several on the mountain built for that contingency. The blast door was slightly ajar when rescuers dug down to the bunker the next day. The men had burned to death."

On 15 June, pyroclastic flows reached a distance of 4.5 km SE along the Gendol River. Pyroclastic flows continued during 16-19 June as a new dome grew. The Alert Level remained at 4.

During 21-25 June, seismic signals at Merapi indicated almost daily occurrences of rockfalls and pyroclastic flows. Due to inclement weather, pyroclastic flows were only observed on 24 June and reached a distance of 4 km SE along the Gendol River and 2.5 km SW along the Krasak River. Gas plumes were observed during 22-25 June and reached 1.5 km above the summit on 24 June.

Reference. Stone, Richard, 2006, Volcanology?Scientists steal a daring look at Merapi's explosive potential; Science, American Association for the Advancement of Science (AAAS), v. 312, pp. 1724-6.

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities during historical time.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Associated Press (URL: http://news.yahoo.com/s/ap/indonesia_volcano); Reuters (URL: http://news.yahoo.com/s/nm/20060418/wl_nm/indonesia_volcano_dc_2).


NW Rota-1 (United States) — May 2006 Citation iconCite this Report

NW Rota-1

United States

14.601°N, 144.775°E; summit elev. -517 m

All times are local (unless otherwise noted)


Views of submarine volcano ejecting lava and bombs

During 18 April-13 May 2006, scientists from the National Oceanic and Atmospheric Agency (NOAA) and Oregon State University completed the 2006 Submarine Ring of Fire Expedition aboard the research vessel Melville. This expedition was the third in a series of explorations of the submarine volcanoes lying along the Mariana intra-ocean volcanic arc. That arc extends from S of the island of Guam northward more than 1,450 km through the Commonwealth of the Northern Mariana Islands (see map in above report on Daikoku). A previous expedition to Northwest Rota-1 in 2004 discovered and named this volcano and found it erupting (BGVN 29:03). Daily logs of the 2006 expedition, including photographs and video clips, can be viewed on the NOAA Ocean Explorer web site noted below, from which much of this report was taken.

On 23 and 24 April 2006, the unmanned (remotely operated vessel, ROV) submersible Jason 2 revisited Brimstone Pit, a spot on the volcano where an ash-and-gas plume was discovered in 2004 and observed again in 2005 (Embley and others, 2004 and 2006). The changes were striking. According to Robert Embley (Oregon State University press release, 25 May 2006), "we saw features of submarine volcanic activity never before directly observed, including explosions of lava from a crater accompanied by a red glow and voluminous volcanic gases and ejected rocks." A degassing event at Brimstone Pit began releasing bubbles that formed a growing submarine plume cloud. The Pit, at a depth of 560 m, was significantly deeper (by ~ 20 m) than it was in the previous visits and there appeared to have been a recent collapse of the summit area. The Pit exuded a sluggish pulsating cloud of white color along with some gas bubbles. Some time later, the pit was almost filled with the white cloud, which appeared to come from the lavas themselves. The observers concluded that they witnessed lava extruding on the seafloor.

Particle plumes were mapped using a light-scattering sensor (LSS), part of the CTD (conductivity-temperature-depth) instrument package towed over the summit and flanks of the volcano. The CTD revealed layers of turbid (cloudy) water extending as far as 8 km down the S flank, and to depths up to 2,900 m. The turbid layers may arise from periodic collapse of the unstable slopes of volcanic fallout material similar to that found in the white cloud observed at the summit.

Submersible dives on 25 April 2006 to the Brimstone Pit revealed a lava flow forming there. The initial approach to the Pit revealed a line of bubbles (mainly CO2) escaping from a fracture in the underlying rock. However, in place of the previously flat ground that described the Pit on 24 April, a small ash cone had formed. It was ~ 6 m in diameter with walls about 1 m high, made up entirely of fine-grained ash. As the submersible approached, observers saw a plume discharging out of the cone's center and, on closer inspection, it appeared that ash was raining out of the bottom of the plume and falling onto the flanks of the small cone.

Near Brimstone Pit, the submersible collected a piece of newly erupted andesite lava containing elemental sulfur filling vesicles. The lava flow advanced but slowly, traveling forward bit by bit, chunk by chunk. As the lava advanced, the flow's toe vigorously degassed. The emitted gas and the associated plume took on a yellow hue. Scientists interpreted the escaping gases as mainly sulfur-rich (SO2 and H2S), which can mix with and make the surrounding seawater strongly acidic and precipitate elemental sulfur, the source of the plume's yellow hue. Liquid native sulfur inside the plume was seen raining on the seafloor as small droplets and filled in the numerous holes in the lava where the gases escaped. Locally, carbon dioxide formed bubbles in front of the advancing lava. These different gases provided the force behind the vigorous 'mini-explosions' within the lava flow.

Finishing the last of six dives at Northwest Rota-1 on 29 April 2006, and combining observations from the two previous expeditions, scientists developed some conclusions about processes at this extremely dynamic site. Prior to arrival in 2006, a major landslide must have originated near Brimstone Pit. During the first day of 2006 submersible observations, a turbid layer generated by the slide surrounded the lower flanks. The next day, when the water had cleared, half of Brimstone Pit had fallen away and the seafloor around the vent was swept clean of recent lava. Over the next week, eruptive activity gradually increased in intensity and vigor. By the end of the week, a 5-m-high cone made of ash and lava blocks had built up over the vent, and the turbid layer on the flanks was almost gone. On the last dive, scientists saw glowing lava jetting from the vent (figure 5).

Figure (see Caption) Figure 5. Glowing red lava jetting out of the vent at Northwest Rota-1 Brimstone Pit at depth of 560 m. Photo taken from the submersible Jason II, 29 April 2006. Image courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program.

The scientists concluded that observing explosive volcanic activity at a submarine volcano was easier and more revealing in many ways than on land, perhaps because the eruptive activity, although violent at times, is usually limited to a small area due to the dampening effect of the surrounding water (figure 6). For example, at Brimstone Pit the pressure of 560 m of water over the site reduced the power of the explosive bursts. Also, the water quickly slows down the rocks and ash violently thrown out of the vent. The scientists viewed the release of volcanic gases from the erupting lava with new clarity, with the help of the streams of bubbles and multicolored plumes as they were emitted. In addition, the scientists recorded the activity using a portable underwater microphone (hydrophone).

Figure (see Caption) Figure 6. Eruption at Brimstone Pit in Northwest Rota-1 at a depth of 560 m. Photo taken by the submersible Jason II, 29 April 2006. Image courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program.

Chadwick and his associates at NOAA have identified and named 56 seamounts in the Mariana Arc, 11 of which show hydrothermal activity, based primarily on CTD instrument tows (table 1; see figure 5 for map showing locations).

Table 1. Seamounts in the Mariana arc that are active volcanos based on submersible observations and/or that registered signs of hydrothermal activity on CTD tows. Brief comments on noteworthy observations from several of those visited in 2006 are included. Courtesy of William Chadwick, NOAA, June 2006.

Seamounts (listed S to N) Shallowest summit depth Longitude Latitude Comments
[Seamount X] 1,230 m 144.0167°E 13.2500°N --
Northwest Rota-1 517 m 144.7750°E 14.6000°N --
Esmeralda Bank 54 m 145.2458°E 14.9583°N --
E. Diamante 127 m 145.6583°E 15.9167°N Active, metal-rich, ephemeral 'black smokers' shallowest yet discovered.
Zealandia Bank 144 m 145.8000°E 16.8833°N --
Maug 54 m 145.2217°E 20.0208°N --
NW Uracas 703 m 144.8400°E 20.5833°N --
Daikoku 323 m 144.1942°E 21.3242°N See report in this issue.
NW Eifuku 1,551 m 144.0433°E 21.4875°N Liquid CO2 venting from 'white smokers.'
Kasuga 297 m 143.6417°E 21.6100°N --
Nikko 392 m 142.3255°E 23.0784°N Sulfur chimneys, boiling pots of molten sulfur surrounded by a thin crust on a larger lava lake.

References. Embley, R.W., Baker, E.T., Chadwick, W.W., Jr., Lipton, J.E., Resing, J.A., Massoth, G.J., and Nakamura, K., 2004, Explorations of Mariana Arc volcanoes reveal new hydrothermal systems: EOS, Transactions, American Geophysical Union, v. 85, no. 2, p. 37, 40.

Embley, R.W., Chadwick, W.W., Jr, Baker, E.T., Butterfield, D.A., Resing, J.A., de Ronde, C. E.J., Tunnicliffe, V., Lupton, J.E., Juniper, S.K., Rubin, K.H., Stern, R.J., Lebon, G.T., Nakamura, K., Merle, S.G., Hein, J.R., Wiens, D.A., and Tamura, Y., 2006, Long-term eruptive activity at a submarine arc volcano: Nature, v. 441, no. 7092, p. 494-497.

Oregon State University, 25 May 2006, Press Release: Nature paper details eruption activity at submarine volcano: College of Oceanic and Atmospheric Science (COAS), 104 COAS Admininstration Building, Corvallis, OR 97331.

Geologic Background. A submarine volcano detected during a 2003 NOAA bathymetric survey of the Mariana Island arc was found to be hydrothermally active and named NW Rota-1. The basaltic to basaltic-andesite seamount rises to within 517 m of the sea surface SW of Esmeralda Bank and lies 64 km NW of Rota Island and about 100 km north of Guam. When Northwest Rota-1 was revisited in 2004, a minor submarine eruption from a vent named Brimstone Pit on the upper south flank about 40 m below the summit intermittently ejected a plume several hundred meters high containing ash, rock particles, and molten sulfur droplets that adhered to the surface of the remotely operated submersible vehicle. The active vent was funnel-shaped, about 20 m wide and 12 m deep. NW Rota-1 is a large submarine volcano with prominent structural lineaments about a kilometer apart cutting across the summit of the edifice and down the NE and SW flanks.

Information Contacts: William W. Chadwick, Jr., Cooperative Institute for Marine Resources Studies (CIMRS), NOAA Pacific Marine Environmental Laboratory (PMEL), 2115 SE OSU Drive, Newport, OR 97365 USA; NOAA Ocean Explorer (URL: http://oceanexplorer.noaa.gov/explorations/06fire/welcome.html).


Popocatepetl (Mexico) — May 2006 Citation iconCite this Report

Popocatepetl

Mexico

19.023°N, 98.622°W; summit elev. 5393 m

All times are local (unless otherwise noted)


During first half of 2006, several ash plumes rose to ~ 7-8 km altitude

The last report on Popocatépetl covered February-December 2005 (BGVN 30:12). This report covers January-June 2006. Throughout this reporting interval, the warning level remained at Yellow. Seismicity is summarized on table 18.

Table 18. Recorded earthquakes near Popocatépetl during April-June 2006. Courtesy of CENAPRED.

Date Local Time Depth (km) Magnitude
04 Apr 2006 1426 5.4 2.2
05 Apr 2006 0416 5.4 2.3
05 Apr 2006 1557 8.0 2.4
06 Apr 2006 0921 1.0 2.3
07 Apr 2006 0339 6.3 1.9
12 Apr 2006 0457 5 2.8
18 Apr 2006 0101 6.4 2.6
27 Apr 2006 1024 4.3 2.2
25 May 2006 2019 4.9 2.3
29 May 2006 1548 5.6 2.1
30 May 2006 1224 7.7 2.2
31 May 2006 0238 9.3 2.4
31 May 2006 1253 4.2 2.0
02 Jun 2006 0502 5.4 2.2
08 Jun 2006 0637 4.7 3.0

On 6 January 2006, a small explosion occurred at Popocatépetl around 0042. According to the Washington VAAC, the resultant ash plume was visible on satellite imagery and its top reached ~ 5.8 km altitude, extending NE. Centro Nacional de Prevención de Desastres (CENAPRED) reported that after the explosion overall activity decreased to previous levels. During 24-30 January, several emissions of gas, steam, and small amounts of ash occurred. A moderate explosion on 26 January at 0957 produced an ash plume that rose to ~ 8.4 km altitude and drifted NE.

Throughout the month of February, several small-to-moderate emissions of steam, gas, and ash occurred. On the 4th, an explosion produced a plume that rose to ~ 6.7 km altitude. Aerial photos taken on 10 February showed a 130-m-diameter lava dome at the bottom of the crater. At 0528 on 24 February an M 2.3 earthquake was detected and was located 0.5 km to the N of the crater at a depth of 4.1 km.

During April-June, the volcano issued several small emissions of steam, gas, and ash; reports also noted several small coincident earthquakes. At 1807 on 23 May, an ash emission was observed that reached a height of ~ 7.4 km altitude. The ash column was dispersed towards the SE and was followed by a high-frequency, low-amplitude tremor signal that lasted 90 minutes and then returned to previous low levels.

Geologic Background. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.

Information Contacts: Centro Nacional de Prevención de Desastres (CENAPRED), Av. Delfín Madrigal No.665. Coyoacan, México D.F. 04360, México (URL: https://www.gob.mx/cenapred/).


Rabaul (Papua New Guinea) — May 2006 Citation iconCite this Report

Rabaul

Papua New Guinea

4.271°S, 152.203°E; summit elev. 688 m

All times are local (unless otherwise noted)


Gas emissions and earthquakes during March-April 2006

Despite minor inflationary movements that began in mid-February 2006, Tavurvur remained relatively quiet from the end of March to mid-April 2006. Variable amounts of white vapor were released from the summit area and from an active fumarole on the upper W flank during this period. Vapor emissions became denser during and after rainfall. There were no noises heard or visible glow detected at night. Seismic activity remained at a low level. A high-frequency earthquake that originated NE of the caldera was recorded on 22 March. No other distinct high-frequency events were recorded, but 53 low-frequency earthquakes were recorded during 1-14 April.

Geologic Background. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor utilized by what was the island's largest city prior to a major eruption in 1994. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the east, where its floor is flooded by Blanche Bay and was formed about 1400 years ago. An earlier caldera-forming eruption about 7100 years ago is now considered to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city.

Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.


Soufriere Hills (United Kingdom) — May 2006 Citation iconCite this Report

Soufriere Hills

United Kingdom

16.72°N, 62.18°W; summit elev. 915 m

All times are local (unless otherwise noted)


Big dome collapse and tall plume on 20 May 2006 leave a W-leaning crater

Activity at Soufrière Hills remained at elevated levels (table 63), similar to that previously reported (BGVN 30:12), a state that culminated with a dome collapse on 20 May 2006. Although that event took away considerable portions of the dome (and caused a small tsunami), photographs revealed post-collapse dome growth focused over a broad SE sector extending from the SW around to the NE. Numerous rockfalls continued from the S, E, and NE flanks of the lava dome. The NE-side rockfalls added talus to the upper reaches of the Tar River valley and were visible at night.

Table 63. Soufrière Hills seismicity during 28 December 2005 to 12 May 2006. * Due to weather conditions, gas measurements were not made. ** As a result of the collapse, instrumentation was lost and gas measurements were not able to be measured. Courtesy of MVO.

Date Hybrid EQ's Volcano-tectonic EQ's Long-period EQ's Rockfall signals SO2 flux (metric tons/day)
28 Dec-06 Jan 2006 -- -- 11 37 522
06 Jan-13 Jan 2006 -- 1 30 116 724
13 Jan-20 Jan 2006 -- -- 17 61 767
20 Jan-27 Jan 2006 -- -- 11 60 470
27 Jan-03 Feb 2006 1 3 11 92 594
03 Feb-10 Feb 2006 2 39 61 84 465
10 Feb-17 Feb 2006 2 9 121 10 568
17 Feb-24 Feb 2006 1 3 26 30 286
22 Feb-03 Mar 2006 1 7 157 18 388
03 Mar-10 Mar 2006 2 2 148 282 454
10 Mar-17 Mar 2006 -- 4 115 319 480
17 Mar-24 Mar 2006 13 3 231 336 1,034
24 Mar-31 Mar 2006 12 1 230 316 523
31 Mar-07 Apr 2006 -- 3 38 507 578
07 Apr-14 Apr 2006 -- 3 99 620 540
14 Apr-21 Apr 2006 3 -- 80 100 *
21 Apr-28 Apr 2006 -- -- 30 589 521
28 Apr-05 May 2006 -- -- 109 279 310
05 May-12 May 2006 -- -- 74 571 702
12 May-19 May 2006 7 1 130 753 674
19 May-26 May 2006 89 11 229 373 **
26 May-02 Jun 2006 62 4 172 195 **
02 Jun-09 Jun 2006 20 -- 28 163 **

A central spine was first observed on 17 January 2006 when clouds briefly cleared from the dome. On 22 January, two new relatively thin, vertical planar spines were seen on the SE flank of the lava dome and collapsed on 29 January. Helicopter and field observations indicated continued dome growth, particularly in the SE (figure 64).

Figure (see Caption) Figure 64. A photo showing the growing dome on SoufriPre Hills as viewed from Tar River at the seaward (E) end of the delta. Photo taken 23 January 2006 along the SW coastline. Courtesy of Montserrat Volcano Observatory (MVO).

On 10 February, MVO reported increased activity to the Washington VAAC. Satellite imagery showed a prominent hotspot at the volcano and a NW-drifting ash plume at an altitude of ~3 km. A small dark lobe of lava was observed on the western side of the lava dome in the crater. Steaming and venting were observed throughout the day. A photo appears as figure 65.

Figure (see Caption) Figure 65. A 10 February 2006 photo taken at Soufriere Hills showing ash and steam venting from the dome. This view is from the SE; the ash cloud drifted N. Courtesy of MVO. Courtesy of MVO.

By early 11 February, this lobe had advanced rapidly towards the NE side of the dome and was visible as a steep-sided plateau of lava from inhabited areas around Salem. Photographs from fixed cameras showed continued changes to this lava lobe over the next few days, and the NE margin could be seen glowing at night and shedding rockfalls into the NE part of the crater. Ash-and-gas emissions continued through 15 February, producing plumes to an altitude of ~2.7 km. The initial growth rate of this lobe surpassed 5 cubic meters per second, but the rate declined around 17 February. The new lava lobe began to fill the gap between the lava dome and the N and W crater walls, raising the possibility that small rockfalls could spill over those areas in coming weeks. After 22 February, incandescent rockfalls were visible at night, coursing down the N, E, and SW sides of the dome and into the Tar River Valley (figure 66).

Figure (see Caption) Figure 66. A Soufriere Hills photo showing the incandescent rockfalls at night taken from Perches Mountain, SE of the volcano. This photo was taken on 22 February 2006. Courtesy of MVO.

On 26 February, rapid vertical growth of the lava dome at Soufrière Hills was visible on camera images, and by 27 February a large spine about 30 m wide and at least 30 m high had developed at the dome's summit. By 28 February this spine had split into two parts and was leaning precariously to the NE. At about 2115 on 28 February the overhanging parts of the spine disintegrated and generated pyroclastic flows that traveled down the Tar River Valley almost as far as the coast. A low-level ash cloud drifted W. Additional changes to the shape of the spines and the upper NE flank of the volcano were noted in the following days as they disintegrated further. Rockfalls were visible on the N, NE, and E flanks of the volcano. Some fumaroles were observed on the upper outside part of Gages Wall (W of the lava dome) on 27 February, suggesting movement of fluids in this area.

During 3-17 March, lava-dome growth continued and the dome reached an altitude of ~950 m. The active lava lobe shed rockfalls and small pyroclastic flows to the W, N, and E. A vigorous gas vent was seen on the W side of the lava dome on 8 March, above Gages valley. Small fumaroles were visible at the top of Gages valley and below the lava dome remnant that stands at the top of Gages Valley.

Observations during 17 March-7 April revealed that lava-dome growth was focused in the summit area and towards the E and NE (figure 67). The N side of the lava dome showed little change. Rockfalls and pyroclastic flows were restricted to the Tar River Valley and were numerous on 19-20 March. The largest pyroclastic flows traveled as far as 2 km.

Figure (see Caption) Figure 67. A Soufriere Hills photo of the growing lava dome taken on 30 March 2006. The photographer stood on Jack Boy Hill and looked NE. Courtesy of MVO.

Lava extrusion continued during 7-21 April. Growth occurred to the E and N, and an eastward-facing lobe developed on the NE side of the dome. Numerous small rockfalls continued from the active eastern flanks of the dome, adding to the talus in the upper reaches of the Tar River valley. Rockfalls were accompanied by minor ash venting. Due to unusual wind conditions, plumes were predominately transported N and NW, shifting to the E on 20 April. As a result of this process, light ashfall occurred over much of Montserrat. Thermal images taken on 27 April indicated some very hot areas on the E flank of the dome.

Deposits from a series of pyroclastic flows occurring on 4 May extended as far as the Tar River delta. Northerly directed winds during the reporting period resulted in light ashfall in areas north of the Belham valley. The dome volume was approximately 80 million cubic meters and the average growth rate through April was about 8 cubic meters per second.

On 18 May, a survey conducted on the southern half of the dome was carried out using a terrestrial laser scanner and showed that the summit of the dome had reached a height of 1,006 m, this is 83 m higher than Chance's Peak (figure 68).

Figure (see Caption) Figure 68. The SE side of the Soufriere Hills lava dome as viewed from Galways Mountain on 11 May 2006. A new shear lobe forms the highest point of the dome and is growing toward the S. Chance's Peak is in the back left and Centre Hills in the back right. Courtesy of MVO.

20 May collapse. A major lava dome collapse took place on the morning of 20 May (figure 69). A helicopter flight in the afternoon confirmed that most of the lava dome had gone, together with some remnants of the 2003 lava dome, leaving a broad, deep, eastward-sloping crater at the summit of the volcano. The volume of the lava dome was believed to be about 90 million cubic meters and most of this collapsed over a period of less than three hours. Views of the W part of the crater where ash venting is continuing were not possible but it is unlikely that there is significant dome material remaining there.

Figure (see Caption) Figure 69. A set of photos taken 1600 on 20 May 2006 after the lava dome collapse. (A) A shot taken from the E showing an overview of the delta, Tar River Valley, and dome complex. (B) The crater as viewed from the NE above the Tar River Valley. Ash emission continued from a vent on the W side of the crater and rose to an altitude of 1.8 km. (C) A photo taken from E of the steaming summit crater showing most of the lava dome, including parts of the remaining 2003 dome. (D) A photo shot from MVO showing the towns of Flemings, Hope, and Salem in the early afternoon as the ash-and-gas cloud dissipated. Belham River Valley, Old Towne, and Garibaldi Hill remained obscured by the cloud of ash and gas. Courtesy of MVO.

At 0222 on 20 May there was a single precursor, a long-period seismic event located 3 km below the dome. A brief episode of heightened seismic amplitude corresponding to ash venting occurred during 0300-0330. During heavy rain, another episode of increased seismic amplitude, interpreted as ash venting, began at 0552, and it developed into a high-amplitude seismic signal. The heavy rain caused mudflows in Belham River valley. By 0632 low-level ash clouds were drifting to the NW of the volcano from the crater area and a steam plume was rising to 6,000 ft (~1800 m). Unconfirmed reports suggested that pyroclastic flows first reached the sea at about 0645. Regular pulses of pyroclastic flows were reaching the sea down the Tar River valley by 0720 with major pulses recorded in seismic amplitude at 0736, 0743, and between 0801 and 0804. Also between 0730 and 0810 a number of long-period seismic events were detected. At 0740 an ash cloud was reported at nearly 17 km, altitude the highest reported ash cloud during the ten years of the eruption. At 0743, pyroclastic surges were observed spreading across the NE flanks of the volcano reaching the Spanish Point area. It was also estimated at this time that surges had spread 3 km offshore from Tar River valley, across the surface of the ocean.

By 0750, lithics were falling in areas NW of the volcano; most were less than 3.5 cm across, and the largest found in the inhabited area was 6 cm across. Six car windscreens were reported broken. The deepest ash fall in inhabited areas was about 3 cm. Activity began to reduce in intensity after 0815 and a high-amplitude seismic signal remained until 0900. At this time, residents in the Old Towne and Salem area were subjected to high levels of volcanic gases particularly hydrogen chloride causing some to move N (figure 69). Widespread and noisy mudflows were reported in the Trants area to the NE of the volcano. Ash venting from the W of the crater continued until about 1700 when it began to decline.

A 1-m-high tsunami was reported from Deshaies beach in Guadeloupe and swells were detected in Little Bay, Montserrat, and at Jolly and English Harbour, Antigua. Relatively light but continuous ash-and-steam venting followed the collapse.

The weeks after the 20 May collapse. Wind direction shifted towards the N late on 21 May causing ash fall and raining mud in most parts of the island. Scientists remained alert to the possibility of further explosive activity but seismic activity was at low levels after the event on 20 May.

Since the May collapse, the lava dome continued to grow. As of 9 June it was approximately 20 million cubic meters in size. This is similar to the size of the dome in early January 2006. The average growth rate since the dome collapsed on 20 May was close to 10 cubic meters per second, well above the average growth rate of 6 cubic meters per second noted between January and April 2006.

By the end of the report period the dome was broad and flat-topped with a growing talus slope extending E. The lava on the summit of the dome is blocky, which is typical of lava extruded at a high rate. Vigorous ash and gas emitted by a vent W of the lava dome occurred during the week of 2 June. The venting is accompanied by a roaring sound that is sometimes audible in the Salem area. Prevailing winds have taken most of this ash and gas to the west over Plymouth. Satellite imagery on 4 June showed a thin area of ash out to St. Croix. In addition, there were multiple SFC and pilot reports of ash over the E portion of Puerto Rico and the Virgin Islands. Mudflows were reported on the 11 and 13 June during heavy rainfall.

Geologic Background. The complex, dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. The volcano is flanked by Pleistocene complexes to the north and south. English's Crater, a 1-km-wide crater breached widely to the east by edifice collapse, was formed about 2000 years ago as a result of the youngest of several collapse events producing submarine debris-avalanche deposits. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits, including those from an eruption that likely preceded the 1632 CE settlement of the island, allowing cultivation on recently devegetated land to near the summit. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but no historical eruptions were recorded until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.

Information Contacts: Montserrat Volcano Observatory (MVO), Fleming, Montserrat, West Indies (URL: http://www.mvo.ms/).


St. Helens (United States) — May 2006 Citation iconCite this Report

St. Helens

United States

46.2°N, 122.18°W; summit elev. 2549 m

All times are local (unless otherwise noted)


Intracrater lava dome continues to grow through at least May 2006

From August to December 2005, the lava dome inside the crater of Mount St. Helens continued to grow, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash (BGVN 30:12). The hazard status was at Volcano Advisory (Alert Level 2); aviation color code Orange.

Based on the online reports of the Cascades Volcano Observatory (CVO) of the U.S. Geological Survey (USGS), this pattern of activity continued in January and February 2006 and suggests that the slow extrusion of dacite onto the crater floor at Mount St. Helens continued. Slight decreases in seismicity occurred on two occasions after larger than normal earthquakes. By mid-January the new dome was noticeably taller and broader than in December. Rockfalls from its summit generated small ash plumes that slowly rose above the crater rim and dissipated as they drifted E.

On 24 January a shallow M 2.7 earthquake triggered a rockfall from the new lava dome, which in turn produced an ash plume that filled the crater before dissipating and drifting N over the pumice plain. Analysis of recent photographs from cameras in the crater showed that the top of the new lava dome was at an elevation of ~ 2,240 m, about 90 m higher than it was in early November 2005.

In February, occasional clear views of the volcano revealed incandescence on the currently growing lava lobe and a few incandescent rockfalls. Comparison of photos taken between 17 December and 7 February showed that the base of the active lobe of the lava dome enlarged by about 100 m. Photographs taken during the week of 5 February showed that the active part of the new lava dome continued to extrude, with points on the surface of the dome moving a couple of meters per day (figure 61).

Figure (see Caption) Figure 61. High-angle view of Mount St. Helens new dome from the NNW, taken on 5 February 2006 by John Pallister. Photograph courtesy of USGS.

Gas measurements made on 15 February suggested that the volcanic-gas flux remained unchanged from recent measurements. Observations made on 17 February revealed that the active NE part of the new lava dome was developing a steeply inclined jagged spine. At its top, temperatures as high as 580°C were measured using a thermal sensor.

Growth of the new lava dome inside the crater of Mount St. Helens continued during March, April, and May 2006, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. Small earthquakes occurred every several minutes, punctuated by occasional larger earthquakes. The Global Positioning System (GPS) receiver on the new lava dome showed that lava emerging from the vent was still advancing WNW at about a meter per day. Small rockfalls produced small ash clouds that rose from the dome's NW flank. The eruption of lava into the crater continued, shown by ongoing rockfalls and continuous GPS measurements made on the growing lava lobe.

Analysis of photographs revealed that a slab of rock approximately 50,000 cubic meters in volume was shed from the N margin of the growing spine during 6-7 May. This probably coincided with a large seismic signal recorded on the night of 7 May. Rock-avalanche deposits extended a few hundred meters to the NE. The avalanche was accompanied by an ash cloud. The spine continued to grow during 10-15 May, producing rockfalls that intensified on the evening of 14 May. Incandescence was visible on satellite imagery. On 17 May night-time incandescence from rockfalls was observed.

During 24-25 May, seismicity was at levels typical of the continuing lava-dome extrusion at Mount St. Helens. On 29 May, a M 3.1 earthquake and simultaneous large rockfall occurred. An ash plume produced at 0810 reached an altitude of 4.9 km - 6.1 km according to ground observations and pilot reports (figure 62). One pilot report suggested that the plume reached an altitude of 7.3 km. By 1308, ash from the event was no longer visible on satellite imagery. The rockfall originated primarily from the N side of the growing fin (figures 63 and 64).

Figure (see Caption) Figure 62. At Mt. St. Helens, a view from the Brutus camera at 0914 on 29 May 2006. Vapor with light ash obscures most of the extruding lava spine. The light gray swath in the center of the photograph shows the path of the rock avalanche as it flowed downhill. The dark areas adjacent to the rock-avalanche path shows the ash cloud (finer material) that accompanied the avalanche. Photograph courtesy USGS.
Figure (see Caption) Figure 63. Mount St. Helens crater and dome showing aftermath of rockfall event of 29 May 2006, seen from the N. Taken on 30 May 2006 by Willie Scott and Jim Vallance. Photograph courtesy USGS.
Figure (see Caption) Figure 64. Aerial view showing Mount St. Helens crater and dome as seen from the SW. Spirit Lake can just be seen in the upper right corner. Taken on 30 May 2006 by Willie Scott and Jim Vallance. Photograph courtesy USGS.

During June 2006, seismicity indicated that the lava spine continued to grow inside the crater of Mount St. Helens and occasionally produced minor rockfalls. On 9 June, pilots reported that an ash-and-steam plume, generated after a rockfall following a M 3.2 earthquake, reached an altitude of 4.6 km. According to seismic data, a medium-sized rockfall occurred on 13 June. Incandescence was observed on satellite imagery. A small steam plume from the lava dome and dust from minor rockfalls were visible from the US Forest Service's web camera at the Johnston Ridge Observatory on 25 and 26 June. On 26 June, a pilot reported that dust and ash reached an altitude of ~ 2.4 km and drifted W.

From January through June 2006, St Helens remained at Volcano Advisory (Alert Level 2); aviation color code Orange.

Geologic Background. Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago and has been the most active volcano in the Cascade Range during the Holocene. Prior to 2200 years ago, tephra, lava domes, and pyroclastic flows were erupted, forming the older St. Helens edifice, but few lava flows extended beyond the base of the volcano. The modern edifice was constructed during the last 2200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the north flank, and were witnessed by early settlers.

Information Contacts: Cascades Volcano Observatory (CVO), U.S. Geological Survey, 1300 SE Cardinal Court, Building 10, Suite 100, Vancouver, WA 98683-9589, USA (URL: https://volcanoes.usgs.gov/observatories/cvo/).


Ubinas (Peru) — May 2006 Citation iconCite this Report

Ubinas

Peru

16.355°S, 70.903°W; summit elev. 5672 m

All times are local (unless otherwise noted)


Ash and steam emissions stir hazard and environmental concerns

Ubinas began erupting ash on 25 March 2006 (BGVN 31:03). Randall White from the U.S. Geological Survey (USGS) reported on 1 April that increased fumarolic activity occurred during the end of March. Victor Aguilar from the Universidad de San Agustint, visited the volcano on 31 March. He found strong steam-and-ash emissions occurring. Also, leaves of nearby crops were burned and a sound similar to a jet engine emanated from the vent area. Table 1 gives a summary of some recent plumes. Figure 3 contains an ASTER image of the volcano and surroundings on 8 May 2006.

Table 1. Summary of some recent plume activity from Ubinas. Courtesy of the Buenos Aires VAAC and INGEMMET; satellite imagery courtesy of NASA Earth Observatory.

Date (time) Altitude Drift direction Comments
06 Apr (1220) 6.1-9.1 km -- Ash absent on satellite imagery
06 Apr (1900) 6.1-7.3 km NE --
08 Apr -- -- Volcanic activity ceased
09 Apr 6.1-7.3 km SW --
11 Apr -- -- Volcanic activity ceased
13 Apr -- -- Ash emissions increased, ashfall reached 7 km from volcano
15 Apr 6.1-9.1 km -- Ash cloud
16 Apr -- -- Volcanic activity ceased
18 Apr (0715-1600) 1-3 km -- Continuous emissions of ash and gas
19 Apr ~3 km -- Plume containing ash/lava fragments lasted 6-7 hours
20 Apr-22 Apr -- NW, W, SW Plume reached 60 km from the volcano; traces of ash reached the Arequipa airport.
25 Apr-26 Apr 0.2-0.7 km -- --
04 May-08 May ~6.7 km -- See fig. 15
9-11, 13-14 May 7.3 km (max) -- --
20 May-25 May 7.3 km (max) -- --
24 May 6.7 km E Plume reported by pilot
25 May 7 km NW --
30 May 7.9 km E Ash plume seen on satellite imagery
31 May-05 Jun 7.9 km N, NE, SE, S --
09 Jun-11 Jun 6.7 km E, SW Ash clouds reported by pilots
Figure (see Caption) Figure 3. A faint white plume rose from the summit of Ubinas on 8 May 2006, when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image. Courtesy NASA Earth Observatory.

The Perú Instituto Geológico Minero y Metalúrgico (INGEMMET) reported that gas and ash were emitted from Ubinas from 27 March to at least 19 April. On 13 April, ash emissions increased noticeably in comparison to the previous days, with ashfall in the villages of Ubinas, Querapi, and Sacuaya, and as far as 7 km from the volcano. Acid rain was also noted in these villages, particularly between 1400 and 1600 hours on 14 April. Explosions on 13 and 14 April were heard in nearby villages. According to a news report on 18 April, however, officials urged residents of the town of Querapi ~ 5 km from the volcano to evacuate.

On 19 April, a lava dome was observed on the crater floor for the first time. It was incandescent, 60 m in diameter, and 4 m high. Explosions were heard as far as 6 km from the volcano and a plume composed of ash and lava fragments rose ~ 3 km above the volcano. Plumes lasted for 6-7 hours and hazard statements suggested significant danger within 4 km of the crater. The Buenos Aires Volcanic Ash Advisory Center (VAAC) released volcanic ash advisory statements during the report period.

According to news reports, as of 19 April at least 1,000 people living N of the volcano suffered respiratory problems, dozens of livestock died and many more were ill after eating ash-covered grass, and water sources were polluted with ash. Dozens of people from Querapi, the town closest to the volcano, began to evacuate on 21 April. On 22 April, officials declared a state of emergency for the area near the volcano and sent aid for evacuees.

During 25 and 26 April, the volume of ash emitted from the volcano decreased significantly. Gas plumes rose between 200 and 700 m above the volcano's caldera. Seismicity during 22-26 April was higher than normal. The Buenos Aires VAAC posted volcanic ash advisories during the report period.

Several thermal anomalies were observed by MODIS/MODVOLC in 2006 at the following local times: 0105 hours, 27 May; 2220 hours, 31 May; 2225 hours, 7 June; 2210 hours, 18 June; and 2235 hours, 30 June. On 3 June, the Alert Level for Ubinas was increased to Orange due to heightened explosive activity. According to a news report, on 5 June, officials in S Perú prepared to evacuate approximately 480 families; approximately 550 families were evacuated on 10 and 11 June. Ubinas emitted a plume of ash and/or steam on 24 June 2006. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying onboard NASA's Aqua satellite showed the plume moving E.

Geologic Background. A small, 1.4-km-wide caldera cuts the top of Ubinas, Perú's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one of Holocene age about 1,000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.

Information Contacts: Randall A. White, USGS/OFDA Volcano Disaster Assistance Program; Victor Aguilar, Universidad de San Agustin, Perú; Buenos Aires Volcanic Ash Advisory Center; Instituto Geológico Minero y Metalúrgico (INGEMMET ? Institution of Mining and Metallurgical Geology); National Aeronautics and Space Administration (NASA) Earth Observer (URL: http://earthobservatory.nasa.gov/NaturalHarards/).


Villarrica (Chile) — May 2006 Citation iconCite this Report

Villarrica

Chile

39.42°S, 71.93°W; summit elev. 2847 m

All times are local (unless otherwise noted)


Unusual seismicity, minor pyroclastic, and gas explosions, January-April 2005

Our last report on Villarrica, through January 2005, described plumes, the growth of a lava lake in the crater, and some night-time Strombolian explosions (BGVN 29:12). This report covers January to April 2005.

According to the March 2005 newsletter of the Multinational Andean Project: Geoscience for Andean Communities (MAP-GAC) produced by the Geological Survey of Canada, both seismic activity and degassing from the permanent fumarole increased in January. One of the early January explosions described above sent pyroclastic material (ash and scoriaceous lapilli) onto the flanks of the snow-and-ice covered volcano, covering an area 1 km wide and 3 km long. Subsequent minor explosions have sent pyroclastic material to estimated heights of 300 m above the crater. Onlookers have reported incandescent material within the gas-and-pyroclastic column.

On 19 January 2005, volcanologists Hugo Moreno and Edmundo Polanco of OVDAS–SERNAGEOMIN observed the lava lake actively spattering at a distance of 30 m below the edge of the principal crater; the crater interior and perimeter were covered in spatter. The glacier covering the cone had developed new fractures and crevasses. Activity in February 2005 lessened.

During 29 March to 3 April 2005, the lava lake inside Villarrica's crater remained active, with Strombolian explosions occurring. Some gas explosions were observed to hurl volcanic bombs as far as ~ 300 m. According to a news report on 12 April 2005, the Oficina Nacional de Emergencia reported that unusual seismicity was recorded at Villarrica during early April. Fresh ash deposits were seen outside of the volcano's crater. Visitors were banned from climbing the volcano.

Geologic Background. Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.

Information Contacts: Werner Keller, Proyecto de Observacion Villarrica (POVI), Wiesenstrasse 8, 86438 Kissing, Germany (URL: http://www.povi.cl/); Hugo Moreno and Edmundo Polanco, Observatorio Volcanológico de los Andes del Sur (OVDAS), Servicio Nacional de Geología y Minería, Casilla 23D, Temuco, Chile (URL: http://www.sernageomin.cl/); MAP:GAC Newsletter, Geological Survey of Canada, 101-605 Robson Street, Vancouver, BC,V6B 5J3, Canada.

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