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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

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

Dukono (Indonesia) Numerous ash explosions continue through March 2020

Etna (Italy) Strombolian explosions and ash emissions continue, October 2019-March 2020

Merapi (Indonesia) Explosions produced ash plumes, ashfall, and pyroclastic flows during October 2019-March 2020



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/).


Dukono (Indonesia) — May 2020 Citation iconCite this Report

Dukono

Indonesia

1.693°N, 127.894°E; summit elev. 1229 m

All times are local (unless otherwise noted)


Numerous ash explosions continue through March 2020

The ongoing eruption at Dukono is characterized by frequent explosions that send ash plumes to about 1.5-3 km altitude (0.3-1.8 km above the summit), although a few have risen higher. This type of typical activity (figure 13) continued through at least March 2020. The ash plume data below (table 21) were primarily provided by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and the Darwin Volcanic Ash Advisory Centre (VAAC). During the reporting period of October 2019-March 2020, the Alert Level remained at 2 (on a scale of 1-4) and the public was warned to remain outside of the 2-km exclusion zone.

Table 21. Monthly summary of reported ash plumes from Dukono for October 2019-March 2020. The direction of drift for the ash plume through each month was highly variable; notable plume drift each month was only indicated in the table if at least two weekly reports were consistent. Data courtesy of the Darwin VAAC and PVMBG.

Month Plume Altitude (km) Notable Plume Drift
Oct 2019 1.8-3 Multiple
Nov 2019 1.8-2.3 E, SE, NE
Dec 2019 1.8-2.1 E, SE
Jan 2020 1.8-2.1 E, SE, SW, S
Feb 2020 2.1-2.4 S, SW
Mar 2020 1.5-2.3 Multiple
Figure (see Caption) Figure 13.Satellite image of Dukono from Sentinel-2 on 12 November 2019, showing an ash plume drifting E. Image uses natural color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

During the reporting period, high levels of sulfur dioxide were only recorded above or near the volcano during 30-31 October and 4 November 2019. High levels were recorded by the Ozone Mapping and Profiler Suite (OMPS) instrument aboard the Suomi National Polar-orbiting Partnership (NPP) satellite on 30 October 2019, in a plume drifting E. The next day high levels were also recorded by the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Copernicus Sentinel-5 Precursor satellite on 31 October (figure 14) and 4 November 2019, in plumes drifting SE and NE, respectively.

Figure (see Caption) Figure 14. Sulfur dioxide emission on 31 October 2019 drifting E, probably from Dukono, as recorded by the TROPOMI instrument aboard the Sentinel-5P satellite. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Geologic Background. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

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/); 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/); 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).


Etna (Italy) — April 2020 Citation iconCite this Report

Etna

Italy

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

All times are local (unless otherwise noted)


Strombolian explosions and ash emissions continue, October 2019-March 2020

Mount Etna is a stratovolcano located on the island of Sicily, Italy, with historical eruptions that date back 3,500 years. The most recent eruptive period began in September 2013 and has continued through March 2020. Activity is characterized by Strombolian explosions, lava flows, and ash plumes that commonly occur from the summit area, including the Northeast Crater (NEC), the Voragine-Bocca Nuova (or Central) complex (VOR-BN), the Southeast Crater (SEC, formed in 1978), and the New Southeast Crater (NSEC, formed in 2011). The newest crater, referred to as the "cono della sella" (saddle cone), emerged during early 2017 in the area between SEC and NSEC. This reporting period covers information from October 2019 through March 2020 and includes frequent explosions and ash plumes. The primary source of information comes from the Osservatorio Etneo (OE), part of the Catania Branch of Italy's Istituo Nazionale di Geofisica e Vulcanologica (INGV).

Summary of activity during October 2019-March 2020. Strombolian activity and gas-and-steam and ash emissions were frequently observed at Etna throughout the entire reporting period, according to INGV and Toulouse VAAC notices. Activity was largely located within the main cone (Voragine-Bocca Nuova complex), the Northeast Crater (NEC), and the New Southeast Crater (NSEC). On 1, 17, and 19 October, ash plumes rose to a maximum altitude of 5 km. Due to constant Strombolian explosions, ground observations showed that a scoria cone located on the floor of the VOR Crater had begun to grow in late November and again in late January 2020. A lava flow was first detected on 6 December at the base of the scoria cone in the VOR Crater, which traveled toward the adjacent BN Crater. Additional lava flows were observed intermittently throughout the reporting period in the same crater. On 13 March, another small scoria cone had formed in the main VOR-BN complex due to Strombolian explosions.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data shows multiple episodes of thermal activity varying in power from 22 June 2019 to March 2020 (figure 286). The power and frequency of these thermal anomalies significantly decreased between August to mid-September. The pulse of activity in mid-September reflected a lava flow from the VOR Crater (BGVN 44:10). By late October through November, thermal anomalies were relatively weaker and less frequent. The next pulse in thermal activity reflected in the MIROVA graph occurred in early December, followed by another shortly after in early January, both of which were due to new lava flows from the VOR Crater. After 9 January the thermal anomalies remained frequent and strong; active lava flows continued through March accompanied by Strombolian explosions, gas-and-steam, SO2, and ash emissions. The most recent distinct pulse in thermal activity was seen in mid-March; on 13 March, another lava flow formed, accompanied by an increase in seismicity. This lava flow, like the previous ones, also originated in the VOR Crater and traveled W toward the BN Crater.

Figure (see Caption) Figure 286. Multiple episodes of varying activity at Etna from 22 June 2019 through March 2020 were reflected in the MIROVA thermal energy data (Log Radiative Power). Courtesy of MIROVA.

Activity during October-December 2019. During October 2019, VONA (Volcano Observatory Notice for Aviation) notices issued by INGV reported ash plumes rose to a maximum altitude of 5 km on 1, 17, and 19 October. Strombolian explosions occurred frequently. Explosions were detected primarily in the VOR-BN Craters, ejecting coarse pyroclastic material that fell back into the crater area and occasionally rising above the crater rim. Ash emissions rose from the VOR-BN and NEC while intense gas-and-steam emissions were observed in the NSEC (figure 287). Between 10-12 and 14-20 October fine ashfall was observed in Pedara, Mascalucia, Nicolosi, San Giovanni La Punta, and Catania. In addition to these ash emissions, the explosive Strombolian activity contributed to significant SO2 plumes that drifted in different directions (figure 288).

Figure (see Caption) Figure 287. Webcam images of ash emissions from the NE Crater at Etna from the a) CUAD (Catania) webcam on 10 October 2019; b) Milo webcam on 11 October 2019; c) Milo webcam on 12 October 2019; d) M.te Cagliato webcam on 13 October 2019. Courtesy of INGV (Report 42/2019, ETNA, Bollettino Settimanale, 07/10/2019 - 13/10/2019, data emissione 15/10/2019).
Figure (see Caption) Figure 288. Strombolian activity at Etna contributed to significant SO2 plumes that drifted in multiple directions during the intermittent explosions in October 2019. Top left: 1 October 2019. Top right: 2 October 2019. Middle left: 15 October 2019. Middle right: 18 October 2019. Bottom left: 13 November 2019. Bottom right: 1 December 2019. Captured by the TROPOMI instrument on the Sentinel 5P satellite, courtesy of NASA Global Sulfur Dioxide Monitoring Page.

The INGV weekly bulletin covering activity between 25 October and 1 November 2019 reported that Strombolian explosions occurred at intervals of 5-10 minutes from within the VOR-BN and NEC, ejecting incandescent material above the crater rim, accompanied by modest ash emissions. In addition, gas-and-steam emissions were observed from all the summit craters. Field observations showed the cone in the crater floor of VOR that began to grow in mid-September 2019 had continued to grow throughout the month. During the week of 4-10 November, Strombolian activity within the Bocca Nuova Crater was accompanied by gas-and-steam emissions. The explosions in the VOR Crater occasionally ejected incandescent ejecta above the crater rim (figures 289 and 290). For the remainder of the month Strombolian explosions continued in the VOR-BN and NEC, producing sporadic ash emissions. Isolated and discontinuous explosions in the New Southeast Crater (NSEC) also produced fine ash, though gas-and-steam emissions still dominated the activity at this crater. Additionally, the explosions from these summit craters were frequently accompanied by strong SO2 emissions that drifted in different directions as discrete plumes.

Figure (see Caption) Figure 289. Photo of Strombolian activity and crater incandescence in the Voragine Crater at Etna on 15 November 2019. Photo by B. Behncke, taken by Tremestieri Etneo. Courtesy of INGV (Report 47/2019, ETNA, Bollettino Settimanale, 11/11/2019 - 17/11/2019, data emissione 19/11/2019).
Figure (see Caption) Figure 290. Webcam images of summit crater activity during 26-29 November and 1 December 2019 at Etna. a) image recorded by the high-resolution camera on Montagnola (EMOV); b) and c) webcam images taken from Tremestieri Etneo on the southern slope of Etna showing summit incandescence; d) image recorded by the thermal camera on Montagnola (EMOT) showing summit incandescence at the NSEC. Courtesy of INGV (Report 49/2019, ETNA, Bollettino Settimanale, 25/11/2019 - 01/12/2019, data emissione 03/12/2019).

Frequent Strombolian explosions continued through December 2019 within the VOR-BN, NEC, and NSEC Craters with sporadic ash emissions observed in the VOR-BN and NEC. On 6 December, Strombolian explosions increased in the NSEC; webcam images showed incandescent pyroclastic material ejected above the crater rim. On the morning of 6 December a lava flow was observed from the base of the scoria cone in the VOR Crater that traveled toward the adjacent Bocca Nuova Crater. INGV reported that a new vent opened on the side of the saddle cone (NSEC) on 11 December and produced explosions until 14 December.

Activity during January-March 2020. On 9 January 2020 an aerial flight organized by RAI Linea Bianca and the state police showed the VOR Crater continuing to produce lava that was flowing over the crater rim into the BN Crater with some explosive activity in the scoria cone. Explosive Strombolian activity produced strong and distinct SO2 plumes (figure 291) and ash emissions through March, according to the weekly INGV reports, VONA notices, and satellite imagery. Several ash emissions during 21-22 January rose from the vent that opened on 11 December. According to INGV’s weekly bulletin for 21-26 January, the scoria cone in the VOR crater produced Strombolian explosions that increased in frequency and contributed to rapid cone growth, particularly the N part of the cone. Lava traveled down the S flank of the cone and into the adjacent Bocca Nuova Crater, filling the E crater (BN-2) (figure 292). The NEC had discontinuous Strombolian activity and periodic, diffuse ash emissions.

Figure (see Caption) Figure 291. Distinct SO2 plumes drifting in multiple directions from Etna were visible in satellite imagery as Strombolian activity continued through March 2020. Top left: 21 January 2020. Top right: 2 February 2020. Bottom left: 10 March 2020. Bottom right: 19 March 2020. Captured by the TROPOMI instrument on the Sentinel 5P satellite, courtesy of NASA Global Sulfur Dioxide Monitoring Page.
Figure (see Caption) Figure 292. a) A map of the lava field at Etna showing cooled flows (yellow) and active flows (red). The base of the scoria cone is outlined in black while the crater rim is outlined in red. b) Thermal image of the Bocca Nuova and Voragine Craters. The bright orange is the warmest temperature measure in the flow. Courtesy of INGV, photos by Laboratorio di Cartografia FlyeEye Team (Report 10/2020, ETNA, Bollettino Settimanale, 24/02/2020 - 01/03/2020, data emissione 03/03/2020).

Strombolian explosions continued into February 2020, accompanied by ash emissions and lava flows from the previous months (figure 293). During 17-23 February, INGV reported that some subsidence was observed in the central portion of the Bocca Nuova Crater. During 24 February to 1 March, the Strombolian explosions ejected lava from the VOR Crater up to 150-200 m above the vent as bombs fell on the W edge of the VOR crater rim (figure 294). Lava flows continued to move into the W part of the Bocca Nuova Crater.

Figure (see Caption) Figure 293. Webcam images of A) Strombolian activity and B) effusive activity fed by the scoria cone grown inside the VOR Crater at Etna taken on 1 February 2020. C) Thermal image of the lava field produced by the VOR Crater taken by L. Lodato on 3 February (bottom left). Image of BN-1 taken by F. Ciancitto on 3 February in the summit area (bottom right). Courtesy of INGV; Report 06/2020, ETNA, Bollettino Settimanale, 27/01/2020 - 02/02/2020, data emissione 04/02/2020 (top) and Report 07/2020, ETNA, Bollettino Settimanale, 03/02/2020 - 09/02/2020, data emissione 11/02/2020 (bottom).
Figure (see Caption) Figure 294. Photos of the VOR intra-crater scoria cone at Etna: a) Strombolian activity resumed on 25 February 2020 from the SW edge of BN taken by B. Behncke; b) weak Strombolian activity from the vent at the base N of the cone on 29 February 2020 from the W edge of VOR taken by V. Greco; c) old vent present at the base N of the cone, taken on 17 February 2020 from the E edge of VOR taken by B. Behncke; d) view of the flank of the cone, taken on 24 February 2020 from the W edge of VOR taken by F. Ciancitto. Courtesy of INGV (Report 10/2020, ETNA, Bollettino Settimanale, 24/02/2020 - 01/03/2020, data emissione 03/03/2020).

During 9-15 March 2020 Strombolian activity was detected in the VOR Crater while discontinuous ash emissions rose from the NEC and NSEC. Bombs were found in the N saddle between the VOR and NSEC craters. On 9 March, a small scoria cone that had formed in the Bocca Nuova Crater and was ejecting bombs and lava tens of meters above the S crater rim. The lava flow from the VOR Crater was no longer advancing. A third scoria cone had formed on 13 March NE in the main VOR-BN complex due to the Strombolian explosions on 29 February. Another lava flow formed on 13 March, accompanied by an increase in seismicity. The weekly report for 16-22 March reported Strombolian activity detected in the VOR Crater and gas-and-steam and rare ash emissions observed in the NEC and NSEC (figure 295). Explosions in the Bocca Nuova Crater ejected spatter and bombs 100 m high.

Figure (see Caption) Figure 295. Map of the summit crater area of Etna showing the active vents and lava flows during 16-22 March 2020. Black hatch marks indicate the crater rims: BN = Bocca Nuova, with NW BN-1 and SE BN-2; VOR = Voragine; NEC = North East Crater; SEC = South East Crater; NSEC = New South East Crater. Red circles indicate areas with ash emissions and/or Strombolian activity, yellow circles indicate steam and/or gas emissions only. The base is modified from a 2014 DEM created by Laboratorio di Aerogeofisica-Sezione Roma 2. Courtesy of INGV (Report 13/2020, ETNA, Bollettino Settimanale, 16/03/2020 - 22/03/2020, data emissione 24/03/2020).

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

Information Contacts: Sezione di Catania - Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/it/); Toulouse Volcanic Ash Advisory Center (VAAC), Météo-France, 42 Avenue Gaspard Coriolis, F-31057 Toulouse cedex, France (URL: http://www.meteo.fr/aeroweb/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Boris Behncke, Sonia Calvari, and Marco Neri, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: https://twitter.com/etnaboris, Image at https://twitter.com/etnaboris/status/1183640328760414209/photo/1).


Merapi (Indonesia) — April 2020 Citation iconCite this Report

Merapi

Indonesia

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

All times are local (unless otherwise noted)


Explosions produced ash plumes, ashfall, and pyroclastic flows during October 2019-March 2020

Merapi is a highly active stratovolcano located in Indonesia, just north of the city of Yogyakarta. The current eruption episode began in May 2018 and was characterized by phreatic explosions, ash plumes, block avalanches, and a newly active lava dome at the summit. This reporting period updates information from October 2019-March 2020 that includes explosions, pyroclastic flows, ash plumes, and ashfall. The primary reporting source of activity comes from Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG, the Center for Research and Development of Geological Disaster Technology, a branch of PVMBG) and Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM).

Some ongoing lava dome growth continued in October 2019 in the NE-SW direction measuring 100 m in length, 30 m in width, and 20 m in depth. Gas-and-steam emissions were frequent, reaching a maximum height of 700 m above the crater on 31 October. An explosion at 1631 on 14 October removed the NE-SW trending section of the lava dome and produced an ash plume that rose 3 km above the crater and extended SW for about 2 km (figures 90 and 91). The plume resulted in ashfall as far as 25 km to the SW. According to a Darwin VAAC notice, a thermal hotspot was detected in HIMAWARI-8 satellite imagery. A pyroclastic flow associated with the eruption traveled down the SW flank in the Gendol drainage. During 14-20 October lava flows from the crater generated block-and-ash flows that traveled 1 km SW, according to BPPTKG.

Figure (see Caption) Figure 90. An ash plume rising 3 km above Merapi on 14 October 2019.
Figure (see Caption) Figure 91. Webcam image of an ash plume rising above Merapi at 1733 on 14 October 2019. Courtesy of BPPTKG via Jaime S. Sincioco.

At 0621 on 9 November 2019, an eruption produced an ash plume that rose 1.5 km above the crater and drifted W. Ashfall was observed in the W region as far as 15 km from the summit in Wonolelo and Sawangan in Magelang Regency, as well as Tlogolele and Selo in Boyolali Regency. An associated pyroclastic flow traveled 2 km down the Gendol drainage on the SE flank. On 12 November aerial drone photographs were used to measure the volume of the lava dome, which was 407,000 m3. On 17 November, an eruption produced an ash plume that rose 1 km above the crater, resulting in ashfall as far as 15 km W from the summit in the Dukun District, Magelang Regency (figure 92). A pyroclastic flow accompanying the eruption traveled 1 km down the SE flank in the Gendol drainage. By 30 November low-frequency earthquakes and CO2 gas emissions had increased.

Figure (see Caption) Figure 92. An ash plume rising 1 km above Merapi on 17 November 2019. Courtesy of BPPTKG.

Volcanism was relatively low from 18 November 2019 through 12 February 2020, characterized primarily by gas-and-steam emissions and intermittent volcanic earthquakes. On 4 January a pyroclastic flow was recorded by the seismic network at 2036, but it wasn’t observed due to weather conditions. On 13 February an explosion was detected at 0516, which ejected incandescent material within a 1-km radius from the summit (figure 93). Ash plumes rose 2 km above the crater and drifted NW, resulting in ashfall within 10 km, primarily S of the summit; lightning was also seen in the plume. Ash was observed in Hargobinangun, Glagaharjo, and Kepuharjo. On 19 February aerial drone photographs were used to measure the change in the lava dome after the eruption; the volume of the lava had decreased, measuring 291,000 m3.

Figure (see Caption) Figure 93. Webcam image of an ash plume rising from Merapi at 0516 on 13 February 2020. Courtesy of MAGMA Indonesia and PVMBG.

An explosion on 3 March at 0522 produced an ash plume that rose 6 km above the crater (figure 94), resulting in ashfall within 10 km of the summit, primarily to the NE in the Musuk and Cepogo Boyolali sub-districts and Mriyan Village, Boyolali (3 km from the summit). A pyroclastic flow accompanied this eruption, traveling down the SSE flank less than 2 km. Explosions continued to be detected on 25 and 27-28 March, resulting in ash plumes. The eruption on 27 March at 0530 produced an ash plume that rose 5 km above the crater, causing ashfall as far as 20 km to the W in the Mungkid subdistrict, Magelang Regency, and Banyubiru Village, Dukun District, Magelang Regency. An associated pyroclastic flow descended the SSE flank, traveling as far as 2 km. The ash plume from the 28 March eruption rose 2 km above the crater, causing ashfall within 5 km from the summit in the Krinjing subdistrict primarily to the W (figure 94).

Figure (see Caption) Figure 94. Images of ash plumes rising from Merapi during 3 March (left) and 28 March 2020 (right). Images courtesy of BPPTKG (left) and PVMBG (right).

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: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Center for Research and Development of Geological Disaster Technology (URL: http://merapi.bgl.esdm.go.id/, Twitter: @BPPTKG); Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/, Twitter: https://twitter.com/BNPB_Indonesia); 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/); Jamie S. Sincioco, Phillipines (Twitter: @jaimessincioco, Image at https://twitter.com/jaimessincioco/status/1227966075519635456/photo/1).

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Bulletin of the Global Volcanism Network - Volume 33, Number 06 (June 2008)

Managing Editor: Richard Wunderman

Arenal (Costa Rica)

Continuing explosive and effusive eruptions; block-and-ash flows

Barren Island (India)

Thermal anomalies and red glow indicate that a new eruption started in May 2008

Chaiten (Chile)

Events of June-July include diminished plumes, substantial seismicity, and lateral blast

Erta Ale (Ethiopia)

Active lava lake visited in February 2008

Lengai, Ol Doinyo (Tanzania)

Explosive eruptions continue into June 2008

Llaima (Chile)

Summary of January-February 2008 eruption; minor eruptions late March-early April 2008

Okmok (United States)

Large explosive eruption started on 12 July, ash plumes initially rose to 15.2 km altitude

Papandayan (Indonesia)

Minor seismic activity and fumarolic plumes through 16 April 2008

Raung (Indonesia)

New eruption during 12-17 June sends ash plumes to 4.5 km altitude

Tungurahua (Ecuador)

Explosions up to 14 km altitude during July 2007 to February 2008

Ubinas (Peru)

Frequent ash plumes pose risk to aviation and residents

Witori (Papua New Guinea)

Ejection of lava fragments in late August 2007; quiet steaming



Arenal (Costa Rica) — June 2008 Citation iconCite this Report

Arenal

Costa Rica

10.463°N, 84.703°W; summit elev. 1670 m

All times are local (unless otherwise noted)


Continuing explosive and effusive eruptions; block-and-ash flows

Our last report covered generally low-level activity at Arenal through September 2007 (BGVN 32:09). Behavior then included pyroclastic flows to a runout distance of ~ 1 km and a new lava flow emerging from Crater C. This report covers the interval October 2007?June 2008 and originated from those of both the Observatorio Vulcanologico Sismologica de Costa Rica- Universidad Nacional (OVSICORI-UNA) and (ICE).

Impressive incandescent avalanches (block-and-ash flows or pyroclastic flows) traveled down several flanks during June 2008. At least portions of those avalanches broke off from a cone in Crater C and active lava flows high on the edifice.

During the reporting interval, Crater C continued to produce lava flows, gases, sporadic Strombolian eruptions, and avalanches from the lava flow fronts. Observers noticed acid rain and small amounts of ejected pyroclastic material impacting the NE, E, and SE flanks. They also cited loss of vegetation, steep slopes, poorly consolidated material, and high precipitation as factors that triggered small cold avalanches in Calle de Arenas, Manolo, Guillermina, and the river Agua Caliente. Crater D remained fumarolic. Except for the June avalanches, eruptive activity generally remained modest. Some reports noted that the eruptive vigor continued to drop both in terms of the number of eruptions and the amount of ejected pyroclastic material.

OVSICORI-UNA reported that by March 2008, the flow of lava down the S flank had stopped, but a new flow that had begun in February 2008 toward the SW flank was still active. A few eruptions produced ash columns that exceeded 500 m above the vent.

During April 2008, lava moving toward the S flank descended to about 1,400 m elevation. Some blocks had detached near the border of the crater. Sporadically small avalanches occurred and some blocks managed to reach vegetation below, igniting small fires. Some April eruptions produced dark gray ash columns.

Glowing avalanches of June. Jorge Barquero sent us a report on Arenal's behavior during June 2008. Prior to the June events a distinct cone had appeared in Crater C. Its steep sides generated small avalanches of loosened rocks. At about 1000 on 6 June, that cone collapsed, causing a pyroclastic (block-and-ash) flow that descended SE, forming a gully or channel, and laying down a deposit that fanned out at the base of Arenal. Lava also descended into or towards the gully, causing small avalanches.

Some residents heard noises and felt ashfall starting at 0600 on 10 June. At about 0800 these block-and-ash flows became larger. The wind blew ash NW to 4 km from the crater.

After 1730 on 14 June, the failure of the lava flow front sent down an avalanche more violent than those earlier. An hour later the largest block-and-ash flow of the month descended. It descended the channel and produced a large quantity of ash that blew SE and W to distances of 6 km. The area of greatest impact was in the SW portion of the Arenal National Park, where the branches of some vegetation cracked under the weight of the ash. More block-and-ash flows were also observed on 15 and 18 June.

On 11 June Eliecer Duarte and E. Fernández (OVSICORI-UNA) visited the distal parts of the new deposits, documenting the new flow field (figures 102 and 103). The distal area occurred at ~ 900 m elevation on Arenal's outer margins where the slope changes abruptly. A series of alternating lobes contained deposits that were 500°C on 11 June. The individual lobe's thickness reached up to about 3-4 m. The heterogeneous nature of the often angular blocks contrasted with a gray and quite sandy matrix, and included both pre-existing material eroded from the valley walls and more recent juvenile material from the summit. Conspicuous blocls from the block-and-ash flow (10% were 2-3 m in diameter and ~ 20% were ~ 1 m in diameter) are mostly juvenile material from the lava flow. The margins of the fan were covered by a fine dust layer several centimeters thick. On the S flanks, the block-and-ash deposit barely reached a few meters thick. On the N flanks, the deposit reached many tens of meters thick, the result of wind carrying the abundant fine materials in that direction.

Figure (see Caption) Figure 102. A view of the early June 2008 incandescent avalanche deposits on Arenal's S flanks. Courtesy of OVSICORI-UNA.
Figure (see Caption) Figure 103. Previously incandescent avalanche deposits at Arenal seen on 11 June 2008. Courtesy of OVSICORI-UNA.

Major S-flank avalanches reported on 6 and 10 June 2008 eroded a radially oriented gully (an avalanche chute). Later avalanches down this direction tended to form channelized deposits. A dark colored thick lava flow present at the summit (figure 104) provided an important source of materials in the deposits. The S-flank avalanches funneled through the gully, fracturing particles into finer grain sizes and generating columns of ash. During the visit, the team observed several avalanches containing large blocks that were similarly reduced in volume as they bounced through the gully. Some of these blocks arrived at the lower part of the fan with temperatures between 800 and 1,000°C. The large blocks seemingly cracked as the result of thermal shock, a process accelerated during a strong rainstorm.

Figure (see Caption) Figure 104. Arenal's summit as seen looking up the new avalanche chute (steaming). At the head of the chute lies a thick black lava flow (labeled lava front "Frente de colada"). Courtesy of OVSICORI-UNA.

Geologic Background. Conical Volcán Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1670-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. Arenal lies along a volcanic chain that has migrated to the NW from the late-Pleistocene Los Perdidos lava domes through the Pleistocene-to-Holocene Chato volcano, which contains a 500-m-wide, lake-filled summit crater. The earliest known eruptions of Arenal took place about 7000 years ago, and it was active concurrently with Cerro Chato until the activity of Chato ended about 3500 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. An eruptive period that began with a major explosive eruption in 1968 ended in December 2010; continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows characterized the eruption from vents at the summit and on the upper western flank.

Information Contacts: E. Fernández, E. Duarte, W. Sáenz, V. Barboza, M. Martinez, E. Malavassi, and R. Sáenz, Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica (URL: http://www.ovsicori.una.ac.cr/); Jorge Barquero Hernandez, Instituto Costarricense de Electricidad (ICE), Apartado 5 -2400, Desamparados, San José, Costa Rica.


Barren Island (India) — June 2008 Citation iconCite this Report

Barren Island

India

12.278°N, 93.858°E; summit elev. 354 m

All times are local (unless otherwise noted)


Thermal anomalies and red glow indicate that a new eruption started in May 2008

A scientific expedition in February 2008 observed that the morphology of the volcano had changed considerably since 2005. The eruption that began in May 2005 (BGVN 30:05) ejected lava and tephra that built a new scoria cone NE of the previous central cone. Lava flows covered all of the earlier flows, and several new spatter cones were formed. Fumarolic activity was continuing in February, with a large amount of steam from the central cone.

Activity seemingly decreased in late March 2006, as shown by a significant decline in the number and frequency of thermal anomalies (BGVN 32:07). However, intermittent anomalies continued until 5 October 2007, and ash plumes were seen in satellite imagery on 23 December 2007 (BGVN 33:02). Thermal anomalies detected by MODIS instruments began to be detected again on 12 May 2008 at 1935 (UTC), suggesting a renewal of eruptive activity. Anomalies continued to be identified on 19 days through the end of June.

During 15-30 June 2008 observers on an Indian Coast Guard patrol boat could see red glow from the central cone summit at night from a distance of about 10 km. There were also twelve earthquakes between 27 and 29 June, centered SW of Port Blair (140 km SW of Barren Island) in the Andaman Islands.

Geologic Background. Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S volcanic arc extending between Sumatra and Burma (Myanmar). It is the emergent summit of a volcano that rises from a depth of about 2250 m. The small, uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with walls 250-350 m high. The caldera, which is open to the sea on the west, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic-flow and -surge deposits. Historical eruptions have changed the morphology of the pyroclastic cone in the center of the caldera, and lava flows that fill much of the caldera floor have reached the sea along the western coast.

Information Contacts: Dornadula Chandrasekharam, Dept. Earth Sciences, Centre of Studies in Resources Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India (URL: http://www.geos.iitb.ac.in/index.php/dc); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Chaiten (Chile) — June 2008 Citation iconCite this Report

Chaiten

Chile

42.833°S, 72.646°W; summit elev. 1122 m

All times are local (unless otherwise noted)


Events of June-July include diminished plumes, substantial seismicity, and lateral blast

Follow previous reports of May 2008 activity (BGVN 33:04, 33:05), this report summarizes Chaitén's behavior from 31 May through 25 July 2008. The bulk of this report came from SERNAGEOMIN (Servicio Nacional de Geología y Minería) and to some extent ONEMI (Oficina Nacional de Emergencia - Ministerio del Interior). A web camera located on a tower in Chaitén town and aimed upstream along the Blanco (Chaitén) river has helped authorities assess both the state of the volcano's plumes and the river (see URL in Information Contacts). In a later section are included some descriptions and photos by Richard Roscoe taken on 9 July.

On 3 June it was reported that lateral blasts or surges (or related processes) had devastated ~ 25 km2 of native forest. Other behavior during this interval included consistent ash plumes, which were generally present when the volcano was visible, and continued growth of the intracrater dome and tephra cone. Vent areas and the dome and tephra cone's morphology changed as the dome grew more elongate.

The late May to early June behavior included a short-term seismic decrease, and a weakened eruptive column. During the reporting interval, the column was often noticeably weaker than in early May, but the seismicity was still relatively high. The two main seismic instruments monitoring the volcano (figure 13) registered numerous sustained events through late July, which began to cluster NNE of Chaitén. Some of the earthquakes were up to M 2.6.

Figure (see Caption) Figure 13. Monitoring instrumentation includes two telemetered seismic stations, PUMA (short for Pumalín) and STAB (short for Santa Barbara), which sit adjacent the coast and monitor Chaitén volcano (Cv). On 12 July the stations detected two earthquakes centered NE of the volcano along a major fault trace there (the Liquiñe-Ofqui fault system). The colored versions of the map distinguish second-order faults, which mostly have left-lateral kinematics (red lines), and eroded scarps (yellow lines). Snow-covered Michinmahuida stratovolcano is also a prominent feature (M, along the E margin of map), as is the town of Chaitén (Ct). Courtesy of Luis E. Lara.

SERNAGEOMIN repeatedly interpreted the earthquakes to signify magma ascending from depth. If this magma reached the surface, they noted, vigorous eruptions might return. The high-viscosity of rhyolitic magmas seen here increases potential explosivity. This rhyolitic eruption at Chaitén is the first historically at a monitored volcano. The last significant rhyolitic eruption was at Novarupta volcano in Alaska in 1912.

Chaitén town has largely survived the lahars thus far. A deeper concern is that the growing dome and tephra cone sent bouncing rocks and smaller debris into the caldera's moat. In an early July SERNAGEOMIN report, the authors noted that the caldera's breach, located on the S, appeared blocked by recently eroded products. Small lakes were also then seen on the crater floor. Since the moat area drains to the S through this breach and feeds into the Blanco river, temporary dams in the moat area might seal the caldera's outflow, only to suddenly fail and release large volumes of debris towards the town. Despite this concern, as of 25 July such an event had been absent; however, on 12 July a sudden flood struck Chaitén town (see below).

Activity during June 2008. On 1 June, Chaitén's plume blew W, affecting Chiloé island (including the towns of Queilen, Lebjn, Chonchi, Dalcahue, and Castro, the island's capital). These conditions thwarted work on the seismic network. On 2 June dense fog affected the Gulf of Corcovado, especially adjacent Chiloé island, an atmosphere attributed to remobilization of air-fall ash by wind. That day, a helicopter managed to take off and the view enabled scientists to see an eruptive column to no higher than 3.0 km altitude dispersing SSE.

Seismicity on 2 July was higher than the previous days. Abundant were VT earthquakes, followed by long- period (LP) earthquakes. Between 1 and 2 July, seismic stations registered an average of 5 VT earthquakes per hour (below M 2). At some stations, some of the LP signals were sporadic, lasting less than a minute.

A 5 June SERNAGEOMIN report noted that explosions diminished gradually. Although ash was present, vapor dominated the emissions. A 3 June aerial inspection revealed that the dome's volume and footprint had increased, although it still had not reached the caldera's N wall.

The effects of N and NE flank blasts (or surges, pyroclastic flows, or related processes) were noted during aerial observations from the 3 June flight. The surges had scorched and burned an area of native forest. On this day observers computed an estimate of the damaged area, ~ 2,500 hectares (~ 25 km2). An undated photo looking down on part of the destruction appeared in BGVN 33:05 and more photos appear below. Several SERNAGEOMIN reports mentioned small pyroclastic flows during early and mid-May (12 May in particular, BGVN 33:05). Bulletin editors take the 3 June estimate as reflecting the sum of all devastation to that point in time.

On 3 and 4 June the plume's top stood below 3 km altitude. A 10 June SERNAGEOMIN report noted the continued lowered eruptive and seismic intensity through that time. Plumes continued to remain under 3 km altitude and they still affected air travel.

On 12 June observers at Chaitén town noticed tephra-bearing emissions. Noises had emanated from the volcano that day and the previous one. The SERNAGEOMIN report associated these emissions with two new vents seen on the S flank of the old dome, where craters had developed. Vapor-rich plumes had emerged from these areas and the observers inferred that the vents were possibly due to magma-water interactions. In addition, sudden floods swept into Chaitén town in the afternoon on 12 June, despite a lack of evidence for greater rains across the region. They were inferred as related to the emissions the same day.

Seismicity beneath the volcano on 12 June increased in the morning both in terms of the number of earthquakes and their magnitudes. Most of these events were less than M 2. Two prominent earthquakes struck ~ 5 km farther NE of the volcano, along the Liquiñe-Ofqui fault zone.

The 22 June report noted that observers looking at the contact between the old and new domes had seen two craters there that emitted ash plumes. The observers also noted near-source falls of both blocks and ash.

The same report said that a 17 June aerial inspection documented an ash plume to over 2 km over the volcano's summit that blew N and NW. Roars and associated noise from the eruption included the sound of an explosion at 1430 on 17 June. The resulting column rose to a height above the summit of over 3 km but later dropped to 2 km. Emissions continued from a crater S of the contact between the old and new domes. Immediately to the W of this crater, a new and growing crater issued increasingly large emissions of ash and gas. Numerous smaller vents were also apparent, chiefly emitting steam. Loose material covered parts of the old dome, forming a ring-shaped structure (a tephra cone). That structure's steep sides and inner and outer walls occasionally underwent mass wasting. Poor weather during 19-25 June halted aerial inspections then, but ash fell in Chaitén town and to the W and SE, as well as Queilen and other portions of E Chiloé island.

Following 20 June, seismicity remained stable with ~ 40-45 earthquakes per day. Sporadic numbers of VT earthquakes took place; there was no change in the number of LP earthquakes. Investigators inferred a lack of pressure increase in the volcanic system. During bad weather on 23-25 June some earthquakes again occurred on the Liquiñe-Ofqui fault zone, with epicenters in an area 2-3 km E of the volcano. A power outage struck midday on 25 June. A back-up power supply (UPS) worked for a while, but ultimately the outage caused several hours of lost seismic data at the Queilen processing center. Available data suggested a small increase in both the number and amplitudes of earthquakes during 24-25 June. During 0000-1200 on 25 June, instruments recorded 35 VT earthquakes, and four of those were M 2.2; LP earthquakes were absent.

Seismicity during the days leading up the SERNAGEOMIN report issued on 27 June reflected VT earthquakes generally below M 2, reaching 50 per day. An exception was on the 25th when four earthquakes exceeded M 2.0.

July 2008. On 1 July an ash column rose ~ 3 km above the top of the new dome. It blew N and NE. An aerial observation at close hand discerned two roughly vertical, sub-parallel eruption plumes issuing from vents in the crater. One plume, most active in recent weeks, came from a sector S of the new dome. The second plume came from a sector more to the W of the new dome. A photo of the scene in the 3 July SERNAGEOMIN report also depicted the area of eruption largely engulfed in white clouds from numerous fumaroles on the dome. On 3 July SERNAGEOMIN began a series of reports on unrest at Llaima stratovolcano (which went to Red alert on 10 July). Around 16 July a weather front also moved in across the Chiloé island region. Consecutive SERNAGEOMIN reports discussing Chaitén were only issued on 3 and 21 July, with a lack of much discussion on that volcano for the interval 3-15 July.

During 15-20 July seismicity stood relatively high, with an average of 350-400 VT earthquakes per day. On 20 July more than 20 earthquakes surpassed M 2.6. The next reports noted that on 21 and 22 July VT earthquakes occurred 330 times per day; 60 of those were near M 2.6, and that the number of earthquakes decreased on 24 July. Still, some of the minor earthquakes reached M 2.6 and were detected up to 300 km away. Seismic data around this time were interpreted to reflect magma at depth moving towards the surface, possibly implying a reactivation of the system, although the earthquake's depth was poorly constrained.

Chaitén's plume blew E at ~ 2 km altitude above the summit and appeared weaker than usual when seen as the weather cleared after 1500 on 23 July. During 22-24 July, earthquakes had increased both in number and magnitude, with the largest M ~ 2.6.

A new area of epicenters appeared during 22 and 23 July at a location 6 km ENE of the volcano. Seismic stations located 176 and 296 km from Chaitén, respectively monitoring the volcanoes Calbuco and Puyehue-Cordón Caulle, recorded these events, the first such occurrence since the eruption began. Previously, conspicuous epicenters had mainly occurred to the S and SE. Preliminary hypocenter calculations suggested the larger earthquakes in this NNE area were deeper, at 10-15 km depth.

Arrival times of S- and P-waves at stations Pumalín and Santa Bárbara indicated that the smaller magnitude earthquakes still occurred S and SE of Chaitén, whereas the larger magnitude earthquakes struck in the area 6 km ENE. An inspection flight carried viewers to the N and NE of the volcano on 24 July where they saw that the single active central vent sat to the S of the new dome. The emissions then were intermittent, white, and ash poor. When strongest, a thin plume rose to under 2 km altitude, with strong winds causing dispersion to the S and SE. When viewed on 24 July, the new dome also contained a significant depression in the S sector, at a point immediately N of the main active vent mentioned above. This depression emitted steam and gases. The new dome seemed to have decreased its growth rate, at least in the N sector. Strong steaming emerged from base of the dome's E sector. The observers looked around the new dome on the NW, N and NE sides, and they saw neither ponded areas nor lakes. During 24-27 July, the ash column rose to 2.5 km and occasionally 3.0 km altitude. The most active vent was the previously mentioned one located S of the new dome. The plume blew N and NW where it affected various localities along the coast.

Floating pumice. By early June, the white pumice from the eruption accumulated at river mouths to the volcano's W. Some fragments of pumice were as large as 40 cm in diameter. In addition to the Blanco river, those carrying the pumice included the Yelcho and Negro (respectively entering the sea 2 km and 5 km S of Chaitén town). Pumice rafts in the Gulf were seen in May (BGVN 33:05). During June and at least early July, along beaches of Chiloé (and particularly at Lelbjn, 12 km N of Queilen, a town almost directly W of Chaitén town) floating pumice continued to arrive. This area lies 60-100 km across Corcorvado gulf from the mouth of the Blanco river at Chaitén town. The pumice deposits, which included tree trunks and other debris, covered a thin zone along the shoreline stretching ~ 20 m from the sea's edge when photographed the afternoon of 1 July.

Roscoe's July 2008 photos. One of the subjects Roscoe presented on his PhotoVolcanica website was Chaitén's N devastated area, and some of those photos appear here (figures 14 and 15). The captions were brief and omitted the direction the camera was aimed. He visited the devastated area on 9 July 2008.

Figure (see Caption) Figure 14. One of the parts of the devastation zone containing large lithic blocks (~ 1 m across), the most conspicuous being the one at left, which may have been perched above fallen timber. Trees here fell away from the viewer. Courtesy of Richard Roscoe, PhotoVolcanica.com.
Figure (see Caption) Figure 15. Drainages redirected by Chaitén's eruption caused erosion of this road to the volcano's N. Courtesy of Richard Roscoe, PhotoVolcanica.com.

Roscoe noted that in the area he photographed, "Most trees were snapped off a couple of meters above the ground. The [pyroclastic] flow does not appear to have been hot enough to burn the leaves off the trees at the point we visited at the base of the volcano. Many branches with brown leaves were lying around. Very little pumice was found in the area although much of it may have been swept away during subsequent heavy rainfall."

In Chaitén town, Roscoe documented damage-mitigation and salvaging efforts (figure 16). Two of Roscoe's photos showed heavy equipment (a large backhoe and a bulldozer) reshaping the lahar deposits in an attempt to control encroaching lahars. Other scenes included people retrieving belongings, excavating lahar deposits covering the floor and lower shelves of a grocery store, and improving drainage from and access to their homes.

Figure (see Caption) Figure 16. Work in Chaitén town to strengthen river banks to protect town from lahars. Although laden with tree trunks, the lahars appear quite uniform in color and character, devoid of coarse lithics or large rafted pumices. Courtesy of Richard Roscoe, PhotoVolcanica.com.

Geologic Background. Chaitén is a small, glacier-free caldera with a compound Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. Early work had identified only a single explosive eruption during the early Holocene prior to the major 2008 eruption, but later work has identified multiple explosive eruptions throughout the Holocene. A rhyolitic obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km from the volcano to the N and S. The caldera is breached on the SW side by a river that drains to the bay of Chaitén. The first historical eruption, beginning in 2008, produced major rhyolitic explosive activity and growth of a lava dome that filled much of the caldera.

Information Contacts: Servicio Nacional de Geología y Minería(SERNAGEOMIN), Avda Sta María No 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI), Beaucheff 1637 / 1671, Santiago, Chile (URL: http://www.onemi.cl/); Luis E. Lara, Departamento de Geología Aplicada, SERNAGEOMIN; Richard Roscoe, Photovolcanica.com (URL: http://www.photovolcanica.com/).


Erta Ale (Ethiopia) — June 2008 Citation iconCite this Report

Erta Ale

Ethiopia

13.6°N, 40.67°E; summit elev. 613 m

All times are local (unless otherwise noted)


Active lava lake visited in February 2008

Around 2-3 February 2008, a Volcano Discovery tour visited Erta Ale (figures 18-21). Tom Pfeiffer reported that the northern pit crater contained a lake of molten lava ~ 75 m across. Strong spattering and bursting bubbles were seen. At times, the lava lake rose and flooded the lower terrace. During this phase the usual fountains ceased. Richard Roscoe, who also visited during February 2008, presents animations of the flooding on his Photovolcanica website. He also shows photos of strong fountaining associated with falling lava lake levels.

Figure (see Caption) Figure 18. Wide-angle photo showing the lava lake at Erta Ale, February 2008. Taken with fisheye-lens and a digital reflex camera. Courtesy Marco Fulle.
Figure (see Caption) Figure 19. Folds developed in the crust of the lava lake at Erta Ale, February 2008. Courtesy of Tom Pfeiffer (Volcano Discovery).
Figure (see Caption) Figure 20. Rising magmatic gases drove fountains like this one emerging above the surface of the lava lake at Erta Ale, February 2008. Courtesy of Tom Pfeiffer (Volcano Discovery).
Figure (see Caption) Figure 21. Unusual egg-like sulfate structures at Erta Ale in February 2008. The delicate-looking incrustations cover an area of wet fumaroles on the rim of the North crater. Courtesy of Tom Pfeiffer (Volcano Discovery).

Occasionally, magmatic gas released in the middle of the lake created a zone a few meters in diameter where fountains typically lasted ~ 1 minute (figure 20). Thin threads of lava (Pelee's hair) are visible in some lava-fountain photographs. Richard Roscoe also features similar photos. Marco Fulle noted strong spattering when lava was drawn down (subducted) into the lake.

A Volcanologique de Genève (SVG) trip on 8-9 February 2008 noted extensions of ropy lava in the N crater. The lake was little changed from the group's last visit in 2005. The group visited the N Crater, and, given its constant degassing, was able to take gas samples. They also measured the lake's surface temperature (700°C). The descent into this crater, seemingly easy, was made difficult by a mantle of very unstable lava scoria. An elevated level of the lava lake halted a subsequent descent.

References. Rivallin, P., and Mougin, D., 2008, Trip report of Pierrette Rivallin and Dédé Mougin: LAVE Bulletin, no. 79, May 2008.

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

Information Contacts: Tom Pfeiffer, Volcano Discovery (URL: http://www.VolcanoDiscovery.com/); Marco Fulle, Osservatorio Astronomico, Trieste, Italy; Richard Roscoe (URL: http://www.photovolcanica.com/).


Ol Doinyo Lengai (Tanzania) — June 2008 Citation iconCite this Report

Ol Doinyo Lengai

Tanzania

2.764°S, 35.914°E; summit elev. 2962 m

All times are local (unless otherwise noted)


Explosive eruptions continue into June 2008

According to government authorities in the Ngorongoro district of Tanzania and the 22 March 2008 edition of Arusha Times, nine months after the mountain began continuous eruptive activity (BGVN 33:02), many residents had moved to other villages at a safe distance. Ngorongoro district member of parliament Saning'o Ole Telele told reporters that up to 5,000 people may have moved out of the area. The last major eruption was in August 1966. Since then there had not been an eruption of such magnitude, although notable ones were recorded in 1983, 1993, 2002 and 2006.

Recent observations. Table 19 lists recent observations from April through early July 2008.

On 2 April 2008, Chris Daborn of Tropical Veterinary Services Ltd reported that the color of ash plumes changed from "salty" white to a more inert black, and eruptions were much smaller, barely rising above the mountain. Heavy rains made movement in the area difficult, washing away ash.

Table 19. Summary of visitors to Ol Doinyo Lengai and their brief observations (from a climb, aerial overflight, flank, or satellite) April-early July 2008 (continued from BGVN 33:02). Most of this list is courtesy of Frederick Belton.

Date Observer Observation Location Brief Observations
02 Apr 2008 Chris Daborn Flank? See text.
03 Apr 2008 Jurgis Klaudius Satellite MODIS thermal anomaly data from N crater indicated that eruptions continued (see table 20).
07-08 Apr 2008 Ben Wilhelmi Aerial See text.
early Apr 2008 Ben Wilhelmi, Michael Dalton-Smith Aerial See text.
17 Apr 2008 Matthieu Kervyn Satellite MODIS/MODLEN data indicated a significant hotspot on Lengai on 17 April, showing that activity, although intermittent, continued (see text).
14-16 May 2008 Chris Weber, Marc Szeglat Climb See text.
03, 10, 12 Jun 2008 Ben Wilhelmi Aerial No activity observed.
08 Jun 2008 Ben Wilhelmi Aerial Ash eruption.
12 Jun 2008 Fred Belton Aerial? Ash-poor plume above Lengai ~1500 m.
17 Jun 2008 Local Masaai from Engare Sero village Climb Climbed Lengai via the W route through the Pearly Gates (closed to climbers for several months due to dangerous activity).
18 Jun 2008 Fred Belton, Paul Hloben, Paul Mongi, Mweena Hosa, Peter (Masaai guide) Climb See text.
18 Jun 2008 Ben Wilhelmi Aerial See text.
19 Jun 2008 Ben Wilhelmi Aerial No activity observed.
30 Jun 2008 Ben Wilhelmi Aerial Gray plumes emerging from crater.
01 Jul 2008 Ben Wilhelmi Aerial Small collapse of the S part of the new crater rim.

Ben Wilhelmi flew over on 7 and 8 April 2008 just prior to an eruption on the 7th and following the start of an eruption on the 8th. The flanks showed newly formed erosion gullies in the recently deposited ash (figure 111). Pilots Wilhelmi and Michael Dalton-Smith observed little activity during early April, although visibility was hampered by atmospheric clouds on several occasions; aerial photos showed no activity on 11 April.

Figure (see Caption) Figure 111. Aerial photographs of Ol Doinyo Lengai crater on (a, top) 7 April and (b, bottom) 8 April 2008. Photos courtesy Ben Wilhelmi.

On 14-16 May 2008, Chris Weber and Marc Szeglat visited. Weber noted that only minor ash eruptions were reported by local Masaai after the eruptions on 8 and 17 April 2008. Some of the evacuated Masaai had returned to their settlements, but part of the livestock had not returned by the middle of May. The fall-out of pyroclastics was still visible around the volcano. Due to a heavy rain season, vegetation damage was not as severe as it could have been. Up to an altitude of ~ 1,000 m the vegetation (mostly 'Elephant grass', normal grass, and some Akazia trees) was undamaged except for the W side, where severe damage occurred as far as 10 km from the summit. Some lahars had occurred on the N and NE sides. The former trekking route was not recommended because of rockfalls and poor conditions. Weber and Szeglat used a very steep route on the SE side (named "simba route"). From ~ 1,000 m altitude ash layers were clearly visible on the ground, but new grass had grown since the eruption. Above ~ 1,500 m on the SE flank all vegetation was covered by pyroclastic material. From an altitude of ~ 2,500 m, additional impacts of volcanic bombs were visible. In the inactive S crater, at their campsite, all vegetation was destroyed, and volcanic bomb impacts from the explosive events on April 2008 were quite impressive.

The active N crater had a new morphology (figure 112). The N-S diameter of the crater was 300 m and it was 283 m E-W. The crater floor was at ~ 2,740 m elevation, ~ 130 m deep below the W crater rim. Two vents, designated as c1 and c2, were present inside the crater (figure 112). Both vents were strongly degassing. On 15 May 2008, fine powdered ash was ejected until midday. It was not possible to determine which vent was responsible for this. After descent, Weber and Szeglat visited an abandoned Masaai boma (hut) a few kilometers W of the summit where ashfall had forced a family to flee.

Figure (see Caption) Figure 112. (a) Sketch map of Lengai, May 2008, and (b) cross section AB. Two vents were located as c1 and c2 inside the crater; older hornito locations are marked as Txx on the map (see hornitos on sketch map of Lengai as of 23 August 2007 in BGVN 32:11). Courtesy of Chris Weber.

On 8 June Wilhelmi saw a small eruption during a flyover. Photos made by Wilhelmi during overflights on 3, 10, and 12 June showed no activity. However, an ash-poor plume was seen by Fred Belton on 12 June.

On 17 June 2008 a group of Masaai from Engare Sero climbed via the W route through the Pearly Gates, which has been closed for several months. Fred Belton and Paul Hloben climbed on 18 June with a Masaai guide, Peter, and two other Tanzanians Paul Mongi and Mweena Hosa, following the route of the group from the previous day, which was covered by thick ash deposits. The route is subject to danger should there be a significant eruption. Belton's group spent about an hour on the rim of the active cone.

The new active cone covered the former crater floor entirely except for a region just N of the summit. The W, N, and E sides of the former crater were ~ 30 m higher than before and enclosed a deep pit crater with a couple of small vents. To the S, the rim of the new cone rested on the crater floor. To the E and W the new cone merged with and covered up the old rim at the points where it intersects the arc formed by the summit ridge. Thus, there was a section of the former crater floor which was bounded to the N by the new cone's S rim and to the E, S, and W by the original curving summit ridge.

From approximately 0920-1020 the pit crater frequently emitted an ash-poor plume from the SW part of its floor, and there was light ashfall on the rim. Loud rumbling was continuous and occasional sounds of gas jetting and rockfalls were heard amid other noises. Occasionally there was a sloshing/hissing noise resembling the sound of 'lava at depth' often heard in the past, but there was no evidence of lava in the crater. The summit and S crater were not visited due to atmospheric clouds around the summit.

On 18 June, Ben Wilhelmi photographed the climbers with Belton during a flyover (figure 113). No activity was seen the next day, but on 30 June Wilhelmi saw gray plumes emerging. A small crater rim collapse was seen on the S part of the crater wall on 1 July 2008.

Figure (see Caption) Figure 113. View of the crater rim on 18 June 2008 showing four climbers at left center just below the rim. Photo courtesy of Ben Wilhelmi.

Satellite thermal anomalies. Table 20 lists MODIS/MODVOLC thermal anomalies measured between November 2007 through July 2008; MODVOLC is the algorithm for identifying thermal anomalies used by the HIGP Thermal Alerts System Group. On 17 April 2008, as noted in table 19, MODIS data analyzed by Matthieu Kervyn's algorithm MODLEN (sensitive to lower temperature anomalies than MODVOLC) indicated a significant hotspot, showing that activity, although intermittent, continued.

Table 20. MODVOLC thermal anomalies measured by MODIS satellite at Ol Doinyo Lengai from November 2007 through July 2008. Courtesy of the MODIS Thermal Alerts System Group at the Hawai'i Institute of Geophysics and Planetology (HIGP).

Date Time (UTC) Number of pixels Satellite
17 Nov 2007 2000 2 Terra
31 Nov 2007 2310 1 Aqua
30 Dec 2007 0815 1 Terra
08 Jan 2008 2030 2 Terra
17 Jan 2008 2025 2 Terra
17 Feb 2008 2240 3 Aqua
22 Feb 2008 2300 1 Aqua
28 Feb 2008 1135 1 Aqua
29 Feb 2008 2305 1 Aqua
07 Mar 2008 2310 1 Aqua
10 Mar 2008 2045 4 Terra
03 Apr 2008 1955 1 Terra

Geologic Background. The symmetrical Ol Doinyo Lengai is the only volcano known to have erupted carbonatite tephras and lavas in historical time. The prominent stratovolcano, known to the Maasai as "The Mountain of God," rises abruptly above the broad plain south of Lake Natron in the Gregory Rift Valley. The cone-building stage ended about 15,000 years ago and was followed by periodic ejection of natrocarbonatitic and nephelinite tephra during the Holocene. Historical eruptions have consisted of smaller tephra ejections and emission of numerous natrocarbonatitic lava flows on the floor of the summit crater and occasionally down the upper flanks. The depth and morphology of the northern crater have changed dramatically during the course of historical eruptions, ranging from steep crater walls about 200 m deep in the mid-20th century to shallow platforms mostly filling the crater. Long-term lava effusion in the summit crater beginning in 1983 had by the turn of the century mostly filled the northern crater; by late 1998 lava had begun overflowing the crater rim.

Information Contacts: Frederick Belton, Developmental Studies Department, PO Box 16, Middle Tennessee State University, Murfreesboro, TN 37132, USA (URL: http://oldoinyolengai.pbworks.com/); Christoph Weber, Volcano Expeditions International (VEI), Muehlweg 11, 74199, Entergruppenbach, Germany (URL: http://www.volcanic-hazards.de/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Matthieu Kervyn De Meerendre, Dept of Geology and Soil Science, Gent University, Krijgslaan 281, S8/A.310, B-9000 Ghent, Belgium (URL: http://homepages.vub.ac.be/~makervyn/).


Llaima (Chile) — June 2008 Citation iconCite this Report

Llaima

Chile

38.692°S, 71.729°W; summit elev. 3125 m

All times are local (unless otherwise noted)


Summary of January-February 2008 eruption; minor eruptions late March-early April 2008

A report from OVDAS-SERNAGEOMIN (Volcanological Observatory of the Southern Andes ? National Service of Geology and Mining) by Naranjo, Peña, and Moreno (2008) summarized the eruption at Llaima of January through February 2008. This and other reports from OVDAS-SERNAGEOMIN supplements earlier reports (BGVN 33:01) and extends observations through late April 2008.

Summary of January-February 2008 eruption. Shortly after 1730 (local time) on 1 January 2008, Llaima began a new eruptive cycle that was very similar in character to a large eruption that had occurred in February 1957. The 2008 activity was centered at the principal crater, a feature 350 x 450 m in diameter with the major axis trending NW-SE. This new continuous eruptive phase began with strong Strombolian eruptions. Strong ejections of lava fragments fell on the glaciers on the high flanks NE and W of the principal cone (figure 18), generating lahars that flowed ~15 km to reach the Captrén River to the N and the Calbuco River to the W (figure 19). The eruptive plume rose to an altitude of ~ 11 km and blew ESE; ash accumulated to a depth of ~11 cm at a distance of 7 km from the crater.

Figure (see Caption) Figure 18. Satellite images depicting Llaima before and after the recent eruptions. The left image shows Llaima on 17 September 2006 covered with a white blanket of snow and ice; the right image shows Llaima on 22 February 2008 after numerous eruptions, with ash covering the remnants of the glacier. Courtesy of the Japan Aerospace Exploration Agency-Earth Observation Research Center (JAXA-EORC) Advanced Land-Observing Satellite (ALOS) website.
Figure (see Caption) Figure 19. Map showing areas of principal effects of the eruption at Llaima on 1 January 2008. Courtesy of OVDAS-SERNAGEOMIN.

The 1 January 2008 phase was preceded by a slight increase in tremor and a swarm of low frequency earthquakes, but with an absence of volcano-tectonic (VT) or hybrid (HB) events. On 2 January 2008, the activity began to decline. However, a plume of sulfur dioxide (SO2) was tracked by satellite (figure 20).

Figure (see Caption) Figure 20. A plume of sulfur dioxide (SO2) was released on 2 January 2008. The initially intense plume thinned as it moved E. On 4 January 2008, the plume passed over Tristan da Cunha. This image, acquired by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite, shows the progress of that plume from 2-4 January 2008. OMI measures the total column amount of SO2 in Dobson Units. (If all the SO2 in a column of atmosphere is compressed into a flat layer at standard temperature (0°C) and pressure (1 atmosphere), a single Dobson Unit of SO2 would measure 0.01 mm in thickness and would contain 0.0285 grams of SO2/m2.) Courtesy, NASA Earth Observatory website.

An explosion on 7 January 2008 resulted in an ash plume that rose 5 km above the crater and traveled E toward Argentina. This explosion was associated with a low frequency, large magnitude event.

On 9 January, a series of explosions occurred. The seismicity included a swarm of low frequency, high-amplitude events and an abrupt increase in microseismicity that decreased gradually until 14 January and more slowly thereafter. On 18 January, after discrete low frequency tremors, explosions from the crater resulted in a pyroclastic flow on the upper E flank (figure 21).

Figure (see Caption) Figure 21. Pyroclastic flow on Llaima's E flank on 18 January 2008. Courtesy, OVDAS-SERNAGEOMIN and Gentileza M. Yarur.

On 21 January seismic activity increased. This was followed on 25 January by continuous Strombolian activity in the main crater. During the night of 26 January, a significant increase in activity occured. Pyroclastic-flow deposits were noted during 28 January on the E flank.

A lava lake that had formed in the main crater began to overflow the W rim on 3 February and a lava flow descended for 2.5 km, making channels in the ice tens of meters deep. The 'a'a lava flow, which was 30-40 m wide and 10 m thick, lasted until 13 February.

Between 8-13 February, explosions in the main crater propelled incandescent material 200-500 m in the air. Explosions occasionally alternated between N and S cones in the main crater. On 9 February, the Calbuco River was about 1 m higher than the normal level, likely due to melt water from the lava and glacier interaction. Strombolian eruptions from the main crater were observed during an overflight on 10 February. A strong explosion ejected bombs onto the E and NE flanks of the volcano on 12 February. Then, on 13 February, incandescence at the summit was noted. Thereafter seismic activity decreased, with only sporadic low frequency signals. The volcano was quiet until 21 February, when a small explosion occurred. Pyroclastic flows were also observed on 21 February descending the E and possibly the W flanks.

During the January-February eruptive phase, various types of plumes were observed, including steam plumes, sulfur dioxide plumes, small ash plumes, and ash-and-gas plumes. The Alert Level remained at Yellow.

March-April 2008. Fumarolic activity from the central pyroclastic cone in Llaima's main crater reactivated on 13 March and intensified during 15-17 March. SO2 plumes rose to an altitude of 3.6 km and drifted E. During 20-21 March, incandescent material propelled from the crater was observed at night.

During 28 March-4 April, fumarolic plumes from Llaima drifted several tens of kilometers, mainly to the SE. Explosions produced ash and gas emissions, and on 4 April, incandescence was reflected in a gas-and-ash plume. An overflight of the main crater on 2 April revealed pyroclastic material and ash and gas emissions, accompanied by small explosions, that originated from three cones.

On 24 April 2008, seismicity from Llaima again increased. Bluish gas (SO2) rose from the main crater, and ash-and-gas plumes associated with explosions rose to an altitude of 4.6 km. No morphological changes to the summit were observed during an overflight on 25 April except for a small increase of the diameter of the SE crater.

Thermal anomalies. Thermal anomalies measured by MODIS in 2008 began with an eruption on 1 January 2008 (BGVN 33:01) and continued almost daily through 13 February (table 3). Following a brief period of no measured anomalies, a new group occurred 30 March through 4 April, after which none were recorded through 1 June 2008. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images and reports by ground observers from Projecto Observación Visual Volcán Llaima (POVI) indicated incandescence at the volcano during periods when no anomalies were measured by the MODIS satellites (19-21 March and 24 April 2008), perhaps due to cloud cover. All periods of reported incandescence by ground observers during January 2008 were substantiated by MODIS measured thermal anomalies.

Table 3. MODIS thermal anomalies over Llaima from February through 1 June 2008; data processed by MODVOLC analysis. Daily anomalies were measured from 1-13 February 2008, followed by no anomalies through 29 March. After a period of anomalies from 30 March through 4 April 2008, none were measured through 1 June 2008. Some absences may be due to weather. Courtesy of HIGP Thermal Alerts System.

Date Time (UTC) Pixels Satellite
01 Feb 2008 0305 2 Terra
01 Feb 2008 0620 2 Aqua
01 Feb 2008 1405 1 Terra
01 Feb 2008 1820 1 Aqua
02 Feb 2008 0345 2 Terra
02 Feb 2008 0525 1 Aqua
02 Feb 2008 1450 2 Terra
03 Feb 2008 0250 4 Terra
03 Feb 2008 0430 4 Terra
03 Feb 2008 0605 2 Aqua
03 Feb 2008 1355 1 Terra
03 Feb 2008 1535 2 Terra
03 Feb 2008 1810 1 Aqua
04 Feb 2008 0335 4 Terra
04 Feb 2008 0510 6 Aqua
04 Feb 2008 1850 2 Aqua
05 Feb 2008 0415 2 Terra
05 Feb 2008 0555 4 Aqua
05 Feb 2008 1520 2 Terra
06 Feb 2008 0320 3 Terra
06 Feb 2008 0500 3 Aqua
06 Feb 2008 0640 4 Aqua
06 Feb 2008 1425 2 Terra
07 Feb 2008 0405 4 Terra
07 Feb 2008 0545 2 Aqua
07 Feb 2008 1510 2 Terra
08 Feb 2008 0625 6 Aqua
08 Feb 2008 1415 3 Terra
09 Feb 2008 0350 3 Terra
09 Feb 2008 0530 6 Aqua
09 Feb 2008 1455 2 Terra
09 Feb 2008 1910 2 Aqua
10 Feb 2008 0255 4 Terra
10 Feb 2008 0435 4 Aqua
10 Feb 2008 0615 5 Aqua
10 Feb 2008 1540 4 Terra
11 Feb 2008 0340 4 Terra
11 Feb 2008 0520 4 Aqua
11 Feb 2008 1445 5 Terra
11 Feb 2008 1855 1 Aqua
12 Feb 2008 0425 4 Terra
12 Feb 2008 0600 7 Aqua
12 Feb 2008 1525 5 Terra
12 Feb 2008 1940 4 Aqua
13 Feb 2008 0330 2 Terra
13 Feb 2008 0645 2 Aqua
30 Mar 2008 0340 1 Terra
01 Apr 2008 0505 1 Aqua
02 Apr 2008 0550 1 Aqua
04 Apr 2008 0400 1 Terra
04 Apr 2008 0535 2 Aqua

Reference. Naranjo, J.A., Peña, P., and Moreno, H., 2008, Summary of the eruption at Llaima through February 2008: National Service of Geology and Mining (Servico Nacional de Geologia y Mineria - SERNAGEOMIN).

Geologic Background. Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other, Pichillaima, to the SE. The massive, dominantly basaltic-to-andesitic, stratovolcano has a volume of 400 km3. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following the eruption of the 24 km3 Curacautín Ignimbrite. More than 40 scoria cones dot the volcano's flanks. Following the end of an explosive stage about 7200 years ago, construction of the present edifice began, characterized by Strombolian, Hawaiian, and infrequent subplinian eruptions. Frequent moderate explosive eruptions with occasional lava flows have been recorded since the 17th century.

Information Contacts: OVDAS-SERNAGEOMIN (Observatorio Volcanológico de los Andes del Sur-Servico Nacional de Geologia y Mineria) (Southern Andes Volcanological Observatory-National Geology and Mining Service), Avda Sta María 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); 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/productos.php); POVI (Projecto Observación Visual Volcán Llaima) (Project of Visual Observation of Llaima Volcano) (URL: http://www.povi.cl/llaima/); Japan Aerospace Exploration Agency-Earth Observation Research Center (JAXA-EORC) (URL: http://www.eorc.jaxa.jp/); ONEMI (Oficina Nacional de Emergencia - Ministerio del Interior) (National Bureau of Emergency - Ministry of Interior), Chile (URL: http://www.onemi.cl/).


Okmok (United States) — June 2008 Citation iconCite this Report

Okmok

United States

53.43°N, 168.13°W; summit elev. 1073 m

All times are local (unless otherwise noted)


Large explosive eruption started on 12 July, ash plumes initially rose to 15.2 km altitude

The Alaska Volcano Observatory (AVO) reported that on 12 July 2008 at 1143 a strong explosive eruption at Okmok began abruptly after about an hour of rapidly escalating earthquake activity. The Volcano Alert Level was raised to Warning and the Aviation Color Code was raised to Red from the previous Alert Level of Normal/Green. The last explosive eruption began on 13 February, 1997 (BGVN 22:01) from a cone on the south side of the caldera floor. Lava flowed across the caldera floor until 9 May. Ash plumes generally rose to altitudes of 1.5-4.9 km from 13 February to about 23 May, when thermal anomalies and plumes were no longer seen on satellite imagery. One ash plume rose to an altitude of 10.5 km on 11 March. In May 2001 a small seismic swarm (BGVN 26:08) was detected in the vicinity of the volcano. The earthquake locations could not be pinpointed because Okmok is not monitored by a local seismic network.

The initial phase of the 2008 eruption was very explosive, with high levels of seismicity that peaked at 2200 then began to decline. A wet gas-and-ash-rich plume was estimated to have risen to altitudes of 10.7-15.2 km or greater. Wet, sand-sized ash fell within minutes of the onset of the eruption in Fort Glenn, about 10 km WSW. Heavy ashfall occurred on the eastern portion of Umnak Island; a dusting of ash that started at 0345 also occurred for several hours about 105 km NE in Unalaska/Dutch Harbor. News media reported that residents of Umnak Island heard thundering noises the morning of 12 July and quickly realized an eruption had begun. After calling the US Coast Guard for assistance, they began to evacuate to Unalaska using a small helicopter. A fishing boat evacuated the remaining residents after heavy ashfall made further flights impossible.

On 13 July, reports from Unalaska indicated no ashfall had occurred in Unalaska/Dutch Harbor since the previous night. The National Weather Service reported that the ash plume rose to an altitude of 13.7 km (figure 1). Plumes drifted SE and E. Based on observations of satellite imagery, the ash plume altitude was 9.1 km and drifted SE. However, satellite tracking of the ash cloud by traditional techniques was hampered by the high water content due to interaction of rising magma with very shallow groundwater and surficial water inside the caldera.

Figure (see Caption) Figure 1. Photograph of Okmok by flight attendant Kelly Reeves during Alaska airlines flight on 13 July 2008. Image courtesy of Alaska Airlines.

Ash erupted from a vent or vents near composite cinder cone called Cone D in the eastern portion of the 9.7-km wide caldera. Activity during the past three significant eruptions (1945, 1958, and 1997) occurred from Cone A, a cinder cone on the far western portion of the caldera floor. Each of the three previous eruptions was generally mildly to moderately explosive with most ash clouds produced rising to less than 9.1 km altitude. Each eruption also produced a lava flow that traveled about 5 km across the caldera floor.

AVO reported that during 15-16 July seismicity changed from nearly continuous to episodic volcanic tremor, and the overall seismic intensity declined. Little to no ash was detected by satellite, but meteorological clouds obscured views. Satellite imagery from 0533 on 16 July indicated elevated surface temperatures in the NE sector of the caldera. On 16 July, a light dusting of ash was reported in Unalaska/Dutch Harbor. A plume at an altitude of 9.1 km was visible on satellite imagery at 0800. On 17 July, a pilot reported that an ash plume rose to altitudes of 4.6-6.1 km and drifted E and NE. The sulfur dioxide plume had drifted at least as far as eastern Montana (figure 2). On 18 July, the eruption was episodic, with occasional ash-producing explosions occurring every 15 to 30 minutes. The plumes from these explosions were limited to about 6.1 km.

Figure (see Caption) Figure 2. OMI composite image from NOAA showing the extent of the sulfur dioxide gas cloud from the eruption of Okmok imaged at about 1200 AKDT on 17 July, 2008. The large mass shows the location of the high altitude sulfur dioxide cloud from the main explosive phase on 12 July 2008. Image created by Rick Wessels (AVO); courtesy of the OMI near-real-time decision support project funded by NASA.

Geologic Background. The broad, basaltic Okmok shield volcano, which forms the NE end of Umnak Island, has a dramatically different profile than most other Aleutian volcanoes. The summit of the low, 35-km-wide volcano is cut by two overlapping 10-km-wide calderas formed during eruptions about 12,000 and 2050 years ago that produced dacitic pyroclastic flows that reached the coast. More than 60 tephra layers from Okmok have been found overlying the 12,000-year-old caldera-forming tephra layer. Numerous satellitic cones and lava domes dot the flanks of the volcano down to the coast, including 1253-m Mount Tulik on the SE flank, which is almost 200 m higher than the caldera rim. Some of the post-caldera cones show evidence of wave-cut lake terraces; the more recent cones, some of which have been active historically, were formed after the caldera lake, once 150 m deep, disappeared. Hot springs and fumaroles are found within the caldera. Historical eruptions have occurred since 1805 from cinder cones within the caldera.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA; Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA; and Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://www.avo.alaska.edu/); Associated Press (URL: http://www.ap.org/).


Papandayan (Indonesia) — June 2008 Citation iconCite this Report

Papandayan

Indonesia

7.32°S, 107.73°E; summit elev. 2665 m

All times are local (unless otherwise noted)


Minor seismic activity and fumarolic plumes through 16 April 2008

Our last report on Papandayan (BGVN 29:08) described a modest surge in seismicity that began in July 2004, which rose for a short time but began to subside in mid-August 2004. We received no subsequent reports until June 2005. This report discusses non-eruptive restlessness from early June 2005 through the middle of April 2008, including wide fumarolic temperature variations, seismicity, and occasional minor steam plumes.

Beginning in early June 2005, the number of volcanic earthquakes increased in comparison to the previous months, and fumarole temperatures increased 3-9°C above normal levels. People were not permitted to visit Mas and Baru craters. On 16 June 2005, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) in Indonesia raised the Alert Level at Papandayan from 1 to 2 (on a scale of 1-4) due to increased activity at the volcano. The Alert Level remained at 2 at least through 13 December 2005.

No subsequent reports were received until July 2007. On 15 July there was one volcanic earthquake; the next day 2-10 volcanic earthquakes were recorded. By 31 July, fumarole temperatures had increased 10°C above normal levels in Mas crater. On 1 August up to 53 volcanic earthquakes were recorded and a diffuse white plume rose to an altitude of 2.7 km. Residents and tourists were not permitted within a 1 km radius of the active craters.

On 2 August 2007, CVGHM raised the Alert Level from 1 to 2 (on a scale of 1-4) due to increased seismic activity at the volcano. Seismic events decreased in number after 2 August; earthquake tremors were not recorded after 14 November 2007, and on 7 January 2008, CVGHM lowered the Alert Level at Papandayan from 2 to 1 due to the decrease in activity during the previous four months. Data from deformation-monitoring instruments indicated deflation. White fumarolic plumes rose to an altitude of 2.9 km.

No subsequent reports were received until April 2008. According to the CVGHM, on 15 April the seismic network recorded one tremor signal. On 16 April, measurements of summit fumaroles revealed that the temperature had increased and water chemistry had changed since 7 April. White plumes continued to rise to an altitude of 2.7 km. CVGHM again increased the Alert Level to 2 and warned people not to venture within 1 km of the active crater.

Geologic Background. Papandayan is a complex stratovolcano with four large summit craters, the youngest of which was breached to the NE by collapse during a brief eruption in 1772 and contains active fumarole fields. The broad 1.1-km-wide, flat-floored Alun-Alun crater truncates the summit of Papandayan, and Gunung Puntang to the north gives a twin-peaked appearance. Several episodes of collapse have created an irregular profile and produced debris avalanches that have impacted lowland areas. A sulfur-encrusted fumarole field occupies historically active Kawah Mas ("Golden Crater"). After its first historical eruption in 1772, in which collapse of the NE flank produced a catastrophic debris avalanche that destroyed 40 villages and killed nearly 3000 people, only small phreatic eruptions had occurred prior to an explosive eruption that began in November 2002.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.go.id/).


Raung (Indonesia) — June 2008 Citation iconCite this Report

Raung

Indonesia

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

All times are local (unless otherwise noted)


New eruption during 12-17 June sends ash plumes to 4.5 km altitude

In an Antara News report, Balok Suryadi, an observer at the Center of Volcanology and Geological Hazard Mitigation (CVGHM) Raung monitoring post at Sumber Arum village, described clouds of "smoke and ash" that occurred on 12 and 13 June. He was also quoted in the 19 June article as saying that activity was "likely" continuing but that it could not be clearly monitored from the observation post.

Another ash eruption was seen rising through the clouds on 17 June 2008 around 1500. This event was photographed by Karim Kebaili while flying from Bali to Jakarta approximately 30 minutes after take-off (figure 4). The same eruption was seen at 1430 by pilot Nigel Demery, who stated that the ash cloud initially rose to about 4.5 km altitude but had dissipated on his return flight about two hours later. The Darwin VAAC was unable to identify the plume in satellite imagery due to meteorological clouds.

Figure (see Caption) Figure 4. Ash plume rising from Raung at about 1500 on 17 June 2008. Courtesy of Karim Kebaili.

Thermal anomalies were detected by the MODIS instrument aboard the Terra satellite on 23 July 2005 and 15 August 2005. No additional thermal anomalies were detected through the end of June 2008. However, ash plumes were reported by pilots on 26 July 2007 and seen in satellite imagery on 26 August 2007 (BGVN 32:09).

Geologic Background. Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively.

Information Contacts: Rebecca Patrick, Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac); Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Nigel Demery, Indonesia; Karim Kebaili, Indonesia; Antara News (URL: http://www.antara.co.id/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Tungurahua (Ecuador) — June 2008 Citation iconCite this Report

Tungurahua

Ecuador

1.467°S, 78.442°W; summit elev. 5023 m

All times are local (unless otherwise noted)


Explosions up to 14 km altitude during July 2007 to February 2008

Our previous report on Tungurahua (BGVN 32:08) discussed the volcano's activity during March-July 2007. During that period, Ecuador's Instituto Geofisico (IG) reported significant, but variable eruptive behavior, along with many lahars, ash plumes that reached 4 km above the summit, and semi-continuous ashfall.

Table 15 presents a brief summary of the weekly activity at Tungurahua between 18 July 2007 and 19 February 2008. The plumes were described variously as ash, ash-and-gas, steam-and-gas, steam, or steam-and-ash. They rose up to 13 or 14 km altitude (25-26 October 2007 and 7 February 2008, respectively) but more typically, for many weeks, to below 8 km altitude. Around December 2007 IG stated a caution. They likened Tungurahua's behavior as similar to after its explosive phase of 14 July 2006. In that case, volcanic activity kept going, and this lead to the most explosive phase on 16 August 2006. That dramatic pattern was not repeated the next month, but the pace of volcanism kept up and led to the vigorous 7 February eruption.

Table 15. Summary of weekly activity at Tungurahua between 18 July 2007 and 19 February 2008. Courtesy of IG.

Date Plume altitude Activity
18 Jul-24 Jul 2007 5.2-8 km Roaring, noises resembling cannon shots or rolling blocks, lahars, ashfall.
25 Jul-31 Jul 2007 up to 2-3 km above crater Many small ash-bearing explosions and several unusually large ones, blocks fell up to 0.5 km below crater's rim, ashfall.
01 Aug-07 Aug 2007 up to 5.5 km Roaring, explosions, rolling blocks, steam emissions, ashfall.
08 Aug-14 Aug 2007 up to 6 km Explosions, incandescent material fell inside the crater and on the flanks, ashfalls, lahars down NW drainage disrupted road traffic between Ambato and Banos.
15 Aug-21 Aug 2007 5.5 km Cannon shot noises, explosions, ash emissions, ashfall.
22 Aug-28 Aug 2007 6-9 km Explosions, incandescent blocks down flanks, lahars in the NW drainage disrupted road traffic, ashfall.
29 Aug-04 Sep 2007 7 km Explosions, roaring and cannon shot noises, incandescent blocks ejected, lahars disrupted road traffic, ashfall. On 4 September incandescence and rolling blocks on the E and N flanks.
05 Sep-11 Sep 2007 5.3-8 km Explosions, incandescent blocks rolled down flanks, ashfall.
12 Sep-18 Sep 2007 5.5-8 km Strombolian eruption, explosions, incandescent material ejected above the summit and blocks rolled 100 m down the flanks, roaring and cannon shot noises, ashfall.
19 Sep-25 Sep 2007 5.3-7 km Explosions, roaring and cannon shot noises, incandescent material ejected above the summit and blocks rolled 500 m down the flanks, ashfall.
26 Sep-02 Oct 2007 6-7 km Roaring and cannon shot noises, 28 September, blocks ejected above the summit and descended 500 m down the flanks, ashfall.
03 Oct-09 Oct 2007 6-8 km Ash plumes, roaring and cannon shot noises, noise of rolling blocks, ashfall.
10 Oct-16 Oct 2007 6.2-8 km Ash plumes. During 11-12 October incandescent blocks ejected and descended 300 m down the W flank; roaring noises from multiple areas on 11, 13, and 14 October. Ashfall.
17 Oct-23 Oct 2007 5.5-9 km Ash plumes. 17 October, roaring, incandescent material erupted from the summit fell onto the flanks. Fumarolic activity on NW flank, lahars closed road on NW drainage. Ashfall SW on 21 October.
24 Oct-30 Oct 2007 up to 13 km Ash and steam plumes. 25-26 October, incandescence at summit, roaring and cannon shot noises, blocks rolling down the flanks; ashfall.
31 Oct-06 Nov 2007 5.5-8 km Explosions, roaring, incandescent blocks at summit, lahars closed road, ashfall.
07 Nov-13 Nov 2007 6-9 km Roaring and cannon shot noises, incandescent blocks rolled a few hundred meters (1 km on 12 Nov) down the flanks, fumarolic activity, lahar, ashfall.
14 Nov-20 Nov 2007 up to 7.3 km Roaring and cannon shot noises, incandescent blocks rolled down flanks, thermal anomaly detected.
21 Nov-27 Nov 2007 6-8 km Explosions, roaring, incandescent blocks 1 km down the flanks, lahars (4-5 m high in one area) closed road, ashfall.
28 Nov-04 Dec 2007 6-8 km Elevated seismicity, explosions, continuous emissions of steam and ash, roaring and cannon shot noises, incandescent blocks 0.5-1 km down flanks, ashfall.
05 Dec-11 Dec 2007 6-8 km Explosions, roaring and cannon shot noises, incandescent material about 1 km down flanks, ashfall.
12 Dec-18 Dec 2007 6-7 km Explosions, roaring and cannon shot noises, almost constant emission of of ash plumes, incandescent blocks rolled down flanks, ashfall.
19 Dec-25 Dec 2007 6-8.5 km Roaring and cannon shot noises, incandescent blocks hundreds of meters down flanks, ashfall. News reports indicated that 1,200 people from Penipe were evacuated nightly.
26 Dec-01 Jan 2008 6-8 km Explosions, roaring, and cannon-shot noises, incandescent blocks 500 m down flanks, ashfall.
02 Jan-08 Jan 2008 5.5-8 km Explosions, roaring and cannon shot noises, continuous ash emissions, incandescent blocks 500 m down flanks, ashfall. News reports indicated that nearly 1,000 people were evacuated for the night on 6 Jan.
09 Jan-15 Jan 2008 6-9 km Strombolian eruption, roaring and cannon shot noises, incandescent blocks 0.5-1 km down flanks. News reports indicated that residents from two provinces evacuated at night and about 20,000 health masks were distributed in Banos and Quero.
16 Jan-22 Jan 2008 5.5-9 km Strombolian eruption, roaring and cannon shot noises, incandescent blocks 1-2 km down flanks, small pyroclastic flow 400 m down NW side of crater, ashfall.
23 Jan-29 Jan 2008 5.5-9 km Roaring and cannon shot noises, incandescent blocks 500-800 m down flanks, lahars blocked road to Banos, ashfall up to at least 40 km from summit.
30 Jan-06 Feb 2008 6-9 km Explosions (65-208 per day), roaring and cannon shot noises, incandescent blocks rolled 600 m down flanks, lahar, ashfall.
06 Feb 2008 -- New phase of eruptions began with a moderate explosion.
07 Feb 2008 6-14.3 km Tremors of variable intensity, ash columns to heights of 3 km beginning a new phase of eruptive activity; satellite images show a hot spot in the crater. Strombolian eruptions, explosions, strong roaring and cannon shot noises, incandescent material rolled 1.2 km down the flanks, tremors followed by pyroclastic flows on the NW and W flank, tephra fall SW, ashfall. News articles stated several hundred to 2,000 people evacuated.
08 Feb 2008 -- Internal volcanic activity as well as emissions of ash, incandescent material, and explosions and roaring noises slowly diminished; current eruptive episode should not be considered as finished.
09 Feb-12 Feb 2008 -- Strombolian eruptions, explosions, strong roaring and cannon shot noises, incandescent material rolled 1.2 km down the flanks, pyroclastic flows, tephra fall, ashfall. News articles stated several hundred to 2,000 people evacuated.
13 Feb-19 Feb 2008 6-9 km Roaring, noises resembling blocks rolling down flanks, lahar, ashfall.

Geologic Background. Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater, accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.

Information Contacts: Geophysical Institute (IG), Escuela Politécnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); Reuters (URL: http://www.reuters.com/); Associated Press (URL: http://www.ap.org/); Pan American Health Organization (PAHO), 525 23rd St. NW, Washington, DC 20037, USA (URL: http://www.paho.org/).


Ubinas (Peru) — June 2008 Citation iconCite this Report

Ubinas

Peru

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

All times are local (unless otherwise noted)


Frequent ash plumes pose risk to aviation and residents

Our most recent report on Ubinas (BGVN 33:01) discussed ongoing eruptions with continuous emissions of volcanic ash, rock, and gases during 2006-2007. During that previously discussed interval, ash plumes sometimes reached ~ 9 km altitudes at times, posing a hazard to aviation, ashfall was heavy. The current report discusses activity from the end of the previous report (17 December 2007) through 15 July 2008. During this period, ash plumes were frequent, as indicated in table 4. No thermal alerts have been detected by the University of Hawaii's Institute of Geophysics and Planetology (HIGP) MODIS satellite-based thermal alert system since 27 December 2006.

Table 4. Compilation of Volcanic Ash Advisories for aviation from Ubinas during 19 December 2007 through July 1, 2008. Courtesy of the Buenos Aires Volcanic Ash Advisory Center (VAAC) and the Instituto Geológical Minero y Metalúrgico (INGEMMET).

Date Plume altitude (km) Plume direction
19-25 Dec 2007 5.5-7 NE, SW
23 Feb 2008 5.5-8.5 SE
02 Mar 2008 5.5-6.1 SE
09 Mar 2008 7 W, SW
17 Mar 2008 5.5-6.1 N
26 Mar 2008 3.7-6.7 SW
01 Apr 2008 3.7-6.7 NW
06 Apr 2008 5.5-6.7 E
15 Apr 2008 5.5-7 ENE
19-22 Apr 2008 5.5-7.6 ESE, NE
23 Apr 2008 5.5-9.1 SE, S
30 Apr-03 May 2008 5.5-9.1 NE, E, SE
09 May 2008 5.5-7 E
12 May 2008 5.5-7 SE
15 May 2008 5.5 E, SW
19 May 2008 8.5 E, SW
22-24 May 2008 4.9-7.9 S, E, NE, SE
26 May 2008 5.4 SSE
28-29 May 2008 5.5-6.1 NE, SE
03 Jun 2008 4.6 SSW
07 Jun 2008 7.3 S
13 Jun 2008 6.7 S
18 Jun 2008 5.5-5.8 S, SE, and NE
22 Jun 2008 5.5-7.6 S, SE, NE
26 Jun 2008 5.5-6.1 NE
07 Jul 2008 5.5-5.8 NE
09-10 Jul 2008 5.5-5.8 E
15 Jul 2008 5.5-5.8 E

According to the ash advisories issued from the Buenos Aires VAAC, the aviation warning color code for Ubinas during the reporting period was variously orange or red. In terms of hazard status on the ground, a news article on 30 June 2008 indicated that local civil defense officials had maintained the Alert level at Yellow. They noted that small explosions and ash-and-gas emissions had continued during the previous two months. Families at immediate risk from the village of San Pedro de Querapi in the vicinity of the volcano have been relocated but have returned to their fields to pursue their agacultural activities. The population of local communities and their livestock had suffered the effects of gas and ash emissions, and local authorities had begun to discuss the possible relocation of about 650 affected families from six towns (Escacha, Tonoaya, San Migues, San Pedro de Querapi, Huataga and Ubinas). The article noted that officials recognized that the relocation process could take several years and should be the villager's decision and not one forced on them.

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: Instituto Geológical Minero y Metalúrgico (INGEMMET), Av. Canadá 1470, San Borja, Lima 41, Perú (URL: http://www.ingemmet.gob.pe/); Buenos Aires Volcanic Ash Advisory Center (VAAC), Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/productos.php); La República Online (URL: http://www.larepublica.com.pe).


Witori (Papua New Guinea) — June 2008 Citation iconCite this Report

Witori

Papua New Guinea

5.576°S, 150.516°E; summit elev. 724 m

All times are local (unless otherwise noted)


Ejection of lava fragments in late August 2007; quiet steaming

Reports about Pago early in 2006 (BGVN 31:02) noted small vapor emissions, but no noises or glow, and low levels of seismicity. Similar observations were reported by the Rabaul Volcano Observatory (RVO) for December 2006. A local security company reported that sometime during 27-31 October 2006 there was a single booming noise accompanied by a white-gray emissions above the summit. Volcanologists were sent to verify the activity, but no report about the event was received. A March 2007 report only noted diffuse white vapor emissions and low seismicity.

On 28 August 2007 lava fragments were observed being ejected during the daytime from one of the Upper vents (2nd Crater). People in a nearby village heard only a single booming noise in the early hours of 27 August. The residents also indicated increased white vapor emissions from 2nd Crater on the 27th that returned to normal levels the following day. Seismic activity had increased on 27-28 August, and the Real-Time Seismic Amplitude Measurement (RSAM) increased from background level (around 100 units) to a peak of about 400 units. RSAM levels began to decline on the 29th, returning to background levels on 30 August. An inspection on 1 October revealed that only the 2nd Crater of the Upper Vents was releasing diffuse white vapor, and that there were no noises or glow.

Pago remained quiet during September-November 2007. When observations were made, only diffuse white vapor was being released from the Upper Vents. A handful of high-frequency earthquakes and 18 low-frequency events were recorded during September. The daily number of earthquakes ranged from 1 to 4 from 1 to 24 September, with none after through the end of the month. There was a slight increase in gas emission during 9-11 November. The vapor plume was blown N, where villagers reported nose and windpipe irritation, and watery eyes. The daily number of high-frequency earthquakes ranged from 1 to 3, while low-frequency earthquakes ranged from 1 to 9. During January 2008 Pago was still quiet with diffuse white vapor from the upper vents and very occasional low-frequency seismic events.

Geologic Background. The 5.5 x 7.5 km Witori caldera on the northern coast of central New Britain contains the young historically active cone of Pago. The Buru caldera cuts the SW flank of Witori volcano. The gently sloping outer flanks of Witori volcano consist primarily of dacitic pyroclastic-flow and airfall deposits produced during a series of five major explosive eruptions from about 5600 to 1200 years ago, many of which may have been associated with caldera formation. The post-caldera Pago cone may have formed less than 350 years ago. Pago has grown to a height above that of the Witori caldera rim, and a series of ten dacitic lava flows from it covers much of the caldera floor. The youngest of these was erupted during 2002-2003 from vents extending from the summit nearly to the NW caldera wall.

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

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