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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

Ibu (Indonesia) Daily ash explosions continue, along with thermal anomalies in the crater, October 2022-May 2023

Dukono (Indonesia) Continuing ash emissions, SO2 plumes, and thermal signals during October 2022-May 2023

Sabancaya (Peru) Explosions, gas-and-ash plumes, and thermal activity persist during November 2022-April 2023

Sheveluch (Russia) Significant explosions destroyed part of the lava-dome complex during April 2023

Bezymianny (Russia) Explosions, ash plumes, lava flows, and avalanches during November 2022-April 2023

Chikurachki (Russia) New explosive eruption during late January-early February 2023

Marapi (Indonesia) New explosive eruption with ash emissions during January-March 2023

Kikai (Japan) Intermittent white gas-and-steam plumes, discolored water, and seismicity during May 2021-April 2023

Lewotolok (Indonesia) Strombolian eruption continues through April 2023 with intermittent ash plumes

Barren Island (India) Thermal activity during December 2022-March 2023

Villarrica (Chile) Nighttime crater incandescence, ash emissions, and seismicity during October 2022-March 2023

Fuego (Guatemala) Daily explosions, gas-and-ash plumes, avalanches, and ashfall during December 2022-March 2023



Ibu (Indonesia) — June 2023 Citation iconCite this Report

Ibu

Indonesia

1.488°N, 127.63°E; summit elev. 1325 m

All times are local (unless otherwise noted)


Daily ash explosions continue, along with thermal anomalies in the crater, October 2022-May 2023

Persistent eruptive activity since April 2008 at Ibu, a stratovolcano on Indonesian’s Halmahera Island, has consisted of daily explosive ash emissions and plumes, along with observations of thermal anomalies (BGVN 47:04). The current eruption continued during October 2022-May 2023, described below, based on advisories issued by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), daily reports by MAGMA Indonesia (a PVMBG platform), and the Darwin Volcanic Ash Advisory Centre (VAAC), and various satellite data. The Alert Level during the reporting period remained at 2 (on a scale of 1-4), except raised briefly to 3 on 27 May, and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side of the volcano.

According to MAGMA Indonesia, during October 2022-May 2023, daily gray-and-white ash plumes of variable densities rose 200-1,000 m above the summit and drifted in multiple directions. On 30 October and 11 November, plumes rose a maximum of 2 km and 1.5 km above the summit, respectively (figures 42 and 43). According to the Darwin VAAC, discrete ash emissions on 13 November rose to 2.1 km altitude, or 800 m above the summit, and drifted W, and multiple ash emissions on 15 November rose 1.4 km above the summit and drifted NE. Occasional larger ash explosions through May 2023 prompted PVMBG to issue Volcano Observatory Notice for Aviation (VONA) alerts (table 6); the Aviation Color Code remained at Orange throughout this period.

Figure (see Caption) Figure 42. Larger explosion from Ibu’s summit crater on 30 October 2022 that generated a plume that rose 2 km above the summit. Photo has been color corrected. Courtesy of MAGMA Indonesia.
Figure (see Caption) Figure 43. Larger explosion from Ibu’s summit crater on 11 November 2022 that generated a plume that rose 1.5 km above the summit. Courtesy of MAGMA Indonesia.

Table 6. Volcano Observatory Notice for Aviation (VONA) ash plume alerts for Ibu issued by PVMBG during October 2022-May 2023. Maximum height above the summit was estimated by a ground observer. VONAs in January-May 2023 all described the ash plumes as dense.

Date Time (local) Max height above summit Direction
17 Oct 2022 0858 800 m SW
18 Oct 2022 1425 800 m S
19 Oct 2022 2017 600 m SW
21 Oct 2022 0916 800 m NW
16 Jan 2023 1959 600 m NE
22 Jan 2023 0942 1,000 m E
29 Jan 2023 2138 1,000 m E
10 May 2023 0940 800 m NW
10 May 2023 2035 600 m E
21 May 2023 2021 600 m W
21 May 2023 2140 1,000 m W
29 May 2023 1342 800 m N
31 May 2023 1011 1,000 m SW

Sentinel-2 L1C satellite images throughout the reporting period show two, sometimes three persistent thermal anomalies in the summit crater, with the most prominent hotspot from the top of a cone within the crater. Clear views were more common during March-April 2023, when a vent and lava flows on the NE flank of the intra-crater cone could be distinguished (figure 44). White-to-grayish emissions were also observed during brief periods when weather clouds allowed clear views.

Figure (see Caption) Figure 44. Sentinel-2 L2A satellite images of Ibu on 10 April 2023. The central cone within the summit crater (1.3 km diameter) and lava flows (gray) can be seen in the true color image (left, bands 4, 3, 2). Thermal anomalies from the small crater of the intra-crater cone, a NE-flank vent, and the end of the lava flow are apparent in the infrared image (right, bands 12, 11, 8A). Courtesy of Copernicus Browser.

The MIROVA space-based volcano hotspot detection system recorded almost daily thermal anomalies throughout the reporting period, though cloud cover often interfered with detections. Data from imaging spectroradiometers aboard NASA’s Aqua and Terra satellites and processed using the MODVOLC algorithm (MODIS-MODVOLC) recorded hotspots on one day during October 2022 and December 2022, two days in April 2023, three days in November 2022 and May 2023, and four days in March 2023.

Geologic Background. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, has contained several small crater lakes. The 1.2-km-wide outer crater is breached on the N, creating a steep-walled valley. A large cone grew ENE of the summit, and a smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. The first observed and recorded eruption was a small explosion from the summit crater in 1911. Eruptive activity began again in December 1998, producing a lava dome that eventually covered much of the floor of the inner summit crater along with ongoing explosive ash emissions.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia (Multiplatform Application for Geohazard Mitigation and Assessment in Indonesia), Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.esdm.go.id/v1); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/); 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/).


Dukono (Indonesia) — June 2023 Citation iconCite this Report

Dukono

Indonesia

1.6992°N, 127.8783°E; summit elev. 1273 m

All times are local (unless otherwise noted)


Continuing ash emissions, SO2 plumes, and thermal signals during October 2022-May 2023

Dukono, a remote volcano on Indonesia’s Halmahera Island, has been erupting continuously since 1933, with frequent ash explosions and sulfur dioxide plumes (BGVN 46:11, 47:10). This activity continued during October 2022 through May 2023, based on reports from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG; also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), the Darwin Volcanic Ash Advisory Centre (VAAC), and satellite data. During this period, 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. The highest reported plume of the period reached 9.4 km above the summit on 14 November 2022.

According to MAGMA Indonesia (a platform developed by PVMBG), white, gray, or dark plumes of variable densities were observed almost every day during the reporting period, except when fog obscured the volcano (figure 33). Plumes generally rose 25-450 m above the summit, but rose as high as 700-800 m on several days, somewhat lower than the maximum heights reached earlier in 2022 when plumes reached as high as 1 km. However, the Darwin VAAC reported that on 14 November 2022, a discrete ash plume rose 9.4 km above the summit (10.7 km altitude), accompanied by a strong hotspot and a sulfur dioxide signal observed in satellite imagery; a continuous ash plume that day and through the 15th rose to 2.1-2.4 km altitude and drifted NE.

Figure (see Caption) Figure 33. Webcam photo of a gas-and-steam plume rising from Dukono on the morning of 28 January 2023. Courtesy of MAGMA Indonesia.

Sentinel-2 images were obscured by weather clouds almost every viewing day during the reporting period. However, the few reasonably clear images showed a hotspot and white or gray emissions and plumes. Strong SO2 plumes from Dukono were present on many days during October 2022-May 2023, as detected using the TROPOMI instrument on the Sentinel-5P satellite (figure 34).

Figure (see Caption) Figure 34. A strong SO2 signal from Dukono on 23 April 2023 was the most extensive plume detected during the reporting period. Courtesy of the 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, have occurred since 1933. During a major eruption in 1550 CE, a lava flow filled in the strait between Halmahera and the N-flank Gunung Mamuya cone. 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/); MAGMA Indonesia (Multiplatform Application for Geohazard Mitigation and Assessment in Indonesia), Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.esdm.go.id/v1); 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/); NASA 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).


Sabancaya (Peru) — May 2023 Citation iconCite this Report

Sabancaya

Peru

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

All times are local (unless otherwise noted)


Explosions, gas-and-ash plumes, and thermal activity persist during November 2022-April 2023

Sabancaya is located in Peru, NE of Ampato and SE of Hualca Hualca. Eruptions date back to 1750 and have been characterized by explosions, phreatic activity, ash plumes, and ashfall. The current eruption period began in November 2016 and has more recently consisted of daily explosions, gas-and-ash plumes, and thermal activity (BGVN 47:11). This report updates activity during November 2022 through April 2023 using information from Instituto Geophysico del Peru (IGP) that use weekly activity reports and various satellite data.

Intermittent low-to-moderate power thermal anomalies were reported by the MIROVA project during November 2022 through April 2023 (figure 119). There were few short gaps in thermal activity during mid-December 2022, late December-to-early January 2023, late January to mid-February, and late February. According to data recorded by the MODVOLC thermal algorithm, there were a total of eight thermal hotspots: three in November 2022, three in February 2023, one in March, and one in April. On clear weather days, some of this thermal anomaly was visible in infrared satellite imagery showing the active lava dome in the summit crater (figure 120). Almost daily moderate-to-strong sulfur dioxide plumes were recorded during the reporting period by the TROPOMI instrument on the Sentinel-5P satellite (figure 121). Many of these plumes exceeded 2 Dobson Units (DU) and drifted in multiple directions.

Figure (see Caption) Figure 119. Intermittent low-to-moderate thermal anomalies were detected during November 2022 through April 2023 at Sabancaya, as shown in this MIROVA graph (Log Radiative Power). There were brief gaps in thermal activity during mid-December 2022, late December-to-early January 2023, late January to mid-February, and late February. Courtesy of MIROVA.
Figure (see Caption) Figure 120. Infrared (bands 12, 11, 8A) satellite images showed a constant thermal anomaly in the summit crater of Sabancaya on 14 January 2023 (top left), 28 February 2023 (top right), 5 March 2023 (bottom left), and 19 April 2023 (bottom right), represented by the active lava dome. Sometimes gas-and-steam and ash emissions also accompanied this activity. Courtesy of Copernicus Browser.
Figure (see Caption) Figure 121. Moderate-to-strong sulfur dioxide plumes were detected almost every day, rising from Sabancaya by the TROPOMI instrument on the Sentinel-5P satellite throughout the reporting period; the DU (Dobson Unit) density values were often greater than 2. Plumes from 23 November 2022 (top left), 26 December 2022 (top middle), 10 January 2023 (top right), 15 February 2023 (bottom left), 13 March 2023 (bottom middle), and 21 April 2023 (bottom right) that drifted SW, SW, W, SE, W, and SW, respectively. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

IGP reported that moderate activity during November and December 2022 continued; during November, an average number of explosions were reported each week: 30, 33, 36, and 35, and during December, it was 32, 40, 47, 52, and 67. Gas-and-ash plumes in November rose 3-3.5 km above the summit and drifted E, NE, SE, S, N, W, and SW. During December the gas-and-ash plumes rose 2-4 km above the summit and drifted in different directions. There were 1,259 volcanic earthquakes recorded during November and 1,693 during December. Seismicity also included volcano-tectonic-type events that indicate rock fracturing events. Slight inflation was observed in the N part of the volcano near Hualca Hualca (4 km N). Thermal activity was frequently reported in the crater at the active lava dome (figure 120).

Explosive activity continued during January and February 2023. The average number of explosions were reported each week during January (51, 50, 60, and 59) and February (43, 54, 51, and 50). Gas-and-ash plumes rose 1.6-2.9 km above the summit and drifted NW, SW, and W during January and rose 1.4-2.8 above the summit and drifted W, SW, E, SE, N, S, NW, and NE during February. IGP also detected 1,881 volcanic earthquakes during January and 1,661 during February. VT-type earthquakes were also reported. Minor inflation persisted near Hualca Hualca. Satellite imagery showed continuous thermal activity in the crater at the lava dome (figure 120).

During March, the average number of explosions each week was 46, 48, 31, 35, and 22 and during April, it was 29, 41, 31, and 27. Accompanying gas-and-ash plumes rose 1.7-2.6 km above the summit crater and drifted W, SW, NW, S, and SE during March. According to a Buenos Aires Volcano Ash Advisory Center (VAAC) notice, on 22 March at 1800 through 23 March an ash plume rose to 7 km altitude and drifted NW. By 0430 an ash plume rose to 7.6 km altitude and drifted W. On 24 and 26 March continuous ash emissions rose to 7.3 km altitude and drifted SW and on 28 March ash emissions rose to 7.6 km altitude. During April, gas-and-ash plumes rose 1.6-2.5 km above the summit and drifted W, SW, S, NW, NE, and E. Frequent volcanic earthquakes were recorded, with 1,828 in March and 1,077 in April, in addition to VT-type events. Thermal activity continued to be reported in the summit crater at the lava dome (figure 120).

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: Instituto Geofisico del Peru (IGP), Centro Vulcanológico Nacional (CENVUL), Calle Badajoz N° 169 Urb. Mayorazgo IV Etapa, Ate, Lima 15012, Perú (URL: https://www.igp.gob.pe/servicios/centro-vulcanologico-nacional/inicio); 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); 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/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard MD 20771, USA (URL: https://so2.gsfc.nasa.gov/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Sheveluch (Russia) — May 2023 Citation iconCite this Report

Sheveluch

Russia

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

All times are local (unless otherwise noted)


Significant explosions destroyed part of the lava-dome complex during April 2023

Sheveluch (also spelled Shiveluch) in Kamchatka, has had at least 60 large eruptions during the last 10,000 years. The summit is truncated by a broad 9-km-wide caldera that is breached to the S, and many lava domes occur on the outer flanks. The lava dome complex was constructed within the large open caldera. Frequent collapses of the dome complex have produced debris avalanches; the resulting deposits cover much of the caldera floor. A major south-flank collapse during a 1964 Plinian explosion produced a scarp in which a “Young Sheveluch” dome began to form in 1980. Repeated episodes of dome formation and destruction since then have produced major and minor ash plumes, pyroclastic flows, block-and-ash flows, and “whaleback domes” of spine-like extrusions in 1993 and 2020 (BGVN 45:11). The current eruption period began in August 1999 and has more recently consisted of lava dome growth, explosions, ash plumes, and avalanches (BGVN 48:01). This report covers a significant explosive eruption during early-to-mid-April 2023 that generated a 20 km altitude ash plume, produced a strong sulfur dioxide plume, and destroyed part of the lava-dome complex; activity described during January through April 2023 use information primarily from the Kamchatka Volcanic Eruptions Response Team (KVERT) and various satellite data.

Satellite data. Activity during the majority of this reporting period was characterized by continued lava dome growth, strong fumarole activity, explosions, and hot avalanches. According to the MODVOLC Thermal Alerts System, 140 hotspots were detected through the reporting period, with 33 recorded in January 2023, 29 in February, 44 in March, and 34 in April. Frequent strong thermal activity was recorded during January 2023 through April, according to the MIROVA (Middle InfraRed Observation of Volcanic Activity) graph and resulted from the continuously growing lava dome (figure 94). A slightly stronger pulse in thermal activity was detected in early-to-mid-April, which represented the significant eruption that destroyed part of the lava-dome complex. Thermal anomalies were also visible in infrared satellite imagery at the summit crater (figure 95).

Figure (see Caption) Figure 94. Strong and frequent thermal activity was detected at Sheveluch during January through April 2023, according to this MIROVA graph (Log Radiative Power). These thermal anomalies represented the continuously growing lava dome and frequent hot avalanches that affected the flanks. During early-to-mid-April a slightly stronger pulse represented the notable explosive eruption. Courtesy of MIROVA.
Figure (see Caption) Figure 95. Infrared (bands B12, B11, B4) satellite imagery showed persistent thermal anomalies at the lava dome of Sheveluch on 14 January 2023 (top left), 26 February 2023 (top right), and 15 March 2023 (bottom left). The true color image on 12 April 2023 (bottom right) showed a strong ash plume that drifted SW; this activity was a result of the strong explosive eruption during 11-12 April 2023. Courtesy of Copernicus Browser.

During January 2023 KVERT reported continued growth of the lava dome, accompanied by strong fumarolic activity, incandescence from the lava dome, explosions, ash plumes, and avalanches. Satellite data showed a daily thermal anomaly over the volcano. Video data showed ash plumes associated with collapses at the dome that generated avalanches that in turn produced ash plumes rising to 3.5 km altitude and drifting 40 km W on 4 January and rising to 7-7.5 km altitude and drifting 15 km SW on 5 January. A gas-and-steam plume containing some ash that was associated with avalanches rose to 5-6 km altitude and extended 52-92 km W on 7 January. Explosions that same day produced ash plumes that rose to 7-7.5 km altitude and drifted 10 km W. According to a Volcano Observatory Notice for Aviation (VONA) issued at 1344 on 19 January, explosions produced an ash cloud that was 15 x 25 km in size and rose to 9.6-10 km altitude, drifting 21-25 km W; as a result, the Aviation Color Code (ACC) was raised to Red (the highest level on a four-color scale). Another VONA issued at 1635 reported that no more ash plumes were observed, and the ACC was lowered to Orange (the second highest level on a four-color scale). On 22 January an ash plume from collapses and avalanches rose to 5 km altitude and drifted 25 km NE and SW; ash plumes associated with collapses extended 70 km NE on 27 and 31 January.

Lava dome growth, fumarolic activity, dome incandescence, and occasional explosions and avalanches continued during February and March. A daily thermal anomaly was visible in satellite data. Explosions on 1 February generated ash plumes that rose to 6.3-6.5 km altitude and extended 15 km NE. Video data showed an ash cloud from avalanches rising to 5.5 km altitude and drifting 5 km SE on 2 February. Satellite data showed gas-and-steam plumes containing some ash rose to 5-5.5 km altitude and drifted 68-110 km ENE and NE on 6 February, to 4.5-5 km altitude and drifted 35 km WNW on 22 February, and to 3.7-4 km altitude and drifted 47 km NE on 28 February. Scientists from the Kamchatka Volcanological Station (KVS) went on a field excursion on 25 February to document the growing lava dome, and although it was cloudy most of the day, nighttime incandescence was visible. Satellite data showed an ash plume extending up to 118 km E during 4-5 March. Video data from 1150 showed an ash cloud from avalanches rose to 3.7-5.5 km altitude and drifted 5-10 km ENE and E on 5 March. On 11 March an ash plume drifted 62 km E. On 27 March ash plumes rose to 3.5 km altitude and drifted 100 km E. Avalanches and constant incandescence at the lava dome was focused on the E and NE slopes on 28 March. A gas-and-steam plume containing some ash rose to 3.5 km altitude and moved 40 km E on 29 March. Ash plumes on 30 March rose to 3.5-3.7 km altitude and drifted 70 km NE.

Similar activity continued during April, with lava dome growth, strong fumarolic activity, incandescence in the dome, occasional explosions, and avalanches. A thermal anomaly persisted throughout the month. During 1-4 April weak ash plumes rose to 2.5-3 km altitude and extended 13-65 km SE and E.

Activity during 11 April 2023. The Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS) reported a significant increase in seismicity around 0054 on 11 April, as reported by strong explosions detected on 11 April beginning at 0110 that sent ash plumes up to 7-10 km altitude and extended 100-435 km W, WNW, NNW, WSW, and SW. According to a Tokyo VAAC report the ash plume rose to 15.8 km altitude. By 0158 the plume extended over a 75 x 100 km area. According to an IVS FEB RAS report, the eruptive column was not vertical: the initial plume at 0120 on 11 April deviated to the NNE, at 0000 on 12 April, it drifted NW, and by 1900 it drifted SW. KVS reported that significant pulses of activity occurred at around 0200, 0320, and then a stronger phase around 0600. Levin Dmitry took a video from near Békés (3 km away) at around 0600 showing a rising plume; he also reported that a pyroclastic flow traveled across the road behind him as he left the area. According to IVS FEB RAS, the pyroclastic flow traveled several kilometers SSE, stopping a few hundred meters from a bridge on the road between Klyuchi and Petropavlovsk-Kamchatsky.

Ashfall was first observed in Klyuchi (45 km SW) at 0630, and a large, black ash plume blocked light by 0700. At 0729 KVERT issued a Volcano Observatory Notice for Aviation (VONA) raising the Aviation Color Code to Red (the highest level on a four-color scale). It also stated that a large ash plume had risen to 10 km altitude and drifted 100 km W. Near-constant lightning strikes were reported in the plume and sounds like thunderclaps were heard until about 1000. According to IVS FEB RAS the cloud was 200 km long and 76 km wide by 0830, and was spreading W at altitudes of 6-12 km. In the Klyuchi Village, the layer of both ash and snow reached 8.5 cm (figure 96); ashfall was also reported in Kozyrevsk (112 km SW) at 0930, Mayskoye, Anavgay, Atlasovo, Lazo, and Esso. Residents in Klyuchi reported continued darkness and ashfall at 1100. In some areas, ashfall was 6 cm deep and some residents reported dirty water coming from their plumbing. According to IVS FEB RAS, an ash cloud at 1150 rose to 5-20 km altitude and was 400 km long and 250 km wide, extending W. A VONA issued at 1155 reported that ash had risen to 10 km and drifted 340 km NNW and 240 km WSW. According to Simon Carn (Michigan Technological University), about 0.2 Tg of sulfur dioxide in the plume was measured in a satellite image from the TROPOMI instrument on the Sentinel-5P satellite acquired at 1343 that covered an area of about 189,000 km2 (figure 97). Satellite data at 1748 showed an ash plume that rose to 8 km altitude and drifted 430 km WSW and S, according to a VONA.

Figure (see Caption) Figure 96. Photo of ash deposited in Klyuchi village on 11 April 2023 by the eruption of Sheveluch. About 8.5 cm of ash was measured. Courtesy of Kam 24 News Agency.
Figure (see Caption) Figure 97. A strong sulfur dioxide plume from the 11 April 2023 eruption at Sheveluch was visible in satellite data from the TROPOMI instrument on the Sentinel-5P satellite. Courtesy of Simon Carn, MTU.

Activity during 12-15 April 2023. On 12 April at 0730 satellite images showed ash plumes rose to 7-8 km altitude and extended 600 km SW, 1,050 km ESE, and 1,300-3,000 km E. By 1710 that day, the explosions weakened. According to news sources, the ash-and-gas plumes drifted E toward the Aleutian Islands and reached the Gulf of Alaska by 13 April, causing flight disruptions. More than 100 flights involving Alaska airspace were cancelled due to the plume. Satellite data showed ash plumes rising to 4-5.5 km altitude and drifted 400-415 km SE and ESE on 13 April. KVS volcanologists observed the pyroclastic flow deposits and noted that steam rose from downed, smoldering trees. They also noted that the deposits were thin with very few large fragments, which differed from previous flows. The ash clouds traveled across the Pacific Ocean. Flight cancellations were also reported in NW Canada (British Columbia) during 13-14 April. During 14-15 April ash plumes rose to 6 km altitude and drifted 700 km NW.

Alaskan flight schedules were mostly back to normal by 15 April, with only minor delays and far less cancellations; a few cancellations continued to be reported in Canada. Clear weather on 15 April showed that most of the previous lava-dome complex was gone and a new crater roughly 1 km in diameter was observed (figure 98); gas-and-steam emissions were rising from this crater. Evidence suggested that there had been a directed blast to the SE, and pyroclastic flows traveled more than 20 km. An ash plume rose to 4.5-5.2 km altitude and drifted 93-870 km NW on 15 April.

Figure (see Caption) Figure 98. A comparison of the crater at Sheveluch showing the previous lava dome (top) taken on 29 November 2022 and a large crater in place of the dome (bottom) due to strong explosions during 10-13 April 2023, accompanied by gas-and-ash plumes. The bottom photo was taken on 15 April 2023. Photos has been color corrected. Both photos are courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.

Activity during 16-30 April 2023. Resuspended ash was lifted by the wind from the slopes and rose to 4 km altitude and drifted 224 km NW on 17 April. KVERT reported a plume of resuspended ash from the activity during 10-13 April on 19 April that rose to 3.5-4 km altitude and drifted 146-204 km WNW. During 21-22 April a plume stretched over the Scandinavian Peninsula. A gas-and-steam plume containing some ash rose to 3-3.5 km altitude and drifted 60 km SE on 30 April. A possible new lava dome was visible on the W slope of the volcano on 29-30 April (figure 99); satellite data showed two thermal anomalies, a bright one over the existing lava dome and a weaker one over the possible new one.

Figure (see Caption) Figure 99. Photo showing new lava dome growth at Sheveluch after a previous explosion destroyed much of the complex, accompanied by a white gas-and-steam plume. Photo has been color corrected. Courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.

References. Girina, O., Loupian, E., Horvath, A., Melnikov, D., Manevich, A., Nuzhdaev, A., Bril, A., Ozerov, A., Kramareva, L., Sorokin, A., 2023, Analysis of the development of the paroxysmal eruption of Sheveluch volcano on April 10–13, 2023, based on data from various satellite systems, ??????????? ???????? ??? ?? ???????, 20(2).

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. 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 occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. 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/); Kamchatka Volcanological Station, Kamchatka Branch of Geophysical Survey, (KB GS RAS), Klyuchi, Kamchatka Krai, Russia (URL: http://volkstat.ru/); 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/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/); Kam 24 News Agency, 683032, Kamchatka Territory, Petropavlovsk-Kamchatsky, Vysotnaya St., 2A (URL: https://kam24.ru/news/main/20230411/96657.html#.Cj5Jrky6.dpuf); Simon Carn, Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA (URL: http://www.volcarno.com/, Twitter: @simoncarn).


Bezymianny (Russia) — May 2023 Citation iconCite this Report

Bezymianny

Russia

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

All times are local (unless otherwise noted)


Explosions, ash plumes, lava flows, and avalanches during November 2022-April 2023

Bezymianny is located on the Kamchatka Peninsula of Russia as part of the Klyuchevskoy volcano group. Historic eruptions began in 1955 and have been characterized by dome growth, explosions, pyroclastic flows, ash plumes, and ashfall. During the 1955-56 eruption a large open crater was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater. The current eruption period began in December 2016 and more recent activity has consisted of strong explosions, ash plumes, and thermal activity (BGVN 47:11). This report covers activity during November 2022 through April 2023, based on weekly and daily reports from the Kamchatka Volcano Eruptions Response Team (KVERT) and satellite data.

Activity during November and March 2023 was relatively low and mostly consisted of gas-and-steam emissions, occasional small collapses that generated avalanches along the lava dome slopes, and a persistent thermal anomaly over the volcano that was observed in satellite data on clear weather days. According to the Tokyo VAAC and KVERT, an explosion produced an ash plume that rose to 6 km altitude and drifted 25 km NE at 1825 on 29 March.

Gas-and-steam emissions, collapses generating avalanches, and thermal activity continued during April. According to two Volcano Observatory Notice for Aviation (VONA) issued on 2 and 6 April (local time) ash plumes rose to 3 km and 3.5-3.8 km altitude and drifted 35 km E and 140 km E, respectively. Satellite data from KVERT showed weak ash plumes extending up to 550 km E on 2 and 5-6 April.

A VONA issued at 0843 on 7 April described an ash plume that rose to 4.5-5 km altitude and drifted 250 km ESE. Later that day at 1326 satellite data showed an ash plume that rose to 5.5-6 km altitude and drifted 150 km ESE. A satellite image from 1600 showed an ash plume extending as far as 230 km ESE; KVERT noted that ash emissions were intensifying, likely due to avalanches from the growing lava dome. The Aviation Color Code (ACC) was raised to Red (the highest level on a four-color scale). At 1520 satellite data showed an ash plume rising to 5-5.5 km altitude and drifting 230 km ESE. That same day, Kamchatka Volcanological Station (KVS) volcanologists traveled to Ambon to collect ash; they reported that a notable eruption began at 1730, and within 20 minutes a large ash plume rose to 10 km altitude and drifted NW. KVERT reported that the strong explosive phase began at 1738. Video and satellite data taken at 1738 showed an ash plume that rose to 10-12 km altitude and drifted up to 2,800 km SE and E. Explosions were clearly audible 20 km away for 90 minutes, according to KVS. Significant amounts of ash fell at the Apakhonchich station, which turned the snow gray; ash continued to fall until the morning of 8 April. In a VONA issued at 0906 on 8 April, KVERT stated that the explosive eruption had ended; ash plumes had drifted 2,000 km E. The ACC was lowered to Orange (the third highest level on a four-color scale). The KVS team saw a lava flow on the active dome once the conditions were clear that same day (figure 53). On 20 April lava dome extrusion was reported; lava flows were noted on the flanks of the dome, and according to KVERT satellite data, a thermal anomaly was observed in the area. The ACC was lowered to Yellow (the second lowest on a four-color scale).

Figure (see Caption) Figure 53. Photo showing an active lava flow descending the SE flank of Bezymianny from the lava dome on 8 April 2023. Courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.

Satellite data showed an increase in thermal activity beginning in early April 2023. A total of 31 thermal hotspots were detected by the MODVOLC thermal algorithm on 4, 5, 7, and 12 April 2023. The elevated thermal activity resulted from an increase in explosive activity and the start of an active lava flow. The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system based on the analysis of MODIS data also showed a pulse in thermal activity during the same time (figure 54). Infrared satellite imagery captured a continuous thermal anomaly at the summit crater, often accompanied by white gas-and-steam emissions (figure 55). On 4 April 2023 an active lava flow was observed descending the SE flank.

Figure (see Caption) Figure 54. Intermittent and low-power thermal anomalies were detected at Bezymianny during December 2022 through mid-March 2023, according to this MIROVA graph (Log Radiative Power). In early April 2023, an increase in explosive activity and eruption of a lava flow resulted in a marked increase in thermal activity. Courtesy of MIROVA.
Figure (see Caption) Figure 55. Infrared satellite images of Bezymianny showed a persistent thermal anomaly over the lava dome on 18 November 2022 (top left), 28 December 2022 (top right), 15 March 2023 (bottom left), and 4 April 2023 (bottom right), often accompanied by white gas-and-steam plumes. On 4 April a lava flow was active and descending the SE flank. Images using infrared (bands 12, 11, 8a). Courtesy of Copernicus Browser.

Geologic Background. The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Kamchatka Volcanological Station, Kamchatka Branch of Geophysical Survey, (KB GS RAS), Klyuchi, Kamchatka Krai, Russia (URL: http://volkstat.ru/); 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/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Chikurachki (Russia) — May 2023 Citation iconCite this Report

Chikurachki

Russia

50.324°N, 155.461°E; summit elev. 1781 m

All times are local (unless otherwise noted)


New explosive eruption during late January-early February 2023

Chikurachki, located on Paramushir Island in the northern Kuriles, has had Plinian eruptions during the Holocene. Lava flows have reached the sea and formed capes on the NW coast; several young lava flows are also present on the E flank beneath a scoria deposit. Reported eruptions date back to 1690, with the most recent eruption period occurring during January through October 2022, characterized by occasional explosions, ash plumes, and thermal activity (BGVN 47:11). This report covers a new eruptive period during January through February 2023 that consisted of ash explosions and ash plumes, based on information from the Kamchatka Volcanic Eruptions Response Team (KVERT) and satellite data.

According to reports from KVERT, an explosive eruption began around 0630 on 29 January. Explosions generated ash plumes that rose to 3-3.5 km altitude and drifted 6-75 km SE and E, based on satellite data. As a result, the Aviation Color Code (ACC) was raised to Orange (the second highest level on a four-color scale). At 1406 and 1720 ash plumes were identified in satellite images that rose to 4.3 km altitude and extended 70 km E. By 2320 the ash plume had dissipated. A thermal anomaly was visible at the volcano on 31 January, according to a satellite image, and an ash plume was observed drifting 66 km NE.

Occasional explosions and ash plumes continued during early February. At 0850 on 1 February an ash plume rose to 3.5 km altitude and drifted 35 km NE. Satellite data showed an ash plume that rose to 3.2-3.5 km altitude and drifted 50 km NE at 1222 later that day (figure 22). A thermal anomaly was detected over the volcano during 5-6 February and ash plumes drifted as far as 125 km SE, E, and NE. Explosive events were reported at 0330 on 6 February that produced ash plumes rising to 4-4.5 km altitude and drifting 72-90 km N, NE, and ENE. KVERT noted that the last gas-and steam plume that contained some ash was observed on 8 February and drifted 55 km NE before the explosive eruption ended. The ACC was lowered to Yellow and then Green (the lowest level on a four-color scale) on 18 February.

Figure (see Caption) Figure 22. Satellite image showing a true color view of a strong ash plume rising above Chikurachki on 1 February 2023. The plume drifted NE and ash deposits (dark brown-to-gray) are visible on the NE flank due to explosive activity. Courtesy of Copernicus Browser.

Geologic Background. Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is a relatively small cone constructed on a high Pleistocene edifice. Oxidized basaltic-to-andesitic scoria deposits covering the upper part of the young cone give it a distinctive red color. Frequent basaltic Plinian eruptions have occurred during the Holocene. Lava flows have reached the sea and formed capes on the NW coast; several young lava flows are also present on the E flank beneath a scoria deposit. The Tatarinov group of six volcanic centers is located immediately to the south, and the Lomonosov cinder cone group, the source of an early Holocene lava flow that reached the saddle between it and Fuss Peak to the west, lies at the southern end of the N-S-trending Chikurachki-Tatarinov complex. In contrast to the frequently active Chikurachki, the Tatarinov centers are extensively modified by erosion and have a more complex structure. Tephrochronology gives evidence of an eruption around 1690 CE from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Marapi (Indonesia) — May 2023 Citation iconCite this Report

Marapi

Indonesia

0.38°S, 100.474°E; summit elev. 2885 m

All times are local (unless otherwise noted)


New explosive eruption with ash emissions during January-March 2023

Marapi in Sumatra, Indonesia, is a massive stratovolcano that rises 2 km above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera and trending ENE-WSW, with volcanism migrating to the west. Since the end of the 18th century, more than 50 eruptions, typically characterized by small-to-moderate explosive activity, have been recorded. The previous eruption consisted of two explosions during April-May 2018, which caused ashfall to the SE (BGVN 43:06). This report covers a new eruption during January-March 2023, which included explosive events and ash emissions, as reported by Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM) and MAGMA Indonesia.

According to a press release issued by PVMBG and MAGMA Indonesia on 26 December, primary volcanic activity at Marapi consisted of white gas-and-steam puffs that rose 500-100 m above the summit during April-December 2022. On 25 December 2022 there was an increase in the number of deep volcanic earthquakes and summit inflation. White gas-and-steam emissions rose 80-158 m above the summit on 5 January. An explosive eruption began at 0611 on 7 January 2023, which generated white gas-and-steam emissions and gray ash emissions mixed with ejecta that rose 300 m above the summit and drifted SE (figure 10). According to ground observations, white-to-gray ash clouds during 0944-1034 rose 200-250 m above the summit and drifted SE and around 1451 emissions rose 200 m above the summit. Seismic signals indicated that eruptive events also occurred at 1135, 1144, 1230, 1715, and 1821, but no ash emissions were visually observed. On 8 January white-and-gray emissions rose 150-250 m above the summit that drifted E and SE. Seismic signals indicated eruptive events at 0447, 1038, and 1145, but again no ash emissions were visually observed on 8 January. White-to-gray ash plumes continued to be observed on clear weather days during 9-15, 18-21, 25, and 29-30 January, rising 100-1,000 m above the summit and drifted generally NE, SE, N, and E, based on ground observations (figure 11).

Figure (see Caption) Figure 10. Webcam image of the start of the explosive eruption at Marapi at 0651 on 7 January 2023. White gas-and-steam emissions are visible to the left and gray ash emissions are visible on the right, drifting SE. Distinct ejecta was also visible mixed within the ash cloud. Courtesy of PVMBG and MAGMA Indonesia.
Figure (see Caption) Figure 11. Webcam image showing thick, gray ash emissions rising 500 m above the summit of Marapi and drifting N and NE at 0953 on 11 January 2023. Courtesy of PVMBG and MAGMA Indonesia.

White-and-gray and brown emissions persisted in February, rising 50-500 m above the summit and drifting E, S, SW, N, NE, and W, though weather sometimes prevented clear views of the summit. An eruption at 1827 on 10 February produced a black ash plume that rose 400 m above the summit and drifted NE and E (figure 12). Similar activity was reported on clear weather days, with white gas-and-steam emissions rising 50 m above the summit on 9, 11-12, 20, and 27 March and drifted E, SE, SW, NE, E, and N. On 17 March white-and-gray emissions rose 400 m above the summit and drifted N and E.

Figure (see Caption) Figure 12. Webcam image showing an eruptive event at 1829 on 10 February 2023 with an ash plume rising 400 m above the summit and drifting NE and E. Courtesy of PVMBG and MAGMA Indonesia.

Geologic Background. Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra's most active volcano. This massive complex stratovolcano rises 2,000 m above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been reported in 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/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.esdm.go.id/v1).


Kikai (Japan) — May 2023 Citation iconCite this Report

Kikai

Japan

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

All times are local (unless otherwise noted)


Intermittent white gas-and-steam plumes, discolored water, and seismicity during May 2021-April 2023

Kikai, located just S of the Ryukyu islands of Japan, contains a 19-km-wide mostly submarine caldera. The island of Satsuma Iwo Jima (also known as Satsuma-Iwo Jima and Tokara Iojima) is located at the NW caldera rim, as well as the island’s highest peak, Iodake. Its previous eruption period occurred on 6 October 2020 and was characterized by an explosion and thermal anomalies in the crater (BGVN 45:11). More recent activity has consisted of intermittent thermal activity and gas-and-steam plumes (BGVN 46:06). This report covers similar low-level activity including white gas-and-steam plumes, nighttime incandescence, seismicity, and discolored water during May 2021 through April 2023, using information from the Japan Meteorological Agency (JMA) and various satellite data. During this time, the Alert Level remained at a 2 (on a 5-level scale), according to JMA.

Activity was relatively low throughout the reporting period and has consisted of intermittent white gas-and-steam emissions that rose 200-1,400 m above the Iodake crater and nighttime incandescence was observed at the Iodake crater using a high-sensitivity surveillance camera. Each month, frequent volcanic earthquakes were detected, and sulfur dioxide masses were measured by the University of Tokyo Graduate School of Science, Kyoto University Disaster Prevention Research Institute, Mishima Village, and JMA (table 6).

Table 6. Summary of gas-and-steam plume heights, number of volcanic earthquakes detected, and amount of sulfur dioxide emissions in tons per day (t/d). Courtesy of JMA monthly reports.

Month Max plume height (m) Volcanic earthquakes Sulfur dioxide emissions (t/d)
May 2021 400 162 900-1,300
Jun 2021 800 117 500
Jul 2021 1,400 324 800-1,500
Aug 2021 1,000 235 700-1,000
Sep 2021 800 194 500-1,100
Oct 2021 800 223 600-800
Nov 2021 900 200 400-900
Dec 2021 1,000 161 500-1,800
Jan 2022 1,000 164 600-1,100
Feb 2022 1,000 146 500-1,600
Mar 2022 1,200 171 500-1,200
Apr 2022 1,000 144 600-1,000
May 2022 1,200 126 300-500
Jun 2022 1,000 154 400
Jul 2022 1,300 153 600-1,100
Aug 2022 1,100 109 600-1,500
Sep 2022 1,000 170 900
Oct 2022 800 249 700-1,200
Nov 2022 800 198 800-1,200
Dec 2022 700 116 600-1,500
Jan 2023 800 146 500-1,400
Feb 2023 800 135 600-800
Mar 2023 1,100 94 500-600
Apr 2023 800 82 500-700

Sentinel-2 satellite images show weak thermal anomalies at the Iodake crater on clear weather days, accompanied by white gas-and-steam emissions and occasional discolored water (figure 24). On 17 January 2022 JMA conducted an aerial overflight in cooperation with the Japan Maritime Self-Defense Force’s 1st Air Group, which confirmed a white gas-and-steam plume rising from the Iodake crater (figure 25). They also observed plumes from fumaroles rising from around the crater and on the E, SW, and N slopes. In addition, discolored water was reported near the coast around Iodake, which JMA stated was likely related to volcanic activity (figure 25). Similarly, an overflight taken on 11 January 2023 showed white gas-and-steam emissions rising from the Iodake crater, as well as discolored water that spread E from the coast around the island. On 14 February 2023 white fumaroles and discolored water were also captured during an overflight (figure 26).

Figure (see Caption) Figure 24. Sentinel-2 satellite images of Satsuma Iwo Jima (Kikai) showing sets of visual (true color) and infrared (bands 12, 11, 8a) views on 7 December 2021 (top), 23 October 2022 (middle), and 11 January 2023 (bottom). Courtesy of Copernicus Browser.
Figure (see Caption) Figure 25. Aerial image of Satsuma Iwo Jima (Kikai) showing a white gas-and-steam plume rising above the Iodake crater at 1119 on 17 January 2022. There was also green-yellow discolored water surrounding the coast of Mt. Iodake. Courtesy of JMSDF via JMA.
Figure (see Caption) Figure 26. Aerial image of Satsuma Iwo Jima (Kikai) showing white gas-and-steam plumes rising above the Iodake crater on 14 February 2023. Green-yellow discolored water surrounded Mt. Iodake. Courtesy of JCG.

Geologic Background. Multiple eruption centers have exhibited recent activity at Kikai, 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 (or Iwo-dake) lava dome and Inamuradake scoria cone, as well as submarine lava domes. Recorded 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 Satsuma-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 Satsuma-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); Japan Coast Guard (JCG) Volcano Database, Hydrographic and Oceanographic Department, 3-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8932, Japan (URL: https://www1.kaiho.mlit.go.jp/kaiikiDB/kaiyo30-2.htm); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Lewotolok (Indonesia) — May 2023 Citation iconCite this Report

Lewotolok

Indonesia

8.274°S, 123.508°E; summit elev. 1431 m

All times are local (unless otherwise noted)


Strombolian eruption continues through April 2023 with intermittent ash plumes

The current eruption at Lewotolok, in Indonesian’s Lesser Sunda Islands, began in late November 2020 and has included Strombolian explosions, occasional ash plumes, incandescent ejecta, intermittent thermal anomalies, and persistent white and white-and-gray emissions (BGVN 47:10). Similar activity continued during October 2022-April 2023, as described in this report based on information provided by Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM, or the Center of Volcanology and Geological Hazard Mitigation), MAGMA Indonesia, the Darwin Volcanic Ash Advisory Centre (VAAC), and satellite data.

During most days in October 2022 white and white-gray emissions rose as high as 200-600 m above the summit. Webcam images often showed incandescence above the crater rim. At 0351 on 14 October, an explosion produced a dense ash plume that rose about 1.2 km above the summit and drifted SW (figure 43). After this event, activity subsided and remained low through the rest of the year, but with almost daily white emissions.

Figure (see Caption) Figure 43. Webcam image of Lewotolok on 14 October 2022 showing a dense ash plume and incandescence above the crater. Courtesy of MAGMA Indonesia.

After more than two months of relative quiet, PVMBG reported that explosions at 0747 on 14 January 2023 and at 2055 on 16 January produced white-and-gray ash plumes that rose around 400 m above the summit and drifted E and SE (figure 44). During the latter half of January through April, almost daily white or white-and-gray emissions were observed rising 25-800 m above the summit, and nighttime webcam images often showed incandescent material being ejected above the summit crater. Strombolian activity was visible in webcam images at 2140 on 11 February, 0210 on 18 February, and during 22-28 March. Frequent hotspots were recorded by the MIROVA detection system starting in approximately the second week of March 2023 that progressively increased into April (figure 45).

Figure (see Caption) Figure 44. Webcam image of an explosion at Lewotolok on 14 January 2023 ejecting a small ash plume along with white emissions. Courtesy of MAGMA Indonesia.
Figure (see Caption) Figure 45. MIROVA Log Radiative Power graph of thermal anomalies detected by the VIIRS satellite instrument at Lewotolok’s summit crater for the year beginning 24 July 2022. Clusters of mostly low-power hotspots occurred during August-October 2022, followed by a gap of more than four months before persistent and progressively stronger anomalies began in early March 2023. Courtesy of MIROVA.

Explosions that produced dense ash plumes as high as 750 m above the summit were described in Volcano Observatory Notices for Aviation (VONA) at 0517, 1623, and 2016 on 22 March, at 1744 on 24 March, at 0103 on 26 March, at 0845 and 1604 on 27 March (figure 46), and at 0538 on 28 March. According to the Darwin VAAC, on 6 April another ash plume rose to 1.8 km altitude (about 370 m above the summit) and drifted N.

Figure (see Caption) Figure 46. Webcam image of Lewotolok at 0847 on 27 March 2023 showing a dense ash plume from an explosion along with clouds and white emissions. Courtesy of MAGMA-Indonesia.

Sentinel-2 images over the previous year recorded thermal anomalies as well as the development of a lava flow that descended the NE flank beginning in June 2022 (figure 47). The volcano was often obscured by weather clouds, which also often hampered ground observations. Ash emissions were reported in March 2022 (BGVN 47:10), and clear imagery from 4 March 2022 showed recent lava flows confined to the crater, two thermal anomaly spots in the eastern part of the crater, and mainly white emissions from the SE. Thermal anomalies became stronger and more frequent in mid-May 2022, followed by strong Strombolian activity through June and July (BGVN 47:10); Sentinel-2 images on 2 June 2022 showed active lava flows within the crater and overflowing onto the NE flank. Clear images from 23 April 2023 (figure 47) show the extent of the cooled NE-flank lava flow, more extensive intra-crater flows, and two hotspots in slightly different locations compared to the previous March.

Figure (see Caption) Figure 47. Sentinel-2 satellite images of Lewotolok showing sets of visual (true color) and infrared (bands 12, 11, 8a) views on 4 March 2022, 2 June 2022, and 23 April 2023. Courtesy of Copernicus Browser.

Geologic Background. The Lewotolok (or Lewotolo) stratovolcano occupies the eastern end of an elongated peninsula extending north into the Flores Sea, connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is symmetrical when viewed from the north and east. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano's high point. Many lava flows have reached the coastline. Eruptions recorded since 1660 have consisted of explosive activity from the summit crater.

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.esdm.go.id/v1); 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/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Barren Island (India) — April 2023 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 activity during December 2022-March 2023

Barren Island is part of a N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). 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. Eruptions dating back to 1787, 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. Previous activity was detected during mid-May 2022, consisting of intermittent thermal activity. This report covers June 2022 through March 2023, which included strong thermal activity beginning in late December 2022, based on various satellite data.

Activity was relatively quiet during June through late December 2022 and mostly consisted of low-power thermal anomalies, based on the MIROVA (Middle InfraRed Observation of Volcanic Activity) graph. During late December, a spike in both power and frequency of thermal anomalies was detected (figure 58). There was another pulse in thermal activity in mid-March, which consisted of more frequent and relatively strong anomalies.

Figure (see Caption) Figure 58. Occasional thermal anomalies were detected during June through late December 2022 at Barren Island, but by late December through early January 2023, there was a marked increase in thermal activity, both in power and frequency, according to this MIROVA graph (Log Radiative Power). After this spike in activity, anomalies occurred at a more frequent rate. In late March, another pulse in activity was detected, although the power was not as strong as that initial spike during December-January. Courtesy of MIROVA.

The Suomi NPP/VIIRS sensor data showed five thermal alerts on 29 December 2022. The number of alerts increased to 19 on 30 December. According to the Darwin VAAC, ash plumes identified in satellite images captured at 2340 on 30 December and at 0050 on 31 December rose to 1.5 km altitude and drifted SW. The ash emissions dissipated by 0940. On 31 December, a large thermal anomaly was detected; based on a Sentinel-2 infrared satellite image, the anomaly was relatively strong and extended to the N (figure 59).

Figure (see Caption) Figure 59. Thermal anomalies of varying intensities were visible in the crater of Barren Island on 31 December 2022 (top left), 15 January 2023 (top right), 24 February 2023 (bottom left), and 31 March 2023 (bottom right), as seen in these Sentinel-2 infrared satellite images. The anomalies on 31 December and 31 March were notably strong and extended to the N and N-S, respectively. Images using “Atmospheric penetration” rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Thermal activity continued during January through March. Sentinel-2 infrared satellite data showed some thermal anomalies of varying intensity on clear weather days on 5, 10, 15, 20, and 30 January 2023, 9, 14, 19, and 24 February 2023, and 21, 26, and 31 March (figure 59). According to Suomi NPP/VIIRS sensor data, a total of 30 thermal anomalies were detected over 18 days on 2-3, 7, 9-14, 16-17, 20, 23, 25, and 28-31 January. The sensor data showed a total of six hotspots detected over six days on 1, 4-5, and 10-12 February. During March, a total of 33 hotspots were visible over 11 days on 20-31 March. Four MODVOLC thermal alerts were issued on 25, 27, and 29 March.

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: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); NASA Worldview (URL: https://worldview.earthdata.nasa.gov/).


Villarrica (Chile) — April 2023 Citation iconCite this Report

Villarrica

Chile

39.42°S, 71.93°W; summit elev. 2847 m

All times are local (unless otherwise noted)


Nighttime crater incandescence, ash emissions, and seismicity during October 2022-March 2023

Villarrica, located in central Chile, consists of a 2-km-wide caldera that formed about 3,500 years ago, located at the base of the presently active cone. Historical eruptions date back to 1558 and have been characterized by mild-to-moderate explosive activity with occasional lava effusions. The current eruption period began in December 2014 and has recently consisted of ongoing seismicity, gas-and-steam emissions, and thermal activity (BGVN 47:10). This report covers activity during October 2022 through March 2023 and describes Strombolian explosions, ash emissions, and crater incandescence. Information for this report primarily comes from the Southern Andes Volcano Observatory (Observatorio Volcanológico de Los Andes del Sur, OVDAS), part of Chile's National Service of Geology and Mining (Servicio Nacional de Geología y Minería, SERNAGEOMIN) and satellite data.

Seismicity during October consisted of discrete long-period (LP)-type events, tremor (TR), and volcano-tectonic (VT)-type events. Webcam images showed eruption plumes rising as high as 460 m above the crater rim; plumes deposited tephra on the E, S, and SW flanks within 500 m of the crater on 2, 18, 23, and 31 October. White gas-and-steam emissions rose 80-300 m above the crater accompanied by crater incandescence during 2-3 October. There was a total of 5 VT-type events, 10,625 LP-type events, and 2,232 TR-type events detected throughout the month. Sulfur dioxide data was obtained by the Differential Absorption Optical Spectroscopy Equipment (DOAS) installed 6 km in an ESE direction. The average value of the sulfur dioxide emissions was 535 ± 115 tons per day (t/d); the highest daily maximum was 1,273 t/d on 13 October. These values were within normal levels and were lower compared to September. During the night of 3-4 October Strombolian activity ejected blocks as far as 40 m toward the NW flank. Small, gray-brown ash pulses rose 60 m above the crater accompanied white gas-and-steam emissions that rose 40-300 m high during 4-5 October. In addition, crater incandescence and Strombolian explosions that ejected blocks were reported during 4-5 and 9-11 October. Based on satellite images from 12 October, ballistic ejecta traveled as far as 400 m and the resulting ash was deposited 3.2 km to the E and SE and 900 m to the NW.

Satellite images from 14 October showed an active lava lake that covered an area of 36 square meters in the E part of the crater floor. There was also evidence of a partial collapse (less than 300 square meters) at the inner SSW crater rim. POVI posted an 18 October photo that showed incandescence above the crater rim, noting that crater incandescence was visible during clear weather nights. In addition, webcam images at 1917 showed lava fountaining and Strombolian explosions; tourists also described seeing splashes of lava ejected from a depth of 80 m and hearing loud degassing sounds. Tephra deposits were visible around the crater rim and on the upper flanks on 24 October. On 25 October SERNAGEOMIN reported that both the number and amplitude of LP earthquakes had increased, and continuous tremor also increased; intense crater incandescence was visible in satellite images. On 31 October Strombolian explosions intensified and ejected material onto the upper flanks.

Activity during November consisted of above-baseline seismicity, including intensifying continuous tremor and an increase in the number of LP earthquakes. On 1 November a lava fountain was visible rising above the crater rim. Nighttime crater incandescence was captured in webcam images on clear weather days. Strombolian explosions ejected incandescent material on the NW and SW flanks during 1, 2, and 6-7 November. POVI reported that the width of the lava fountains that rose above the crater rim on 2 November suggested that the vent on the crater floor was roughly 6 m in diameter. Based on reports from observers and analyses of satellite imagery, material that was deposited on the upper flanks, primarily to the NW, consisted of clasts up to 20 cm in diameter. During an overflight on 19 November SERNAGEOMIN scientists observed a cone on the crater floor with an incandescent vent at its center that contained a lava lake. Deposits of ejecta were also visible on the flanks. That same day a 75-minute-long series of volcano-tectonic earthquakes was detected at 1940; a total of 21 events occurred 7.8 km ESE of the crater. Another overflight on 25 November showed the small cone on the crater floor with an incandescent lava lake at the center; the temperature of the lava lake was 1,043 °C, based data gathered during the overflight.

Similar seismicity, crater incandescence, and gas-and-steam emissions continued during December. On 1 December incandescent material was ejected 80-220 m above the crater rim. During an overflight on 6 December, intense gas-and-steam emissions from the lava lake was reported, in addition to tephra deposits on the S and SE flanks as far as 500 m from the crater. During 7-12 December seismicity increased slightly and white, low-altitude gas-and-steam emissions and crater incandescence were occasionally visible. On 24 December at 0845 SERNAGEOMIN reported an increase in Strombolian activity; explosions ejected material that generally rose 100 m above the crater, although one explosion ejected incandescent tephra as far as 400 m from the crater onto the SW flank. According to POVI, 11 explosions ejected incandescent material that affected the upper SW flank between 2225 on 25 December to 0519 on 26 December. POVI recorded 21 Strombolian explosions that ejected incandescent material onto the upper SW flank from 2200 on 28 December to 0540 on 29 December. More than 100 Strombolian explosions ejected material onto the upper W and NW flanks during 30-31 December. On 30 December at 2250 an explosion was detected that generated an eruptive column rising 120 m above the crater and ejecting incandescent material 300 m on the NW flank (figure 120). Explosions detected at 2356 on 31 December ejected material 480 m from the crater rim onto the NW flank and at 0219 material was deposited on the same flank as far as 150 m. Both explosions ejected material as high as 120 m above the crater rim.

Figure (see Caption) Figure 120. Webcam image of a Strombolian explosion at Villarrica on 30 December 2022 (local time) that ejected incandescent material 300 m onto the NW flank, accompanied by emissions and crater incandescence. Courtesy of SERNAGEOMIN (Reporte Especial de Actividad Volcanica (REAV), Region De La Araucania y Los Rios, Volcan Villarrica, 30 de diciembre de 2022, 23:55 Hora local).

During January 2023, Strombolian explosions and lava fountaining continued mainly in the crater, ejecting material 100 m above the crater. Gas-and-steam emissions rose 40-260 m above the crater and drifted in different directions, and LP-type events continued. Emissions during the night of 11 January including some ash rose 80 m above the crater and as far as 250 m NE flank. POVI scientists reported about 70 lava fountaining events from 2130 on 14 January to 0600 on 15 January. At 2211 on 15 January there was an increase in frequency of Strombolian explosions that ejected incandescent material 60-150 m above the crater. Some ashfall was detected around the crater. POVI noted that on 19 January lava was ejected as high as 140 m above the crater rim and onto the W and SW flanks. Explosion noises were heard on 19 and 22 January in areas within a radius of 10 km. During 22-23 January Strombolian explosions ejected incandescent material 60-100 m above the crater that drifted SE. A seismic event at 1204 on 27 January was accompanied by an ash plume that rose 220 m above the crater and drifted E (figure 121); later that same day at 2102 an ash plume rose 180 m above the crater and drifted E.

Figure (see Caption) Figure 121. Webcam image of an ash plume at Villarrica on 27 January rising 220 m above the crater and drifting E. Courtesy of SERNAGEOMIN (Reporte Especial de Actividad Volcanica (REAV), Region De La Araucania y Los Rios, Volcan Villarrica, 27 de enero de 2023, 12:35 Hora local).

Seismicity, primarily characterized by LP-type events, and Strombolian explosions persisted during February and March. POVI reported that three explosions were heard during 1940-1942 on 6 February, and spatter was seen rising 30 m above the crater rim hours later. On 9 February lava fountains were visible rising 50 m above the crater rim. On 17 February Strombolian explosions ejected material 100 m above the crater rim and onto the upper SW flank. Webcam images from 20 February showed two separate fountains of incandescent material, which suggested that a second vent had opened to the E of the first vent. Spatter was ejected as high as 80 m above the crater rim and onto the upper NE flank. A sequence of Strombolian explosions was visible from 2030 on 20 February to 0630 on 21 February. Material was ejected as high as 80 m above the crater rim and onto the upper E flank. LP-type earthquakes recorded 1056 and at 1301 on 27 February were associated with ash plumes that rose 300 m above the crater and drifted NE (figure 122). Crater incandescence above the crater rim was observed in webcam images on 13 March, which indicated Strombolian activity. POVI posted a webcam image from 2227 on 18 March showing Strombolian explosions that ejected material as high as 100 m above the crater rim. Explosions were heard up to 8 km away. On 19 March at 1921 an ash emission rose 340 m above the crater and drifted NE. On 21 and 26 March Strombolian explosions ejected material 100 and 110 m above the crater rim, respectively. On 21 March Strombolian explosions ejected material 100 m above the crater rim. Low-intensity nighttime crater incandescence was detected by surveillance cameras on 24 March.

Figure (see Caption) Figure 122. Photo of an ash plume rising 300 m above the crater of Villarrica and drifting NE on 27 February 2023. Courtesy of SERNAGEOMIN (Reporte Especial de Actividad Volcanica (REAV), Region De La Araucania y Los Rios, Volcan Villarrica, 27 de febrero de 2023, 11:10 Hora local).

Infrared MODIS satellite data processed by MIROVA (Middle InfraRed Observation of Volcanic Activity) detected an increase in thermal activity during mid-November, which corresponds to sustained Strombolian explosions, lava fountaining, and crater incandescence (figure 123). This activity was also consistently captured on clear weather days throughout the reporting period in Sentinel-2 infrared satellite images (figure 124).

Figure (see Caption) Figure 123. Low-power thermal anomalies were detected during August through October 2022 at Villarrica, based on this MIROVA graph (Log Radiative Power). During mid-November, the power and frequency of the anomalies increased and remained at a consistent level through March 2023. Thermal activity consisted of Strombolian explosions, lava fountains, and crater incandescence. Courtesy of MIROVA.
Figure (see Caption) Figure 124. Consistent bright thermal anomalies were visible at the summit crater of Villarrica in Sentinel-2 infrared satellite images throughout the reporting period, as shown here on 19 December 2022 (left) and 9 February 2023 (right). Occasional gas-and-steam emissions also accompanied the thermal activity. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Geologic Background. The glacier-covered Villarrica stratovolcano, in the northern Lakes District of central Chile, is ~15 km south of the city of Pucon. A 2-km-wide caldera that formed about 3,500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesite cone at the NW margin of a 6-km-wide Pleistocene caldera. More than 30 scoria cones and fissure vents are present on the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Eruptions documented since 1558 CE have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.

Information Contacts: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/); Proyecto Observación Villarrica Internet (POVI) (URL: http://www.povi.cl/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Fuego (Guatemala) — April 2023 Citation iconCite this Report

Fuego

Guatemala

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

All times are local (unless otherwise noted)


Daily explosions, gas-and-ash plumes, avalanches, and ashfall during December 2022-March 2023

Fuego, one of three large stratovolcanoes overlooking the city of Antigua, Guatemala, has been vigorously erupting since January 2002, with recorded eruptions dating back to 1531 CE. Eruptive activity has included major ashfalls, pyroclastic flows, lava flows, and lahars. Frequent explosions with ash emissions, block avalanches, and lava flows have persisted since 2018. More recently, activity remained relatively consistent with daily explosions, ash plumes, ashfall, avalanches, and lahars (BGVN 48:03). This report covers similar activity during December 2022 through March 2023, based on information from the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH) daily reports, Coordinadora Nacional para la Reducción de Desastres (CONRED) newsletters, and various satellite data.

Daily explosions reported throughout December 2022-March 2023 generated ash plumes to 6 km altitude that drifted as far as 60 km in multiple directions. The explosions also caused rumbling sounds of varying intensities, with shock waves that vibrated the roofs and windows of homes near the volcano. Incandescent pulses of material rose 100-500 m above the crater, which caused block avalanches around the crater and toward the Santa Teresa, Taniluyá (SW), Ceniza (SSW), El Jute, Honda, Las Lajas (SE), Seca (W), and Trinidad (S) drainages. Fine ashfall was also frequently reported in nearby communities (table 27). MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed frequent, moderate thermal activity throughout the reporting period; however, there was a brief decline in both power and frequency during late-to-mid-January 2023 (figure 166). A total of 79 MODVOLC thermal alerts were issued: 16 during December 2022, 17 during January 2023, 23 during February, and 23 during March. Some of these thermal evets were also visible in Sentinel-2 infrared satellite imagery at the summit crater, which also showed occasional incandescent block avalanches descending the S, W, and NW flanks, and accompanying ash plumes that drifted W (figure 167).

Table 27. Activity at Fuego during December 2022 through March 2023 included multiple explosions every hour. Ash emissions rose as high as 6 km altitude and drifted generally W and SW as far as 60 km, causing ashfall in many communities around the volcano. Data from daily INSIVUMEH reports and CONRED newsletters.

Month Explosions per hour Ash plume altitude (max) Ash plume distance (km) and direction Drainages affected by block avalanches Communities reporting ashfall
Dec 2022 1-12 6 km WSW, W, SW, NW, S, SE, NE, and E, 10-30 km Santa Teresa, Taniluyá, Ceniza, El Jute, Honda, Las Lajas, Seca, and Trinidad Panimaché I and II, Morelia, Santa Sofía, El Porvenir, Finca Palo Verde, Yepocapa, Yucales, Sangre de Cristo, La Rochela, Ceilán, San Andrés Osuna, and Aldea La Cruz
Jan 2023 1-12 5 km W, SW, NW, S, N, NE, E, and SE, 7-60 km Ceniza, Las Lajas, Santa Teresa, Taniluyá, Trinidad, Seca, Honda, and El Jute Panimaché I and II, Morelia, Santa Sofía, El Porvenir, Palo Verde, Yucales, Yepocapa, Sangre de Cristo, La Rochela, Ceylon, Alotenango, and San Andrés Osuna
Feb 2023 1-12 4.9 km SW, W, NW, and N, 10-30 km Santa Teresa, Taniluyá, Ceniza, Las Lajas, Seca, Trinidad, El Jute, and Honda Panimaché I and II, Morelia, Santa Sofía, Palo Verde, San Pedro Yepocapa, El Porvenir, Sangre de Cristo, La Soledad, Acatenango, El Campamento, and La Asunción
Mar 2023 3-11 5 km W, SW, NW, NE, N, S, SE, and E, 10-30 km Seca, Ceniza, Taniluyá, Las Lajas, Honda, Trinidad, El Jute, and Santa Teresa Yepocapa, Sangre de Cristo, Panimaché I and II, Morelia, Santa Sofía, El Porvenir, La Asunción, Palo Verde, La Rochela, San Andrés Osuna, Ceilán, and Aldeas
Figure (see Caption) Figure 166. Thermal activity at Fuego shown in the MIROVA graph (Log Radiative Power) was at moderate levels during a majority of December 2022 through March 2023, with a brief decline in both power and frequency during late-to-mid-January 2023. Courtesy of MIROVA.
Figure (see Caption) Figure 167. Frequent incandescent block avalanches descended multiple drainages at Fuego during December 2022 through March 2023, as shown in these Sentinel-2 infrared satellite images on 10 December 2022 (top left), 4 January 2023 (top right), 18 February 2023 (bottom left), and 30 March 2023 (bottom right). Gray ash plumes were also occasionally visible rising above the summit crater and drifting W, as seen on 4 January and 30 March. Avalanches affected the NW and S flanks on 10 December, the SW and W flanks on 18 February, and the NW, W, and SW flanks on 30 March. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Daily explosions ranged between 1 and 12 per hour during December 2022, generating ash plumes that rose to 4.5-6 km altitude and drifted 10-30 km in multiple directions. These explosions created rumbling sounds with a shock wave that vibrated the roofs and windows of homes near the volcano. Frequent white gas-and-steam plumes rose to 4.6 km altitude. Strombolian activity resulted in incandescent pulses that generally rose 100-500 m above the crater, which generated weak-to-moderate avalanches around the crater and toward the Santa Teresa, Taniluyá, Ceniza, El Jute, Honda, Las Lajas, Seca, and Trinidad drainages, where material sometimes reached vegetation. Fine ashfall was recorded in Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Finca Palo Verde, Yepocapa (8 km NW), Yucales (12 km SW), Sangre de Cristo (8 km WSW), La Rochela, Ceilán, San Andrés Osuna, and Aldea La Cruz. INSIVUMEH reported that on 10 December a lava flow formed in the Ceniza drainage and measured 800 m long; it remained active at least through 12 December and block avalanches were reported at the front of the flow. A pyroclastic flow was reported at 1100 on 10 December, descending the Las Lajas drainage for several kilometers and reaching the base of the volcano. Pyroclastic flows were also observed in the Ceniza drainage for several kilometers, reaching the base of the volcano on 11 December. Ash plumes rose as high as 6 km altitude, according to a special bulletin from INSIVUMEH. On 31 December explosions produced incandescent pulses that rose 300 m above the crater, which covered the upper part of the cone.

Activity during January 2023 consisted of 1-12 daily explosions, which produced ash plumes that rose to 4.2-5 km altitude and drifted 7-60 km in multiple directions (figure 168). Incandescent pulses of material were observed 100-350 m above the crater, which generated avalanches around the crater and down the Ceniza, Las Lajas, Santa Teresa, Taniluyá, Trinidad, Seca, Honda, and El Jute drainages. Sometimes, the avalanches resuspended older fine material 100-500 m above the surface that drifted W and SW. Ashfall was recorded in Panimaché I and II, Morelia, Santa Sofía, El Porvenir, Palo Verde, Yucales, Yepocapa, Sangre de Cristo, La Rochela, Ceylon, Alotenango, and San Andrés Osuna. Intermittent white gas-and-steam plumes rose to 4.5 km altitude and drifted W and NW.

Figure (see Caption) Figure 168. Webcam image showing an ash plume rising above Fuego on 15 January 2023. Courtesy of INSIVUMEH.

There were 1-12 daily explosions recorded through February, which generated ash plumes that rose to 4.2-4.9 km altitude and drifted 10-30 km SW, W, NW, and N. Intermittent white gas-and-steam emissions rose 4.5 km altitude and drifted W and SW. During the nights and early mornings, incandescent pulses were observed 100-400 m above the crater. Weak-to-moderate avalanches were also observed down the Santa Teresa, Taniluyá, Ceniza, Las Lajas, Seca, Trinidad, El Jute, and Honda drainages, sometimes reaching the edge of vegetated areas. Occasional ashfall was reported in Panimaché I and II, Morelia, Santa Sofía, Palo Verde, San Pedro Yepocapa, El Porvenir, Sangre de Cristo, La Soledad, Acatenango, El Campamento, and La Asunción. On 18 February strong winds resuspended previous ash deposits as high as 1 km above the surface that blew 12 km SW and S.

During March, daily explosions ranged from 3-11 per hour, producing ash plumes that rose to 4-5 km altitude and drifted 10-30 km W, SW, NW, NE, N, S, SE, and E. During the night and early morning, crater incandescence (figure 169) and incandescent pulses of material were observed 50-400 m above the crater. Weak-to-moderate avalanches affected the Seca, Ceniza, Taniluyá, Las Lajas, Honda, Trinidad, El Jute, and Santa Teresa drainages, sometimes reaching the edge of vegetation. Frequent ashfall was detected in Yepocapa, Sangre de Cristo, Panimaché I and II, Morelia, Santa Sofía, El Porvenir, La Asunción, Palo Verde, La Rochela, San Andrés Osuna, Ceilán, and Aldeas. Weak ashfall was recorded in San Andrés Osuna, La Rochela, Ceylon during 8-9 March. A lahar was reported in the Ceniza drainage on 15 March, carrying fine, hot volcanic material, tree branches, trunks, and blocks from 30 cm to 1.5 m in diameter. On 18 March lahars were observed in the Las Lajas and El Jute drainages, carrying fine volcanic material, tree branches and trunks, and blocks from 30 cm to 1.5 m in diameter. As a result, there was also damage to the road infrastructure between El Rodeo and El Zapote.

Figure (see Caption) Figure 169. Sentinel-2 infrared satellite image showing Fuego’s crater incandescence accompanied by a gas-and-ash plume that drifted SW on 25 March 2023. Images use bands 12, 11, 5. Courtesy of INSIVUMEH.

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/); 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).

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Bulletin of the Global Volcanism Network - Volume 36, Number 06 (June 2011)

Managing Editor: Richard Wunderman

Barren Island (India)

Evolving eruption emits tephra and continues in January 2011

Batur (Indonesia)

Thousands of dead fish floating in caldera lake during June 2011

Dieng Volcanic Complex (Indonesia)

Seismicity and dangerous gas emissions; 1,200 evacuate in May-June 2011

Erta Ale (Ethiopia)

Observers watch dynamic lava lake during November 2010

Fuego (Guatemala)

Frequent plumes and avalanches; occasional incandescence and lahars

Grimsvotn (Iceland)

Eruption of 21-28 May 2011; ash plumes affect parts of Europe's air space

Lokon-Empung (Indonesia)

July 2011 ash plumes spur 4,000 to 6,000 to evacuate

Manam (Papua New Guinea)

Eruptions ongoing from August 2010 to January 2011



Barren Island (India) — June 2011 Citation iconCite this Report

Barren Island

India

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

All times are local (unless otherwise noted)


Evolving eruption emits tephra and continues in January 2011

Barren Island, a young and growing mafic island-arc volcano in the Andaman Sea (figure 16), produced its first historically recorded eruption in 1787; a series of eruptions followed in later years. Evidence of eruptions again became clear in May 2005 as a result observations by the Indian Coast Guard.

Figure (see Caption) Figure 16. Map showing the location of Barren Island as part the S-trending volcanic arc extending between Burma (Myanmar) and Sumatra. It shows major geological and tectonic features of the NE Indian Ocean and SE Asia, along with the locations of the Andaman and Nicobar Islands, Barren Island, and Narcondam. White triangles are Holocene volcanoes (Siebert, and others, 2010). Taken from Sheth and others (2009) and from BGVN 36:03.

A recent report on Barren Island (BGVN 35:01) reported occasional ash plumes and decreasing thermal alerts through January 2010. In our last report on Barren Island (BGVN 36:03) we described some new details about this volcano, particularly during the years 2005-2009, as reported by Sheth and others (2009) and the Geological Survey of India (GSI, 2009). The current report discusses activity at the volcano during January 2010-April 2011, including observations made by GSI (2011) during a January 2011 field trip and thermal anomalies detected by satellite.

Ash plumes. During 2010 and through mid-2011, the Darwin Volcanic Ash Advisory Centre reported ash plumes from Barren Island. Figure 17 shows a plume rising from the volcano in a 25 September 2010 satellite image.

Figure (see Caption) Figure 17. A plume of ash rises from Barren Island on 25 September 2010. The Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite shows a dark-gray ash cloud rising from a volcanic cone that fills the island's central caldera. Dark, hardened lava flows cover the caldera floor, some extending to the ocean. Green vegetation covers the caldera rim and the outer slopes. Breaking waves line the southern coastline in white. This remote, uninhabited volcanic island is not monitored directly, but the Indian Coast Guard, passing pilots, and satellites have observed lava flows and ash plumes periodically since 2005. Courtesy of NASA Earth Observatory, image by Robert Simmon using ALI data from the NASA EO-1 team.

The Darwin VAAC documented other plumes, for example, on 3 January 2010 a pilot reported that a plume rose to an altitude of 1.5 km. On 11 January 2010 an ash plume visible through satellite imagery rose to an altitude of 1.5 km and drifted 45 km S. On 23 January 2010 a pilot observed an ash plume that rose to a reported altitude of 3 km, but it was not identified on satellite imagery.

New insights from GSI. GSI (2011) discussed a scientific expedition to Barren Island made during 2-8 January 2011. The eruption still continued, but with lesser intensity as compared to the violent eruption observed during 2005 to 2009. The eruption was of a pulsative and explosive character (Strombolian type) where dark columns of a dense ash-laden steam with coarser pyroclasts (cinders, juvenile lava blocks) were ejected at 2- to 8-minute intervals.

The eruption discharged from two vents on the parasitic crater. That crater had developed over a subsidiary cinder cone (~ 500 m high) on the S wall of the main cinder cone of the 1991-95 eruption. Coarser incandescent pyroclasts rose sub-vertically to 100-150 m in height and tumbled down the volcanic cone. A thick column of ash-laden gray vapor was ejected to heights of ~ 150-200 m and typically rose in a mushroom shaped ash cloud.

Figure 18 shows the lower portion of an ash plume.

Figure (see Caption) Figure 18. Barren Island emitting a column of ash-laden vapor. Bulletin editors noted two minor features: (1) dark spots to the left of the vent suggestive of local ash fall, and (2) small plumes near the ground surface, which appear similar to those discussed in the Fuego report (this issue, BGVN 36:06). Taken from GSI (2011).

Significant changes were observed in the shape and height of the cinder cone in the 2-km-diameter caldera. The height of the cinder cone increased from ~ 350 m in 2005 to ~ 500 m in 2011. The main approach to the center of the island follows a valley leads to the breached NW side of the caldera wall. The valley was covered totally by a thick pile of repetitive sequences of assorted pyroclasts and lava from recent eruptions. Near the base of the cinder cone, in the NW part of the island, the accumulated thickness of the products from recent eruptions was ~ 100 m. Besides the main pyroclast deposits from lava in the W part of the valley, considerable deposits had filled up the valley in the NNW part of the island, overflowing the caldera wall and covering the pre-historic lava. The recent lava flows reached the sea front attaining a width of ~ 250 m at the coast (figure 19).

Figure (see Caption) Figure 19. Lava flow emplaced between 2009-Jan 2011. Located on the NNW side of Barren Island with a width of flow at the coast of ~250 m. From GSI (2011).

This is the first report of the lava and pyroclasts of recent eruptions in the NNW part of the island. The main lava flow and pyroclastic deposits discharged from the NW part of the crater,carried towards the W and NNW part of the valley, giving rise to new land forms.

The lava and associated eruptive products of the 1991 and 1994-95 explosions, which were exposed earlier near the mouth of the valley and on the S side of the valley, were covered by the recent tephra The coarser pyroclasts are highly vesiculated basaltic rocks where plagioclase occurs as the dominant phenocryst set in a glassy matrix. The pile of pyroclasts formed very uneven. Maximum height of the accumulated material was ~20 m. Fusion of individual cinders, spatter, and blocks produced bigger blocks.

MODVOLC Thermal Alerts. MODVOLC satellite thermal measurement showed frequent alerts for the following periods: 17 September through 5 November 2010 (nearly daily alerts), 14 December 2010 through 10 January 2011, and 29 March through 11 April 2011 (daily alerts). Alerts were absent during 13 February through 17 September 2010.

Recent history of major ash eruptions. Awasthi and others (2010) measured 14C dates of inorganic carbon in sediment beds, and Sr and Nd isotopic ratios of seven discrete ash layers, in a marine sediment core collected from 32 km SE of the Barren volcano. The study revealed that the volcano had seven major ash eruptions, at ~70, 69, 61, 24, 19, 15, and 10 kiloyears (ka) before present. The ash layers erupted from 70 ka through 19 ka have highly uniform Nd isotopic composition; eruptions since ~15 ka have highly variable isotopic compositions. The authors found that during 10-24 ka, the volcano had large ash eruptions spaced at ~4.5 ka intervals (~10, ~15, 19, and 24 ka). Isotopically correlating the precaldera lavas and ash exposed on the volcano to the uppermost ash layer in the core, the authors inferred that the caldera was younger than the last ~10 ka ash layer found in the core. This represents the hypothesis that the caldera formed as a result of a single, simple, symmetric collapse after Barren Islands major ash eruptions.

References. Awasthi, N., Ray, J.S., Laskar, A.H., Kumar, A., Sudhakar, M., Bhutani, R., Sheth, H.C., and Yadava, M.G., 2010, Major ash eruptions of Barren Island volcano (Andaman Sea) during the past 72 kyr: clues from a sediment core record, Bulletin of Volcanology, v. 72, pp. 1131-1136.

Geological Survey of India, 2009, The Barren Island Volcano, Explosive Strombolian type eruption observed during January 2009, Jan 2009 URL: http://www.portal.gsi.gov.in/ gsiImages/information/ N_BarrenJan09Note.pdf)

Geological Survey of India, 2011, Barren Volcano in January 2011: An explosive pulsative eruption (Strombolian) still continues, Eastern Region Geological Survey of India URL: http://www.portal.gsi.gov.in/gsiDoc/pub/cs_barren-eruption.pdf)

Sheth, H.C. , Ray, J.S., Bhutani, R., Kumar, A., and Smitha, R. S., 2009, Volcanology and eruptive styles of Barren Island: an active mafic stratovolcano in the Andaman Sea, NE Indian Ocean, Bulletin of Volcanology, v. 71, pp. 1021-1039 (DOI: 10.1007/s00445-009-0280-z).

Siebert, L., Simkin, T., and Kimberly, P, 2010, Volcanoes of the World: Third Edition, University of California Press, Berkeley, 551 p.

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: Geological Survey of India (GSI), GSI Complex, Bhu Bijnan Bhavan, Block: DK-6, Sector-II, Salt LakeKolkata-700091 West Bengal, India (URL: http://www.portal.gsi.gov.in/); 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/).


Batur (Indonesia) — June 2011 Citation iconCite this Report

Batur

Indonesia

8.2403°S, 115.3775°E; summit elev. 1711 m

All times are local (unless otherwise noted)


Thousands of dead fish floating in caldera lake during June 2011

Batur stratovolcano sits at the E end of the island of Bali amid nested calderas (figure 4) and rises 686 m above the surface of an intra-caldera lake of the same name (Sutawidjaja, 2009). The entire complex remained non-eruptive through at least mid-2011 as it has for at least a decade (since a moderate eruption in 1974 and a series of smaller eruptions in the 1990s ceasing in about 2000). Local authorities reported that, following some variable seismicity during 2009-2010, starting 19 June 2011 residents smelled sulfurous gas and saw many dead fish floating on the lake's surface. The kill took place in the volcano's caldera lake but in the absence of visible eruptive activity and without anomalous geophysical perturbations.

Figure (see Caption) Figure 4. Physiographic map of the island of Bali highlighting Batur caldera. The topographic high in the N-central caldera is Batur stratovolcano (summit elevation, 1,717 m). The lake (not delineated) lies along the caldera's SE side. Taken from Sutawidjaja (2009).

Our previous report on Batur (BGVN 34:11) had noted increased seismicity from September to 7 November 2009. Since that report, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) has reported that seismicity from Batur decreased from 1 June to 17 November 2010 and fumarolic plumes rose from the crater. On 19 November the Alert level was lowered to Normal, or 1.

Investigation of thousands of dead fish. CVGHM scientists visited Lake Batur (figure 5) to learn more about the incident. They learned that residents of lakeside villages first observed lake water discoloration and acrid (like sulfur) odors on the morning of 19 June 2011. A greenish-white discoloration first emerged in spots, but these spots soon connected and spread. The residents had seen a slick on the water surface spread from the E-central lake shore towards the S (from Toya Bungkah to Buahan, figure 6). In conjunction with these changes in color, thousands of dead fish were found at the surface of the lake (figure 7).

Figure (see Caption) Figure 5. Photo of Lake Batur with two farmers for scale. The tops of fish cages (kerambah) can be seen in the lake water. Note steep caldera wall in background. Photo taken from allvoices.com. (Photographer unknown and other details undisclosed.)
Figure (see Caption) Figure 6. Map showing location of Lake Batur, with the locations of the greenish-white water seen near the coast (shaded). The lake is 7.7 km in the long dimension and has a surface area of 16 km2. Courtesy of CVGHM.
Figure (see Caption) Figure 7. Photo of dead fish floating on the surface of Lake Batur associated with the fish kill of 2011. Thousand of fish died, many near the village of Toya Bungkah. Undated photo taken from indosurflife.com.

The translated report contained this important passage. "According to information from a resident (Made Yuni, age 59), the change in color of the lake water, consisting of patches of whitish green, is a yearly event, although [typically] small in scale and not causing the death of fish. The change in color of the lake water occurs during the change of seasons (i.e. the transition), between the wet and dry parts of the year when there is a stiff wind from the S. The incident of the lake water changing color and the death of the fish on 19 June 2011 occurred about two weeks into the dry season. The death of fish in Batur on the present scale happened before, in 1995."

Scientists conducted an examination during 21-22 June 2011. They also had pre-event temperature and pH for multiple sites on the lake going back at least several months. At the time of the visit, all residual odors had dispersed. Results of ambient gas measurements showed no traces of anomalous carbon monoxide, carbon dioxide, methane, or hydrogen sulfide. The lake temperature was found to be 15°C, which is considered normal. pH levels in the lake were found to be constant with other measurements taken in normal times as well. No increase in volcanic earthquakes were reported before or after the fish kill (the pattern of earthquakes was constant at typical background, 1 event/day). The colors seen were attributed to both warm water welling up (springs at Toya Bungkah) but also at places where such springs are absent.

On 20 June the water by the village of Seked returned to its normal color. Late in 21 June the water by the other villages involved returned to its normal color. Scientists found neither dead weeds or algae nor gas bubbles associated with the fish kill.

Scientists from CVGHM found no evidence to conclude the fish kill was volcanically triggered nor did they mention it portending eruptive activity. Rather, the scientists noted the comparatively high diurnal-temperature difference during the onset of the dry season. As a result of these temperature differences, the lake water developed currents, which carried mud from the lake bottom to the surface. This was thought to correspond to the observed odors ('muddy smells') and color changes on the lake surface. In a broad sense, the currents and mud were thought to upset the lake's ecological balance in a manner toxic to the fish.

Residents were advised to not consume dead fish from the incident, but fish that had survived were still considered fit for human consumption. Many inhabitants around Lake Batur are fisherman by trade and it is estimated that the fish kill resulted in losses up to billions of Rupiah (1 billion Rupiah currently equivalent to ~120,000 US Dollars). The water of Lake Batur is also irrigated into surrounding farms. There is no official documentation on whether or not the recent events at Lake Batur have affected the neighboring agriculture.

Reference. Sutawidjaja, I.S., 2009, Ignimbrite Analyses of Batur Caldera, Bali, based on 14C dating, Jurnal Geologi Indonesia, Vol. 4 No. 3, September 2009: 189-202 [http://www.bgl.esdm.go.id/dmdocuments/jurnal20090304.pdf].

Geologic Background. The historically active Batur is located at the center of two concentric calderas NW of Agung volcano. The outer 10 x 13.5 km caldera was formed during eruption of the Bali (or Ubud) Ignimbrite about 29,300 years ago and now contains a caldera lake on its SE side, opposite the Gunung Abang cone, the topographic high of the complex. The inner 6.4 x 9.4 km caldera was formed about 20,150 years ago during eruption of the Gunungkawi Ignimbrite. The SE wall of the inner caldera lies beneath Lake Batur; Batur cone has been constructed within the inner caldera to a height above the outer caldera rim. The Batur stratovolcano has produced vents over much of the inner caldera, but a NE-SW fissure system has localized the Batur I, II, and III craters along the summit ridge. Recorded eruptions have been characterized by mild-to-moderate explosive activity sometimes accompanied by lava emission. Basaltic lava flows from both summit and flank vents have reached the caldera floor and the shores of Lake Batur in historical time.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Bali Discovery Tours, Komplek Pertokoan Sanur Raya No. 27 Jl. By Pass Ngurah Rai,Sanur, Bali, Indonesia (URL: http://www.balidiscovery.com)


Dieng Volcanic Complex (Indonesia) — June 2011 Citation iconCite this Report

Dieng Volcanic Complex

Indonesia

7.2°S, 109.879°E; summit elev. 2565 m

All times are local (unless otherwise noted)


Seismicity and dangerous gas emissions; 1,200 evacuate in May-June 2011

This report on Dieng volcanic complex (figure 2) notes both toxic gas emissions and episodes of high seismicity during 1 October 2009-July 2011. A late May 2011 visit, after increased gas emissions were noted the previous week, revealed dead birds and damaged vegetation at Timbang crater. Gas measurements at several sites confirmed the presence of hazardous gases; however, there were no human fatalities or injuries noted. According to news reports, 1,200 people were evacuated. Our previous report on Dieng discussed a phreatic eruption on 26 September 2009, preceded by a series of volcanic earthquakes (BGVN 34:08).

Figure (see Caption) Figure 2. A sketch map for Dieng Volcanic Complex, which lies in Central Java associated with the ~2-km-high plateau of the same name. The Dieng plateau is E-trending and roughly 14 by 6 km. Taken from Van Bergen and others (2000).

During January 2010, landslides took place near Dieng, followed by others at distance. One landslide crossed the highway between Dieng and Wonosobo (the regional capital, 18 km S of Dieng). The second landslide struck a village called Wonoaji, and according to a Jakarta Post article (by Suherdjoko, 21 January 2010), "Two people [there] have died and three are still missing, while five others were injured. . . ."

Although little was reported regarding Dieng during October 2009-2010, Relief Web posted a graphic describing heavy rains and regional flooding during February 2010 in the portion of Central Java hundreds of kilometers E of Dieng near Bandung. This episode triggered a landslide in Ciwidey village taking 17 lives.

The latest reported activity at Dieng began in mid-2011. According to the Center of Volcanology and Geological Hazard Mitigation (CVGHM), seismicity at Dieng increased during 18-22 May 2011. On 22 May, diffuse white plumes rose from the Timbang cone; plumes from the cone had not been previously observed. The next day carbon dioxide (CO2) emissions increased. On 23 May, CVGHM raised the Alert Level to 2 (on a scale of 1-4).

CVGHM reported that on 29 May 2011, gas plumes rose 50 m above Timbang cone. The gas plumes drifted S through the valley. Observers who visited the cone noted the previously mentioned damaged vegetation and dead birds. Seismicity and CO2 emissions remained elevated, thus prompting CVGHM to raise the Alert Level to 3.

During 4-5 June white plumes from Sileri crater rose 20-60 m and white plumes from Timbang rose only 2 m and drifted 300 m S. Seismicity and carbon dioxide remained high through 5 June

According to CVGHM, carbon-dioxide emissions from Timbang declined during 31 May-10 June, while seismicity decreased during 5-7 June and was not detected during 8-10 June. White plumes were not observed. On 10 June the Alert Level was lowered to 2.

Stated gas concentrations. In early June, low levels of hydrogen sulfide (H2S, 0.002-0.05% by volume) were recorded at Sikendang, Sikidang, Sibanteng, and Sileri craters. Carbon monoxide gas (CO) was only detected along the steam vents of Sikendang crater, at a concentration of 0.004% by volume. CO2 was measured at a concentration of 5.0% by volume. On 5 June, the CO2 from Timbang was at its highest level at, 1.54% by volume. The scientists added that weather patterns had brought low atmospheric pressure, which had enhanced gas escape at the vent.

John Seach presents modest-resolution photos from 2010 showing the Sikidang vent mentioned above, and Telega Warna crater lake (see Information Contacts).

Figure 3 shows one approach to communicating gas-hazards warnings.

Figure (see Caption) Figure 3. A sign written in Indonesian warning people crossing a part of the Dieng complex susceptible to dangerous gas emissions. The sign states, "Caution—Contaminated Area—Poisonous Gases." This photo appeared in an article published 5 June 2011 in the news source ANTARA/Anis Efizudin.

Dieng plateau. In the modern record, Dieng has a history of lethal gas emissions, phreatic explosions, and other hazards. The complex contains rocks ranging from andesite to rhyodacite, extrusives filling and sitting upon a large older (Pleistocene) caldera. It contains several stratovolcanoes, and many cones, craters, domes, and thermal features (see subsections below).

Van Bergen and others (2000) described the plateau and associated volcanic complex, portions of which follow.

"The Dieng Volcanic Complex in Central Java is situated on a highland plateau at about 2000 m above sea level, approximately 25 km N of the city of Wonosobo. It belongs to a series of Quaternary volcanoes, which includes the historically active Sumbing and Sundoro volcanoes. The plateau is a rich agricultural area for potatoes, cabbages, tomatoes and other vegetables. There are numerous surface manifestations of hydrothermal activity, including lakes, fumaroles/solfatara and hotsprings. The area is also known for the development of geothermal resources and lethal outbursts of gas. Scattered temples are the witnesses of the ancient Hindu culture that once reigned.

"In terms of chemical composition, Telaga Warna is the most interesting crater lake in the Dieng area. The original shape of the crater has been modified by a lava flow. The water occupies less than 1 km2. Gas bubbles can be seen rising to the lake surface, and the air has a sulfurous odor. Its colorful appearance (warna stands for color(s) in Indonesian) makes the lake an interesting tourist attraction. The water has a pH of about 3, which may fluctuate depending on seasonal variations. Sulfate and chloride contents are moderately high. . . . Strong emissions of CO2-rich gas on-shore have occasionally killed animals, so that a path on the N side used to be closed to avoid risks for local villagers."

The same report presents some composition data from 1994. Some of the 'dry' gas from several vents in the complex were up to 90% CO2.

Geothermal energy. According to Geo Dip Energi, the Dieng #1 project is currently in operation and producing 60 MegaWatts (MW) of energy. Two more projects, each of 60 MW are underway. The Dieng area is thought to have more potential and could produce 300 MW.

Reference. Van Bergen, M., Bernard, A., Sumarti, S., Sriwana, T., and Sitorus, K., 2000. Crater Lakes of Java: Dieng, Kelud, and Ijen. Excursion Guidebook, IAVCEI General Assembly, Bali 2000, 9 pp. URL: http://www.ulb.ac.be/sciences/cvl/DKIPART1.pdf).

Geologic Background. The Dieng plateau in the highlands of central Java is renowned both for the variety of its volcanic scenery and as a sacred area housing Java's oldest Hindu temples, dating back to the 9th century CE. The Dieng Volcanic Complex consists of multiple stratovolcanoes and more than 20 small Pleistocene-to-Holocene craters and cones over a 6 x 14 km area. Prahu stratovolcano was truncated by a large Pleistocene caldera, which was subsequently filled by a series of cones, lava domes, and craters, many containing lakes. Lava flows cover much of the plateau, but observed activity has been restricted to minor phreatic eruptions. Gas emissions are a hazard at several craters and have caused fatalities. There are abundant thermal features and high heat flow across the area.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.go.id/); Geo Dipa Energi, Recapital Building 8th Floor, Jl. Aditiawarman Kav. 55 Jakarta Selatan 12160 Indonesia (URL: http://www.geodipa.co.id); John Seach, Volcano Live (URL: http://volcanolive.com); Xinhua News (URL: http://www.xinhuanet.com/english2010/); Jakarta Globe (URL: http://www.thejakartaglobe.com/home/).


Erta Ale (Ethiopia) — June 2011 Citation iconCite this Report

Erta Ale

Ethiopia

13.601°N, 40.666°E; summit elev. 585 m

All times are local (unless otherwise noted)


Observers watch dynamic lava lake during November 2010

Erta Ale contains two lava lakes within its caldera. During the last three years, several expeditions have visited the volcano to examine changes (BGVN 33:06, 34:07, and 35:01). This report synthesizes the reports of two teams that visited Erta Ale during November 2010. Both teams noted that the lava lake within the southern crater has risen, nearly filling the entire crater and overflowing onto the caldera floor.

Southern Crater activity. Afar Rift Consortium (ARC) scientists visited Erta Ale during 21-23 November 2010 (figures 28 and 29). Tom Pfeiffer (Volcano Discovery) and Micheal Dalton-Smith visited Erta Ale during 25-28 November 2010. The lava lake had risen above previously formed terraces (see BGVN 35:01 for information on terraces). Both teams noted that the lava lake had risen ~40 m, nearly filling the S crater and breaching its W rim, spilling lava flows onto the larger caldera floor. The still-hot overflows traveled distances of 50-100 m on the caldera floor, and one recent long flow (estimated to be from November 24th given its temperature) had almost reached the W caldera walls.

Figure (see Caption) Figure 28. Satellite image of the Erte Ale caldera showing the two crater pits. Courtesy of Google Earth, with labels by Afar Rift Consortium in reference to their 21-23 November 2010 visit (Field and Keir, 2010).
Figure (see Caption) Figure 29. Photograph of the Erte Ale showing the lava lake with an elevated rim, taken 22 November 2010. Person in bottom left of photo for scale. Photo by L. Field (Afar Rift Consortium). Taken from Field and Keir (2010).

The ARC team noted Strombolian activity from the lava lake in the southern pit crater (figure 30).Throughout their visit, the ARC team saw extensive amounts of Pele's Hair and clouds rich in hydrogen-sulfide gas. Fountaining was reported by Pfeiffer to reach heights of 30-70 m. Degassing fountains kept the whole lava-lake surface violently boiling for a large portion of the latter team's visit.

Figure (see Caption) Figure 30. Photograph of the first lava to breach the rim of Erta Ale's S crater and then to enter the main caldera. Taken 21 November 2010 by L. Field (from Field and Keir, 2010).

The still-active lake was circular, ~40 m in diameter (about half to two-thirds its size in 2008 and 2009). The lava lake was reported to be encompassed by a bounding ring of chilled material that was ~ 4 m high on the S side. The morphology of the ring wall constantly changed as more lava overflowed, with parts collapsing and rebuilding.

From the night of the 22 November 2010 until the ARC team left on 23 November, the team observed a periodic rise and decline of the lava lake level.

According to Pfeiffer the lava level rose and fell by about 2-4 m about every 30 minutes. During the 25-28 November observations intense eruptive phases were observed. Lava overflowed about 12 times and fed new flows that topped older flows. During 25-28 November, the overall average level of the lake's surface rose an estimated 3-5 m.

Northern Crater activity. The ARC noted that during 21-23 November the northern crater pit was relatively quiet. They observed a small amount of incandescence during the night of 21 November (figure 31). During the day, they noted a new cone about 1 m high and lava flows of limited extent.

Figure (see Caption) Figure 31. Photograph taken in January 2011 of an Erta Ale hornito with an incandescent vent in the N crater. Photo taken by M. Fulle.

According to the Volcano Discovery team, the deeper N crater had not changed much since their previous visit in February 2008 (BGVN 33:06). During their 2010 visit they saw a 7-10 m high hornito, in the N crater's center, with a glowing vent that sometimes spattered lava. According to Dalton-Smith, flaming gas was seen during the day and on 25 November, an extremely bright glow was seen at night. Upon the team's arrival at the volcano, a large fresh flow had recently surged from the hornito and covered most of the N crater floor.

Location and tectonics. Erta Ale is located in the Afar rift, a region that shows signs of undergoing a continent to ocean transition. The Afar rift is located between the Nubian and the Somalian plates. There is reason to believe that the mantle below the Afar rift region has an above average temperature (Bastow and Keir, 2011). The Afar Rift Consortium also noted that recent fissure eruptions occurred on Erta Ale's N flank.

References. Field, L, and Keir, D. 2010, Observations from the Erta Ale eruption 21st Nov-23rd Nov 2010. Afar Rift Consortium (ARC) (URL: http://www.see.leeds.ac.uk/afar/new-afar/home-page-assets/Observations_from_Erta_Ale.pdf). Additional information about the work of the ARC can be found at URL: http://www.see.leeds.ac.uk/afar/.

Fulle, M, 2011, Stromboli Online (URL: http://www.swisseduc.ch/stromboli/perm/erta/lake-2011-en.html).

Bastow, ID, and Keir, D, 2011, The protracted development of the continent-ocean transition in Afar, Letters, Nature Geoscience, DOI: 10.1038/NGEO1095 published online on March 11, 2011.

Keir, D, Pagli, C, Bastow, ID, Ayele, A., 2011, The magma-assisted removal of Arabia in Afar: Evidence from dike injection in the Ethiopian rift captured using InSAR and seismicity, Tectonics, v. 30, TC2008, DOI: 10.1029/2010TC002785, published 22 March 2011.

Geologic Background. The Erta Ale basaltic shield volcano in Ethiopia has a 50-km-wide edifice that rises more than 600 m from below sea level in the Danakil depression. The volcano includes a 0.7 x 1.6 km summit crater hosting 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. Basaltic lava flows from these fissures have poured into the caldera and locally overflowed its rim. The summit caldera usually also holds at least one long-term lava lake that has been active since at least 1967, and possibly since 1906. Recent fissure eruptions have occurred on the N flank.

Information Contacts: Afar Rift Consortium (URL: http://www.see.leeds.ac.uk/afar/); Tom Pfeiffer, Volcano Discovery (URL: http://www.VolcanoDiscovery.com/); Michael-Dalton-Smith, Digital Crossing Productions (URL: http://www.digitalcrossing.ca/); Marco Fulle, Osservatorio Astronomico, Trieste, Italy (URL: http://www.ts.astro.it/) and atStromboli Online (URL: http://www.swisseduc.ch/stromboli/perm/erta/lake-2011-en.html).


Fuego (Guatemala) — June 2011 Citation iconCite this Report

Fuego

Guatemala

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

All times are local (unless otherwise noted)


Frequent plumes and avalanches; occasional incandescence and lahars

As previously noted, minor plumes, occasional avalanches, and lahars were reported at Fuego during January 2008-January 2010 (BGVN 34:12). Explosive activity occurred with a similar style from 2002 through December 2010, although the report heights of ash plumes was seldom over 1 km during February to December 2010. As is typical, the bulk of the reporting on Fuego comes from INSIVUMEH (the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia) and collaborating agencies. The tallest plumes of this interval reached 1.2 km (on 23 December 2010).

This report first presents the February to December 2010 summary, followed by a May 2011 photo. In the next subsection we skip back in time to discuss observations from a visit to Fuego in February 2009. In the final subsection, we note some 2010-2011 studies made at Fuego.

The February to December 2010 information in this report was initially synthesized and edited by Dan Eungard, as part of a graduate student writing assignment in a volcanology class at Oregon State University under the guidance of professor Shan de Silva.

February through December 2010 activity. According to INSIVUMEH, typical activity during February through December 2010 included degassing plumes that rose above the crater punctuated by occasional Strombolian and Vulcanian explosions that produced small ash plumes. These plumes would occasionally rise to 1.2 km above the summit and become large enough for ash to reach local communities, including Alotenángo (8 km ENE), Ciudad Vieja (13.5 km NE), San Miguel Dueñas (10 km NE), Antigua Guatemala (18 km NE), Sangre de Cristo (9.5 km WSW), Yepocapa (9 km WNW), Morelia (11.5 km SW), and Panimache (9 km SW). Major ashfall events occurred on 2-4 March, 10 June, 19 July, 27 August, 13 and 21 September, 28 October, and 22 November 2010 (table 7). Explosions would occasionally generate shockwaves that rattled windows of structures within 15 km of the summit.

Table 7. Summary of activity reported at Fuego during February to December 2010. "--" indicates no reported data. Terms for explosion frequency: Few signifies undisclosed or under 5; Multiple, 5-20; Many, over 20. Information courtesy of INSIVUMEH and Washington Volcanic Ash Advisory Center (VAAC).

Date Explosions Ash plume height (m) Drift Incandescence (m) Avalanches
08 Oct 2010 Multiple 600-800 S 100 --
11 Oct 2010 Many 500-800 S-SW -- --
14 Oct 2010 Many 1000 SW 125 x
18 Oct 2010 Multiple 800 12 km W-S 100 x
22 Oct 2010 Multiple 500-700 SW weak x
26 Oct 2010 Many 500 N-NW 75 x
28 Oct 2010 Multiple 400-600 W-NE 75 x
29 Oct 2010 Multiple 300-500 W-SW 75 x
31 Oct 2010 Few -- 20 km W -- --
05 Nov 2010 Few 900 E -- --
08 Nov 2010 Few 900 12 km E 100 x
12 Nov 2010 Few 800 S-SW weak x
13 Nov 2010 Few -- 37 km SW -- --
19 Nov 2010 Few 1000 10 km W 100 x
22 Nov 2010 Many 900-1000 15 km SW -- --
25 Nov 2010 Few 300 W-NW -- --
04 Dec 2010 Few -- SW -- --
06 Dec 2010 Few 900 6 km SW -- --
08 Dec 2010 Few 500 S-SW -- x
10 Dec 2010 Few -- SW -- --
17 Dec 2010 Few 300-800 E-SE -- --
20 Dec 2010 Few 500 W-NW -- --
22 Dec 2010 Few -- 28 km NW -- --
23 Dec 2010 Many 600-1200 10-15 km SE -- --
24 Dec 2010 Multiple 400 N -- --
28 Dec 2010 Few 500 5 km S-SW weak x
30 Dec 2010 Many 600-800 8 km W-SW -- x

Antigua Guatemala, a major tourist location with a local population of ~40,000, has occasionally experienced ashfall from Fuego and Pacaya volcanoes (Pacaya is ~30 km ESE of Fuego). Ashfall was heavy enough to damage infrastructure and collapse roofs in the town of Yepocapa during the 1971 and 1974 eruptions of Fuego. Tephra thicknesses of 300 mm with 50 mm bombs were recorded in the area of Yepocapa during the 1971 eruption, causing 20% of the roofs to collapse "including those of many public buildings" (Bonis and Salazar, 1973). From several case studies, including Fuego, Stromboli, and Deception Island, R.J. Blong (1984) suggests a 100 mm threshold for tephra thickness on roofs. Greater thickness may mean serious structural damage, especially if rainfall accompanies or follows the tephra load.

INSIVUMEH issued civil-aviation alerts several times throughout 2010 due to large ash outputs from Fuego. Washington VAAC released advisories for ash plumes including those that occurred on 31 October; 12-13 November; and 4, 10, and 22 December. Over the course of the year, plume height averaged 530 m above the summit. The plumes drifted laterally up to 37 km from the summit and frequently drifted W, SW, S, and NW.

During the year, local reports and INSIVUMEH observations noted block avalanches within the crater and on the slopes; occasionally they were large enough to reach vegetation. Incandescent pulses were fairly common during Strombolian eruptions and juvenile material reached heights up to 125 m.

Lahars were reported on 20 and 30 April, 29 May, 16 June, 21 September, and 2 October 2010. Flooding from tropical storm Agatha triggered destructive landslides and lahars on 29 May 2010. Rivers affected included the Seca (SW), Taniluya (SW), Pantaleon (W), Ceniza (SW), Las Lajitas (SE), and El Jute (SE, see figure 14) BBC News reported that in Guatemala alone, at least 83 fatalities occurred during the storm and ~112,000 people were displaced countrywide. The lahar on 16 June reportedly caused minor road damage.

Figure (see Caption) Figure 14. The El Jute river channel was a site of major lahar activity at Fuego during tropical storm Agatha in May 2010. This photo was taken 8.7 km SSE from Fuego's summit (seen in the background). The old, dark gray lahar deposits seen here were eroded during the storm leaving this tall 5-m-high scarp. Observers in this 3 May 2011 photo included (from left to right) Marco Antonio Argueta (from the Guatemalan risk group CONRED; Coordinadora Nacional para la Reducción de Desastres), Rosalio Suruy, and Aroldo Surui. Photo by Rüdiger Escobar-Wolf (Michigan Technological University).

February 2009 photos of a minor eruption. During a field campaign, R. Escobar-Wolf visited Fuego and witnessed explosions that emitted a large number of ballistic blocks (not discussed on table 7). On 6 February he photographed the development of a small ash plume as well as a cloud of remobilized ash that rose from the summit area. Figure 15A was taken seconds after the central plume erupted from the summit. Figure 15B shows continued rise of the plume as well as the onset of remobilized ash from the flanks. Figure 15C is a close-up of the central ravine where, after the impact of the ballistic blocks, trails of material fell from the summit.

Figure (see Caption) Figure 15. A sequence of photos (A-C) taken on 6 February 2009, viewing Fuego towards the WNW. See text for more details. Courtesy of Rüdiger Escobar-Wolf (Michigan Technological University).

Escobar-Wolf described this sequence of events as a Vulcanian eruption. The eruption was impulsive and released a central plume that reached ~ 1.5 km above the crater (figure 15B). Around the time of this photo, ballistics appeared to impact the summit and thousands of pale ash clouds rose from the summit's surface. These clouds appeared to spread widely down and along the slope, whereas rising portions dispersed (figure 15C).

Recent publications. Characterization of Fuego's activity and the development of new monitoring techniques have been ongoing for several decades. Three manuscripts were recently published focusing on seismic and gas studies.

Erdem (2010) conducted a geophysical study at Fuego from March to July 2008 using a three-component broadband seismometer and two infrasonic microphones. In order to model temporal changes in eruption dynamics, coda wave interferometry methods were used to analyze a set of highly repetitive seismic events associated with regular discrete degassing explosions. The author found rapid temporal variation in the velocity structure, which may indicate minor fluctuations in volatile content or exsolution at various depths between individual explosions. Variations in seismic and acoustic wave arrival times were used to investigate changes in explosion source depth and wind speed.

Lyons and others (2010) found a cyclic pattern in open-vent eruptive behavior at Fuego based on two years of continuous observations from the Fuego Volcano Observatory made possible by a collaboration between the Peace Corps, Guatemalan scientists, and Michigan Technological University. They found that daily observations of lava flow length and explosion characteristics have a strong correlation with satellite-based remote sensing data and tremor amplitude. The pattern of behavior is interpreted to reflect the slow accumulation and periodic gas release in a foam layer trapped in a relatively deep magma chamber or geometric trap in the conduit. This study highlights the importance of detailed geophysical and field observations as a low-cost option in developing countries, as well as in volcanological training.

Nadeau and others (2011) discuss remote sensing of SO2 emissions using a UV camera. Their analysis of 2009 Fuego data sets assessed SO2 emissions from two closely-spaced vents, compared with both visual observations and seismicity. They concluded that tremor and degassing share a common source process, and they developed a model for small, ash-rich explosions based on evidence for rheological stiffening of magma in the upper conduit. Progressive stiffening may explain why, in time-series data, there is a general increase in time lag between tremor and SO2 escape. This lag may be attributed to a deepening or a reduction in velocity of the gas rise from depth if crystallization and cooling propagates downward through time from the top of the magma column. Different degrees of stiffening and the associated range of confining pressures may cause variability in both degrees of explosivity and durations of inter-explosion quiescent periods.

References. Blong, R. J. 1984. Volcanic hazards: a sourcebook on the effects of eruptions. Sydney; Orlando, Fla., Academic Press.

Bonis, S. and Salazar, O. 1973, The 1971 and 1973 eruptions of volcano Fuego, Guatemala, and some socio-economic considerations for the volcanologist, Bulletin Volcanologique, 31 (1), 394-400.

Erdem, J. 2010, Modeling temporal changes in eruptive behavior using coda wave interferometry and seismo-acoustic observations at Fuego Volcano, Guatemala. Michigan Technological University, United States: 2010. GeoRef, EBSCOhost (accessed 19 April 2011).

Lyons, J. J., Waite, G.P., Rose, W., and Chigna, G., 2010. Patterns in open vent, strombolian behavior at Fuego volcano, Guatemala, 2005-2007. Bulletin of Volcanology 72(1): 1-15.

Nadeau, P.A., Palma, J.L., and Waite, G.P., 2011. Linking volcanic tremor, degassing, and eruption dynamics via SO2 imaging. Geophys. Res. Lett., 38: 1-5.

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, Vulcanología, Meteorología e Hidrologia (INSIVUMEH, Ministero de Communicaciones, Transporto, Obras Públicas y Vivienda, 7a. Av. 14-57, zona 13, Guatemala City 01013, Guatemala (URL: http://www.insivumeh.gob.gt/inicio.html); Washington Volcanic Ash Advisory Center (VAAC), NOAA Science Center Room 401, 5200 Auth road, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); Jemile Erdem, Rüdiger Escobar-Wolf, John Lyons, and Patricia Nadeau, Michigan Technological University, Department of Geological and Mining Engineering and Science, Houghton, MI, USA (URL: http://www.geo.mtu.edu/rs4hazards/index.htm); BBC News (URL: http://www.bbc.co.uk/); Wolfram Alfa Web Resource (URL: http://www.wolframalpha.com/).


Grimsvotn (Iceland) — June 2011 Citation iconCite this Report

Grimsvotn

Iceland

64.416°N, 17.316°W; summit elev. 1719 m

All times are local (unless otherwise noted)


Eruption of 21-28 May 2011; ash plumes affect parts of Europe's air space

Grímsvötn, a subglacial volcano, is located 140 km NE of Eyjafjallajökull volcano (figure 11), within the western region of Vatnajökull glacier, Europe's largest glacier. On 21 May 2011, Grímsvötn erupted and produced ash plumes that drifted toward western Norway, Denmark, and other parts of northern Europe and disrupted flights. This was Grímsvötn's first eruption since 2004, when it sent ash as far as Finland (BGVN 29:10). The eruption continued during 21-28 May 2011.

Figure (see Caption) Figure 11. A sketch map of Iceland showing geological features including the location of Grímsvötn, Vatnajökull glacier, Eyjafjallajökull, the Mid-Atlantic Ridge [MAR], and selected volcanic, seismic, and cultural features such as Keflavík airport [K. Airport]. The ring road referred to in text follows the SE coast. Revised from a copyrighted map by Anthony Newton.

According to scientists from the Institute of Earth Sciences at the University of Iceland (IES) and the Icelandic Meteorological Office (IMO), a GPS-station on the rim of the Grímsvötn caldera recorded continuous inflation of several centimeters per year since the 2004 eruption, interpreted as inflow of magma to a shallow chamber. Other precursors over the previous few months included increased seismicity, bursts of tremor, and increased geothermal activity. The eruption was preceded by about an hour of tremor.

The eruption began during the late afternoon of 21 May 2011. According to IMO, the plume was monitored by two weather radars, one located at Keflavík International Airport more than 220 km from the volcano, and a mobile radar ~80 km from the volcano. B early evening on the 21st, the eruption plume rose to over 20 km in altitude. The plume altitude fell to 15 km during the night, although several times it reached 20 km. Ash from the lower part of the eruption plume drifted S and, at higher altitudes, drifted E. A few hours after the eruption began, ashfall covered an area S of the Vatnajökull ice cap, more than 50 km from the eruption site.

According to the Iceland Review, the State Road Authority closed the ring road in the area of the Skeidarársandur flood plain (located S of Grímsvötn) on 21 May. The road remained closed through 24 May due to the threat of eruption-triggered outwash along Iceland's SE coast. The ring road (Iceland Highway 1) follows the Iceland coastline, providing a connection for major towns.

During the morning of 22 May, the plume rose to an altitude of 10-15 km. The plume was brown-to-grayish, changing at times to black near the source. Most of the ash drifted S, but lower parts traveled SW affecting nearby farmers and their livestock (figure 12). Tephra fall was concentrated to the S and to a lesser extent N and E. Earthquake data as well as limited observations recorded during an initial overflight placed the vent location in the SW part Grímsvötn's caldera, the same site as the 2004 eruption (BGVN 29:10).

Figure (see Caption) Figure 12. Farmers bringing livestock to shelter as ash continued to fall during the eight-day eruption (21-28 May). This photo was taken ~150 km SW of Grímsvötn in the village of Mulakot on 22 May 2011. Local residents wore ash masks for protection and ash smothered buildings and vehicles. Courtesy of The Big Picture, by Vilhelm Gunnarsson, AFP/Getty Images.

A set of photographs taken in the morning on 22 May by Ragnar Th. Sigurdsson shows the plume's N side with a well-defined E boundary and diffusion beginning high up on the W (figure 13). In an interview for Time: LightBox Sigurdsson explained: "When you have an eruption so big, you [get] a mushroom cloud like a nuclear bomb. The photos I shot are at the bottom of the mushroom—30 km wide and 15 km high. It was huge." Sigurdsson used wide-angle and telephoto lenses for this aerial photography and had to perch in the doorway of the plane to take these photos (Wallace, 2011).

Figure (see Caption) Figure 13. (A) Photo of the Grímsvötn eruption plume taken in the morning of 22 May 2011 at an altitude of 4.6 km from a twin engine Cessna aircraft. The compact, white, vertical plume is seen on the horizon. The plane was flying W and the image was shot pointing S through the door opening ~37 km from the volcano. (B) A close-up view of the plume the same morning showing more structural detail, including ash (or precipitation or both) at lower left and the diminishing of the plume's white condensate near the top right. Courtesy of Time: LightBox, by Ragnar Th. Sigurdsson (Arctic-Images.com).

On 22 May 2011, in the afternoon, lightning strikes ranged from 60-70 per hour (up to 300 during one hour) and were most frequent in portions of the ash plume dispersed S of the vent (figure 14). News sources noted that the Keflavík airport closed. Ash fell to the vent's SW, including the Reykjavík area and to the vent's N on the Tröllaskagi Peninsula.

Figure (see Caption) Figure 14. Grímsvötn lightning strikes photographed on 22 May 2011. The right-most lightning strike's path to ground traces through dark ashfall, while the two bolts on the left pass through a considerable zone of comparatively clear air. Photo by Gunnar Gestur.

During 22-23 May, the ash plume rose to an altitude of 5-10 km and drifted S at lower altitudes, and W at altitudes 8 km and higher. Ashfall was detected in several areas throughout Iceland, except in some areas to the NW. On 24 May the ash plume was estimated to be mostly below 5 km because meteorological clouds over the glacier were at 5-7 km altitude and the plume only briefly rose above the cloud deck. Satellite images showed the plume extending more than 800 km from the eruption site towards the S and SE.

Sigurdur Stefnisson, traveling by road on 23 May, took a picture of his car's air filter which had clogged with dark ash after only six hours of use (figure 15). He noted that "A stock of new air filters is a must during an eruption. You can always shake them out every few miles."

Figure (see Caption) Figure 15. A car's engine air filter heavily clogged after six hours of driving during ashfall on 23 May 2011 from Grímsvötn. This photo vividly illustrates a common problem when confronting eruptions with widespread ashfall (Lockwood and Hazlett, 2010). Courtesy of Sigurdur Stefnisson.

According to the IES and IMO, during the evening of 24 May, explosive activity occurred in Grímsvötn's main crater. (Eruptions along fissures outside of the main crater occurred during the last 200 years in ~7 out of the 20 recorded eruptions (Óladóttir and others, 2011).) Venting came from four tephra cones surrounded by meltwater. Regular bursts of ash plumes rose a few kilometers above the cones, producing only local fallout. Seismic tremor decreased.

Aviation issues. The London Volcanic Ash Advisory Centre (VAAC; also known as the Met Office) issued an ash plume advisory on 24 May, updated 26 May, that identified the location of heavy atmospheric ash and warned pilots to plan accordingly.

The graphic associated with that advisory appears as figure 16, presented here as a representative sample of the modeled ash plume at that time. According an Associated Press on 26 May, the European air traffic agency Eurocontrol, about 900 flights out of a total of 90,000 planned flights in Europe were cancelled between 23-25 May. The Associated Press also reported on 23 May that the extensive ash hazard forced U.S. President Barack Obama to shorten a visit to Ireland. The eruption forced cancellations of flights in Scotland, northern England, Germany and parts of Scandinavia. Iceland's main international airport at Keflavík closed for 36 hours.

Figure (see Caption) Figure 16. On 24 May 2011 the London Volcanic Ash Advisory Centre (VAAC) released this map of modeled ash concentrations for 0600 UTC. Concentrations are reported from 200 to over 4,000 micrograms per cubic meter (IFALPA, 2011).

Since the costly disruptions in air traffic during the 2010 eruption at Eyjafjallajökull, aviation regulatory authorities took steps to assess current methods of volcanic ash detection, dispersion models, and air traffic management. According to the Executive Summary of Zehner (2010), the impact of the new guidelines for aviation introduced in Europe shifted from "zero tolerance to new ash threshold values [2 mg/m3 concentrations]"; this shift was the center of previous discussions in numerous scientific conferences and workshops worldwide. A sampling of those meetings was summarized in the BGVN 36:04 Eyjafjallajökull report.

During the 2011 Grímsvötn eruption, the London VAAC presented graphics with ash concentrations. (Prior to 21 April 2010, VAACs were not required to report this information (Zehner, 2010)). Within the London VAAC region, no-fly-zones were determined by atmospheric ash concentrations of 2 mg/m3 or greater. The International Volcanic Ash Task Force (IVATF), convened by the International Civil Aviation Organization (ICAO) in 2010, held a workshop in July 2011 to discuss the regulations regarding ash concentrations, but application of a single threshold value for all nine VAAC jurisdictions remained in review.

"The imposition of a limit implies that the dispersion model is capable of providing a contour showing ash concentrations and in particular that a level of 2 mg/m3 can be delineated. In order to be able to do this, accurate information on the volcanic source (e.g. the mass flux, vertical distribution of mass, the column height and the particle size distribution) is needed. Generally this kind of information is not readily available even at the most advanced and well-instrumented volcano observatories (Zehner, 2010)."

Later observations (25-30 May 2011). On 25 May IMO field investigators visited Grímsvötn and found ash plumes had ceased although steam bursts continued from the crater (figure 17). In addition, tremor was greatly reduced, and ground deformation was minor. Observers noted ash thicknesses varying from 10 to 130 cm in the vicinity of the eruption site (figure 18). Pilots reported widespread airborne ash 5-7 km W of the volcano and also some ash haze below 3 km altitude to the SW.

Figure (see Caption) Figure 17. White plumes drifted S from Grímsvötn's two small vents (center of photo). Tephra encircles the vents and three pools of water were visible within the fissure on 25 May 2011. Courtesy of IMO.
Figure (see Caption) Figure 18. Photo taken 25 May 2011 just W and S of Grímsvötn's eruptive site, at a location where the ice was completely tephra covered. Note ash-covered ice on the steep slope below standing figures. Courtesy of Vilhjálmur Kjartansson, IMO.

On 26 May minor steam explosions continued from the crater. According to news articles, air traffic disruption decreased in parts of Norway and Sweden. In the IESIMO 26 May collective status report, IMO reported that long-term conductivity measurements of the Gígjukvísl river suggested that meltwater was draining freely from Grímsvötn. Monitoring had been continuous since a jökulhlaup (a catastrophic glacier-outburst flood) occurred 31 October 2010. Located 50 km upstream from the glacial edge, Grímsvötn's subglacial lake has overflowed periodically over the past 100 years.

On 28 May tremor rapidly decreased then disappeared, and on 30 May participants on the Iceland Glaciological Society's spring expedition confirmed that the eruption had ended. Satellite imagery and visual observations showed that only small amounts of ice melted during the eruption; no signs of flooding were detected.

References. International Federation of Air Line Pilots' Associations (IFALPA), 2011, Disruption from the eruption of the Grímsvötn volcano: IFALPA Safety Bulletin 12SAB03, 24 May 2011.

Lockwood, J.P., and Hazlett, R.W., 2010, Volcanoes : Global Perspectives: Hoboken, NJ, Wiley-Blackwell, ix, p.539.

Maria, A., Carey, S., Sigurdsson, H., Kincaid, C., and Helgadóttir, G., 2000, Source and dispersal of jökulhlaup sediments discharged to the sea following the 1996 Vatnajökull eruption, GSA Bulletin; v. 112; no. 10; p. 1507–1521.

Óladóttir, B.A., Larsen, G., and Sigmarsson, O., 2011, Holocene volcanic activity at Grímsvötn, Bárdarbunga and Kverkfjöll subglacial centres beneath Vatnajökull, Iceland, Bulletin of Volcanology, 73, 1-22. DOI: 10.1007/s00445-011-0461-4

Wallace, V., 2011, High Above the Glacier, TIME: LightBox, 26 May 2011 (URL: http://lightbox.time.com/2011/05/26/high-above-the-glacier/#6 ).

Zehner, C., Ed. 2010. Monitoring Volcanic Ash from Space. Proceedings of the ESA-EUMETSAT workshop on the 14 April to 23 May 2010 eruption at the Eyjafjoll volcano, South Iceland. Frascati, Italy, 26-27 May 2010. ESA-Publication STM-280. DOI:10.5270/atmch-10-01

Geologic Background. Grímsvötn, Iceland's most frequently active volcano in recent history, lies largely beneath the vast Vatnajökull icecap. The caldera lake is covered by a 200-m-thick ice shelf, and only the southern rim of the 6 x 8 km caldera is exposed. The geothermal area in the caldera causes frequent jökulhlaups (glacier outburst floods) when melting raises the water level high enough to lift its ice dam. Long NE-SW-trending fissure systems extend from the central volcano. The most prominent of these is the noted Laki (Skaftar) fissure, which extends to the SW and produced the world's largest known historical lava flow in 1783. The 15 km3 basaltic Laki lavas were erupted over 7 months from a 27-km-long fissure system. Extensive crop damage and livestock losses caused a severe famine that resulted in the loss of one-fifth of the population of Iceland.

Information Contacts: Icelandic Meteorological Office (URL: http://en.vedur.is/); Institute of Earth Sciences (URL: http://earthice.hi.is/); International Federation of Air Line Pilot's Associations (IFALPA) (URL: http://www.ifalpa.org/); International Civil Aviation Organization (ICAO) (URL: http://www.icao.int/); London Volcanic Ash Advisory Centre (VAAC), Met Office, FitzRoy RoadExeter, Devon, EX1 3PB, UK; Agence France-Presse (AFP) (URL: http://www.afp.com/afpcom/en/); Associated Press (AP) (URL: http://www.ap.org/); Eurocontrol (URL: http://www.eurocontrol.in); Iceland Review (URL: http://icelandreview.com/); National Geographic News (URL: http://news.nationalgeographic.com/); Sigurdur Stefnisson (URL: http://www.flickr.com/photos/); Ragnar Th. Sigurdsson, Arctic-Images.com. (URL: http://www.arctic-images.com/); The Big Picture (URL: http://www.boston.com); The Local (URL: http://www.thelocal.se/33970/20110524).


Lokon-Empung (Indonesia) — June 2011 Citation iconCite this Report

Lokon-Empung

Indonesia

1.358°N, 124.792°E; summit elev. 1580 m

All times are local (unless otherwise noted)


July 2011 ash plumes spur 4,000 to 6,000 to evacuate

This report discusses Lokon-Empung during February to mid-July 2011. There were occasional modest ash-bearing eruptions and elevated seismicity through June. Stronger ash plumes during July spurred evacuations. Our previous report noted unrest during 2007 through March 2008 (BGVN 33:02). According to the Center of Volcanology and Geological Hazard Mitigation (CVGHM), since February 2008 through the reporting period, seismic activity was characterized by daily volcanic earthquakes and occasional phreatic eruptions when rainfall was high.

According to CVGHM and news articles, on 22 February 2011, a phreatic eruption discharged from Tompaluan crater (figures 4 and 5). The eruption was possibly triggered by high rainfall. It produced an ash plume that rose 400 m above the crater rim and drifted SE.

Figure (see Caption) Figure 4. An index map and globe showing Indonesia and some neighboring countries. Note the location of Sulawesi island (Indonesia) and Lokon-Empung volcano. Courtesy of Relief Web.
Figure (see Caption) Figure 5. A 1982 sketch map looking from the N at the three main craters at Lokon-Empung. Note the middle crater (Tompaluan) is the one from which the current eruption is venting. This, multiple photos, and other information appears in the GVP's Photo Gallery associated with this volcano. The word "air" in the bottom of the crater means water in Indonesian; it refers to the shallow lake that periodically appears on the crater floor. Photo courtesy of the Volcanological Survey of Indonesia.

CVGHM reported that, during 1-25 June 2011, white plumes rose 50-200 m above Tompaluan crater. On 26 June, a phreatic eruption ejected material that both fell around the crater and produced a gray plume that rose 400 m above the crater rim and drifted N. Seismicity increased the next day and white plumes rose 50-200 m above the crater. The Alert Level was raised to 3; prohibiting visitors and residents entering within a 3-km radius of the crater.

According to CVGHM, during 28 June-9 July 2011 white plumes rose 50-400 m above Tompaluan crater and gray ash plumes rose 100-500 m above the crater. An ash eruption on 10 July 2011 produced white-to-gray plumes that rose 200-400 m above the crater. Fluctuations in the sulfur dioxide gas emission rate were noted during 30 June-10 July. Based on gas flux, seismicity, visual observations, and hazard assessment, CVGHM raised the Alert Level to 4. On 11 July, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that ash plumes detected in satellite imagery rose to an altitude of 1.5 km and drifted NW. According to news articles, close to 1,000 residents were evacuated from the area during 11-12 July 2011.

HOPE Worldwide, a non-profit non-governmental organization, issued a report on 15 July 2011 stating that at 2331 on the 14 July Lokon erupted and sent lava, ash, and gases 1.5 km over the summit. "No death is yet to be reported due to the eruption, but there are 4,412 persons displaced in the Tomohon city, just south of Manado city, the capital of North Sulawesi Province." Displaced residents went to schools and a city park.

Figures 6-8 show photos of molten material and eruptions taken from various perspectives on 14 and 17 July. The photo shown as figure 8 accompanied another panoramic shot with the eruption.

Figure (see Caption) Figure 6. Lokon volcano photographed at night on 14 July 2011. Tompaluan crater contained a small lake and molten material appeared on the far crater side of the crater. Courtesy of the blog named 11reviews.blogspot.com.
Figure (see Caption) Figure 7. Lokon erupting late on 17 July 2011, spewing rocks, lava and ash hundreds of meters into the air. Courtesy of AFP.
Figure (see Caption) Figure 8. An eruption at Lokon seen across the water from distance (taken at 1100 on 17 July 2011). This photo was posted on the Flickr website. Copyrighted photo by Christian Loader (scubazooimages.com).

A video posted on The Guardian website (on 15 July) shows people dispensing face masks to residents as ash from Lokon falls. The original video apparently came from Associated Press (2011; see Reference list).

According to the news agency AFP, a small eruption—the largest since late June—lit up the night sky on 17 July, sending a large ash plume '3.5 km up into the sky.' A nearby airport was placed on alert, but as of 18 July flights were not affected. The article said that, since this latest (17 July) eruption, more than 5,200 residents had been evacuated. Other reports noted the number of displaced residents in the range 4,000-6,000.

Reference. Associated Press, 2011, Indonesian volcano erupts, Thousands of residents evacuated from slopes of Mount Lokon in Sulawesi province (AP photo used in 15 July 2011 article on The Guardian.co.uk website) (URL: http://www.guardian.co.uk/world/2011/jul/15/indonesian-volcano-erupts).

Geologic Background. The Lokong-Empung volcanic complex, rising above the plain of Tondano in North Sulawesi, includes four peaks and an active crater. Lokon, the highest peak, has a flat craterless top. The morphologically younger Empung cone 2 km NE has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century. A ridge extending 3 km WNW from Lokon includes the Tatawiran and Tetempangan peaks. All eruptions since 1829 have originated from Tompaluan, a 150 x 250 m crater in the saddle between Lokon and Empung. These eruptions have primarily produced small-to-moderate ash plumes that sometimes damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred.

Information Contacts: Center of 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/); HOPE Worldwide, 353 W. Lancaster Avenue, Suite 200, Wayne, PA, 19087 USA URL: http://www.hopeww.org); Associated Press at CBS news (URL: http://www.cbsnews.com); Tempo (URL: http://www.tempointeraktif.com/); Media Indonesia.com (URL: http://www.mediaindonesia.com/); Agence France Press (AFP) (URL: http://www.afp.com/afpcom/en/); Blogspot.com (URL: http://11reviews.blogspot.com)


Manam (Papua New Guinea) — June 2011 Citation iconCite this Report

Manam

Papua New Guinea

4.08°S, 145.037°E; summit elev. 1807 m

All times are local (unless otherwise noted)


Eruptions ongoing from August 2010 to January 2011

Manam eruptions continued, and from 13 November 2010 to 3 January 2011, the MODVOLC satellite-based system registered almost daily alerts. Fewer alerts continued into at least July 2011. This report also describes activity as provided by the Rabaul Volcanological Observatory (RVO) during 31 December 2010 to 11 January 2011, augmenting and extending our previous Bulletin reports (BGVN 35:02, 35:09, and 36:01-02). A map illustrating the edifice's remarkably symmetric form appears below (figure 28).

Figure (see Caption) Figure 28. Map of the island of Manam showing the locations of the Main Crater and South Crater and the four radial "avalanche valleys" that channel pyroclastic flows from the summit. Plus symbols indicate locations of satellitic cones. Base map after Palfreyman and Cooke (1976).

As a review, in BGVN 36:01-02 we noted a new episode of eruptive activity that began on 25 December 2010 and escalated on 30 December, culminating with several destructive pyroclastic flows.

On 31 December 2010, white vapor rose from the crater. Later that day, activity increased again. Gray ash plumes rose 200-300 m above the South Crater and also above the Main Crater. Low booming sounds were noted and incandescence from the crater was observed at night. During 1-4 January eruptive activity continued from South Crater and gray-to-black ash plumes rose above the summit crater. Incandescence emanated from the crater. During 3-4 January incandescent fragments were ejected onto the flanks and rolled down the SE valley. White vapor rose from the Main Crater.

On the website Malum Nalu viewed on 2 January 2011 Sir Peter Leslie Charles Barter (former Minister for Health, Papua New Guinean (PNG) government) reported that as the results of a series of eruptions on 25-30 December 2010, followed by larger eruptions, some panic occurred by people that had returned to Manam Island. At Dugalava, a spokesman for the people told the provincial disaster office that more than 1,000 people needed to be evacuated. Barter flew with former Madang Province Governor and current PNG Attorney General Sir Arnold Amet to Manam on 1 January 2011 for an aerial inspection. At that time there was evidence of lava flows in two valleys, but most of the villages were intact and the eruption had subsided.

RVO reported that during 5-6 January low roaring from Manam's South Crater was heard and weak but steady crater incandescence was observed at night. Diffuse blue vapor was emitted from South Crater on 6 January. During 6-8 January white vapor rose from Main Crater and incandescence from both craters was observed at night. Diffuse brown ash plumes occasionally rose from South Crater on 7 January. On 8 January the volcano Alert status was lowered from Level 3 to Level 2. During 8-9 January Main Crater emitted white vapor and South Crater produced occasional gray ash plumes that drifted to the SE part of the island. Emissions from Main Crater turned to gray on 10 January. White-to-blue vapor plumes rose from South Crater. Both craters were incandescent at night during 8-10 January.

On 11 January 2011, RVO reported that Southern Crater released weak volumes of white vapor, and a steady weak glow was visible at night. Main Crater had similar activity.

Satellite measurements. MODVOLC satellite thermal alerts vary significantly during July 2008-June 2011, with periods of up to months of quiet, and seven weeks of daily to near-daily interval of alerts near the end of 2010. During late July 2008 through mid-November 2010, the MODVOLC satellite thermal alerts system measured very infrequent thermal alerts of 1, 2, and, once, 3 pixels. During the periods of 29 July 2008-19 January 2009 and 4 October 2009-9 August 2010, no alerts were measured. However, during a period of ~7 weeks, 13 November 2010-3 January 2011, almost daily alerts were measured. Subsequently, only two additional, 1-pixel Terra satellite thermal alerts were measured through mid-June 2011; one on 10 January 2011 at 1255 UDT and one on 6 March 2011 at 1300 UDT. Thus, the period of nearly daily measured thermal alerts during the end of 2010 appears to be rather anomalous. Several periods of thermal alerts were measured 28-30 June and 14-19 July 2011, but not accompanied with field observations.

Reference. Palfreyman, W.D., and Cooke, R.J.S., 1976, Eruptive history of Manam volcano, Papua New Guinea in Johnson R.W. (ed.), Volcanism in Australasia, Elsevier, Amsterdam, p. 117-131.

Geologic Background. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Information Contacts: Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Malum Nalu (URL: http://malumnalu.blogspot.com/2011/01/volcano-erupts-on-manam-island.html); Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC) (URL: http://www.bom.gov.au/info/vaac/).

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