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
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.
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.
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
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.
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).
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
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.
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
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).
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.
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.
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.
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
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).
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.
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
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.
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
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).
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.
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
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).
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 Cite 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.
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).
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.
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.
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 Cite 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.
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).
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
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.
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.
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.
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).
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
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 |
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.
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.
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 42, Number 10 (October 2017)
Managing Editor: Edward Venzke
Chillan, Nevados de (Chile)
Intermittent ash emissions from new craters along the E flanks of Volcáns Nuevo and Arrau persist through September 2017
Dieng Volcanic Complex (Indonesia)
Three phreatic eruptions at Sileri Crater; deaths due to helicopter crash involved in evacuations
Etna (Italy)
Extensive lava flows during February-May 2017; new summit crater emerges
Fuego (Guatemala)
Six eruptive episodes with Strombolian fountains, lava flows, ash plumes, and pyroclastic flows during July-December 2016
Heard (Australia)
Expedition visit in March-April 2016, intermittent eruptive activity through September 2017
Ibu (Indonesia)
Occasional weak ash explosions and thermal anomalies during April-August 2017
Marapi (Indonesia)
Four short ash explosions on 4 June 2017
Tolbachik (Russia)
Eruption that started in late November 2012 ends by mid-September 2013
Ubinas (Peru)
Intermittent ash explosions during September 2016-February 2017
Wrangell (United States)
Occasional steam plumes and wind-blown ash, but no recent eruptive activity
Nevados de Chillan (Chile) — October 2017 Cite this Report
Nevados de Chillan
Chile
36.868°S, 71.378°W; summit elev. 3180 m
All times are local (unless otherwise noted)
Intermittent ash emissions from new craters along the E flanks of Volcáns Nuevo and Arrau persist through September 2017
Nevados de Chillán, in the Chilean Central Andes, is a complex of late-Pleistocene to Holocene stratovolcanoes constructed along a NNW-SSE trend (figure 5). The Nuevo and Arrau craters, active during 1906-1945 and 1973-1986, respectively, are adjacent vents on the NW cone of a large stratovolcano complex 5 km SE of Cerro Blanco; the summit 1 km SE of Arrau is named Volcán Viejo (figure 6). A short eruption during August-September 2003 created a new fissure vent between the Nuevo and Arrau craters (BGVN 29:03, figure 3). Increased seismicity and fumarolic activity were recorded during December 2015, and a new eruption started with a phreatic explosion and ash emission on 8 January 2016 from a new crater on the E flank of Nuevo cones (BGVN 41:06). This report adds information about the beginning of the event and continues with activity through September 2017. Information for this report is provided by Chile's Servicio Nacional de Geología y Minería (SERNAGEOMIN) - Observatorio Volcanológico de Los Andes del Sur (OVDAS), Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI), Corporación Ciudadana Red Nacional de Emergencia (RNE), and by the Buenos Aires Volcanic Ash Advisory Center (VAAC).
Ash emissions at Nevados de Chillán began on 8 January 2016, and were intermittent through September 2017. Four new craters emerged in a NNE trend along the flanks of Volcán Nuevo and Volcán Arrau; two eventually merged into a single 100-m-diameter crater. Most plumes were brief pulses of steam and ash that rose 200-300 m above the craters. Larger events sent a few plumes as high as 2.2 km above the summit (to 5.4 km altitude). Strong prevailing winds quickly dissipated most ash plumes. Periods of multiple small explosions lasted for 1-2 weeks, separated by periods of relative quiet characterized by only steam-and-gas emissions from the active craters and nearby fumarolic centers. The first observable incandescence at the craters was noted in early March 2016. Incandescent bombs were thrown 300 m above the craters during July and September 2016, and 500 m high during March-May 2017 when blocks also fell with 500 m of the craters.
Activity during 2016. After the first explosion with ash emissions on 8 January 2016, nine more pulses of ash were emitted the next day, and small sporadic emissions were reported in the following days (figure 7). OVDAS researchers flew over the volcano on 9 January and concluded that the explosions came from a new crater on the E slope of Volcán Nuevo, about 40 m from the edge of the crater. Researchers from the University of Cambridge who visited the site on 13 January observed continuous degassing at the new 20-m-wide crater. The Buenos Aires VAAC noted puffs of steam and gas dissipating a few hundred meters above the summit (at 3.7 km altitude) in satellite imagery on 16 January 2016. ONEMI reported an ash emission on 29 January that originated from the Arrau crater (see figure 6). During an overflight on 30 January, OVDAS researchers saw occasional explosions from the new crater at Nuevo, as well as activity at a new 30-m-diameter crater about 50 m from the Arrau crater on its NE flank (figure 8). Several fumaroles were also identified on the E flank of Arrau crater.
During the first two weeks of February 2016, there were 175 episodes of discrete tremor; webcams recorded explosions that ejected material from both craters. The Buenos Aires VAAC reported a brief ash emission on 3 February that dissipated quickly near the summit. During an overflight on 11 February coordinated with ONEMI, scientists identified a third crater, which created a 150-m-long NNE trend with the other two active craters identified during January. During the second half of February, emissions consisted mostly of steam plumes rising no more than 300 m above the crater.
Activity during March 2016 was characterized by steam plumes rising from the active craters; on 3 March, however, a small ash emission was observed. Incandescence was observed in the crater area on the night of 9 March. SERNAGEOMIN reported the beginning of an episode of long-period (LP) seismicity on 18 March, with a pulsating pattern of 3-4 events per minute. During the second half of March, LP and tremor activity was associated with ash emissions. Notably, a low-energy tremor on 30 March lasted for several hours, and concurrently a dense ash plume rose 200 m.
Ash emissions were observed on 7, 8, 9, 18, and 19 April 2016. Plumes were reported rising 400 m on 8 April, and 200 m on 18 and 19 April. Incandescence was observed along with the ash on 18 April. A significant explosion on 9 May 2016 generated an ash plume that rose 1,700 m above the summit (figure 9). The Buenos Aires VAAC reported the ash plume at 3.9 km altitude (700 m above the summit) drifting SE. An overflight by OVDAS on 9 May confirmed the presence of three active craters on the active summit, with the central one having enlarged by 50% since the previous overflight on 11 February. Only pulsating steam emissions were observed in the webcam during the remainder of May and June 2016.
Only steam emissions were reported during the first half of July 2016, but on 21 July an ash-laden emission sent incandescent bombs 300 m above the crater. The Buenos Aires VAAC reported that the webcam showed an ash emission to 3.4 km altitude (200 m above the craters) that day. Webcam Images obtained on 25 July showed debris from an explosion scattered 300 m down the NE flank. During the next few days, ash emissions were inferred from the seismic tremors, but weather conditions prevented direct observations.
During the first two weeks of August 2016, 14 explosions were recorded from the new craters on the E flanks of Nuevo and Arrau. The largest explosion, on 8 August, sent an ash plume 2 km above the crater, according to SERNAGEOMIN (figure 10). The Buenos Aires VAAC reported brief ash emissions on 1, 4, 8, and 9 August at altitudes of 3.7, 3.4, 4.3, and 3.7 km altitude, respectively. Fresh ashfall was visible on the flanks during a flyover on 12 August (figure 11). On the few days when the weather permitted observation of the summit during the remainder of the month, only steam plumes were observed rising no more than 400 m above the crater.
Pulsating steam plumes, interrupted by periodic ash emissions, were typical during September 2016. During the first two weeks of the month, 37 recorded explosions were characterized by a high concentration of particulate material. The largest explosion, during the evening of 1 September, generated incandescent bombs for 20 minutes. Incandescence was observed during nighttime explosions a number of times. The Buenos Aires VAAC noted a pilot report of an ash cloud moving SW at 5.2 km altitude on 2 September. They also reported a weak emission of steam and gas with possible diffuse ash visible in the webcam that day. Another pilot report on 6 September indicated an ash cloud moving NE at 6.4 km altitude from a brief but intense emission event around 1420 UTC (figure 12). SERNAGEOMIN noted in their late September report that there had been six explosive episodes since January 2016, with the latest one that occurred during 1-10 September being the strongest.
Explosive activity was recorded on 3, 7, and 8 October 2016 by SERNAGEOMIN; The events were low-energy episodes that emitted small quantities of ash. The Buenos Aires VAAC noted a pilot report on 3 October of an ash cloud moving SE near the summit. It was visible in the webcam but not in satellite imagery, and dissipated quickly. The tallest emission of those days rose to 300 m above the crater on 7 October. During an overflight on 22 October, the continued presence of the three craters along the E flanks of Nueva and Arrau reported previously was confirmed. In addition, the existence of a fourth crater was noted along the same trend as the others. The Buenos Aires VAAC noted ash emissions on 26 and 28 October rising to between 3.7 and 4.3 km altitude and dissipating quickly near the summit.
Seismic activity during the first half of November 2016 included 17 explosions from the active craters. An explosion on 18 November generated an ash plume that rose 1.2 km (figure 13). The Buenos Aires VAAC noted a pilot report of possible ash emissions between 4.6 and 6.1 km altitude on 17 and 27 November, although neither were identified in satellite data.
Explosions associated with LP and tremor seismicity continued into December 2016. There were 14 explosive seismic events during the second half of the month, reported by SERNAGEOMIN. The largest occurred on 28 December. The Buenos Aires VAAC noted pilot reports of ash emissions that dissipated near the summit on 13, 28, and 29 December.
Activity during January-September 2017. Explosions related to LP and tremor seismicity increased again on 5 January 2017. The Buenos Aires VAAC reported a dark fumarolic plume drifting E at 4.5 km altitude on 6 January that was observed by a pilot and in the webcam. On 11 and 13 January, the webcam showed sporadic puffs of ash that dissipated very quickly. The largest event occurred on 15 January; the Buenos Aires VAAC reported a narrow plume of ash in satellite imagery at 3.9 km altitude moving W. The webcam also showed sporadic and small puffs that dissipated quickly. An event on 16 January produced an emission that rose 700 m above the crater according to SERNAGEOMIN. This was the last LP-associated explosion of the month. Scientists on a 20 January overflight noted low-intensity steam plumes from the Nuevo and Arrau craters, and from the Chudcún crater which formed in 2003 between them (see figure 6). Yellow and ocher-colored areas, indicating the presence of precipitated sulfur, were visible around the fumaroles and craters.
Low-level degassing rising less than 200 m above the crater was the only surface activity observed during February 2017. A new stage of explosive activity began on 7 March 2017 with emissions that rose as high as 300 m above the crater. The Buenos Aires VAAC noted a pilot report of an ash plume at 3.7 km altitude, and a short-lived puff of ash seen in the webcam. On 11 March, eight explosions sent incandescent blocks up to 0.5 km from the active craters, and emissions rose to 500 m above the crater. Another series of eight explosions on 14 March produced incandescent material and sent an ash plume 1.5 km above the craters. The Buenos Aires VAAC reported intermittent emissions rising up to 4.9 km altitude that day, followed by continuing steam emissions. The following day they noted a small plume near the volcano at 3.9 km altitude visible in satellite data.
During a flyover on 15 March, OVDAS scientists noted that two of the craters (craters 3 and 4) had merged into a single crater 100 m in diameter (figure 14). They also observed five explosions within the space of an hour, the highest resulting plume rose 900 m above the active crater. Webcam images during 16-17 March showed ash emissions rising to 2 km above the crater. The Buenos Aires VAAC reported an ash emission visible in satellite imagery at 5.5 km altitude moving SW on 16 March. For the remainder of the month, only weak degassing under 200 m above the crater was observed. Beginning on 24 March, low-level incandescence at night was reported for the rest of the month.
Between 1 and 12 April 2017, there were 56 intermittent explosions marking a new phase of activity according to SERNAGEOMIN. The webcams around the complex imaged emissions up to 3 km above the crater throughout the month. The Buenos Aires VAAC reported sporadic emissions of ash visible in the webcam on 3 and 6-8 April. A faint emission at 3.7 km altitude was spotted in satellite imagery on 10 April. From 16 to 30 April, there were 79 intermittent explosions recorded. During dusk and dawn, incandescent material was observed traveling 600 m down the flanks, with some episodes lasting for 60 minutes. The Buenos Aires VAAC reported a brief ash emission and incandescent material visible in the webcam on 17 April, and sporadic ash emissions that rose to 3.9 km altitude on 21, 29, and 30 April (figure 15).
Nine intermittent explosions occurred between 1 and 11 May 2017. The webcams showed emissions from the explosions rising generally 300 m above the craters according to SERNAGEOMIN. Intermittent explosions increased again during 27-31 May. Emissions rose to 1.5 km above the craters and incandescent blocks could be seen traveling 600 m down the flank. Periods of constant incandescence lasted for 30 minutes.
This explosive episode continued into June 2017, with 23 intermittent explosions between 1 and 5 June. The largest emission event on 5 June sent a plume 2.2 km above the craters (figure 16). The Buenos Aires VAAC observed the ash plume at 4.6 km altitude in satellite imagery. During 6-15 June, only steam emissions rising to 300 m were reported. Intermittent explosions on 20, 22, 25, and 26 June produced plumes that rose only 200 m above the craters; cloudy weather prevented observation from the webcams during these events.
No explosive events were observed in the webcams during the first half of July 2017; only steam plumes rising 200 m were reported. A single low-energy explosion was recorded on 31 July; the emission rose to only 100 m above the crater. During August 2017, there were 83 intermittent explosions associated with ash emissions recorded by SERNAGEOMIN. The emissions rose to about 300 m above the active craters; a few larger emissions rose 1,000 m. The Buenos Aires VAAC noted a pilot report of ash emissions on 17 August; the webcam captured a brief emission that dissipated rapidly.
About 150 intermittent explosions were reported during September 2017. The highest plumes, generally composed of steam and ash, rose 2,000 m above the craters. The Buenos Aires VAAC observed a narrow plume of ash in satellite imagery moving N at 3.9 km altitude and dissipating rapidly on 15 September, and a similar plume moving SE near the summit on 26 September 2017.
Reference: Orozco, G.; Jara, G.; Bertin, D. 2016. Peligros del Complejo Volcánico Nevados de Chillán, Región del Biobío. Servicio Nacional de Geología y Minería, Carta Geológica de Chile, Serie Geología Ambiental 28: 34 p., 1 mapa escala 1:75.000. Santiago.
Geologic Background. The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The dominantly andesitic Cerro Blanco (Volcán Nevado) stratovolcano is located at the NW end of the massif. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The Volcán Nuevo lava-dome complex formed during 1906-1945 on the NW flank of Viejo. The Volcán Arrau dome complex was then constructed on the SE side of Volcán Nuevo between 1973 and 1986, and eventually exceeded its height. Smaller domes or cones are present in the 5-km valley between the two major edifices.
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/); Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI), Beaucheff 1637/1671, Santiago, Chile (URL: http://www.onemi.cl/); Corporación Ciudadana Red Nacional de Emergencia (RNE, Citizen Corporation National Emergency Network), Avda. Vicuña Mackenna Nº3125, San Joaquín, Santiago de Chile, Chile (URL: http://www.reddeemergencia.cl/); 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?lang=es).
Dieng Volcanic Complex (Indonesia) — October 2017 Cite this Report
Dieng Volcanic Complex
Indonesia
7.2°S, 109.879°E; summit elev. 2565 m
All times are local (unless otherwise noted)
Three phreatic eruptions at Sileri Crater; deaths due to helicopter crash involved in evacuations
Located on an elevated plateau in central Java NW of Yogyakarta (figure 4), multiple craters within the Dieng Volcanic Complex (figure 5) have been intermittently active over the past 200 years. Brief phreatic eruptions took place at Sibanteng crater on 15 January 2009 (BGVN 34:04) and at Sileri crater on 26 September later that year (BGVN 34:08). Increased unrest during March-April 2013 (BGVN 38:08) consisted of elevated volcanic gas emissions from Timbang Crater that resulted in an increase in the Alert Level to as high as 3 on 27 March, then back to Level 2 on 8 May. There was a precautionary evacuation of local villages, but no eruption took place. Regular monitoring is done by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Centre for Volcanology and Geological Hazard Mitigation or CVGHM).
The alert status remained at Level 2 for about 15 months following the hazardous gas emissions in 2013. On 11 August 2014 the PVMBG noted that, due to decreased activity and no observable flow of gas in high concentrations from the crater, the Alert Level was lowered to 1 (on a scale of 1-4). No further activity was reported until late April 2017.
A phreatic event from Sileri Crater at 1303 on 30 April 2017 ejected material 10 m high and 1 m past the crater edge, forming a 1-2 mm thick deposit. Another emission at 0941 on 24 May consisted of gas and black "smoke" that rose 20 m.
The Disaster Management Authority, Badan Nacional Penanggulangan Bencana (BNPB), reported that there had been another phreatic eruption from the Sileri Crater lake at 1154 on 2 July 2017, ejecting mud and material 150 m high, and 50 m to the N and S. The event injured 11 of 18 tourists that were near the crater. According to a news article a helicopter on the way to assist with evacuations after the event crashed, killing all eight people (four crewmen and four rescuers) on board. PVMBG scientists visited the next day and observed weak white emissions rising 60 m.
PVMBG reported that during 8 July-14 September 2017 measurements indicated an increase in water temperature at Sileri Crater lake from 90.7 to 93.5°C. Soil temperatures also increased, from 58.6 to 69.4°C. At Timbang Crater temperatures in the lake increased from 57.3 to 62.7°C, and in the soil they decreased from 18.6 to 17.2°C. The report noted that conditions at Timbang Crater were normal.
Temperature increases at Sileri, along with tremor detected during 13-14 September, prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4). PVMBG warned the public to stay at least 1 km away from the crater rim, and for residents living within that radius to evacuate. However, after 20 September tremor and water temperatures both declined. The Alert Level was lowered back to 1 on 2 October, with a warning to stay at least 100 m from the crater rim.
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: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); Peakery (URL: https://peakery.com/).
Etna
Italy
37.748°N, 14.999°E; summit elev. 3357 m
All times are local (unless otherwise noted)
Extensive lava flows during February-May 2017; new summit crater emerges
Italy's Mount Etna on the island of Sicily has had historically recorded eruptions for the past 3,500 years. Lava flows, explosive eruptions with ash plumes, and lava fountains commonly occur from its major summit crater areas, the North East Crater (NEC), the Voragine-Bocca Nuova (or Central) complex (VOR-BN), the South East Crater (SEC) (formed in 1978), and the New South East Crater (NSEC) (formed in 2011). A new crater, the SEC3 or "saddle cone" emerged during early 2017 from the saddle between SEC and NSEC.
After a major explosive event in December 2015 (BGVN 42:05), activity subsided for a few months before renewed Strombolian eruptions and lava flows affected all of the summit craters during late May 2016 (BGVN 42:09). These events were followed by a lengthy period of subsidence and intense fumarolic activity across the summit that lasted until a new eruptive episode began at the end of January 2017. The Osservatorio Etneo (OE), which provides weekly reports and special updates on activity, is run by the Catania Branch of Italy's Istituo Nazionale di Geofisica e Vulcanologica (INGV). This report uses information from INGV to provide a detailed summary of events between January and August 2017.
Summary of January-August 2017 Activity. Minor ash emissions began from a new vent in the saddle between NSEC and SEC on 20 January 2017, followed by Strombolian activity a few days later. Activity intensified at the end of February when the first of several lava flows emerged from this vent, and then from several other vents on the S flank of the new, rapidly growing cone during March and April. By mid-March 2017, Strombolian activity, ash emissions, and lava flows had created a cone higher than the adjacent NSEC and SEC cones. The last effusive episode at the end of April 2017 sent flows down both the N and S flanks of the new cone from multiple vents. Intermittent weak Strombolian activity at the new summit area was associated with abrupt tremor amplitude increases during May, but no additional flows were reported. During June-August, fumarolic activity persisted at several crater areas, and minor ash emissions were observed a few times, but no major eruptive activity took place. The sharp increase in heat flow resulting from the lava flows of March and April 2017 are clearly visible in the MIROVA thermal anomaly plot of log radiative power for the year ending on 12 October 2017 (figure 186).
Activity during January-February 2017. Sporadic incandescence continued from the 7 August 2016 vent on the E side of VOR during January 2017, and minor ash plumes rose from the NSEC "saddle" vent on 20 January. Modest Strombolian activity began at the saddle vent that on 23 January and continued into February (figure 187). Small bombs were ejected onto the flank of NSEC and minor ash plumes quickly dissipated in the high winds near the summit. Also during February, steady subsidence continued at BN, especially in the BN-1 area (see figure 185, BGVN 42:09), where active degassing with minor amounts of ash was observed on 1 February (figure 187). Debris deposits from Strombolian activity at the saddle vent covered the S side of the pyroclastic cone and travelled to its base during the end of February.
During the late afternoon of 27 February, the Strombolian activity that began on 20 January from the saddle vent between SEC and NSEC rapidly intensified, and lava emerged from the vent and flowed down the S flank of SEC (figure 188). It slowed after reaching the flat ground at the base of the cone, and expanded slowly SE toward the older cones of Monte Frumento Supino. Intense activity that evening sent shards and bombs 200 m above the vent while the flow continued. Ash from the Strombolian activity dispersed NE, with minor ashfall reported in Linguaglossa and Zafferana. A new cone of pyroclastic material that formed around the saddle vent quickly grew to about the same elevation as the NSEC and SEC crater rims, approximately 3,290 m (figure 189). The lava continued to flow until 2 March 2017, when it stopped at about 2,750 m elevation with an overall length of 2,180 m, covering an area of 306 x 103 m2, for a total volume of slightly less than 1 x 106 m3.
Activity during March 2017. Sporadic ash emissions continued from the new saddle vent during early March 2017, accompanied by weak Strombolian activity during the night of 12-13 March. Intense degassing continued from VOR during March as well, with incandescent bursts visible on many clear nights. On the morning of 15 March the Montagnola webcam recorded a lava overflow from the saddle vent down the S flank of NSEC, and an intensification of explosive activity that caused the flow to reach the base of the complex at about 3,000 m elevation. During the day, it advanced towards Monte Frumento Supino; it had reached elevation 2,800 m by the late evening, overlapping significantly with the earlier flow from 27 February. Strombolian eruptions were nearly constant until late afternoon, and continued intermittently, along with ash emissions, for several days.
Shortly before 2300 UTC on 15 March (0100 on 16 March local time), a second new flow emerged from a vent near the base of the S flank of the new NSEC/SEC cone (at about 3,200 m elevation) and travelled SE (figure 190), splitting into two lobes. INGV personnel in the summit area reported a series of phreato-magmatic explosions at 0043 (just after midnight) along the lava front at an elevation of approximately 2,700 m along the W edge of the Valle del Bove. The contact of the active flow with the underlying snow caused several explosions. An INGV volcanologist suffered minor injuries during one of the explosions. Increased emissions also caused minor ashfall in Adrano and Santa Maria di Licodia (both about 17 km SW).
By the afternoon of 17 March 2017, the second flow had reached an elevation of about 2,600 m, near the base of the W slope of the Valle del Bove. INGV personnel at Monte Zoccolaro (1.5 km S) spotted a third flow on 18 March, located S of the other two (figure 191). The front had reached about 2,200 m elevation, and was responsible for some phreato-magmatic explosions during 18 and 19 March. Several avalanches of incandescent material reached the base of the slope at the edge of Valle del Bove as the flow fronts collapsed during 18 March. Two Landsat 8 Operational Land Imager images on 18 and 19 March captured evidence of the lava flows, an ash plume, and Strombolian activity during this episode (figure 192). By 19 March, the advance had slowed as the flows began to spread out over the valley floor. The flows into the Valle del Bove ceased on 20 March.
Strombolian activity and ash emissions ceased at the summit vent of the NSEC/SEC cone between 20 and 22 March 2017 leaving a new pyroclastic cone that rose above the adjacent NSEC and SEC cones (figure 193). Once the Strombolian activity had ended, yet another lava flow emerged from the base of the cone at an elevation of about 3,010-3,030 m, and spread into several segments, one of which flowed W around Monti Barbagallo (near the former Torre del Filosofo) and then turned SW following the valley between Monti Barbagallo and Monte Frumento Supino. By 26 March the front of this flow segment had reached an elevation of 2,300 m and travelled about 2.5 km from the vent. A second segment of the flow travelled E of Monti Barbagallo, following the earlier flows that had been active along the W slope of the Valle del Bove; it slowed and broke into several additional segments, reaching 1.3 km from the vent on 26 March, and advancing through the first week of April.
Activity during April 2017. The active lava flow continued WSW towards the cones of the 2002-2003 eruption from the vent at the base of the NSEC/SEC cone until it stopped advancing sometime during the night between 8 and 9 April (figure 194). Another new flow then emerged from the same vent on 10 April and was active for just over 24 hours. This flow travelled SE to the W edge of the Valle del Bove and moved a few hundred meters along the edge before stopping during the day of 12 April.
During the evening of 13 April 2017, Strombolian activity at the summit crater of the NSEC/SEC cone accompanied the emergence of flows from three vents along the S flank at elevations of approximately 3,200 m, 3,150 m, and 3,010 m which headed S and SE. The upper flows were active for only a few hours, but the lower flow continued SE towards the Valle del Bove and had overlapped the 10-11 April flow by the next day. The active front of the flow was at an elevation of 2,400 m on the western slope of the Valle del Bove, just north of the Serra Giannicola Grande. A flyover on 14 April revealed the extent of the fracture system on the flank of the NSEC/SEC complex from which the numerous flows emerged (figure 195). The flow rate diminished during the day of 15 April, and the flow stopped sometime during the next night.
A thermal anomaly appeared at the S edge of the NSEC/SEC summit vent, which INGV began calling SEC3, on the morning of 19 April. Weak Strombolian activity from the vent was followed by the emergence of a lava flow from the S side of the crater rim that flowed down the S flank of the cone. Dense, brown ash emissions about an hour later accompanied the re-opening of three vents on the S flank from which new lava flows emerged (figure 196). Lava jets rose tens of meters above the crater rim for about an hour in the afternoon. The lava flows from the three vents formed into two branches moving down the S flank (figure 197), then turned E and spread over the W slope of the Valle del Bove; by 20 April they had reached an elevation of 1,950 m. Explosive activity ceased at SEC3 that afternoon, and the flows stopped advancing sometime during the night of 20-21 April. Observations of the summit of SEC3 on 22 April revealed a N-S trending graben formed in the S rim of the summit crater about 100 m long, 10 m wide, and several tens of meters deep.
The next eruptive episode began late in the day on 26 April 2017, with a slow-moving lava flow that emerged from the summit vent of SEC3. The flow made it part way down the S flank before another flow from the same vent covered it and reached the base of the flank. Strombolian activity began at the summit vent during the late evening while the flow continued to spread SE toward the Valle del Bove (figure 198). Strombolian activity intensified during the early hours of 27 April and a new vent opened at the summit immediately N of the first one. At around 0220, two new eruptive fractures opened on the N flank of SEC3, from which lava flowed N toward the Valle del Leone (figure 199). At daybreak, an ash plume was visible about 1.5 km above the summit drifting E. Phreato-magmatic explosions were observed in the Valle del Leone when the northern lava flow encountered snow on the ground. Strombolian activity ceased around noon and the flows on both the N and S flanks had ceased by the following morning.
Activity during May-August 2017. Intense degassing with incandescence at night continued from the vent at VOR throughout April and into May 2017. At NEC, degassing continued from the large fumarole field at the bottom of the summit crater. No further lava flows erupted during May 2017, however, there were several short, high-energy tremor episodes in the area around SEC3. During May, more than 35 episodes of transient increases in tremor amplitude were recorded by INGV seismic instruments (figure 200). During 15-18 May, there were 11 episodes of Strombolian activity from the northern SEC3 summit vent, repeated at regular intervals of about every 8-9 hours. Lava fragments were ejected outside the crater rim and rolled down the flanks (figure 201). Each episode was accompanied by a sharp increase in volcanic tremor amplitude. Eight additional episodes of weak and discontinuous Strombolian activity occurred between 25 and 28 May at intervals ranging from 3 to 14 hours, each lasting about an hour, and accompanied by increased tremor amplitude. A short sequence of dense ash emissions from BN-1 on the morning of 31 May was the only ash plume reported during May.
Weak and discontinuous Strombolian activity resumed at NSEC on 6 June 2017, along with a sudden increase in tremor. The activity lasted until 9 June and included four episodes of roughly one hour each. Very little material fell outside the crater rim during these events. Vigorous degassing and nighttime incandescence continued at the VOR vent during June. INGV-OE personnel inspected the summit on 23 and 29 June, and 2 July 2017. High temperatures (around 600°C) were recorded at the VOR vent on 23 June. The other fumarolic areas, especially in the fracture field between NEC and VOR, were around 250°C, cooler than when last measured on 31 August 2016. Occasional weak ash emissions began on 24 June from SEC3; they lasted for a few days and quickly dissipated near the top of the cone. They ceased late in the evening of 28 June.
In a survey by drone on 4 July 2017, INGV-OE personnel noted widespread degassing along the rim and E side of the SEC3 crater. The vent that had formed during 27 February-26 April appeared to be blocked (figure 202). During the late morning of 9 July, the vent that had formed during 26-27 April emitted a small amount of red-gray ash. The next day a small amount of ash emerged from the base of BN-1. Incandescence was frequently observed at night from the VOR vent and from the NSEC. Degassing was observed regularly throughout the month at the VOR vent, the bottom of BN-1, and NEC (figure 203).
Occasional weak, diffuse ash emissions continued during August 2017 from the bottom of BN-1. INGV-OE scientists attributed this to collapse at the base of the crater. Limited degassing was noted at NEC, but persistent degassing continued from the 7 August 2016 vent at VOR, and from a vent on the E side of NSEC in addition to a vent at the SEC3 summit (figures 204 and 205).
Geologic Background. Mount Etna, towering above Catania on the island of Sicily, has one of the world's longest documented records of volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.
Information Contacts: Sezione di Catania - Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia (INGV-OE), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/it/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Times, http://www.globaltimes.cn/galleries/774.html.
Fuego (Guatemala) — October 2017 Cite this Report
Fuego
Guatemala
14.473°N, 90.88°W; summit elev. 3763 m
All times are local (unless otherwise noted)
Six eruptive episodes with Strombolian fountains, lava flows, ash plumes, and pyroclastic flows during July-December 2016
Volcán de Fuego has been erupting continuously since 2002. Historical observations of eruptions date back to 1531, and radiocarbon dates are confirmed back to 1580 BCE. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars. Fuego was continuously active from January to June 2016. Daily explosions that generated ash plumes to within 1 km above the summit (less than 5 km altitude) were typical. In addition, there were ten eruptive episodes that included Strombolian activity, lava flows, pyroclastic flows, and ash plumes rising above 5 km altitude (BGVN 42:06). Every month, lahars flowed down several drainages. This report continues with a summary of similar activity during July-December 2016. In addition to regular reports from the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), the Washington Volcanic Ash Advisory Center (VAAC) provides aviation alerts. Locations of many towns and drainages are listed in table 12 (BGVN 42:05).
Activity during July-December 2016 was very similar to the previous six months. Background activity included daily explosions, and ash emissions that often generated minor ashfall in communities within 15 km, generally to the SW. Strombolian activity sent material 300 m above the crater, and block avalanches down the flanks. Six eruptive episodes occurred during the second half of 2016, with characteristics very similar to the ten that occurred during the first half of the year (table 13). The episodes usually lasted around 48 hours. During the eruptive episodes, the amplitude and frequency of explosions increased to several per hour, and ash emissions that rose 1-3 km above the summit crater (4.8-7.8 km altitude) distributed ash tens of kilometers away. Diffuse ash plumes were often visible in satellite imagery several hundred kilometers from the volcano. Each episode was also accompanied by Strombolian activity that sent incandescent material 200-500 m above the summit crater, creating lava flows that descended major drainages. Episodes 11 and 16, in July and December, also included pyroclastic flows. The thermal signature recorded in the University of Hawaii's MODVOLC thermal alert system closely correlated with the increased heat flow from the lava flows during the eruptive episodes. Numerous lahars descended major drainages after heavy rains during August, but no damage was reported. A modest lahar was reported near the end of September.
Table 13. Eruptive episodes at Fuego during 2016. Details of episodes 1-10 are described in BGVN 42:06, episodes 11-16 are discussed in this report. The eruptive episode number is just for 2016 and was assigned by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH).
Dates |
Episode |
Max Ash Plume altitude |
Ash Plume drift |
Ash Plume max distance |
Ashfall report locations |
Lava Flow drainages |
Lava Flow lengths |
Incandescence above crater |
Pyroclastic Flow drainages |
3-5 Jan 2016 |
1 |
6.0 km |
SW, SE, S |
40 km |
8-12 km SW and SE |
Las Lajas (SE), Trinidad (S), Santa Teresa (S) |
2.5 km |
400 m |
-- |
19-21 Jan 2016 |
2 |
6.7 km |
NE |
90 km |
8-18 km NE, 12 km NW |
Las Lajas (SE), Trinidad (S), Santa Teresa (S) |
3 km |
400-500 m |
Las Lajas (SE), El Jute (SE) |
9-10 Feb 2016 |
3 |
5.2 km |
NNW |
40 km |
45 km N, NE |
Las Lajas (SE), Trinidad (S), Santa Teresa (S) |
800 m-3 km |
300-400 m |
Las Lajas (SE), El Jute (SE) |
29 Feb-3 Mar 2016 |
4 |
7.3 km |
N |
400 km |
10 km SW, N, NW |
Las Lajas (SE), El Jute (SE) |
2-3 km |
yes |
Las Lajas (SE), El Jute (SE) |
26-27 Mar 2016 |
5 |
6.1 km |
W |
150 km |
9-12 km, SW, NW |
Las Lajas (SE), Santa Theresa (S), Trinidad (SE) |
2.0, 1.3, 1.0 km |
500 m |
-- |
12-14 Apr 2016 |
6 |
5.8 km |
SW |
185 km |
10 km SW |
Las Lajas (SE), Santa Theresa (S) |
2.0, 1.0 km |
100-300 m |
-- |
6-7 May 2016 |
7 |
5.5 km |
S, SW, SE |
65 km |
21 km SE |
Las Lajas (SE), Trinidad (SE) |
3.0 km, 1.5 km |
300 m |
-- |
18-19 May 2016 |
8 |
5.5 km |
SSW |
90 km |
30 km NW, S, SW, W |
-- |
-- |
-- |
Las Lajas (SE), Honda (E) |
21-23 May 2016 |
9 |
5.5 km |
SW, W, S |
75 km |
8-12 km, SW, ENE |
Las Lajas (SE) |
2 km |
200-300 m |
-- |
24-26 Jun 2016 |
10 |
5.5 km |
S, SW, W |
120 km |
8-12 km NW, SW |
Las Lajas (SE), El Jute (SE), Taniluyá (SW) |
2.5 km, 2.3 km, 600 m |
300 m |
-- |
28-29 Jul 2016 |
11 |
5.5 km |
SW, W, NW |
250 km |
12 km SW, W, 27 km NW |
Santa Teresa, Las Lajas |
1.5 km, 3 km |
500 m |
Santa Teresa |
6-8 Sep 2016 |
12 |
5.0 km |
W, SW |
25 km |
SW, W |
Las Lajas, Taniluyá |
1.2 km, 500 m |
300 m |
-- |
27-28 Sep 2016 |
13 |
5.0 km |
W, SW |
20 km |
-- |
Las Lajas, Santa Theresa |
1.5 km, 1.8 km |
300 m |
-- |
29-30 Oct 2016 |
14 |
7.0 km |
W, NW |
110 km |
10 km NW, SW |
Las Lajas, Santa Teresa, Taniluyá |
2.0 km, 300 m, 500 m |
400-500 m |
-- |
20-21 Nov 2016 |
15 |
5.0 km |
SSW |
175 km |
8-12 km SW |
Trinidad, Ceniza, Las Lajas |
1.0 km, 2.0 km, 2.5 km |
300 m |
-- |
20-21 Dec 2016 |
16 |
5.2 km |
W, SW |
230 km |
8-12 km SW |
Santa Teresa, Taniluyá, Trinidad, Las Lajas |
2.5, 2.0, 600, 1.8 |
400 m |
3.5 km Taniluyá |
Activity during July 2016. Explosions of incandescent material from the summit crater of Fuego were constant during July 2016, according to INSIVUMEH. On 5 July, an increase in the number of explosions per hour led to an ash plume rising to 4.5 km altitude and drifting W and SW. Incandescent blocks reached the vegetation on the W flank a few hundred meters from the summit. Ashfall was reported in the villages of Morelia, Santa Sofia, Sangre de Cristo (all around 10-12 km SW), and San Pedro Yepocapa (9 km NW). Another increase in activity on 15 July resulted in eight weak-to-moderate explosions per hour, which generated ash plumes that rose to about 4.3-4.8 km altitude and drifted more than 15 km W and SW; ash fell on the flanks in those directions. The Washington VAAC reported ash emissions rising to 4.6-5.2 km altitude, and MODVOLC issued one thermal alert. On 17 July, the Washington VAAC reported an ash emission drifting about 18 km W at 4.9 km altitude. Another ash emission was observed in satellite imagery on 19 July, at 5.2 km altitude drifting NW. The Washington VAAC also reported that the webcam showed lava on the flank near the summit that day.
Eruptive episode 11 began on 28 July 2016 and lasted for about 48 hours. Moderate-to-strong explosions expelled ash plumes to 5.5 km altitude that eventually drifted more than 250 km SW, W, and NW. The INSIVUMEH webcam at Finca La Reunion (SE) captured an image of the ash plume accompanied by a pyroclastic flow which descended the Santa Teresa ravine (barranca) around midday on 29 July (figure 50). Incandescent material was ejected about 500 m above the crater and fed two lava flows; one traveled 1.5 km down the Santa Teresa ravine, and the other traveled 3 km down the Las Lajas ravine. Some of the villages that reported ashfall included Sangre de Cristo, San Pedro Yepocapa, and Patzún (27 km NW). The Washington VAAC observed the ash plume in the early morning of 29 July extending 30 km WNW from the summit at 5.8 km altitude. By late morning, the plume had risen to 6.7 km altitude and was visible 150 km NW. The plume altitude dropped later in the day to 5.2 km, and the drift direction changed more toward the W. The farthest edge of the plume was faintly visible over 250 km W before it dissipated that evening. Incandescent explosions continued into the night, but had subsided by the next morning. A MODVOLC thermal anomaly signal first appeared on 26 July and persisted through 31 July; there were 17 thermal alert pixels reported on 29 July.
Activity during August 2016. Weak and moderate explosions that generated ash plumes characterized activity during August 2016. Although a few strong explosions were recorded, there were no distinct eruptive episodes documented by INSIVUMEH. Constant rains, however, led to several lahars descending the major ravines. Persistent steam plumes rose to 4.2 km and drifted W and SW. Weak-to-moderate explosions with ash reached 4.3 to 4.8 km altitude, and drifted more than 15 km SW and W before dissipating. Ashfall was reported primarily in the communities of Sangre de Cristo, Yepocapa, Morelia, Hagia Sophia, and Panimaché I and II. Incandescent material was ejected 300 m above the crater, and generated weak-to-moderate avalanches within the crater.
The Washington VAAC reported an ash plume visible in satellite imagery on 7 August at 4.9 km altitude extending about 10 km WNW from the summit. On 11 August, a narrow plume was spotted in both visible and multispectral imagery extending about 80 km W at the same altitude. A puff of volcanic ash appeared in clear satellite and webcam images drifting W at 4.9 km on 19 August. A series of ash emissions were spotted on 20 August in satellite imagery. The head of the plume was about 35 km W of the summit. The highest altitude plume reported by the Washington VAAC during August was at 5.8 km on 25 August, drifting 25 km W. A single MODVOLC thermal alert was also recorded that day. On 15 and 16 August moderate-to-large lahars descended the Las Lajas and El Jute ravines, carrying blocks as large as 3 m in diameter, tree trunks, branches, and other debris. Another lahar recorded on 28 August descended the Santa Teresa tributary of the Pantaleón River, where the residents noted the warm temperature of the debris.
Activity during September 2016. Two eruptive episodes took place during September 2016. Episode 12 began on 6 September and lasted about 48 hours. Moderate-to-strong explosions generated ash plumes that rose to 5 km altitude and drifted 25 km W and SW. Incandescent material rose to 300 m above the crater and fed two lava flows, one traveled 1.2 km down the Las Lajas ravine (figure 51), and the other travelled 500 m down the Taniluyá. The Washington VAAC reported an ash plume, identified in satellite imagery, on 7 September moving WSW at 4.9 km altitude. MODVOLC thermal alerts were issued during 4-8 September, with 10 alerts appearing on 8 September.
A bright hotspot in satellite imagery was reported by the Washington VAAC on 25 September 2016. A modest lahar descended the Santa Teresa ravine on 26 September, carrying 50-cm-diameter blocks, branches, and tree trunks; it was 10 m wide and 1 m high. Eruptive episode 13 began the next day, 27 September 2016, with moderate-to-strong explosions, and an ash plume that rose to 5 km altitude and drifted more than 20 km W and SW (figure 52). Incandescent material rose 300 m above the crater, feeding two lava flows. Lava traveled 1.5 km down the Las Lajas ravine (figure 53) and 1.8 km down the Santa Teresa ravine. A fissure developed on the S flank of the crater rim, and new fumarolic activity was observed during the day. Constant rumbling noises were audible in the areas of Finca Palo Verde, Sangre de Cristo, and San Pedro Yepocapa on the W and SW flanks. The Washington VAAC reported an intense hotspot in shortwave imagery. Activity subsided on 28 September. A strong multi-pixel thermal alert signal appeared in the MODVOLC data from 24-29 September.
Activity during October 2016. Six to ten explosions per day were recorded at Fuego during October 2016. Some of them generated ashfall on the SW flank. Episode 14, which began at the end of the month, produced three lava flows and strong explosions with an ash plume that rose to 7 km altitude and drifted N and NW. The Washington VAAC reported multiple ash emissions at 5.2 km altitude on 3 October, with the furthest one extending 35 km S. The next day, ash emissions were observed at 4.9 km altitude and drifted 22 km SSE. Pyroclastic flows were seen in an INSIVUMEH webcam on 10 October. They also reported ashfall in nearby communities that day.
Incandescent material rose 150-200 m above the summit crater on 28 October, and lava traveled 500 m down the Las Lajas ravine. Episode 14 began the next day with a strong explosion that generated an ash plume to 7 km altitude that drifted 110 km W and NW. Constant loud rumbling was reported up to 15 km from the volcano, and ashfall was reported in San Pedro Yepocapa, Sangre de Cristo, and La Conchita. Three incandescent lava fountains were seen in the early hours of 30 October (figure 54). The first, 450 m above the crater, fed a 2-km-long flow in the Las Lajas ravine. The second fountain rose to 250 m and fed a flow that traveled 300 m down the Santa Teresa canyon. The third fountain rose 200 m and formed a flow that traveled down the Taniluyá drainage for 500 m. Activity declined during the night of 30 October, but weak and moderate avalanches of incandescent material continued into the first part of the next day.
The first ash emissions of episode 14 were visible in satellite imagery on 29 October, extending roughly 45 km NNW from the summit. By early the next day, the ash emissions were detected at 7.3 km altitude, based on a pilot report. They extended about 110 km NNW from the summit. Later in the day, the plume had lowered to 5 km altitude and drifted 15 km N and NW. A single MODVOLC thermal alert was reported on 13 October, but a lengthy series of multi-pixel alerts were generated during 24-31 October, including 19 pixels on 30 October at the peak of episode 14.
Activity during November 2016. Activity during November 2016 remained at background levels until the third week of the month; explosions increased in amplitude and frequency to as many as 15 per hour, leading to episode 15 which began on 20 November. The background levels of the second and third weeks included incandescent material rising to 300 m above the crater, causing avalanches down the flanks around the crater rim and continuous explosions of weak-to-moderate energy that generated ash plumes rising to altitudes between 4.3 and 4.7 km that drifted W and SW.
The Washington VAAC reported ash emissions in satellite imagery every day from 8 to15 November 2016. A plume was seen on 8 November rising to 4.6 km altitude and drifting 25 km SW. The next day, a plume at the same altitude drifted 45 km NW. On 10 November, a faint plume was seen in visible imagery, extending about 25 km NNW. A larger plume was visible in morning imagery on 11 November at 5.5 km altitude extending 35 km WSW. The next day, at the same altitude, a diffuse plume was visible 10 km W of the summit. Multiple emissions were spotted drifting W from the summit at 4.6-4.9 km altitude on 13 and 14 November. Two single MODVOLC thermal alerts were reported on 12 and 14 November. A hotspot was detected in satellite imagery on 15 November, along with continuing emissions to 4.6 km altitude that drifted within 10 km SW of the summit. On 17 November ashfall was reported in Morelia, Santa Sofia, and Panimache I and II. Emissions on 18 November rose to 4.7 km altitude and drifted 10 km SW, and on 20 November they rose to 4.9 km altitude and drifted 24 km from the summit (figure 55).
Eruptive episode 15 began on 20 November with strong explosions that caused ash plumes to rise to 5 km altitude and drift as far as 175 km SSW and W, generating ashfall again in Morelia, Santa Sofia, and Panimache I and II. Three lava flows emerged from the 300-m-high Strombolian ejections; one traveled 1 km down the Trinidad ravine, one descended 2 km down barranca Ceniza, and the third flowed 2.5 km down barranca Las Lajas (figure 56). Numerous clouds of volcanic ash rose from block avalanches in Las Ceniza ravine on 20 and 21 November.
The Washington VAAC reported an extremely large hotspot on 20 November 2016 (local time) in infrared imagery, along with ash emissions at 4.9 km altitude drifting SW to 65 km. Emissions at 3.8 km persisted into the night. By early morning on 21 November, they were visible extending 175 km W. A lengthy period of multi-pixel MODVOLC thermal alerts coincided with eruptive episode 15 during 17-23 November, and included 26 pixels on 21 November 2016. Eruptive activity decreased to background levels by 22 November, and only weak explosions and fumarolic activity were reported for the rest of the month.
Activity during December 2016. Weak-to-moderate explosions and ash plumes characterized background activity at Fuego during December 2016. Minor ashfall was regularly reported in communities located 8-12 km SW. Activity increased somewhat during 15-16 December, and eruptive episode 16 was recorded during 20-21 December. During episode 16, Strombolian activity created three lava flows that descended major ravines, and a large pyroclastic flow traveled 3.5 km from the summit, burning vegetation in its path.
The Washington VAAC reported an ash emission on 5 December at 5.8 km altitude drifting N. On 8 December, intermittent ash plumes were drifting W over the East Pacific Ocean at 6.1 km altitude. Remnants over 450 km W were seen in multispectral imagery by early on 9 December. Multiple new detached plumes continued moving WNW between 5.5 and 6.1 km altitude on 9 December. They were 80 km NW by late afternoon. New discrete emissions at 4.6 km altitude appeared in satellite imagery on 10 December, drifting W up to 130 km before dissipating.
During the afternoon of 20 December 2016, eruptive episode 16 began with moderate-to-strong ash emissions producing an ash plume that rose to 4.7 km altitude and drifted more than 15 km W and SW. Incandescent material rose 400 m above the crater, and bombs fell more than 300 m away. Block avalanches were concentrated in the Ceniza and Trinidad ravines. By the evening of 20 December, three lava flows had formed, in the Santa Teresa, the Taniluyá, and the Las Lajas ravines (figure 57). By the morning of 21 December, they were 2.5, 2.0, and 1.8 km long, respectively. During that day, strong explosions generated ash plumes that rose to 5.2 km altitude and drifted 18 km S, SW, W, and NW. Some of the communities that reported ash from this event included Panimaché, Morelia, Santa Sofia, Sangre de Cristo, San Pedro Yepocapa, and Palo Verde.
Around 1000 on 21 December, pyroclastic flows that descended the Taniluyá ravine generated an ash plume that rose 2 km and drifted W and SW. The flows traveled 3.5 km and were estimated to be 300 m wide. They descended the ravine at high speed and high temperature, burning everything in their path (figure 58). These were the first pyroclastic flows in several months. By the end of eruptive episode 16, the lava flow in the Taniluyá ravine had reached 2.8 km in length (figure 59).
During episode 16, the Washington VAAC reported ash emissions rising to 5.2 km (about 1.4 km above the summit crater) altitude and drifting about 230 km SW. Continuing ash emissions on 23 December were visible in satellite imagery moving 45 km SW from the summit at 4.3 km altitude. Intermittent diffuse ash emissions extended up to 30 km WSW and NW from the summit during 28-31 December at 4.3-5.2 km altitude.
MODVOLC thermal alerts were intermittent throughout December. They were recorded on 8 (2), 11 (2), 12, 14 (2), 16 (3), and 18 (3) December prior to episode 16. The biggest interval of multi-pixel alerts was during episode 16 from 20-22 December, and included 14 alerts on 21 December 2016. Additional single alerts were recorded on 25 and 29 December.
Geologic Background. Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.
Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/, archive at: http://www.ssd.noaa.gov/VAAC/archive.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/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Martin Rietze (URL: http://www.mrietze.com/index.htm).
Heard (Australia) — October 2017 Cite this Report
Heard
Australia
53.106°S, 73.513°E; summit elev. 2745 m
All times are local (unless otherwise noted)
Expedition visit in March-April 2016, intermittent eruptive activity through September 2017
The remote island of Heard in the southern Indian Ocean is home to the Big Ben stratovolcano, which has had confirmed intermittent activity since 1910. The nearest continental landmass, Antarctica, lies over 1,000 km S. Visual confirmation of lava flows on Heard are rare; thermal anomalies detected by satellite-based instruments provide the most reliable information about eruptive activity. Thermal alerts reappeared in September 2012 after a four-year hiatus (BGVN 38:01), and have been intermittent since that time. Information comes primarily from MODVOLC and MIROVA thermal anomaly data, but Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) also provides reports from research expeditions. The independent March-April 2016 Cordell Expedition also provided recent ground-based observations mentioned in this report, which covers activity through September 2017.
Expeditions during January-April 2016. Scientists aboard the CSIRO Research Vessel Investigator observed an eruption of Big Ben on 31 January 2016. Vapor was seen emanating from the peak and lava flowed down the flank over a glacier (see figure 23, BGVN 41:08, and video link in Information Contacts). The research team, lead by the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS), was conducting a study of the link between active volcanoes on the seafloor and the mobilization of iron by hydrothermal systems which enriches and supports life in the Southern Ocean.
During a private expedition from 22 March to 11 April 2016, scientists and engineers from the 2016 Cordell Expedition documented changes to the island and its life since a prior visit in 1997, and tested radio operations. On 23 March the team was able to photograph the usually cloud-covered Mawson Peak, the summit of Big Ben (figure 24). Steam was visible above the flat upper surface, possibly a crater rim or fissure. They estimated a height of about 45 m of an edifice rising above the adjacent slope. The ground at the site of the team campsite, near Atlas Cove on the NW side of the island, was covered with lava flows (figure 25). While the expedition had to cancel a planned expedition to the summit, rocks collected from the shoreline confirmed the diversity of volcanic rocks on the island (figure 26).
At the southern end of Sydney Cove, near Magnet Point on the northern tip of Laurens Peninsula (the NW side of the island), the team identified a small islet, with dimensions of about 40 x 120 m and nearly vertical sides about 100 m high. Columnar jointing in the volcanic rocks is well exposed at the base and on the nearly flat upper surface (figure 27).
Satellite thermal and visual data, 2012-2017. The most consistent source of information about eruptive activity at Heard comes from satellite instruments in the form of visual and thermal imagery, and thermal anomaly detection. From the time that renewed activity was detected in MODVOLC data in late September 2012 through September 2017, either the MODVOLC or MIROVA systems have consistently detected thermal signals, with only a few short breaks. A four-month span from mid-July to mid-November 2014, and a two-month gap during February and March 2015 are the only periods longer than a month when no thermal signal was reported. Continuous MIROVA information from late January 2016 through September 2017 shows intermittent but persistent thermal anomalies throughout the period (figure 28).
The moderate signal at the very end of January 2016 coincides with the CSIRO expedition observing the lava flows on the flank of Big Ben. Low-level MIROVA anomalies were recorded in April and early May 2016. Activity picked up during June, and strengthened through July and August 2016. Late September through November 2016 was a period with heightened activity as well. From December 2016 through August 2017, intermittent low-to-moderate intensity anomalies were recorded every month. Activity appeared to increase briefly during early February and September 2017. On 4 February 2017, Landsat 8 captured a rare clear view that showed fresh lava and debris flows emanating from the summit on top of the snow (figure 29). The longest flow is estimated to be 1,300 m long. False-color infrared imagery of the same image of Mawson Peak also reveals two vents separated by about 250 m (figure 30). Subsequent imagery on 20 and 27 February also detected thermal anomalies at the summit. The visual imagery of the lava flows on 4 February 2017 corresponds to the early February spike in MIROVA thermal anomaly data.
Geologic Background. Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben because of its extensive ice cover. The active Mawson Peak forms the island's high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported at this isolated volcano, but observations are infrequent and additional activity may have occurred.
Information Contacts: Commonwealth Scientific and Industrial Research Organisation (CSIRO) (URL: http://www.csiro.au/); CSIROscope, CSIRO Blog, Big Ben Erupts: Australia's active volcano cluster blows its lid (URL: https://blog.csiro.au/big-ben-erupts/); Robert W. Schmieder, 2016 Cordell Expedition, 4295 Walnut Blvd., Walnut Creek, CA 94596, Post Expedition report to the Australian Antarctic Division (AAD) (URL: http://www.cordell.org/, http://www.heardisland.org/); 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 Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Bill Mitchell, The Inquisitive Rockhopper, Big Ben eruption update 2017-02-27 (URL: https://inquisitiverockhopper.wordpress.com/2017/02/).
Ibu
Indonesia
1.488°N, 127.63°E; summit elev. 1325 m
All times are local (unless otherwise noted)
Occasional weak ash explosions and thermal anomalies during April-August 2017
During March 2014-March 2017, activity at Ibu consisted of lava-dome growth, occasional weak emissions containing ash (figure 11), and frequent thermal anomalies (BGVN 40:11 and 42:05). Ongoing activity between April and August 2017 consisted primarily of intermittent ash explosions. Data come from Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) and the Darwin Volcanic Ash Advisory Centre (VAAC).
On 3 April 2017, at 0757 (local), an explosion produced an ash plume that rose to an altitude of 1.7 km and drifted S. Seismic signals indicated explosions and avalanches. During the rest of April through August, occasional explosions generated weak ash plumes that generally rose to altitudes of 1.5-1.8 km (0.2-0.5 km above the volcano) and drifted in various directions (table 2).
Table 2. Ash plume data for Ibu, April-August 2017. Courtesy of PVMBG and Darwin VAAC.
Date |
Maximum plume altitude (km) |
Plume drift direction |
03 Apr 2017 |
1.7 |
S |
07-08 Apr 2017 |
1.7 |
N |
10-11 Apr 2017 |
1.5-1.6 |
S |
12-13, 17 Apr 2017 |
1.5-1.8 |
S, SW |
19-21 Apr 2017 |
1.5-1.8 |
E, N |
26-27, 29-30 Apr 2017 |
1.5-1.8 |
E, NE, N |
10-11 May 2017 |
1.8 |
E, SW |
16 May 2017 |
1.5 |
-- |
19-20, 23 May 2017 |
1.5-1.8 |
E, NE, S |
01, 05 Jun 2017 |
0.15-0.25 |
N, SE |
09-12, 14 Jun 2017 |
1.5-1.8 |
N, W, SSW |
14, 17-19 Jun 2017 |
1.5-1.8 |
S, SW, W, N |
15 Aug 2017 |
1.8 |
N |
24, 28 Aug 2017 |
1.5-1.8 |
W |
Between April and August 2017, thermal anomalies (based on MODIS satellite instruments analyzed using the MODVOLC algorithm) were recorded 2-5 days per month, with no monthly trend. The MIROVA (Middle InfraRed Observation of Volcanic Activity) system detected numerous hotspots each month; all except one were within 3 km of the volcano, and all were of low or moderately-low power.
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/); 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/); Tom Pfeiffer, Volcano Discovery (URL: http://www.volcanodiscovery.com/).
Marapi (Indonesia) — October 2017 Cite this Report
Marapi
Indonesia
0.38°S, 100.474°E; summit elev. 2885 m
All times are local (unless otherwise noted)
Four short ash explosions on 4 June 2017
Recent activity at the large Gunung Marapi stratovolcano on Sumatra has consisted of small ash plumes, with eruptions of a single day to periods of a few months. Ashfall around the active crater rim (figure 5) and thin layers of ash deposits seen in the crater wall (figure 6) provide evidence of both the recent and very long history of explosive activity. Since 2011 there have been eruptive episodes during August-October 2011, March-May 2012, 26 September 2012, February 2014, and 14 November 2015. As reported by the Indonesian Center of Volcanology and Geological Hazard Mitigation (PVMBG), another series of explosions took place on 4 June 2017.
Four explosions on 4 June lasted less than one minute each, and generated ash plumes above the summit (figure 7) and drifted E. The explosions occurred at 1001 local time (0301 UTC), 1011, 1256, and 1550. Dense ash-and-steam plumes from each explosion rose 300 m, at least 700 m, 200 m, and 250 m above the crater, respectively. The Darwin VAAC reported ash at about 3.6 km altitude extending 37 km ENE, based on satellite imagery. Ejected bombs were deposited around the crater, and minor ashfall was reported in the Pariangan District (8 km SSE), Tanah Datar Regency. Seismicity increased after the explosions. The Alert Level remained at 2 (on a scale of 1-4); residents and visitors were advised not to enter an area within 3 km of the summit.
The broad summit area with multiple craters is a popular destination for hiking expeditions. A video posted by YouTube user "SiGiTZ" documented the experience of one group during visits on 30 April 2016 and on 11 May 2017. The video provides excellent views from 2016 of the entire crater complex and of the Verbeek Crater, from which a steam-and-gas plume appears to be rising. A video posted by YouTube user "yogi antula" included a television broadcast from the Anak Borneo Channel of a video from climbers in the crater area during the 4 June explosions, taken from approximately 400-500 m away. In that video, a significant dark ash plume can be seen rising from Bungsu-Verbeek crater complex, along with a smaller white plume from a closer location. The news report was concerned with 16 hikers known to be on the mountain; there were no later reports of anyone being injured.
References: SiGiTZ, 1 August 2017, Expedisi puncak Gunung Marapi Bukittingi Sumbar Mei 2017 (URL: https://www.youtube.com/watch?v=pVxhWAbo2VA).
yogi antula, 5 June 2017, Video amatir pendakian saat Gunung Marapi Erupsi – 4 Juni 2017 (by Anak Borneo Channel) (URL: https://www.youtube.com/watch?v=8GAY6lsTLEE).
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/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); Sutopo Purwo Nugroho, Badan Nasional Penanggulangan Bencana (BNPB) (URL: https://twitter.com/Sutopo_BNPB); Axel Drainville, Flickr.com, with Creative Commons license Attribution-NonCommercial 2.0 Generic (CC BY-NC 2.0, https://creativecommons.org/licenses/by-nc/2.0/) (URL: https://www.flickr.com/photos/axelrd/).
Tolbachik (Russia) — October 2017 Cite this Report
Tolbachik
Russia
55.832°N, 160.326°E; summit elev. 3611 m
All times are local (unless otherwise noted)
Eruption that started in late November 2012 ends by mid-September 2013
The most recent eruption began on 27 November 2012 along two fissures a few kilometers S of the main Tolbachik edifice, within the Tolbachinsky Dol lava plateau (BGVN 37:12). Monitoring is done by the Kamchatkan Volcanic Eruption Response Team (KVERT); they recorded an end date for this eruption as 15 September 2013.
Activity reported through February 2013 included Strombolian fire fountains (figure 14), voluminous lava flows on the surface (figure 15 and 16) and under the ice and snow cover (figure 17), ash explosions, and the building of cinder cones (BGVN 37:12). Satellite imagery in early June 2013 revealed both a lava pond at the active vent and a large lava flow lower down the flank, with multiple flow-front breakouts (figure 18). Cinder cones continued to grow along the S fissure through 16-22 August 2013, and lava flows remained active (figure 19), but then gas-and-ash plumes weakened and seismicity decreased during the last week of the month (BGVN 38:08).
Seismicity continued to decrease during 22-24 August 2013, and KVERT noted on 27 August that no incandescence had been seen in recent days, and there were no current ash plumes. Satellite data did still show a large thermal anomaly in the northern area of Tolbachinsky Dol, which KVERT attributed to the lava flows remaining hot. The MODIS thermal anomaly data recorded in the MODVOLC system identified the latest hotspot on 27 August 2013. According to the Kamchatkan Volcanic Eruption Response Team (KVERT), the Aviation Color Code (ACC) was lowered from Orange to Yellow on 27 August 2013.
When the ACC was lowered to Green on 31 January 2014, KVERT reported that weak seismic activity and episodes of tremor continued, gas-and-steam activity was sometimes observed, and satellite data continued to show a weak thermal anomaly. However, they also stated that "probably its active phase was finishing in September 2013." The KVERT website recorded an end date of 15 September 2013. The new lava flows were still noticeable in visible satellite imagery more than a year after the eruption ended (figure 20).
Geologic Background. The massive Tolbachik volcano is located at the southern end of the Kliuchevskaya volcano group. The massif is composed of two overlapping, but morphologically distinct, volcanoes. The flat-topped Plosky Tolbachik shield volcano with its nested Holocene calderas up to 3 km in diameter is located east of the older and higher sharp-topped Ostry Tolbachik stratovolcano. The summit caldera at Plosky Tolbachik was formed in association with major lava effusion about 6,500 years ago and simultaneously with a major southward-directed sector collapse of Ostry Tolbachik. Long rift zones extending NE and SSW of the volcano have erupted voluminous basaltic lava flows during the Holocene, with activity during the past two thousand years being confined to the narrow axial zone of the rifts. The 1975-76 eruption originating from the SSW-flank fissure system and the summit was the largest historical basaltic eruption in Kamchatka.
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/); 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 Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Google Earth (URL: https://www.google.com/earth/).
Ubinas
Peru
16.345°S, 70.8972°W; summit elev. 5608 m
All times are local (unless otherwise noted)
Intermittent ash explosions during September 2016-February 2017
Ubinas is an active stratovolcano in southern Peru about 70 km E of the city of Arequipa. Holocene lava flows cover its flanks, and the historical record since the mid-1500's contains evidence of minor explosive eruptions, debris avalanches, tephra deposits, phreatic outbursts, and pyroclastic flows and lahars. An eruptive episode that began with phreatic explosions on 1 September 2013 lasted through 27 February 2016, producing numerous small ash emissions, several large explosions with ash plumes that rose above 10 km altitude, large SO2 anomalies, evacuations, and several millimeters of ashfall in surrounding villages. Significant MIROVA thermal anomalies first appeared in mid-June 2015 and persisted through January 2016. A smaller eruptive episode described below began on 13 September 2016 and continued with intermittent explosive activity through 2 March 2017. Information is provided by the Instituto Geofísico del Perú, Observatoria Vulcanologico del Sur (IGP-OVS), the Observatorio Volcanológico del INGEMMET (Instituto Geológical Minero y Metalúrgico) (OVI-INGEMMET), and the Buenos Aires VAAC (Volcanic Ash Advisory Center).
After activity subsided at the end of February 2016, Ubinas remained quiet through August 2016, with only sporadic steam and gas emissions, and very low levels of seismicity. Seismicity increased again beginning on 9 September, and the first ash emission of a new episode was reported on 13 September 2016. An explosion on 3 October released a significant ash plume that rose 2 km above the 5,672-m-summit. Four additional explosions with minor ash emissions were reported in November, and one occurred on 6 December. Webcams captured images of sporadic low-density ash emissions throughout February 2017, with the last report of possible emissions on 2 March 2017. Emissions of steam and gas and seismicity decreased throughout April 2017, and IGP-OVS lowered the alert level to Green by the end of May. Ubinas remained quiet through September 2017.
Activity during April-December 2016. After the small ash emission of 27 February 2016, seismicity at Ubinas dropped to very low levels of a few events per day (BGVN 41:10, figure 40). Sporadic steam emissions with small quantities of bluish magmatic gases rose no more than a few hundred meters above the summit during March-August 2016; there were no reports of ash emissions. A small seismic swarm of about 100 earthquakes was recorded on 5 April. The first "tornillo" type earthquakes seen in several months appeared beginning on 4 June, indicating to IGP-OVS the beginning of a new eruptive cycle. The lagoon that had formed at the bottom of the summit crater due to rains earlier in the year began to disappear as the dry season approached (figure 41).
Beginning on 9 September 2016, both OVI and OVS noted an increase in seismic activity of LP, hybrid, and VT-type events (figure 42). On 13 September, OVS reported that steam plumes rose higher than 1,000 m above the summit for the first time in many months, and a minor ash emission was observed. OVI reported possible ash emissions in weekly reports on 12, 17, and 24 September. Emissions of bluish gas and steam were typical for the remainder of September (figure 43).
Both OVI and OVS reported ash emissions from explosions on 3 October 2016 (figure 44). Seismic tremor, associated with ash emissions, lasted for nine and a half hours. The ash plume drifted NE, E, SE, and SW up to 2 km above the summit, according to OVS. Fumarolic activity then returned, with steam and bluish gases rising no more than 1,500 m above the crater rim for the remainder of October. The Buenos Aires VAAC noted the eruption reported by IGP, but was not able to identify volcanic ash from satellite data under clear skies. After peaking in early October at several hundred events per day, seismicity declined to below 50 events on 21 October, and then rose slightly to around 200 events per day for the rest of the month. Steam and gas emissions remained less than 500 m above the summit.
Three explosions with minor ash and gas (mostly SO2) were reported by IGP-OVS on 8 November (local time). NASA Goddard Space Flight Center reported a significant SO2 emission associated with this event. The ash plume rose to about 1,500 m above the crater rim (about 7.2 km altitude). Seismicity remained high, with 250-350 events per day for several days after the explosion before declining back to around 150 events per day by 15 November. Another explosion, with minor ash emissions that rose 500 m, was reported by both OVS and OVI on 17 November 2016. After a small spike in seismicity between 23 and 29 November, the number of seismic events dropped below 50 per day. OVS reported a small ash emission that rose 100 m above the summit and drifted NW on 6 December 2016. OVI noted a modest increase in seismicity between 6 and 15 December, but only sporadic emissions of water vapor and gas were detected for the remainder of the month.
Activity during January-September 2017. Gas and steam emissions remained below 500 m above the crater rim during January 2017. OVS reported an explosion at 0223 on 24 January, but could not confirm ash emissions due to darkness. Occasional emissions of steam and gas rose as high at 2 km above the summit crater, but they generally remained below 500 m. OVI observed five lahars during January, but no damage was reported. Seismicity remained below 60 events per day during the month, except for a few days during 8-12 January when the frequency increased to 100-150 events per day.
OVS reported sporadic low-density ash emissions throughout February 2017 (figure 45). They were accompanied, occasionally, by water vapor and bluish gas, and did not rise more than 1,500 m above the summit crater. Weather clouds obscured the summit for much of the month. OVI reported minor ash emissions on 4, 10, 14, and 18 February (figure 46). Seismicity fluctuated throughout the month from values as high as almost 70 events per day (8 February) to fewer than 10 events per day (10-19 February).
OVS reported only magmatic gas and steam emissions (with no ash) during March 2017, with plumes rising to a maximum height of 300 m above the summit crater. OVI noted possible diffuse ash emissions on 1 and 2 March, but only steam and gas emissions for the remainder of the month. They reported variable seismicity with the frequency of daily events ranging from less than 10 per day to almost 70, averaging about 30 events per day.
Seismic energy decreased significantly during April 2017. Sporadic steam emissions reached maximum heights of only a few hundred meters above the crater. This relative quiet enabled OVS scientist Melquiades Álvarez to make a brief inspection of the summit crater on 14 April where he observed intermittent steam emissions rising from the base of the summit crater (figure 47). No ash emissions were reported during April. OVI reported that the number of seismic events dropped consistently during April from a high of 20 daily events on 1 April, to fewer than 5 events per day at the end of the month.
The reduction in activity continued during May 2017; steam and gas emissions became more sporadic and were rarely reported rising above 500 m over the summit crater. IGP-OVS reduced the alert level from Yellow to Green (2 to 1 on a 4-level scale) during the second half of the month. Seismicity reported by OVI fluctuated between 2 and 14 daily events. Ubinas remained quiet from June through September 2017, with only occasional minor fumarolic activity of steam or magmatic gas plumes that rose a few hundred meters above the summit crater (figure 48). Frequency of seismic events remained below 20 events per day through August and dropped to less than 10 per day in September.
Geologic Background. The truncated appearance of Ubinas, Perú's most active volcano, is a result of a 1.4-km-wide crater at the summit. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45°. The steep-walled, 150-m-deep summit crater contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one from about 1,000 years ago. Holocene lava flows are visible on the flanks, but activity documented since the 16th century has consisted of intermittent minor-to-moderate explosive eruptions.
Information Contacts: Instituto Geofisico del Peru, Observatoria Vulcanologico del Sur (IGP-OVS), Arequipa Regional Office, Urb La Marina B-19, Cayma, Arequipa, Peru (URL: http://ovs.igp.gob.pe/); Observatorio Volcanologico del INGEMMET, (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa (URL: http://ovi.ingemmet.gob.pe); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php?lang=es).
Wrangell (United States) — October 2017 Cite this Report
Wrangell
United States
62.006°N, 144.017°W; summit elev. 4278 m
All times are local (unless otherwise noted)
Occasional steam plumes and wind-blown ash, but no recent eruptive activity
A previous report on Wrangell noted that the heat flux from a crater on the N side of the summit rim had increased by an order of magnitude between 1964 and 1986 (SEAN 11:04). Wrangell has several active fumarolic areas in its summit caldera. These fumaroles frequently produce steam plumes that are mistaken for eruptive activity. The Alaska Volcano Observatory (AVO) receives several reports per year from pilots and local residents who observe larger than normal steam clouds over the summit. Although there have been some events possibly involving wind-blown ash, there have been no recent confirmed eruptions.
Activity during 1996-2000. According to Neal and McGimsey (1997), a pilot reported a suspicious cloud around 18 January 1996 rising about 1.5 km near Wrangell. The National Weather Service (NWS) confirmed that a robust steam plume had been visible over the volcano for several weeks.
McGimsey and Wallace (1999) reported that, on 3 June 1997, a pilot reported steam rising from the summit. On 24 June another report described a steam plume rising about 200 m above the summit. This sighting was not observed on satellite imagery.
McGimsey and others (2004) reported that on the morning of 14 May 1999, a NWS observer in Gulkana (about 75 km WNW) reported anomalous steam emissions containing a small amount of ash. During clear weather at approximately 0930 local time, a rapidly billowing grayish-white plume rose to about 900 m above the N summit crater. The observer stated that at this time of year, on clear days, a small, wispy, steam plume is usually visible above Wrangell in the early morning, and dissipates by early afternoon. On this day, the plume developed quickly, was abnormally voluminous, and had a grayish color.
A pilot had also observed the activity and noticed that more "dirt" surrounded the N crater than usual, and that on the upper part of the Chestnina Glacier high on the SW flank, blocks of ice were chaotically jumbled (higher relief between blocks) and that the glacier surface was much more crevassed than he had ever previously seen. He also observed that one of two known fumaroles at 3,350 m elevation on the S flank, which typically issue steam through ice holes, was surrounded by a sizeable patch of bare rock, a new development since his last recent flight over the area. The pilot further reported that he had observed no sign of flowage or melting events high on the flank, but that he had not flown over the lower reaches of the glacier. As of 1700 that day the NWS observer in Gulkana could still see a small steam plume and with binoculars could see that the snow around the summit area appeared to be light gray and that this was a definite color contrast and not an effect from shadows.
According to Neal and others (2004), a Trans Alaska Pipeline worker reported an unusually strong, white steam plume on 18 March 2000 between 0500 and 0600 local time. Later that day a National Park Service (NPS) employee in Kenny Lake reported robust steaming during the previous month from multiple sources on the SW flank between approximately 600-1,500 m below the summit. AVO found no anomalies in satellite imagery and concluded that no significant unrest had occurred.
Activity during 2002-2003. Neal and others (2005) reported that on 1 August 2002, AVO received several calls reporting a dark cloud drifting downwind from the general summit area and a dark deposit high on its snow-covered flank. AVO seismologists, however, checked data from the Wrangell seismic network and, based on a lack of correlative seismicity, concluded that no eruption or explosion had occurred. AVO also consulted with a local NPS geologist, who suggested that high winds had lofted fine-grained material exposed in the area near the summit fumaroles. On 4 August, an AVO geologist traveling in the area verified that a diffuse, light gray stripe extended a short distance down the flank of the volcano, emanating from the W caldera rim.
Subsequently, a local resident presented AVO with a video showing the waning portion of the event and his written observations. The witness described multiple dark billowing black ash puffs; the wind was from the E and the puffs were not rising over the summit. By the time he had returned to a good vantage point to film, about 10-12 minutes later, the billowing had stopped and the puffs had "turned a more grayish color."
According to the authors, the video showed discrete, light gray "puffs" that moved downwind and retained their individual integrity. There were no other weather clouds in the vicinity. A light gray, relatively motionless and irregular-shaped cloud sat near the caldera rim. A breeze could be observed at ground level (indicated by motion in the trees) but at altitude, clouds were not shearing rapidly. High on the snow-covered flank, a gray-colored swath extended from a high point at the W caldera rim near Wrangell's crater. The end of the video footage showed two distinct dark areas on the rim that were normally snow-covered. The resident's son reported a similar but more vigorous event on 2 August at about the same time of the day, but AVO received no further inquiries or reports.
AVO concluded that no volcanic process of significance had occurred. However, the authors stated "these observations remain enigmatic: lack of any seismicity would seem to preclude a phreatic or magmatic eruption and yet the pulsatory, 'puffing' nature of the dirty clouds is difficult to reconcile with a wind phenomenon."
McGimsey and others (2005) reported that NPS geologist Danny Rosenkrans contacted AVO with photographs taken by a local resident on 11 June 2003 showing an unusual towering cloud over the summit. Although the authors acknowledged that it could simply have been a common cumulus cloud, they noted that the absence of cumulus clouds in the area over nearby Mts. Drum and Sanford suggested that calm weather conditions permitted steam emissions from the known summit fumaroles to coalesce and form the plume-like cloud.
McGimsey and others (2005) also reported that on 18 September 2003 the Center Weather Service Unit called with a Pilot Weather Report of a steam plume 600-700 m over the volcano. The pilot reported no ash or sulfur smell. AVO scientists checked satellite imagery and seismograms and found nothing unusual.
Activity during 2007. McGimsey and others (2011) stated that an M 8.2 earthquake in the Kurile Islands on 13 January 2007 may have triggered seismicity at Wrangell and other nearby volcanoes. There were no reports of steaming immediately following this event; however, two weeks later, on 7 February, a relatively large local earthquake was recorded on the Wrangell network that was followed another two weeks later by steaming from the summit. According to the authors, this was the first report of Wrangell steaming in several years.
The authors also mentioned additional episodes of steaming in March 2007. On 25 March, a resident living about 80 km N of the summit reported a strong sulfur odor, an occurrence the resident stated was rare in his 15 years of living in the area. Earlier that day, the Wrangell network had recorded several multi-station seismic events. The authors note that several months later, local residents sent AVO photographs taken on 20 June of steaming from Wrangell and a deposit of ash extending from the W crater many hundreds of meters down the SW flank (figure 2). According to the authors, this ash was likely redistributed from the summit craters by strong winds. No anomalous seismic activity was observed.
Activity during 2010. A report by Neal and others (2014) noted that no significant eruptive activity or restlessness had occurred in 2010. However, the authors stated that AVO had received a report of possible vapor emission from the summit area. In May 2010, a single LIDAR swath taken during a summit overflight by glaciologists from the Geophysical Institute, University of Alaska-Fairbanks, depicted the topography of North Crater, a long-known fumarolic source on the NW rim of the ice-filled summit caldera. According to the authors, there are several secondary depressions, including a complex, kidney-bean shaped pit about 20 m deep and 200 m across, located in the center of North crater. This result is broadly consistent with previously recorded surveys of North Crater using photogrammetric techniques.
Neal and others (2014) reported that in early November 2010, a long-time local resident called AVO to report "more activity at the Mount Wrangell summit than he had ever seen before." He sent AVO several images of the volcano taken on 2 November and assured AVO that when the activity in question began, there had been no weather clouds in the area. He noted about ten "bursts" from the summit and said this was unusual compared to the typical steady emissions often seen. The authors stated that AVO reviewed available seismic and satellite data and, finding no evidence of volcanic signals, concluded that the phenomenon was most likely weather-related.
Activity during 2012. According to Herrick and others (2014), no eruptive activity or significant unrest had occurred in 2012, but as in previous years AVO received reports of fumarolic activity high on its flanks. The authors noted that, because of seismic station outages, AVO had removed Wrangell from its monitored list on 27 January 2012, where it remained for at least through the rest of the year. At the same time, the Aviation Color Code and Volcano Alert Level were downgraded from Green/Normal to Unassigned.
Herrick and others (2014) reported that on 11 March 2012, local observers noted "puffs of steam." AVO analysts using satellite images detected small plumes above known fumaroles. On 20 March 2012, a citizen noticed unusually rigorous steaming and described it as looking like "a pressure cooker shot through with nails." Steam rose from both the summit and a location on the SW flank at an elevation of about 3 km. Other calls to AVO registered concern about the significant plumes. Because no other evidence of significant volcanic unrest was detected, AVO concluded these events were likely generated by normal fumarolic activity.
References. Neal, C., and McGimsey, R. G., 1997, 1996 volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 97-0433, 34 p.
McGimsey, R. G., and Wallace, K. L., 1999, 1997 volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 99-0448, 42 p.
McGimsey, R. G., Neal, C. A., and Girina, O., 2004, 1999 Volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 2004-1033, 49 p.
McGimsey, R. G., Neal, C. A., Dixon, J. P., Malik, N., and Chibisova, M., 2011, 2007 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2010-5242, 110 p. Available online at http://pubs.usgs.gov/sir/2010/5242/.
Neal, C. A., McGimsey, R. G., and Chubarova, O., 2004, 2000 Volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 2004-1034, 37 p.
Neal, C. A., McGimsey, R. G., and Girina, O., 2005, 2002 Volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report OF 2004-1058, 55 p., available online at http://pubs.usgs.gov/of/2004/1058/.
McGimsey, R. G., Neal, C. A., and Girina, O., 2005, 2003 volcanic activity in Alaska and Kamchatka: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Open-File Report 2005-1310, 62 p., http://pubs.usgs.gov/of/2005/1310/.
McGimsey, R. G., Neal, C. A., Dixon, J. P., Malik, N., and Chibisova, M., 2011, 2007 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2010-5242, 110 p. Available online at http://pubs.usgs.gov/sir/2010/5242/.
Neal, C. A., Herrick, J., Girina, O. A., Chibisova, M., Rybin, A., McGimsey, R. G., and Dixon, J., 2014, 2010 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands - Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2014-5034, 76 p., http://dx.doi.org/10.3133/sir20145034/.
Herrick, J. A., Neal, C. A., Cameron, C. E., Dixon, J. P., and McGimsey, R. G., 2014, 2012 Volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2014-5160, 82p., http://dx.doi.org/10.3133/sir20145160/.
Geologic Background. Mount Wrangell is one of the world's largest continental-margin volcanoes, with a diameter of 30 km at 2,000 m elevation. The andesitic shield volcano has produced fluid lava flows as long as 58 km and contains an ice-filled caldera 4-6 km in diameter and 1 km deep, located within an older 15-km-wide caldera. Most of the edifice was constructed during eruptions between about 600,000 and 200,000 years ago. Formation of the summit caldera followed sometime between about 200,000 and 50,000 years ago. Three post-caldera craters are located at the broad summit, along the northern and western caldera rim. A steep-sided flank cinder cone, Mount Zanetti, is located 6 km NW of the summit. The westernmost cone has been the source of infrequent eruptions beginning in the 18th century. Increased heat flux in recent years has melted large volumes of ice in the northern crater.
Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/).