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Bulletin of the Global Volcanism Network

All reports of volcanic activity published by the Smithsonian since 1968 are available through a monthly table of contents or by searching for a specific volcano. Until 1975, reports were issued for individual volcanoes as information became available; these have been organized by month for convenience. Later publications were done in a monthly newsletter format. Links go to the profile page for each volcano with the Bulletin tab open.

Information is preliminary at time of publication and subject to change.

Recently Published Bulletin Reports

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

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

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

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

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

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

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

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

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

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

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

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



Ibu (Indonesia) — June 2023 Citation iconCite this Report

Ibu

Indonesia

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia (Multiplatform Application for Geohazard Mitigation and Assessment in Indonesia), Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.esdm.go.id/v1); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Dukono (Indonesia) — June 2023 Citation iconCite this Report

Dukono

Indonesia

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

All times are local (unless otherwise noted)


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

Dukono, a remote volcano on Indonesia’s Halmahera Island, has been erupting continuously since 1933, with frequent ash explosions and sulfur dioxide plumes (BGVN 46:11, 47:10). This activity continued during October 2022 through May 2023, based on reports from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG; also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), the Darwin Volcanic Ash Advisory Centre (VAAC), and satellite data. During this period, the Alert Level remained at 2 (on a scale of 1-4) and the public was warned to remain outside of the 2-km exclusion zone. The highest reported plume of the period reached 9.4 km above the summit on 14 November 2022.

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

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

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

Figure (see Caption) Figure 34. A strong SO2 signal from Dukono on 23 April 2023 was the most extensive plume detected during the reporting period. Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia (Multiplatform Application for Geohazard Mitigation and Assessment in Indonesia), Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.esdm.go.id/v1); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


Sabancaya (Peru) — May 2023 Citation iconCite this Report

Sabancaya

Peru

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

Information Contacts: Instituto Geofisico del Peru (IGP), Centro Vulcanológico Nacional (CENVUL), Calle Badajoz N° 169 Urb. Mayorazgo IV Etapa, Ate, Lima 15012, Perú (URL: https://www.igp.gob.pe/servicios/centro-vulcanologico-nacional/inicio); Buenos Aires Volcanic Ash Advisory Center (VAAC), Servicio Meteorológico Nacional-Fuerza Aérea Argentina, 25 de mayo 658, Buenos Aires, Argentina (URL: http://www.smn.gov.ar/vaac/buenosaires/inicio.php); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard MD 20771, USA (URL: https://so2.gsfc.nasa.gov/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Sheveluch (Russia) — May 2023 Citation iconCite this Report

Sheveluch

Russia

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Kamchatka Volcanological Station, Kamchatka Branch of Geophysical Survey, (KB GS RAS), Klyuchi, Kamchatka Krai, Russia (URL: http://volkstat.ru/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/); Kam 24 News Agency, 683032, Kamchatka Territory, Petropavlovsk-Kamchatsky, Vysotnaya St., 2A (URL: https://kam24.ru/news/main/20230411/96657.html#.Cj5Jrky6.dpuf); Simon Carn, Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA (URL: http://www.volcarno.com/, Twitter: @simoncarn).


Bezymianny (Russia) — May 2023 Citation iconCite this Report

Bezymianny

Russia

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Kamchatka Volcanological Station, Kamchatka Branch of Geophysical Survey, (KB GS RAS), Klyuchi, Kamchatka Krai, Russia (URL: http://volkstat.ru/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Chikurachki (Russia) — May 2023 Citation iconCite this Report

Chikurachki

Russia

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

All times are local (unless otherwise noted)


New explosive eruption during late January-early February 2023

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

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

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

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

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

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


Marapi (Indonesia) — May 2023 Citation iconCite this Report

Marapi

Indonesia

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

All times are local (unless otherwise noted)


New explosive eruption with ash emissions during January-March 2023

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

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

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

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

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

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.esdm.go.id/v1).


Kikai (Japan) — May 2023 Citation iconCite this Report

Kikai

Japan

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Japan Coast Guard (JCG) Volcano Database, Hydrographic and Oceanographic Department, 3-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8932, Japan (URL: https://www1.kaiho.mlit.go.jp/kaiikiDB/kaiyo30-2.htm); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Lewotolok (Indonesia) — May 2023 Citation iconCite this Report

Lewotolok

Indonesia

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

All times are local (unless otherwise noted)


Strombolian eruption continues through April 2023 with intermittent ash plumes

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

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

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

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

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

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

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

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

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

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

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.esdm.go.id/v1); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).


Barren Island (India) — April 2023 Citation iconCite this Report

Barren Island

India

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

All times are local (unless otherwise noted)


Thermal activity during December 2022-March 2023

Barren Island is part of a N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The caldera, which is open to the sea on the west, was created during a major explosive eruption in the late Pleistocene that produced pyroclastic flow and surge deposits. Eruptions dating back to 1787, have changed the morphology of the pyroclastic cone in the center of the caldera, and lava flows that fill much of the caldera floor have reached the sea along the western coast. Previous activity was detected during mid-May 2022, consisting of intermittent thermal activity. This report covers June 2022 through March 2023, which included strong thermal activity beginning in late December 2022, based on various satellite data.

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

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

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

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

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

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

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


Villarrica (Chile) — April 2023 Citation iconCite this Report

Villarrica

Chile

39.42°S, 71.93°W; summit elev. 2847 m

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


Fuego (Guatemala) — April 2023 Citation iconCite this Report

Fuego

Guatemala

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

All times are local (unless otherwise noted)


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

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

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

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

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

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

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

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

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

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

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

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

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), Unit of Volcanology, Geologic Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/ ); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

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Bulletin of the Global Volcanism Network - Volume 38, Number 06 (June 2013)

Managing Editor: Richard Wunderman

Bravo, Cerro (Colombia)

In repose; 1st report disclosing background conditions and hazards

Dugong (Tonga)

New active submarine volcano found in North Lau Basin, E of Fiji

Kelimutu (Indonesia)

Crater water boils; diffuse, white plume increases to 50 m

Lengai, Ol Doinyo (Tanzania)

Still active in 2012-2013; J.B. Dawson obituary

Lobster (Tonga)

Hydrothermally active submarine volcano found in 2008

Manam (Papua New Guinea)

Sporadic heightened activity, 2011-2013; new vents

Reventador (Ecuador)

Lava dome's summit rises above rim in late 2012

Tolima, Nevado del (Colombia)

Non-eruptive during 2005-2012; hazard assessment and glacial retreat



Cerro Bravo (Colombia) — June 2013 Citation iconCite this Report

Cerro Bravo

Colombia

5.091°N, 75.293°W; summit elev. 3985 m

All times are local (unless otherwise noted)


In repose; 1st report disclosing background conditions and hazards

This report, our first for this volcano, covers the low-level activity of Cerro Bravo and monitoring efforts during 2006-2012 based on reporting by the Servicio Geológico Colombiano (SGC). Cerro Bravo was non-eruptive and the Alert Level remained at IV (Green; "volcanically active with stable behavior") due to minimal seismicity, gas emissions, and deformation.

Data availability. Government and academic investigations during 1980-1990 established the geology and preliminary hazard analysis for Cerro Bravo. Monthly SGC technical bulletins were available online from March 2006 through December 2012 and documented an increasing diversity of datasets that developed as the monitoring network expanded. Those bulletins highlighted low-level seismicity that was frequently dominated by surficial activity (rockfalls and other mass-wasting events); fluctuations in radon gas emissions were also noted and baseline data was established for emission rates. As of December 2012, three seismometers (two short-period and one triaxial station), one tiltmeter, two EDM leveling lines, and 10 diffuse radon detectors comprised the monitoring effort (figure 1).

Figure (see Caption) Figure 1. Location map of Cerro Bravo and the monitoring network maintained by the Servicio Geológico Colombiano (SGC). One seismic station (CAJO) was ~6 km S of the edifice, beyond this map view. The town of Letras (~6 km SW) was the largest community proximal to the volcano. The yellow road crossing the region is Route 50 which continues to Manizales (25 km W of Cerro Bravo) and to Bogota (140 km SE of Cerro Bravo). This map was modified from the original that appeared in the December 2012 Activity Report of the SGC.

Thouret and others (1990) presented a framework for regional volcanic activity after conducting an assessment of the Ruiz-Tolima Massif (figure 2). The investigators determined that, within a 2 Ma-long period, "recent explosive activity has migrated towards the intersections of the Palestina strike-slip fault and the N 50°W normal faults, first around [the volcanic centers] Quindío and Tolima, secondly in the Cerro Espana area, and most recently close to Cerro Bravo and Ruiz." Holocene activity at Cerro Bravo was characterized as dacitic with evidence of magma mixing. They also highlighted the role of caldera collapse within the region, including the case of Quebrada Seca Caldera, a major bounding feature of Cerro Bravo (figure 3). The concluding remarks included an emphasis on mass wasting at Cerro Bravo and lahar hazards for the ice-clad volcanoes in the region, mainly Nevado del Ruiz and Nevado del Tolima.

Figure (see Caption) Figure 2. This map of seven volcanoes includes Cerro Bravo (red triangle) in the far NE region. Fault lines (dashed green lines) cross the area and are labeled with the following abbreviations: P.F.=Palestina Fault; O.-T.-F.=Otun-Pereira Fault; T.F.=Toche Fault; R.-T.F.=Recio-Tolima Fault. The city of Manizales is marked with a blue square in the NE corner. Modified from Thouret and others, 1995.
Figure (see Caption) Figure 3. Two views of Cerro Bravo's SW flank from Letras, a town ~6 km SW of the summit. (A) This profile of merged photos was taken in July 2011; note that the youngest domes in the structure comprise the highest peaks on the left-hand side of the photo (northernmost peaks). Courtesy of Maria Luisa Monsalve, SGC. (B) Panorama view of Cerro Bravo annotated with major structural features by Monsalve (1991).

A government report prepared by Monsalve (1991) assessed the geology of the area and presented several hazard maps for pyroclastic flow, pyroclastic fall, ballistic projectiles, dome collapse, and lahar scenarios. Although ashfall could reach Manizales (~25 km W), most hazards in this study were centrally located around the immediate region of Cerro Bravo, for example pyroclastic flows and flank failures (figure 4). Hazard zones for lahars included the Río Guarino, Río Aguacatal, and Río Gualí which could extend as far as the town of Honda (~80 km E).

Figure (see Caption) Figure 4. This map of hazard zones for Cerro Bravo highlights pyroclastic flow scenarios. The summit of Cerro Bravo is marked with a red star; nearby towns and communities are labeled with green text. Modified from Monsalve (1991).

Seismicity during 2006-2012. During this reporting period, seismicity occurred at very low levels with 0-9 volcano-tectonic events (VT) recorded per month (table 1). Long-period earthquakes (LP) occurred more frequently with 0-80 events recorded per month. The SGC noted avalanche and rockfall signatures and, relative to the other years reviewed during this report, 2008 and 2011 had a notable number of surficial seismic signatures attributed to small avalanches and rockfalls. An average of 22 avalanche and 14 rockfall events occurred per month whereas the averages were between 1.5 and 10.7, respectively, during other years. The largest single rockfall event occurred in May 2012 and lasted for 34 seconds.

Table 1. Monthly seismicity at Cerro Bravo was tabulated by the occurrence of events: volcano-tectonic (VT), long-period (LP), rockfall, and largest earthquake magnitude. Courtesy of SGC.

Date VT LP Rockfall Largest EQ
Mar 2006 3 4 2 1.62
Apr 2006 1 5 12 1.77
May 2006 7 12 15 2.15
Jun 2006 3 12 37 2.19
Jul 2006 0 1 3 1.01
Aug 2006 4 1 7 1.49
Sep 2006 2 0 19 1.53
Oct 2006 2 1 7 0.64
Nov 2006 0 0 5 --
Dec 2006 0 0 0 --
Jan 2007 0 0 0 --
Feb 2007 0 1 0 0.7
Mar 2007 1 7 0 1.73
Apr 2007 2 2 0 2.2
May 2007 9 7 4 2.44
Jun 2007 4 3 3 2.02
Jul 2007 1 2 0 1.67
Aug 2007 4 3 0 2.29
Sep 2007 0 3 8 1.67
Oct 2007 3 2 1 1.77
Nov 2007 1 1 0 1.91
Dec 2007 1 0 2 0.81
Jan 2008 1 0 0 1.3
Feb 2008 1 0 0 0.64
Mar 2008 1 3 11 2.13
Apr 2008 1 0 2 1.9
May 2008 0 2 54 1.01
Jun 2008 0 1 74 0.81
Jul 2008 0 0 34 --
Aug 2008 1 0 44 1.73
Sep 2008 0 0 7 --
Oct 2008 0 0 25 --
Nov 2008 0 0 11 --
Dec 2008 0 79 3 3.4
Jan 2009 1 9 6 2.52
Feb 2009 0 2 6 2.22
Mar 2009 1 6 2 2.32
Apr 2009 0 0 12 --
May 2009 1 0 18 0.88
Jun 2009 0 0 1 --
Jul 2009 0 0 0 --
Aug 2009 0 0 8 --
Sep 2009 0 3 2 2.1
Oct 2009 0 2 11 1.4
Nov 2009 0 0 0 --
Dec 2009 0 1 0 0.86
Jan 2010 1 0 0 1.23
Feb 2010 0 0 5 --
Mar 2010 0 2 5 1.33
Apr 2010 0 3 0 2.1
May 2010 1 5 1 1.89
Jun 2010 0 1 16 1.59
Jul 2010 0 5 2 1.98
Aug 2010 0 0 1 --
Sep 2010 1 8 18 1.91
Oct 2010 0 0 6 --
Nov 2010 0 5 64 2.08
Dec 2010 0 0 6 --
Jan 2011 0 1 1 1.75
Feb 2011 0 0 0 --
Mar 2011 0 3 3 1.7
Apr 2011 0 0 26 --
May 2011 0 2 30 1.67
Jun 2011 0 6 40 2.43
Jul 2011 0 0 14 --
Aug 2011 2 16 19 1.67
Sep 2011 1 1 12 0.64
Oct 2011 0 0 9 --
Nov 2011 3 3 13 1.82
Dec 2011 0 3 5 2.37
Jan 2012 0 2 5 0.86
Feb 2012 1 2 1 1.93
Mar 2012 0 0 2 --
Apr 2012 1 1 3 1.8
May 2012 0 0 2 --
Jun 2012 0 0 3 --
Jul 2012 1 0 0 1.11
Aug 2012 0 0 1 --
Sep 2012 0 1 1 2.22
Oct 2012 0 0 6 --
Nov 2012 0 1 0 1.61
Dec 2012 0 0 0 --

The largest recorded earthquake magnitude, M 3.4, was recorded in December 2008. The average magnitude during this reporting period was M 1.7. An anomalous 2-hour-long signal was recorded in June 2006; that month, seismicity was slightly elevated (3 VT, 11 LP, and 37 rockfalls).

The SGC August 2008 bulletin highlighted a seismic swarm within the region of Cerro Bravo. The swarm was detected on 9 August 2008 comprising 65 earthquakes at an undetermined distance NE of Paramillo del Quindío (located ~40 km S of Cerro Bravo) at relatively shallow depths (2-5 km). The earthquakes had small magnitudes; the largest was M 1.14. A second swarm occurred on 30 December 2008, when ~80 LP earthquakes were detected. The largest event, an M 2.3 earthquake, occurred S of Cerro Bravo and caused shaking that was noted by residents of Manizales (particularly those in tall buildings).

A swarm of 67 earthquakes occurred during 17-29 November 2010. The SGC noted that rockfalls and avalanches were likely responsible for these events. That month, there were five LP earthquakes but no VT earthquakes were detected.

Rockfalls and avalanches were attributed to elevated seismicity in June 2011 when 40 events were detected that month. While those earthquakes were occurring, there were no associated geophysical or geochemical changes observed at the edifice.

Geochemical monitoring efforts. Radon and carbon dioxide data were recorded by the SGC during 2005 through 2012 (figure 5), although CO2 data became unavailable after October 2009. The SGC reported that background level emissions were classified as values 2 data rarely coincided with radon except for a prominent increase around June 2008 at that Cerro Bravo 2 station CO2 measured ~2.7% volume and the radon peak was ~900 pCi/L.

Figure (see Caption) Figure 5. Radon and carbon dioxide emissions from Cerro Bravo during April 2005 - May 2010 (Cerro Bravo 1 Station) and June 2005-May 2010 (Cerro Bravo 2 Station). Note that, at both stations, CO2 data ended in October 2009. Courtesy of SGC.
Figure (see Caption) Figure 6. This plot of radon emissions for 2005-2012 includes increasingly more radon stations over time. Installation of eight new stations occurred in June 2011 at a time when radon emissions were peaking around 2,000 pCi/L. Courtesy of SGC.

Surface deformation monitoring. In October 2009, the SGC installed reflectors and base stations for two EDM (Electronic Distance Measurement) lines (figure 1). An EDM survey was conducted three months later, beginning the establishment of long-term surface deformation monitoring. During 2009-2012, eight EDM surveys were conducted from the El Doce base and four EDM surveys were conducted from El Porton; the SGC stated that no significant changes were calculated from these datasets.

Monitoring with an electronic tilt station began in late March 2011 with an installation on the E flank (figure 1). Stable conditions were recorded by the tiltmeter up until December 2011 when decreasing trends suddenly began from both N and E components (figure 7). The SGC noted that from December 2011 to early April 2012 there was a total change of -5 & mu;m and -8 & mu;m (N and E components respectively). During April-December 2012, generally stable conditions resumed.

Figure (see Caption) Figure 7. The electronic tilt record from CBRE station (located on the E flank). With the exception of December 2011-April 2012 (when significant decreasing trends persisted), this record showed fluctuations within expected range of the instrument. Courtesy of SGC.

References. Lescinsky, D., 1990, Geology, volcanology and petrology of Cerro Bravo, a young dacitic stratovolcano in West-Central Colombia [Master's Thesis]: Hanover, NH, Dartmouth College, 244 pp.

Monsalve, M.L., 1991. Mapa preliminar de amenaza volcánica del Volcán Cerro Bravo, INGEOMINAS, Prepared for the Government of Tolima and CRE-Tolima.

Thouret, J.C., Cantagrel, J-M., Robin, C., Murcia, A., Salinas, R., and Cepeda, H., 1995, Quaternary eruptive history and hazard-zone model at Nevado del Tolima and Cerro Machin volcanoes, Colombia. Journal of Volcanology Geothermal Research, 66 (1-4):397-426.

Thouret, J.C., Murcia, A., Salinas, R., Parra, E., Cepeda, H., and Cantagrel, J-M., Stratigraphy and quaternary eruptive history of the Ruiz-Tolima volcanic massif (Colombia): Implications for assessment of volcanic hazards. Symposium International Géodynamique Andine: Résumés des communications. 15-17 May 1990, Grenoble, France. p. 391-393.

Geologic Background. Cerro Bravo is a relatively low dominantly dacitic lava-dome complex north of Nevado del Ruiz that was constructed within the Pleistocene Quebrada Seca caldera. A series of moderate plinian eruptions during the Holocene were accompanied by pyroclastic flows and lava dome growth. Although historical records of the roughly 4000-m-high Cerro Bravo eruptions have not been found, stratigraphic evidence indicates that it last erupted sometime between the 1595 and 1845 eruptions of Ruiz.

Information Contacts: María Luisa Monsalve, Gloria Patricia Cortés, and Cristian Mauricio López, Servicio Geológico Colombiano (SGC), Volcanological and Seismological Observatory, Avenida 12 Octubre 15-47, Manizales, Colombia (URL: https://www2.sgc.gov.co/volcanes/index.html).


Dugong (Tonga) — June 2013 Citation iconCite this Report

Dugong

Tonga

15.431°S, 175.725°W; summit elev. -1170 m

All times are local (unless otherwise noted)


New active submarine volcano found in North Lau Basin, E of Fiji

According to the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO), several large active submarine volcanoes, spreading ridges, and rift zones have been discovered in the Northwest Lau back-arc basin, NE of Fiji Island (figure 1), by a team of Australian and American scientists aboard the CSIRO Marine National Facility Research Vessel Southern Surveyor during a research cruise in Spring 2008 (CSIRO, 2008b). While mapping previously uncharted areas for submarine volcanic and hot spring activity with multibeam sonar and various other techniques, the team located several active volcanoes, one of which they named Dugong. The depth of Dugong is given in the InterRidge Vents Database [Ver. 3.1] (2013), and its location was plotted on figure 1 based on coordinates given in Lupton and others (2012).

Figure (see Caption) Figure 1. Two maps showing (lower left) North Island, New Zealand (in black) and selected plate tectonic features along the Kermadec and Tonga trenches (hachured line with teeth on upthrown side) and (larger map) Dugong (white square) and other features such as the main spreading centers, geographical features, and subaerial volcanoes (open yellow triangles). Note Niuafo'ou volcano and island. The base maps in figure 1 came from Keller and others (2008), a study primarily discussing the area in the rectangle on the larger map. The sea floor was mapped with multibeam sonar (soundings normal to the ship's track). Abbreviations are as follows: VFR - Valu fa ridge; ELSC - East Lau spreading center; ILSC - Intermediate Lau spreading center; CLSC - Central Lau spreading center; LETZ - Lau Extensional transform zone; PR - Peggy Ridge; NWLSC - Northwest Lau spreading center; NSC - Niuafo'ou spreading center (location of Rochambeau Rifts); NELSC - Northeast Lau spreading center; FSC - Fonualei spreading center; and MTJ - Mangatolu triple junction. Courtesy of Keller and others (2008).

As shown in figure 2, the greater Dugong structure is dominated by a 5-km-diameter caldera at a depth of 1,100 m. Dugong volcano is located ~60 km E of Lobster volcano, ~20 km WNW of Niuafo'ou volcano/island, and ~680 km NE of Suva, Fiji.

Figure (see Caption) Figure 2. Multibeam sonar three-dimensional (30 kHz swathmap) image of submarine volcano Dugong. A Global Positioning System (GPS) and an Inertial Motion Unit (IMU) were used to monitor the ship's position and attitude. The large volcano, 45 km in diameter, is located 25 km NW of the subaerial back-arc island volcano of Niuafo'ou. A 5 km diameter crater forms the summit region of the volcano, with a small hydrothermal plume near its base. The mapping revealed an enormous structure with hundreds of individual eruptive blobs and transected by numerous faults. A dredge of the SW floor of the caldera recovered a few fresh basaltic pillow fragments, volcanic glass, and small pieces of pumice. There is no color scale for the image for conversion to depth, although dark green is the deepest, trending upwards through yellow, orange, red, and tan. Location and distance scales are also missing from the figure. Image from CSIRO (2008b); with ancillary information from Arculus (2008).

During the 6 week research expedition in the Pacific Ocean, scientists from the Australian National University (ANU), CSIRO Exploration & Mining, and the United States collaborated to survey the topography of the seafloor, analyzing rock types and formations, and monitoring deep sea hot spring activity around an area known as the North Lau Basin, 400 km NE of Fiji.

References. Arculus, R.J., 2008, Marine National Facility RV Southern Survey 2008 Program: Voyage Summary SS07/2008 Northern Lau Vents Expedition (NoLauVE), 23 p (URL: http://www.cmar.csiro.au/datacentre/process/data_files/cruise_docs/SS200807sum.pdf).

CSIRO, 2008a, Active submarine volcanoes found near Fiji, CSIRO web site (URL: http://www.csiro.au/Organisation-Structure/Divisions/Earth-Science--Resource-Engineering/SubmarineVolcanoes.aspx).

CSIRO, 2008b, Active submarine volcanoes found near Fiji, CSIRO media release (URL: http://www.scienceimage.csiro.au/mediarelease/mr08-93.html).

de Ronde, C.E.J, Baker, ET, Massoth, G.J, Lupton, J.E, Wright, I.C., Feely, R.A., and Greene, R.R., 2001, Intra-oceanic subduction-related hydrothermal venting, Kermadec volcanic arc, New Zealand, Earth and Planetary Science Letters, v. 193, p. 359-369.

Graham, I.J., Reyes, A.G., Wright, I.C., Peckett, K.M., Smith, I.E.M., and Arculus, R.J., 2008, Structure and petrology of newly discovered volcanic centers in the northern Kermadec-southern Tofua arc, South Pacific Ocean, Journal of Geophysical Research, v. 113, B08S02, doi:10.1029/2007JB005453.

InterRidge Vents Database Ver. 3.1, 2013, Vent Fields (URL: http://www.interridge.org/irvents/ventsfields?).

Keller, N.S., Arculus, R.J., Hermann, J., and Simon, R., 2008, Submarine back arc lava with arc signature: Fonualei Spreading Center, northeast Lau Basin, Tonga, Journal of Geophysical Research, v. 113, B08S07, doi:10.1029/2007JB005451.

Lupton, J.E., Arculus, R.J., Resing, J., Massoth, G.J., Greene, R.R., Evans, L.J., and Buck, N., 2012, Hydrothermal activity in the Northwest Lau Backarc Basin: Evidence from water column measurements, Geochemistry, Geophysics, Geosystems, v. 13, no. 5, doi: 10.1029/2011GC003891. Information Contacts. Commonwealth Scientific and Industrial Research Organization (CSIRO) (URL: http://www.csiro.au).

Geologic Background. This volcano was discovered during an Australian research cruise in 2008. The overall edifice is 45 km in diameter, with a 5-km-diameter summit caldera.

Information Contacts: Commonwealth Scientific and Industrial Research Organization (CSIRO) (URL: http://www.csiro.au); National Oceanic and Atmospheric Agency (NOAA) (URL: http://www.CSC.noaa.gov/crs/rs_apps/sensors/multi_beam.htm); Richard Arculus, Australian National University Research School of Earth Sciences; and Frederick Stein, Director, Marine National Facility, CSIRO.


Kelimutu (Indonesia) — June 2013 Citation iconCite this Report

Kelimutu

Indonesia

8.77°S, 121.82°E; summit elev. 1639 m

All times are local (unless otherwise noted)


Crater water boils; diffuse, white plume increases to 50 m

This volcano is well known for three summit crater lakes, each a different color. We last reported minor bubbling in a crater lake Tiwu Nua Muri Kooh Tai lake in 1995 (BGVN 20:06). Between 15 and 19 May 1995, rescuers searched for the body of a Dutch tourist who had fallen into the crater lake but they did not find it.

2013 activity.The Center of Volcanology and Geological Hazard Mitigation (CVGHM) reported that on 6, 10, and 12 June 2013, and during 14 June-9 July 2013, the color of the water in Kelimutu's Crater II (Tiwu Nua Muri Kooh Tai Crater) was bluish white. Diffuse white plumes rose as high as 50 m above the lake's surface and in some areas the water appeared or sounded like it was boiling. A sulfur odor was also reported. The water in Crater I (Tiwu Ata Polo) was light green and churned, and the water in Crater III (Tiwu Ata Mbupu) was mossy green.

On 3 June 2013, a change was observed in the color of the lake water in Crater II, going from blue to a café au lait (light tan), accompanied by white smoke under weak to medium pressure, rising 50 meters above the surface of the lake. From the southern side of Crater II a bubbling sound of boiling was heard near the wall separating Crater I from Crater II. The smell of sulphur gas was quite sharp in the vicinity of the crater and at nighttime a weak to medium smell of this gas could be discerned in Pemo Village which is 3 kms from the peak of Kelimutu. On 4 June 2013 at 1400 hours local time the status of Kelimutu was upgraded from Alert Level 1 (Normal) to Alert Level 2 (Waspada).

On 6 June 2013 water in Crater II was a bluish white (like a salty egg), with sparse to medium white smoke under weak to strong pressure extending up 10-35 meters above the lake surface. A weak to strong bubbling sound of boiling water was heard on the southern side of the crater. A medium to sharp smell of sulphurous gas was evident as was the withering vegetation.

On 10 June 2013 water in Crater II was still a bluish white with medium to dense white smoke extending up 40-50 m above the lake surface. A bubbling sound of boiling water could be heard on the southern side of the crater. A medium smell of sulphurous gases was discernible.

On 12 June 2013, smoke rising from the surface of the lake extended to only about 10-30 meters above the lip of the crater. There was a rather acrid smell of sulphurous fumes. Eruptive and hot air noises were audible two times and the water in the crater lake still appeared to be boiling.

From 14 June to 9 July 2013, water in Crater II visually still appeared bluish white with sparse white smoke rising from the surface of the lake about 2-10 meters into the atmosphere (dominant height was not observed). There was a weak to medium (with weak dominating) smell of sulphurous gases. At one point bubbling water was noticeable but it was clearly under weak pressure. Water from Crater III was calm and moss-green in color.

During 22-29 June 2013 sulfur dioxide concentrations in Crater II were occasionally 2.8 ppm, when the wind blew the gas towards the sensor. CVGHM noted that plumes rising from the lakes became lower and barely visible during 3 June-9 July, and that the hissing or "rustling sound" of water from near the dividing wall of craters I and II had gradually faded away. Based on visual observations, seismicity, and gas emissions, CVGHM lowered the Alert Level to 1 (on a scale of 1-4) on 12 July (figure 4).

Figure (see Caption) Figure 4. Kelimutu has three summit crater lakes seen in this photo. The lake Tiwi Ata Mbupu (left) is commonly blue. Tiwu Nua Muri Kooh Tai and Tiwu Ata Polo, which share a common crater wall, are typically green and red-colored, respectively. Photo courtesy of https://www.tripping.com. Posted 1 June 2013.

During 13 - 18 June 2013, local tectonic quakes peaked at 139 before undergoing a decrease as of 17 June 2013. Shallow (VB) and deep (VA) volcanic earthquakes occurred intensely each day, reaching a a peak of 13 shallow volcanic quakes 19-24 June 2013 and then tended to decline (figure 5). Deep volcanic quakes peaked at 14 during 1-6 July 2013 and then subsided.

Figure (see Caption) Figure 5. A plot of seismicity at Kelimutu during 1 June 2013 through 11 July 2013. Courtesy of CVGHM.

No thermal alerts were recorded by MODVOLC for the past twelve months beginning in mid-July 2012.

Figure (see Caption) Figure 6. First photo (A) is Tiwu Ata Polo Lake (water color change from red to green), second photo (B) is between Tiwu Ata Polo Lake and Tiwu Nua Muri Kooh Fai Lake, and third photo (C) is Tiwu Nua Muri Kooh Fai Lake (water color change from green to white). Pictures taken on 6 June 2013 by Kristianto.

Geologic Background. Kelimutu is a small, but well-known, Indonesian compound volcano in central Flores Island with three summit crater lakes of varying colors. The western lake, Tiwi Ata Mbupu (Lake of Old People) is commonly blue. Tiwu Nua Muri Kooh Tai (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched, or Enchanted Lake), which share a common crater wall, are commonly colored green and red, respectively, although lake colors periodically vary. Active upwelling, probably fed by subaqueous fumaroles, occurs at the two eastern lakes. The scenic lakes are a popular tourist destination and have been the source of minor phreatic eruptions in historical time. The summit is elongated 2 km in a WNW-ESE direction; the older cones of Kelido (3 km N) and Kelibara (2 km S).

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); and Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822 USA (URL: http;//hotspot.higp.hawaii.edu/).


Ol Doinyo Lengai (Tanzania) — June 2013 Citation iconCite this Report

Ol Doinyo Lengai

Tanzania

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

All times are local (unless otherwise noted)


Still active in 2012-2013; J.B. Dawson obituary

We recently noted that Frederick Belton's web site on Ol Doinyo Lengai has been supplemented by a web site from the Ngare Sero Village Council entitled "Oldoinyo Lengai - The Mountain of God." This new web site has information on climbing, mountain safety, guides, equipment, and fees, as well as activity of the volcano as observed by guides and visitors. According to Belton, Lazaro Saitoti is maintaining the web site from both Arusha and Engare Sero, and it represents a potentially useful source of local information, with an emphasis on tourism.

Abigail Church forwarded to us two aerial photographs of Lengai's active crater and summit, one taken in June 2013 (figure 166) and the other in 28 July 2013 (figure 167). On 29 July, Church reported that she had flown over Lengai a few times in the last year or so, and that Lengai appeared to have small active vents still emitting lava. In addition, these aerial views recorded little other activity except for slippage off the steep walls. She noted that she was in touch with a number of pilots that are often flying over Lengai and that might contact her if they see anything unusual.

Figure (see Caption) Figure 166. Aerial photograph of the crater and summit of Lengai taken in June 2013, looking almost S. In the background one can see the summit of Lengai, due S of the crater (see map, figure 154 of BGVN 37:11). Courtesy of Andy Allan.
Figure (see Caption) Figure 167. Aerial photograph of the crater and summit of Lengai taken 28 July 2013, looking almost S. In the background one can see the summit of Lengai, due S of the crater (see map, figure 154 of BGVN 37:11). Courtesy of Phil Mathews, Heliprops Ltd.

On 10 April 2013, Bonnie Betts climbed Lengai and, on Belton's web site is quoted as reporting: "We started at midnight in a thunderstorm with light rain, but it cleared up. You could hear the lava sloshing around inside the crater before getting to the top; also dark smoke could be seen coming from the crater while ascending in the night . . . Looking into the crater, you can see the lava sloshing back and forth in the dark, black tunnel, and then some would flow out with a different flowing swishing sound." Local guides expressed concerns to Betts that an extensive crack seen in the crater may be the beginning of a collapse of the inner wall of the pit crater. Figures 168 and 169 show photos taken during Betts' climb.

Figure (see Caption) Figure 168. A tall spatter cone was formed 10 April 2013 near the crater wall, as seen looking W from the crater rim, located on the W side of the pit. The flank of that cone had also ruptured and an active lava flow exited the cone. Note that the vent is also present in the photo of the same area taken 14-15 September 2012 (see figure 158 of BGVN 37:11). Photo courtesy of Bonnie Betts.
Figure (see Caption) Figure 169. Photo taken 10 April 2013, looking W from the crater rim. A steaming fissure crossed the photo in mid-ground near the crater rim. Just to the right of center of the photo are the Pearly Gates, cut in the crater rim atop the former climbing route on the W side of the volcano (see figure 154 of BGVN 37:11). Photo courtesy of Bonnie Betts.

Belton received some photos and a description by Gian Schachenmann of a visit to Lengai on 17-18 June 2013. Schachenmann noted sloshing lava sounds from the spatter cone and big cracks on the rim where gases escaped (figure 170).

Figure (see Caption) Figure 170. Photo taken 17 or 18 June 2013 (in the same area as figure 168, above), showing that the tall spatter cone no longer has the vent that was present on the photo taken 10 April 2013. Thus, it also appears that there has been only slight growth of the cone during the two months between the photographs. Photo courtesy of Gian Schachenmann.

Death of John Barry Dawson, Lengai Legend. According to the Mitchell (2013), John B. Dawson, Emeritus Professor of Geology, Lakehead University, Thunder Bay, Ontario, Canada, died 2 February 2013. Excerpts from that obituary are found below.

Dawson was known for his extensive knowledge of kimberlite geology. Subsequent to graduation in 1960, Barry joined the Tanganyika Geological Survey, where he was employed to map areas of the then remote Angata Salei region near Lake Natron, a location of an active volcano. "The first ever descent into the crater of this volcano, Oldoinyo Lengai, (the Maasi Mountain of God), was made by Barry and Ray Pickering in October 1960. It was during this visit that he recognized the unique sodium carbonate volcanism and earned himself a permanent place in petrological history with the publication of his paper on these extraordinary rocks in the journal Nature (Dawson, 1962). Subsequently, he maintained an active research program on the petrology of Oldoinyo Lengai and other volcanoes in the Gregory Rift Valley."

"During this work he narrowly survived one violent silicate ash eruption of Oldoinyo Lengai in 1966, and was fortunate enough to observe, some 40 years later in 2007, the return to silicate pyroclastic activity from the quiet effusive natrocarbonatite eruptions. To the time of his death, Barry was actively involved in studies of Oldoinyo Lengai, Kerimasi, Mosonik and other Tanzanian volcanoes. He was especially pleased with the publication in 2009 [sic] of his comprehensive review of volcanic activity in the Gregory Rift" (Dawson, 2008).

References. Belton, F., 2013, Ol Doinyo Lengai, web site, URL: http://www.oldoinyolengai.pbworks.com.

Dawson, J.B., 1962. Sodium Carbonate Lavas from Oldoinyo Lengai, Tanganyika, Nature, v. 195, pp. 1075-1076.

Dawson, J.B., 2008, The Gregory Rift Valley and Neogene-Recent Volcanoes of Northern Tanzania, Geological Society, London, Memoir 33, pp. viii 102.

Mitchell, R.H., 2013, John Barry Dawson 1932-2013, Mineralogical Magazine, v. 77, no. 3, pp. 401-402.

Ngare Sero Village Council, 2013, Oldoinyo Lengai - The Mountain of God, web site, URL: http://www.oldoinyo-lengai.org

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

Information Contacts: Abigail Church, The Ker and Downey Safari Tradition, James Robertson, chairman, P.O. Box 86, Karen 00502, Kenya (URL: http://www.kerdowneysafaris.com/); Frederick A. Belton, University Studies Department, Middle Tennessee State University, Murfreesboro, TN (URL: http://www.oldoinyolengai.pbworks.com); Lazaro Saitoti, Chairman, Ngare Sero Village Council, and Lemra Kingi, Chairman Tourism, Ngare Sero Village Council, Arusha and Engare Sero, Tanzania (URL: http://www.oldoinyo-lengai.org); and Bonnie Betts (no contact information).


Lobster (Tonga) — June 2013 Citation iconCite this Report

Lobster

Tonga

15.333°S, 176.283°W; summit elev. -1500 m

All times are local (unless otherwise noted)


Hydrothermally active submarine volcano found in 2008

The Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) announced in press releases that several large active submarine volcanoes, spreading ridges, and rift zones had been discovered in the Northwest Lau back-arc basin, NE of Fiji Island (figure 1). The discoveries were made by a team of Australian and American scientists aboard the CSIRO Marine National Facility Research Vessel Southern Surveyor in Spring 2008 (CSIRO, 2008a). While mapping previously uncharted areas for submarine volcanic and hot spring activity, the team located several volcanoes, one of which they named Lobster. The depth of Lobster is given as 1,500 m in the InterRidge Vents Database [Ver. 3.1] (2013). The location of Lobster is shown in figure 1, based on coordinates given in Lupton and others (2012). The base maps in figure 1 came from Keller and others (2008), a study primarily discussing the area in the rectangle on the larger map. The sea floor was mapped with multibeam sonar. Lobster is located ~75 km NNW of Niuafo'ou volcano/island and ~680 km NE of Suva, Fiji (figure 1). Dugong volcano lies ~60 km E of Lobster.

Figure (see Caption) Figure 1. Two maps showing (lower left) North Island, New Zealand (in black) and selected plate tectonic features along the Kermadec and Tonga trenches (hachured line with teeth on upthrown side) and (larger map) Lobster (white square) and other features such as the main spreading centers, geographical features, and subaerial volcanoes (open yellow triangles). Note Niuafo'ou volcano and island, and the location of Lobster (and Dugong, a neighboring volcano discussed in a separate Bulletin report and plotted on a larger map). Abbreviations are as follows: VFR - Valu fa ridge; ELSC - East Lau spreading center; ILSC - Intermediate Lau spreading center; CLSC - Central Lau spreading center; LETZ - Lau Extentional transform zone; PR - Peggy Ridge; NWLSC - Northwest Lau spreading center; NSC - Niuafo'ou spreading center (location of Rochambeau Rifts); NELSC - Northeast Lau spreading center; FSC - Fonualei spreading center; and MTJ - Mangatolu triple junction. Courtesy of Keller and others (2008).

Lobster volcano's caldera is 2x2.5 km in diameter with a floor at 1.5 km depth (figure 2). It was described as residing amid four radiating rift zones.

Figure (see Caption) Figure 2. (a) Multibeam sonar three-dimensional (30 kHz swathmap) image made in 2008 of Lobster which sits in what was described as the center of a rift zone and astride a spreading ridge to its W (CSIRO, 2008). Image lacks scale for depth values, but in relative terms light blue is the deepest, trending upwards through dark-to-light green, yellow, orange, and then red as the shallowest. Image from news release of CSIRO (2008b). (b) Shaded relief, contour map of Lobster caldera on the Rochambeau rifts showing part of a survey track completed in 2010 by the research vessel Dorado Discovery. Taken from Lupton and others (2012). (c) Detail map of Lobster Caldera showing locations and profiles for two chemistry hydrocasts. Inserts show vertical profiles of δ3He (deviation of the 3He/4He ratio measured at depth from the atmospheric ratio), total Mn (manganese), and %T transmission of light (a measure of suspended particles) plotted versus depth. Taken from Lupton and others (2012).

The caldera's rim is about 100 m high on the W side whereas only ~20 m high on the E side.

Dredge samples from Lobster recovered in 2008 contained olivine and plagioclase in pillow basalts. A dredge sample taken on the smooth caldera floor recovered fresh flows as well as thick, black aphyric pillows with glassy rinds.

Age. According to Arculus (2008) and Lupton and others (2012), active venting was identified in the form of high helium anomalies (δ3He), suspended particles (%T), and trace metals (manganese and iron) at 60 m off the bottom in the SE corner of the summit caldera. Lupton and others (2012) reported, in 2012, that the site was still active.

The expedition mapped the seafloor using a 30 kHz multibeam sonar with Global Positioning System (GPS) and an Inertial Motion Unit (IMU) to track the ship's position and attitude. They also made vertical conductivity, temperature, and depth (CTD) measurements as well as rock dredging. In addition, by lowering the CTD package up and down a few hundred meters from the bottom, while moving the ship, they obtained a far greater density of data. This technique, often informally referred to as a CTD tow-yo, is effective for mapping and sampling hydrothermal plumes.

References. Arculus, R.J., 2008, Marine National Facility RV Southern Survey 2008 Program: Voyage Summary SS07/2008 Northern Lau Vents Expedition (NoLauVE), 23 p (URL: http://www.cmar.csiro.au/datacentre/process/data_files/cruise_docs/SS200807sum.pdf).

CSIRO, 2008a, Active submarine volcanoes found near Fiji, CSIRO web site (URL: http://www.csiro.au/Organisation-Structure/Divisions/Earth-Science--Resource-Engineering/SubmarineVolcanoes.aspx).

CSIRO, 2008b, Active submarine volcanoes found near Fiji, CSIRO media release (URL: http://www.scienceimage.csiro.au/mediarelease/mr08-93.html).

de Ronde, C.E.J, Baker, ET, Massoth, G.J, Lupton, J.E, Wright, I.C., Feely, R.A., and Greene, R.R., 2001, Intra-oceanic subduction-related hydrothermal venting, Kermadec volcanic arc, New Zealand, Earth and Planetary Science Letters, v. 193, p. 359-369.

Graham, I.J., Reyes, A.G., Wright, I.C., Peckett, K.M., Smith, I.E.M., and Arculus, R.J., 2008, Structure and petrology of newly discovered volcanic centers in the northern Kermadec–southern Tofua arc, South Pacific Ocean, Journal of Geophysical Research, v. 113, B08S02, doi:10.1029/2007JB005453.

InterRidge Vents Database Ver. 3.1, 2013, Vent Fields (URL: http://www.interridge.org/irvents/ventsfields?).

Keller, N.S., Arculus, R.J., Hermann, J., and Simon, R., 2008, Submarine back-arc lava with arc signature: Fonualei Spreading Center, northeast Lau Basin, Tonga, Journal of Geophysical Research, v. 113, B08S07, doi:10.1029/2007JB005451.

Lupton, J.E., Arculus, R.J., Resing, J., Massoth, G.J., Greene, R.R., Evans, L.J., and Buck, N., 2012, Hydrothermal activity in the Northwest Lau Backarc Basin: Evidence from water column measurements, Geochemistry, Geophysics, Geosystems, v. 13, no. 5, doi: 10.1029/2011GC003891.

Geologic Background. Active hydrothermal venting was noted when this volcano was first discovered in 2008 by an Australian research expedition.

Information Contacts: Commonwealth Scientific and Industrial Research Organization (CSIRO) (URL: http://www.csiro.au).


Manam (Papua New Guinea) — June 2013 Citation iconCite this Report

Manam

Papua New Guinea

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

All times are local (unless otherwise noted)


Sporadic heightened activity, 2011-2013; new vents

Our last report on Manan (BGVN 36:06; figure 29) discussed field observations through 11 January 2011. The following summarizes available Rabaul Volcano Observatory (RVO) reports issued since that time through May 2013. Pyroclastic flows took place during the reporting interval, specifically four times on 16 June 2012, and another four times on 30 July 2012, all of which traveled down the SE valley. No injuries were reported. In addition there were lava fountains, several lava flows, and some cases of sustained emissions lasting hours. Occasional ash plumes triggered the Darwin Volcanic Ash Advisory Centre (Darwin VAAC) to issue notices. Some ash plumes drifted over 200 km. Loud noises, rumbling, tephra ejected above or outside the confines of the crater, and night glow were common observations.

Figure (see Caption) Figure 29. This ALI satellite photo was taken of Manam on [9 June 2009]. Courtesy of NASA Earth Observatory.

2011 activity. During 1-19 August 2011, RVO reported Manam's summit area was obscured by weather clouds on most days. When the summit was clear to viewers on the mainland, 15-20 km away from Manam, both vents emitted white vapor plumes. Main Crater produced light-gray ash clouds during 13 and 17-18 August, and bright, steady incandescence was visible on most clear nights. August seismicity was dominated by volcanic tremor, but discrete high-frequency volcano-tectonic earthquakes were also recorded which, RVO noted, are not very common for Manam. An electronic tiltmeter located ~4 km SW from the summit craters continued to show inflation.

Based on analysis of satellite imagery, the Darwin VAAC reported a series of ash plumes which, during 18-21 August, rose to altitudes of 1.8-2.1 km and drifted 45-90 km NW and W. The VAAC next reported that on 18 October, ash plumes rose to 3.7 km altitude and drifted 150-170 km NW. During 19-21 October ash plumes rose to an altitude of 3.7 km and drifted 150-220 km W. For 11 November 2011, using both satellite imagery and a pilot observation, the VAAC reported an ash plume to an altitude of 3 km drifting up to ~90 km NE.

Activity continued in December 2011. Seismicity was assessed by Real-time Seismic Amplitude Measurements (RSAM) and varied at high levels between 200-350 RSAM. Both craters produced ash and lava fragments. The ash clouds rose to several hundred meters above the vents. Both vents often glowed at night, and expelled glowing fragments. Brown and grey ash was deposited in areas down wind. There were reports of a possible lava flow from the Southern Crater, with the 'V' shaped channel created by the 2005 blast being filled up.

2012 activity. RVO reported continued activity during January 2012. White vapor and grey-to-black ash emissions rising less than 200 m were observed from both craters throughout the month, sometimes with accompanying weak incandescent projections. From the Southern Crater, more sustained emissions on the evening of 20 January occurred with mainly black ash up to 400 m, trending to the SE. At that time low-energy projections observed at 3-4 minute intervals fell back inside the crater. Main Crater produced a bright steady glow and released thick white vapor with a strong blue tinge. On 23 January observers noted that there were possibly three vents emitting columns of vapor and ash. Seismicity during this time remained moderate to high, with a variable RSAM of 200-350.

RVO next reported mainly mild activity at Southern Crater during the first two weeks of May 2012. Diffuse white and blue vapor emerged during 5-6 and 13-14 May, and gray and gray-brown ash clouds were observed on 7, 9, and 12 May. Observers noted incandescence on the nights of 6, 8, 10-11, and 13-14 May, and glowing tephra occasionally falling outside of the crater.

Activity increased on 16 May 2012. Ash cloud colors changed from gray and gray-brown to gray and black. On 27 and 30 May Strombolian emissions occurred and, for periods lasting 1-2 hours, continuously ejected incandescent tephra. On 30 May two vents at the Southern Crater produced lava fountains. Ash plumes rose 100-400 m above the crater and drifted NW. Most of the tephra fell back into the crater, but some was channeled into the SE and SW valleys. Emissions from Main Crater were milder and characterized by white plumes and gray to gray-brown ash plumes noted during 6, 10-11, 13, 26, 28-29, and 31 May. Ash fell on the NW part of the island.

Seismicity during May 2012 maintained a moderate to moderately-high level and was associated with discrete low-frequency earthquakes and low-level, sporadic volcanic tremor in the background occurring during 1-9 May. Daily low frequency totals ranged between 880 and 970. The steady increase in RSAM observed in April continued until about 16 May, and fluctuated in an upward trend thereafter. The fluctuations reflected phases or episodes of low and moderate activity. The highest RSAM of 500 was reached on the 30th. After 30 May RSAM declined again to reach 350 by the end of May. Around this time tremor became dominant and overshadowed the discrete events, making it difficult to conduct event counts. The electronic tiltmeter (located 4 km SW) continued to show gentle uptilt towards the summit.

RVO reported low to moderate activity during 1-15 June 2012. Emissions consisted of gray and sometimes black ash clouds that rose from the crater on most days. Plumes drifted SE on 2 June and NW during 6-15 June. Ash fell in areas downwind between Yassa (WSW) and Baliau (NNW), and Warisi (ESE). Incandescent material was also ejected from the crater.

Pyroclastic flows on 16 June 2012 (at 0700, 0725, 0727, and 0729) all channelled into the SE valley. The last pyroclastic flow was perhaps the largest. It reached the lowest elevation, 300-400 m above sea level, but came to rest far from populated areas. Ash plumes from the pyroclastic flows rose ~1,000 m and drifted WSW and WNW. Small amounts of ash fell in villages between Dugulava (on the SW side of the island) and Yassa. Fine ash also fell in downwind areas on the mainland, including the Bogia government station (25 km SSW, on the mainland). Emissions from Main Crater were milder and mostly characterized by white and bluish plumes. Light gray plumes were noted during 2 and 8-9 June.

Ash fell in the NW part of the island. Weaker emissions occurred on 17 June, mostly consisting of steam with occasional ash. During 18-30 June gray and occasionally black ash clouds rose 100-150 m above the crater and drifted mainly NW. Incandescent tephra was ejected from the crater on most nights. Activity during 28-29 June was almost sub-Plinian. Emissions from Main Crater were milder and mostly characterized by white and bluish plumes. Gray ash plumes were emitted during 18, 23, 26-27, and 29 June. Incandescence from the crater was visible during 18, 20-22, and 24 June. Ash again fell in the NW part of the island. Seismic recording ceased during 12-27 June 2012 due to equipment failure at Bogia apparently caused by a lightning strike. During the period of data recording, seismicity remained at moderate to moderately high level, dominated by sub-continuous to continuous volcanic tremor. RSAM fluctuated between 250 and 550. High peaks in the RSAM between 4 and 10 June were associated with moderate to strong phases of eruptive activity described above. The electronic tiltmeter was generally stable during reporting period, but the long term trend showed slow inflation towards the summit area. When seismic recording resumed on 28 June 2012, the level of seismicity had risen slightly: RSAM 400-600. The high RSAM values corresponded to some of the moderate summit activity reported above. Seismicity was dominated by sub-continuous to continuous volcanic tremor. Around this time, the electronic tiltmeter remained out of service.

During the first half of June RVO recommended authorities declare a Stage 2 alert level. The level remained at Stage 2 for the remainder of June 2012. In their next available report, RVO noted that activity increased slightly during 15-31 July, except during 18-20 July when ash emissions decreased. During most of the reporting period, when visibility was clear, gray-to-sometimes-black ash plumes were observed rising 300-700 m above the crater discharging from two vents. The plumes mainly drifted NW, mainly affecting villages between Yassa and Kuluguma. Rumbling was heard on 25 July from Bogia. Bright glow visible at night was attributed to ejected incandescent tephra. Sub-Plinian activity occurred on most nights during 21-31 July. Small lava flows descended the SW flank.

Four pyroclastic flows traveled down the SE flank on 30 July (at 0638, 0640, during 1200-1300, and at 1428). The first event was the largest, and generated an ash plume that rose 1.8 km above the crater and drifted NW. As before, all four flows were again channeled into the SE valley. Emissions from Main Crater were milder and mostly characterized by white and bluish plumes, and occasional gray ash plumes. The Alert Level remained at Stage 2. Seismicity fluctuated, and was very high during 16-17 July 2012, dominated by sub-continuous to continuous volcanic tremors. RSAM ranged between 500 and 700. It declined thereafter to 150-300 units between 18 and 20 July before increasing again rapidly to 700 on the 21st. The reduced seismicity between 18 and 20 coincided with the reduced summit activity. Seismicity remained at a very high level (700 RSAM units) for the next few days before declining again to another low (300 RSAM units) on 26 July. There was one more phase of high activity (700 RSAM units) between 28 - 30 July, before RSAM became steady at 450 until the end of the month. The electronic tiltmeter remained out of service.

2013 activity. RVO reported that dark gray ash plumes were occasionally emitted from Manam's Southern Crater during 8-12 January. At about 1000 on 12 January a sub-Plinian eruption generated ash plumes that rose 1.4-1.5 km above the crater; activity peaked between 1200 and 1300. The ash plumes drifted SW, S, and SE, producing ashfall on the island in areas downwind and light ashfall in Bogia (23 km SSW). Activity decreased after 1600, and ash plumes rose only 500 m above the crater. At night ejected incandescent material was observed. Ejected material and ashfall was deposited in the SE and SW valleys. Ash plumes drifted S during 13-14 January. White vapor plumes rose from Main Crater during the reporting period. Based on observations of satellite imagery and wind data analyses, the Darwin VAAC reported that an ash plume rose to an altitude of 3 km a.s.l. on 28 January and drifted 22 km E. The next day an ash plume drifted 93 km NE, and then later another ash plume drifted 55 km NE at an altitude of 4.3 km a.s.l.

Seismicity was low on 8 January with RSAM value was 80. But beginning on 9 January it started to gradually increase, reaching a moderate level early on the 11th. RSAM had by then reached 200. Seismicity continued to increase, as RSAM reached 550 between 1000 and 1100, which coincided with the commencement of the small sub-Plinian eruption reported above. RSAM reached a peak of 620 at about 2300 on 12 January before it subsided to about 320 at 0500 on 13 January. RSAM fluctuated between 230 and 600 until the end of the reporting period. Seismicity was characterized by frequent small low frequency earthquakes during low to moderate seismicity and by sub-continuous to continuous volcanic tremors during high seismicity. Data from the electronic tiltmeter did not show any significant changes.

Based on observations of satellite imagery and wind data analyses, the Darwin VAAC reported that an ash plume rose to an altitude of 10.1 km a.s.l. on 12 February and drifted 55 km SW. On 16 February an ash plume rose to an altitude of 3.4 km a.s.l. and drifted over 35 km NW.

RVO reported that on 1 March Main and Southern Craters emitted small amounts of diffuse white vapor; the craters were either partially or totally obscured by meteorological cloud cover. On 4 and 7 March intermittent gray ash plumes rose 300 m, above the cloud cover. RSAM values remained at a near-background level of 120. A gradual increase began on 2 March, reaching a peak of about 350 on 6 March before declining again to 300 on 7 March. The increase in RSAM on the 6 March was attributed to a increase in the number and size of low frequency earthquakes and occasional sub-continuous volcanic tremors. Ground deformation data from the electronic tiltmeter fluctuated within a steady trend.

Based on analysis of satellite images, pilot observations, and wind data analyses, the VAAC reported that on 14 March an ash plume rose to altitudes of 6.1-7.6 km a.s.l. and drifted 110-150 km ESE.

Based on analysis of satellite imagery (MT Sat) and wind data analyses, the Darwin VAAC reported that on 10-11 April an ash plume rose to altitudes of ~ 2 km and and drifted 75 km W. RVO reported that Manam's high level of activity continued on 15 April. Ash plumes rose 500 m above the crater. A loud explosion was heard at 0804. At about 1950 dense ash plumes rose 2 km and drifted SW. At night loud jet-like noises were reported by residents in Bogia. Lava was observed flowing from a new vent on the headwall of SW valley during a brief clear period from 1800 to 1850. Ash and scoria fell in most villages between Dugulava, on the SW side of the island, and Kuluguma on the NW side. Similar activity continued during the first half of 16 April, including a small pyroclastic flow that occurred around 1359 that was channeled into SE valley. Thereafter, the activity was characterized by gentle light gray ash emissions until 20 April.

During the high activity between 13 and 16 April, the formation of two new sub-terminal vents was reported. The exact timing is unclear due to occasional cloud cover around the summit area. The first vent probably formed on 13 April on the side of the headwall of SW valley. The vent was seen releasing lava effusively into SW valley. The second vent formed sometime during the evening of the 15 April E of Southern Crater in SE valley at an approximately similar elevation as those formed in mid 2012.

Seismicity, reflecting activity at the summit, was high on 15 April with RSAM readings fluctuating ~ 700. It declined slowly from 16 April and, as of the 18 April, it reached a moderate level with RSAM of 370, then declined again to 220. The down-tilt or deflation towards the summit area stopped around 15 April. Subsequently, information from the electronic tiltmeter was stable.

RVO reported that on 23 April dense white vapor plumes occasionally rose from Southern Crater. During 25-28 April ash clouds rose from the new sub-terminal vent E of Southern Crater inside the SE valley. The ash clouds rose 600 m and drifted NW. Loud booming noises were heard each day; however, between 0700 and 1900 on 27 April the noises became more frequent, louder, and explosive in nature, and were heard at Bogia. Seismicity remained high and swung around in the latter part of 25 April and increased steadily until it reached peak activity on the 28 April, before dropping slightly. Corresponding RSAM values increased from 220 on the 25 April, to 650 on the 28 April, and thereafter dropped to 500. Seismicity was characterized by small to moderate low frequency earthquakes.

Information from the electronic tiltmeter did not show any significant movements. RVO reported that during 29 April-16 May activity at Manam was low, characterized by white and occasionally blue vapor plumes rising from Southern Crater. White vapor plumes also rose from Main Crater. Seismicity fluctuated at high level between 29 April and 1 May; RSAM ranged between 500-700. After 1 May it started to decline, reaching a low level on 4 May and remaining low for the remainder of the reporting period. The corresponding RSAM at low level ranged between 50 and 100. RVO reminded people to stay away from the four main radial valleys, and especially the SE and SW ones, because most products from the activity at Southern Crater were channeled into these two valleys. No significant surface deformation was detected by the electronic tiltmeter.

Digital book in press. A new academic, digital book has sections that clearly relate to Manam (Johnson, 2013, in press). From the table of contents, those sections are (9) Tony Taylor and an Eruption Time Cluster: 1951-1966, Evacuation of Manam and the 1956-66 Eruptions and (14) Eruptions of the Early Twenty-first Century: 1998-2008. Manam, 2004-5: Abandoning a Volcanic Island?

Reference. Johnson, RW, (2013, in press), Fire Mountains of the Islands: A History of Volcanic Eruptions and Disaster Management in Papua New Guinea and the Solomon Islands, Australian National University E-press (ANU E Press (URL: http://epress.anu.edu.au/).

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

Information Contacts: Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC) (URL: http://www.bom.gov.au/info/vaac/).


Reventador (Ecuador) — June 2013 Citation iconCite this Report

Reventador

Ecuador

0.077°S, 77.656°W; summit elev. 3562 m

All times are local (unless otherwise noted)


Lava dome's summit rises above rim in late 2012

The last report on Reventador covered activity through 26 April 2012 (BGVN 37:03) and this one covers activity through April 2013.

In its Special Report of 9 November 2012, Ecuador's Instituto Geofísico-Escuela Politécnica Nacional (IG) summarized the new phase of activity that began in February 2012. The Special Report noted that lava flows traveled as far as 2 km from the crater down the N and S flanks. Later reports noted that in November-December 2012, lava flows reached 1.3 km in length; in January 2013 they reached up to 1.1 km in length. During this reporting interval, ash plumes rose as high as 5.2 km altitude both in August 2012 and November 2013.

The lava dome in the interior of the crater continued to grow and between November 2012 and January 2013 established a new summit that reached to at least 100 m above the E rim, having completely filled the crater developed in November 2002. This enabled blocks from the lava dome to roll down the flanks.

Table 6. A non-comprehensive synthesis of Reventador's steam and ash plumes generated during the reporting period. Courtesy of IG and the Washington VAAC.

Date Plume altitude OR height above (3.5 km a.s.l.) rim / direction / distance Comments
11 Aug 2012 Ash plume rising to 5.2 km trended W --
20 Sep 2012 Ash plume drifted 22 km SW --
17-18 Oct 2012 Steam and gas plume rose to 1 km and trended W --
3-4 Nov 2012 Steam and ash plume rose to 3 km above the crater. --
5 Nov 2012 Steam and ash plume rose to 3 km; ash plume rose to 2 km and drifted NW --
13 Nov 2012 Gas and ash plume rose to 5.2 km and drifted SE --
16 Nov 2012 Ash plume rose to 4 km above the rim and drifted W and NW Ashfall reported between Reventador and El Chaco (35 km SSW)
22 January 2013 Gas and steam plume rose 1.5 km above the crater; white-to-light grey plumes rose 2 km and drifted W --
24 January 2013 Steam and ash plume rose 2 km --
29 January 2013 Gas plumes rose as high as 1 km and drifted NW and W --
29 January 2013 Overflight revealed steam and ash plume rising to 1.5 km above the lava dome; --
4 February 2013 Ash plume rose to 4 km and drifted NW --
7 February 2013 Ash plume rose to 3 km and drifted S --
2 March 2013 Ash plume rose to 4 km and drifted SW --
8 March 2013 Steam emission rose to 500 above the crater Glow reported
12 March 2013 Emission rose to 2 km and drifted W --
13 March 2013 Ash plumes rose to 3 km --
16 March 2013 Ash plume rose to 1 km and drifted W --
31 March 2013 Steam emission rose to 500 above the crater and trended W --
8 April 2013 Emissions reached to 3 km above the crater --
12 April 2013 Steam emissions reached to 2 km --

Between late April and early August 2012, activity at Reventador remained moderate, and although cloud cover often obscured visual observations, there were occasional reports of steam emissions rising to as high as 1 km above the crater. Long-period (LP) earthquakes occurred with moderate-to-high intensity, a behavior interpreted as the movement of fluids at depths. Seismic signals attributed to rock fall were also prominent, inferred to come from lava flows that descended the N flank, as aerial observers witnessed on both 29 May and 4 June.

Based on analysis of satellite imagery, the Washington Volcanic Ash Advisory Center (VAAC) reported that on 12 August they detected a well-defined thermal anomaly. Thermal images obtained in overflights carried out on 17 and 18 October 2012 revealed a lava flow that descended the flank of the cone and verified that another flow had descended during the preceding days or weeks and at the moment of observation was still warm. The flows did not exceed 1 km in length, and in light of their location within the crater, were not a danger to the public (figure 39).

Figure (see Caption) Figure 39. A) On the left photo, the S flank of Reventador seen on 19 October 2012. A lava flow descending on the upper flank covered much of the flows from previous days and weeks. At right is a corresponding thermal image, permitting definition of the extent of the new hotter flows. Photo and image, courtesy of P. Ramon (Instituto Geofisico).

On 17 and 18 October, IG also verified the presence of a previously known lava dome within the crater, with steep slopes, the top of which was then the highest point of the volcano. Similar observations were carried out on 19 October by IGEPN technicians maintaining the monitoring network, who also stressed the continuous flow of lava blocks spilling off both the fronts of new flows and from the lava dome.

During 31 October-11 December 2012, the IG reported that although cloud cover often prevented visual observations, ash plumes were often seen.

Seismicity increased during this time period. Around 5 November, the seismic network detected an increase in the magnitude of volcanic tremor. IG reported that seismicity indicated falling rock and explosions during 14-15 November. Beginning 16 November IG's seismic network indicated a significant increase in tremor and in signals indicative of emissions and explosions. IG reported that scientists aboard an overflight on 23 November observed intense fumarolic activity and a new crater at the summit of the dome, which contained ash and large blocks. A thermal camera measured temperatures at the dome of ~ 300°C. Lava flows continued to be active on the dome flanks, and elongated block-and-ash deposits were also visible on the flanks. IG reported high seismicity during 5-11 December 2012, indicating multiple explosions almost daily. At least one lava flow was generated between November - December 2012 that descended the N flank to ~1.3 km in length.

2013. Throughout this January-April 2013 reporting period, cloud cover often prevented visual surface observations. The lava dome grew between November 2012 through January 2013 to at least 100 m above the E rim, completely filling the crater generated by the eruption of November 2002. Between November 2002 and 31 January 2013, ~ 20 lava flows had traveled down the N, SE, and S flanks, and affected zones within the caldera.

IG reported moderate seismicity during 16-21 January 2013. During the morning of 22 January seismicity, including tremor, increased significantly, signals indicating that rock falls were detected. Low frequency, high-energy tremor was detected by seismic stations around the volcano with an average of 20 seismic events and an average of 29 explosions. Explosions were heard. Lava flows traveled down the SW and N flanks. Observers reported lava fountains in the crater and lava flows on the flanks, both of which became more intense at 1800. Explosions produced white-to-light-gray plumes that rose 2 km and drifted W (figure 40).

Figure (see Caption) Figure 40. Emission column seen late in the day on 22 January 2013 associated with the explosive activity at Reventador. Courtesy Walter Garcia Synohidro and Instituto Geofisico.

During the night of 22 January a lava flow descending the SE flank had reached a width of 350 m and extended at least 1.1 km (figure 41). Other smaller lava flows up to 200 m long were observed on the N and S flanks.

Figure (see Caption) Figure 41. Thermal image of Reventador on 22 January 2013 shows the dome from which a lava flow descends to the SE. Courtesy S. Vallejo, Instituto Geofisico (IG-EPN).

During 23 January-7 February 2013 seismicity remained high. Lava flows were visible at night. Crater incandescence was observed at night during 29-30 January.

IG reported that seismicity became more moderate during 8-12 February; explosions were detected daily. Ashfall was reported in areas near the volcano on 9 February. Between 16-20 February, activity remained moderate, with continued ash emissions, but an absence of reported ashfall. For the remainder of February 2013, no reports of surface activity were received, and seismic signals ceased transmission.

According to the Washington VAAC, the IG reported that on 2 March lava flows were observed. IG reported that the seismic network recorded multiple explosions during 13-17 March. Observers reported falling and rolling incandescent material on Reventador's S flanks on 12 March. On 15 and 17 March explosions were detected by the seismic network. IG characterized activity as being at a moderate level for most of the remainder of March.

IG noted that moderate activity continued into April 2013 (table 6). Through 12 April seismicity remained moderate. On 15 April IG reported an increase in the number of seismic events. Seismic and surface activity remained moderate to high through 24 April, but became more moderate thereafter and remained so for the remainder of April 2013.

Geologic Background. Volcán El Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic stratovolcano has 4-km-wide avalanche scarp open to the E formed by edifice collapse. A young, unvegetated, cone rises from the amphitheater floor to a height comparable to the rim. It has been the source of numerous lava flows as well as explosive eruptions visible from Quito, about 90 km ESE. Frequent lahars in this region of heavy rainfall have left extensive deposits on the scarp slope. The largest recorded eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Information Contacts: Instituto Geofísico-Escuela Politécnica Nacional (IG), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); and Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/).


Nevado del Tolima (Colombia) — June 2013 Citation iconCite this Report

Nevado del Tolima

Colombia

4.658°N, 75.33°W; summit elev. 5215 m

All times are local (unless otherwise noted)


Non-eruptive during 2005-2012; hazard assessment and glacial retreat

During 2005-2012, Nevado del Tolima was non-eruptive and the Alert Level remained at IV (Green; "volcanically active with stable behavior") due to minimal seismicity and deformation. The Servicio Geológico Colombiano (SGC) monitored Tolima with a seismic network, tilt measurements, and regular field observations. The greatest changes at Tolima during this time period were related to the summit glacier that generated significant seismicity and surface activity. Volcano-tectonic (VT) and long-period (LP) earthquakes were also detected with the monitoring network, although these events were frequently too small to locate.

In this report, we also highlight geological hazards investigations by Thouret and others (1995); among the hazards, runout distances for lahars were determined as well as potential ash distribution areas. Further, we include the results of long-term studies focused on the summit glacier (figure 2); investigators noted significant retreat based on aerial photos and later, with Landsat image analysis.

Figure (see Caption) Figure 2. A) A view toward the S flank of the glacier-clad summit of Tolima taken on 18 February 2010. Fresh snowfall highlights the morphology that includes lava flows and debris fans. B) A view of the N flank taken on 22 January 2010. The extent of the glacier appears in bright contrast to the yellow-gray and red colors of the altered summit rock. Courtesy of SGC.

Seismicity during March 2006 - December 2012. Based on volcano-tectonic (VT) and long-period (LP) earthquake counts, the SGC reported that low-level seismicity persisted during this reporting period (table 1). The occurrence of earthquakes was highest during 2006 when 22-90 VT and 5-20 LP events per month were recorded. From 2007 through 2012, VT and LP events occurred at a lower rate (0-73 VT per month and 0-17 LP per month).

Table 1. Monthly seismicity at Nevado del Tolima was tabulated by the occurrence of events: volcano-tectonic (VT), long-period (LP), Glacier & Rockfall, Unclassified, and Largest Earthquake magnitude. Events considered "Unclassified" are attributed to icequakes or rockfalls that do not fulfill the amplitude or duration parameters in order to be included in the SGC database. Note that these values have been corrected by the SGC database and differ from "Technical Bulletin" reports. Courtesy of SGC.

Month VT LP Glacier & Rockfall Unclassified Largest EQ
Mar 2006 48 17 1717 3295 1.58
Apr 2006 22 20 1150 2572 0.64
May 2006 35 17 1460 2331 0.95
Jun 2006 43 8 675 1551 1.08
Jul 2006 39 8 340 729 1.14
Aug 2006 26 9 352 927 0.81
Sep 2006 31 5 565 1254 1.01
Oct 2006 81 7 904 1639 1.35
Nov 2006 77 8 644 1735 1.53
Dec 2006 90 9 632 2221 1.45
Jan 2007 0 12 1218 2615 1.72
Feb 2007 4 0 979 3825 1.65
Mar 2007 7 1 1345 6513 0.64
Apr 2007 1 1 1171 5939 1.01
May 2007 21 0 1544 4129 1.02
Jun 2007 5 0 615 2107 0.64
Jul 2007 2 2 746 2165 1.14
Aug 2007 6 0 524 1692 2.27
Sep 2007 5 1 522 1472 0.7
Oct 2007 4 1 472 1115 1.96
Nov 2007 3 2 270 966 0.86
Dec 2007 7 0 434 1080 1.73
Jan 2008 3 0 318 968 0.55
Feb 2008 2 0 210 805 0.73
Mar 2008 1 0 275 1083 -0.4
Apr 2008 7 0 256 1453 1.62
May 2008 5 0 265 1931 2.63
Jun 2008 2 0 109 1207 0.88
Jul 2008 6 0 125 1148 1.4
Aug 2008 73 0 158 974 1.14
Sep 2008 12 0 118 864 1.02
Oct 2008 12 2 204 1157 0.81
Nov 2008 2 0 263 1515 0.35
Dec 2008 7 0 197 1242 0.45
Jan 2009 7 0 185 1490 0.64
Feb 2009 1 0 117 1017 0.45
Mar 2009 3 0 257 2272 0.88
Apr 2009 6 0 279 2245 1.3
May 2009 8 0 275 2360 0.73
Jun 2009 1 0 212 1846 0.88
Jul 2009 10 0 100 1127 0.95
Aug 2009 3 0 146 1881 2.2
Sep 2009 8 0 127 1867 0.64
Oct 2009 1 0 176 2757 0.23
Nov 2009 0 0 329 1994 0
Dec 2009 1 0 414 2055 -0.21
Jan 2010 4 0 678 1703 0.35
Feb 2010 0 1 637 1551 0.75
Mar 2010 6 1 698 1638 1.08
Apr 2010 0 1 878 1344 0.43
May 2010 1 2 742 1746 1.4
Jun 2010 0 1 491 1307 0.91
Jul 2010 0 1 505 1173 1.46
Aug 2010 0 0 329 1337 0
Sep 2010 0 1 425 860 0.7
Oct 2010 0 1 204 434 0.1
Nov 2010 5 2 314 1286 0.73
Dec 2010 2 2 256 1075 1.3
Jan 2011 0 0 197 1002 0
Feb 2011 3 2 393 1805 0.81
Mar 2011 1 3 978 443 1.45
Apr 2011 0 1 1370 1043 0.91
May 2011 1 4 1114 659 0.96
Jun 2011 2 1 692 252 1.02
Jul 2011 7 0 709 246 1.58
Aug 2011 0 1 897 216 0.81
Sep 2011 0 5 1404 388 1.22
Oct 2011 1 0 1665 427 0.88
Nov 2011 2 2 1890 601 0.73
Dec 2011 3 2 1923 927 0.96
Jan 2012 2 0 2033 740 0.55
Feb 2012 2 0 1471 159 0.81
Mar 2012 4 15 1348 95 0.75
Apr 2012 9 17 1379 310 1.65
May 2012 30 6 1740 417 1.58
Jun 2012 2 0 1290 372 1.02
Jul 2012 3 2 888 519 0.88
Aug 2012 0 0 792 988 0
Sep 2012 27 0 1077 847 1.45
Oct 2012 3 4 1920 1359 0.64
Nov 2012 2 4 1332 1289 1.08
Dec 2012 12 1 1873 na 1.2

Seismic signals attributed to glacial changes ("icequakes") and rockfalls dominated the records during 2006-2012. Frequently, more than 1,000 events were recorded per month. During 2008-2010, such events were slightly less frequent; an average of 313 earthquakes occurred per month. Coincidentally, LP events were significantly less frequent during that time period as well (less than one event per month). From March 2006 to July 2007, rockfall signals were attributed to surface activity mainly occurring on the N flank and related to small avalanches of ice and rock. The SGC noted that the general summit area was the source of shallow seismicity from mid 2010 through 2012.

Because of sparse activity and low-magnitude events, hypocentral depths of VT earthquakes were rarely calculated during 2006-2012 (table 2). Five earthquakes were located in September 2012, the most to be located in a single month. Three of these earthquakes were located > 5 km of the summit (NW and SE), while 2 were within 1 km (figure 3). That month, seismicity was relatively high compared with previous months; the SGC reported 27 VT earthquakes and 1,077 "Glacier & Rockfall" signals.

Table 2. The number of located VT earthquakes from Tolima during 2011-2012. Located earthquake information was not available for 2006-2010. Courtesy of SGC.

Date Earthquakes Depths (km) Location from Summit
Mar 2011 1 2 ~1 km, N
Jul 2012 1 4 ~6 km, NW
Sep 2012 5 3 & 4  --
Oct 2012 2 ~3.5  --
Figure (see Caption) Figure 3. This map shows five located VT earthquakes in the region of Tolima during September 2012. Red and yellow circles indicate hypocenters and epicenters (colors relate to depths; circle size relates to event magnitude); black squares mark the locations of two seismic stations (ESME and NIDO); the summits of Nevado del Tolima and Nevado del Quindío (~10 km NW) are labeled and marked with green stars; approximate locations of towns are indicated by blue text. Courtesy of SGC.

Surface deformation monitoring. An electronic tilt station was installed in 2011 and, by May 2011, data from the Esmeralda station (~2 km W) was being relayed to the SGC Manizales observatory (figure 4). Through the rest of 2011 and 2012, tilt data suggested the effects of local temperatures and fluctuations were within the expected range of the instrument. Changes of 70-95 and 75-100 μrad from the N and E components, respectively, were recorded on a monthly basis. During August-December 2012, fluctuations in tilt were associated with changes in the summit glacier's mass as well as variability due to local temperature changes.

Figure (see Caption) Figure 4. Tilt data from Nevado del Tolima was recorded from the Esmeralda (ESME) station during May 2011 through December 2012. Primary fluctuations in this data were caused by local temperature variations and changes in glacial mass; a data gap occurred during August-October 2012 due to network problems. Courtesy of SGC.

Hazard assessment. Geologic mapping and a hazards analysis were conducted by Thouret and others (1995) (figure 5). They emphasized that they relied on the same appraisal methods as applied by Parra and others (1986) for Nevado del Ruiz. Three scenarios were developed based on three known events of different magnitudes (VEI 3, VEI 3-4, and VEI 4-5); the two plots within the lower left-hand inset map of figure 6 show the major characteristics of those scenarios.

Figure (see Caption) Figure 5. Stratigraphic, volcanic, and geomorphic map of Nevado del Tolima. Town locations are marked with yellow circles. Abbreviations of labeled faults within the blue-outlined inset map refer to the following: P.F.=Palestina Fault; O.-T.-F.=Otun-Pereira Fault; T.F.=Toche Fault; R.-T.F.=Recio-Tolima Fault. Modified from Thouret and others, 1995.
Figure (see Caption) Figure 6. This hazard map for Nevado del Tolima also includes Cerro Machín (located ~20 km SSW). Based on the work by Thourest and others (1995), the small circles drawn around Nevado del Tolima and Cerro Machín encompass areas likely to be affected by subplinian ballistic ejecta, whereas larger circles encompass areas likely to be seriously affected by plinian tephra-fall. Modified from Thouret and others, 1995.

Parameters for possible pyroclastic surges and ash-cloud surges were assessed for major valleys in the region, particularly Río Combeima, Río Totare and Río San Romualdo valleys, and the headwaters of Río Toche valleys (figure 6).

Rock or debris avalanches and lahars were also considered in the study; the authors stated that such events could be triggered by an earthquake or intrusion, and mobilized material had the likelihood of channelization within the deep Río Combeima gorge, a dangerous scenario due to the connectivity of the drainages that influence areas as distant as Ibague and Río Coello. Recent debris-flow deposits from volcanic and glacial sources dominated the aerial extent of the mapped region, particularly along the N slopes and within channels.

Thouret and others (1995) determined that lava flows would be the least hazardous phenomenon likely to occur; "extrusive activity [at Tolima] has been short-lived and is likely to produce block-lava flows such as those of young-Tolima age. Highly viscous and slow-moving block-lava flows could reach only 5-6 km when channeled, and likely move to the southeast or south. However, the very steep south flank would enable lava flows to travel more than 6 km if the chemical composition, physical properties, and hence viscosity of erupted magma changed."

Tolima glacial retreat. While hazards due to glacial ice interactions and volcanism were noted by some investigators (Thouret and others, 1995), other investigations of glaciers were conducted in this region due to interests in global climate change. An assessment conducted in 1976 concluded that five snowcapped volcanoes were present within the Parque Nacional de los Nevados: Tolima, Nevado del Ruiz (~25 km N of Tolima), Santa Isabel (~18 km NNW of Tolima), El Cisne (~20 km N of Tolima), and El Quindío (~10 km W of Tolima) (Hoyos-Patiño, 1998). According to Hoyos-Patiño (1998), El Cisne and El Quindío had almost lost their ice caps by 1976, maintaining less than 1 km2 of ephemeral snow- and ice-covered areas.

Glaciers and snowfields mapped by Landsat images of Tolima's summit in 1976 calculated a total area of 3.8 km2; aerial photo analysis from 1978 determined that 11 glaciers were present with a total area of 2.22 km2. Based on 2001 Landsat 7 image analysis by Morris and others (2006), the area of glacial extent was 1.26 km2; they calculated a loss of 43% from 1959 to 2001 (figure 7). For comparison, the largest ice loss from this region of Colombia occurred at Nevado del Ruiz, where ice coverage decreased from 21.4 km2 to 10.92 km2 during 1959-2001.

Figure (see Caption) Figure 7. Glacier and generalized drainages of Tolima as drawn from 1959 aerial photography. Area 1 represents the total icecap area of 7 km2 as determined in 1959. Area 2 was thin ice that deglaciated between 1959 and 1987. Area 3 was glaciated during the Little Ice Age. Area 4 was Holocene and uppermost Pleistocene tephra incised by snowmelt-fed, narrow, deep gullies. Area 5 represents the prehistorical scar, mounds, and deposits resulting from a rockslide-debris avalanche off the NE flank. Area 6 includes young and deeply carved deposits from debris flows and tephra-laden ice-and-snow avalanches near the crater and on the SW flank. Area 7 includes high, steep, eroded intrusions, necks, and lava flows, from the pre-existing summit. From Thouret and others, 1995.

References. Hoyos-Patiño, F., 1998: Glaciers of Colombia, p. I:11-30, in R. S. Williams and J. G. Ferrigno, eds: Satellite Image Atlas of Glaciers of the World: South America, U.S. Geological Survey Prof. Paper 1386-1, 1206 pp.

Morris, J.N., Poole, A.J., and Klein, A.G., 2006, Retreat of Tropical Glaciers in Colombia and Venezuela from 1984 to 2004 as Measured from ASTER and Landsat Images, 63rd Eastern Snow Conference, Newark, Delaware.

Thouret, J.C., Cantagrel, J-M., Robin, C., Murcia, A., Salinas, R., and Cepeda, H., 1995, Quaternary eruptive history and hazard-zone model at Nevado del Tolima and Cerro Machín volcanoes, Colombia. Journal of Volcanology Geothermal Research, 66 (1-4):397-426.

Geologic Background. The steep-sided, glacier-covered Nevado del Tolima volcano contrasts with the broad profile of Nevado del Ruiz to the north. The andesitic-dacitic younger Tolima formed during the past 40,000 years, rising above and largely obscuring a 3-km-wide late-Pleistocene caldera. The summit consists of a cluster of late-Pleistocene to Holocene lava domes associated with thick block-lava flows on the N and E flanks, and extensive pyroclastic-flow deposits. The summit contains a funnel-shaped crater 200-300 m deep. Holocene activity has included explosive eruptions ranging in size from moderate to Plinian, and the last major eruption took place about 3,600 years ago. Lava dome growth has produced block-and-ash flows that traveled primarily to the NE and SE. Minor explosive eruptions have been recorded in the 19th and 20th centuries.

Information Contacts: María Luisa Monsalve, Gloria Patricia Cortés, and Lina Constanza García, Servicio Geológico Colombiano (SGC), Volcanological and Seismological Observatory, Avenida 12 Octubre 15-47, Manizales, Colombia (URL: https://www2.sgc.gov.co/volcanes/index.html).

Atmospheric Effects

The enormous aerosol cloud from the March-April 1982 eruption of Mexico's El Chichón persisted for years in the stratosphere, and led to the Atmospheric Effects section becoming a regular feature of the Bulletin. Descriptions of the initial dispersal of major eruption clouds remain with the individual eruption reports, but observations of long-term stratospheric aerosol loading will be found in this section.

Atmospheric Effects (1980-1989)  Atmospheric Effects (1995-2001)

Special Announcements

Special announcements of various kinds and obituaries.

Special Announcements  Obituaries

Misc Reports

Reports are sometimes published that are not related to a Holocene volcano. These might include observations of a Pleistocene volcano, earthquake swarms, or floating pumice. Reports are also sometimes published in which the source of the activity is unknown or the report is determined to be false. All of these types of additional reports are listed below by subject.

Additional Reports  False Reports