Semisopochnoi is the largest subaerial volcano in the western Aleutians. It is 20-km-wide at sea level and contains an 8-km wide caldera. The three-peaked Mount Cerberus was constructed within the caldera during the Holocene. Each of these peaks contains a summit crater; the lava flows on the N flank appear younger than those on the S side. The current eruption period began in early February 2021 and has recently consisted of numerous weak ash explosions, ash plumes, ashfall, elevated surface temperatures, and sulfur dioxide emissions (BGVN 47:06). This report covers activity during June through November 2022 using daily, weekly, and special reports from the Alaska Volcano Observatory (AVO) and satellite data. AVO monitors the volcano using local seismic and infrasound sensors, satellite data, web cameras, and remote infrasound and lightning networks.

AVO reported low-level activity during June that consisted of elevated seismicity with intermittent tremor and explosions, and frequent gas-and-steam emissions that mostly consisted of sulfur dioxide, that rose above the N crater of Cerberus; weather clouds often obscured satellite and webcam views. Minor ash emissions were visible in webcam images rising to low heights during 6-9 and 11-12 June and extended as far as 40 km from the vent. Similar low-level activity during July prompted AVO to reduce the Aviation Color Code (ACC) and Volcano Alert Level (VAL) to Yellow and Advisory, respectively on 7 July. Low levels of seismicity and elevated surface temperatures were reported. Satellite and webcam images were mostly obscured due to weather clouds, though gas-and-steam emissions were visible from the active crater during 6-7 and 12-14 July.

During August, seismicity consisted of occasional small earthquakes and seismic tremor. Elevated surface temperatures were also recorded. Webcam images, when not obscured by weather clouds, showed gas-and-steam emissions rising from the N crater of Mount Cerberus. A short-lived explosion was detected at 1347 on 21 August, based on observations from local webcams. A low-level ash cloud was observed in webcam data and recorded in seismic and infrasound data that rose no higher than 6 km altitude; specific altitudes were not determined due to weather clouds (figure 23). As a result, the ACC and VAL were raised to Orange and Watch, respectively. Gas-and-steam emissions possibly containing minor amounts of ash were observed in clear satellite images after the explosion.

Figure 23. Photo of a dense ash plume rising above the N active crater at Mount Cerberus at Semisopochnoi nine minutes after the start of an eruption event on 21 August 2022. Photo by Matt Loewen, courtesy of AVO.

Gas-and-steam emissions, and seismicity including volcanic tremor, continued during September and October. Several small ash eruptions from the active crater were visible in webcam images and detected in seismic and infrasound data during 2-3 September. During 13-15 September explosions generated ash emissions that rose no higher than 1.2 km altitude and drifted up to 8 km SE. Some local ashfall was observed in cloudy webcam images during 16-17 September. On 3 October an explosion was detected in infrasound data, though no accompanying ash emission was reported. Another small explosion was detected in geophysical data on 31 October.

The active crater continued to emit gas-and-steam emissions during November, and volcanic tremor and small earthquakes persisted, based on geophysical data, since weather clouds often obscured clear views. Small explosions were detected in geophysical data during 7 November; however, ash emissions were not visible in satellite or webcam images. After 7 November seismicity decreased and no explosive activity or ash emissions were observed.

Sentinel-2 satellite imagery showed occasional white gas-and-steam plumes rising above the crater, which sometimes contained ash (figure 24). The plumes drifted in different directions. A small thermal anomaly was detected in the crater on 6 October due to clear weather.

Figure 24. Sentinel-2 satellite imagery showed gas-and-steam plumes rising above the active N crater of Mount Cerberus at Semisopochnoi on 6 June 2022 (top left), 13 July 2022 (top right), and 13 November 2022 (bottom right). A weak thermal anomaly was visible in the active crater on 6 October 2022 (bottom left). Plumes drifted NW and S in these images. Images using “Natural color” (bands 4, 3, 2) and “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

Geologic Background. Semisopochnoi, the largest subaerial volcano of the western Aleutians, is 20 km wide at sea level and contains an 8-km-wide caldera. It formed as a result of collapse of a low-angle, dominantly basaltic volcano following the eruption of a large volume of dacitic pumice. The high point of the island is Anvil Peak, a double-peaked late-Pleistocene cone that forms much of the island's northern part. The three-peaked Mount Cerberus (renamed Mount Young in 2023) was constructed within the caldera during the Holocene. Each of the peaks contains a summit crater; lava flows on the N flank appear younger than those on the south side. Other post-caldera volcanoes include the symmetrical Sugarloaf Peak SSE of the caldera and Lakeshore Cone, a small cinder cone at the edge of Fenner Lake in the NE part of the caldera. Most documented eruptions have originated from Young, although Coats (1950) considered that both Sugarloaf and Lakeshore Cone could have been recently active.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667 USA (URL: https://avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA (URL: http://dggs.alaska.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Nevados de Chillán, located in the Chilean Central Andes, has had multiple recorded eruptions dating back to the seventeenth century. The current eruption began in January 2016 with a phreatic explosion and ash emissions from the new Nicanor crater on the E flank of Nuevo crater. Recently, activity has consisted of pyroclastic flows, gas-and-ash plumes, and a new lava dome (Dome 4) that was detected during early March 2022 (BGVN 47:06). This report updates information during June through October 2022 that describes continued explosions, ash plumes, pyroclastic flows, and thermal activity, based on information from Chile's Servicio Nacional de Geología y Minería (SERNAGEOMIN)-Observatorio Volcanológico de Los Andes del Sur (OVDAS) and satellite data.

During June through 17 October 2022 there was continuing eruptive activity in the Nicanor crater, which initially consisted of seismic events, sulfur dioxide emissions, and thermal anomalies (table 3). During August through mid-October, explosion events became more frequent and generated ash plumes that rose as high as 2.7 km above the crater. Explosions were also accompanied by pyroclastic flows that traveled no farther than 800 m down multiple flanks. Incandescent ejecta was visible above the crater rim in surveillance cameras, with some material falling back onto the proximal flanks.

Table 3. Summary of seismic events, maximum sulfur dioxide values, and number of thermal anomalies at Nevados de Chillán during June-October 2022. Data from SERNAGEOMIN bi-weekly reports.

Low thermal activity was occasionally detected by satellite data during July through October, as shown in the MIROVA (Middle InfraRed Observation of Volcanic Activity) Log Radiative Power graph (figure 99). There was a small cluster of thermal activity that occurred during mid-September through early October, which occurred around the same time as strong explosive eruptions. A single thermal hotspot was detected on 13 October according to the MODVOLC thermal algorithm. Some of this activity was also reflected in Sentinel-2 infrared satellite imagery as a small thermal hotspot in the active Nicanor crater (figure 100).

Figure 99. Occasional low-power thermal anomalies were detected at Nevados de Chillán during mid-July through early October 2022, according to this MIROVA graph (Log Radiative Power). No thermal activity was detected in June and three anomalies were detected during each month in July and August. There was a small cluster of thermal activity during mid-September through early October. Courtesy of MIROVA.

Figure 100. Sentinel-2 infrared satellite imagery of Nevados de Chillán showing a weak but persistent thermal anomaly at the active Nicanor crater on 19 July 2022 (top left), 11 August 2022 (top right), 5 September 2022 (bottom left), and 12 October 2022 (bottom right). Thermal activity was confined to the crater. Images use “Atmospheric penetration” rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Activity during June consisted of explosions that generated eruptive plumes with little to no pyroclastic content and crater incandescence that was visible up to 150 m above the crater; the highest plumes reached 940 m above the crater on 19 June. Seismicity was characterized by 56 volcano-tectonic (VT) events, 1,231 long-period (LP) events, and 472 tremor-type (TR) events. There were 320 LP-type events that were linked to surface-level explosions. Sulfur dioxide emission data was obtained by Differential Absorption Optical Spectroscopy (DOAS) equipment, which were installed on the SSE and ESE flanks of the active Nicanor crater. The average emission value ranged from 445 ± 95 to 453 ± 85 t/d, with a maximum daily value of 767 t/d recorded on 8 June. These sulfur dioxide levels are above base levels but are consistent with the presence of the new lava dome (Dome 4) that formed during early March 2022.

Explosive activity from the active crater continued during July and typically generated white gas-and-steam plumes less than 500 m high; due to weather clouds visibility was often obstructed. Seismicity included 67 VT-type events, 1,416 LP-type events, and 454 TR-type events. Of the 1,416 LP-type events, 212 were linked to surface-level explosions. On 13 July an explosion generated an avalanche mixed with deposits on the NE flank of the Nuevo crater that reached 470 m long. Ejecta traveled less than 200 m from the vent and were deposited on the E slope. On 29 July an eruptive episode produced a plume that rose 1,290 m above the crater. Explosions toward the end of the month also ejected a moderate amount of pyroclastic material less than 200 m from the vent onto the nearby flanks. DOAS data showed that the average sulfur dioxide emission value during the month ranged from 554 ± 29 to 601 ± 273 t/d. The maximum daily value was 1,056 t/d on 21 July.

During August, continuous explosions produced eruption plumes with little pyroclastic content that generally rose less than 500 m above the crater; on 2 and 20 August plumes exceeded 1 km above the crater. Intermittent night incandescence was visible to less than 50 m high and did not go beyond the crater rim. A total of 92 VT-type events, 1,382 LP-type events, and 532 TR-type events were detected throughout the month; of the LP-type events, 364 were linked to surface-level explosions. On 11 August surveillance cameras showed an extrusion of material inside the active crater, which SERNAGEOMIN reported was preceded by an increase in sulfur dioxide rates, plume heights associated with explosions, and increased explosion frequency. An explosion on 29 August generated a plume that rose 2 km above the crater and drifted S (figure 101). In addition, pyroclastic flows were reported, traveling less than 500 m on the E and NE flanks. The average sulfur dioxide emission value throughout the month ranged from 413 ± 69 to 507 ± 83 t/d, according to DOAS data. The maximum daily value was 1,017 t/d on 9 August. There was a slight decrease in sulfur dioxide emission rates toward the end of the month.

Figure 101. Photo of an ash plume that rose 2 km above the crater of Nevados de Chillán on 29 August 2022 and drifted S. The explosion was accompanied by pyroclastic flows that traveled less than 500 m on the E and NE flanks. Courtesy of SERNAGEOMIN (Reporte Especial de Actividad Volcanica (REAV) Region De Nuble, Complejo Volcanico Nevados de Chillan, 29 de agosto de 2022, 1108 Hora local (Chile continental)).

Three surveillance cameras continued to detect explosions and eruption plumes composed of mostly gas-and-steam that rose between 500-1,000 m above the crater during September. Seismicity consisted of 180 LP-type events, 1,200 LP-type events, and 332 TR-type events; of the LP-type events, 237 events were linked to surface-level explosions. On 12 September a strong explosion generated an eruption plume that rose 1.4 km above the crater. Toward the end of the month, the explosive events contained a higher volume of pyroclastic content, according to SERNAGEOMIN; ejecta was dispersed SE and block avalanches traveled as far as 500 from the crater rim. On 16, 19, and 30 September explosions produced plumes that carried a higher volume of pyroclastic material more than 360 m above the crater. Two explosions were reported on 19 September: the first rose 1.1 km above the crater and drifted SE (figure 102). A block avalanche occurred on the W flank that traveled 500 m from the crater rim. The second explosion produced an incandescent eruptive column that rose 1.7 km above the crater and drifted SE; ashfall was visible to the SE and ejecta was reported on the W flank. According to SERNAGEOMIN, these explosions also partially destroyed Dome 4. DOAS data recorded that sulfur dioxide emission rates during the month ranged from 315 ± 85 to 323 ± 76 t/d; the maximum daily value was 870 t/d on 12 September.

Figure 102. Photo of an ash plume rising 1.1 km above the crater of Nevados de Chillán that drifted SE on 19 September 2022. Courtesy of SERNAGEOMIN (Reporte Especial de Actividad Volcanica (REAV) Region De Nuble, Complejo Volcanico Nevados de Chillan, 19 de septiembre de 2022, 0813 Hora local (Chile continental)).

More frequent explosions and incandescent material were reported during early October, based on surveillance camera data. Six explosions generated plumes that rose more than 1 km above the crater and three exceeded 2 km. Seismicity has been characterized by 131 VT-type events, 710 LP-type events, and 122 TR-type events. There were 84 LP-type events that were linked to surface-level explosions. Explosions on 2 and 13 October were accompanied by 300-m-long pyroclastic flows and ejecta that traveled more than 500 m from the crater. A strong explosion on 9 October generated an eruption plume that rose 2.4 km above the crater and drifted NNW (figure 103); ashfall was reported in the same direction. In addition, pyroclastic flows were observed on the N, NNE, NE, and E flanks and traveled as far as 766 m. The flows mixed with snow on the volcano, which resulted in avalanche-type flows that moved 1.3 km down the N and NE flanks. Incandescent ejecta was visible at least as high as 800 m above the crater on 15 October. On 16 and 17 October there were three high-energy explosions; on 17 October the eruption column rose 2.7 km above the crater. During this explosion, pyroclastic flows were generated along the N, NW, W, NE, and E flanks and reached as far as 780 m on the NE flank. Some of these flows interacted with snow on the volcano and produced an avalanche-type flow that reached up to 2 km on the NE flank. DOAS measurements showed that the sulfur dioxide emission rates ranged from 47 ± 18 to 284 ± 83 t/d, with a maximum daily value of 911 t/d on 12 October. After the event on 17 October, there was an abrupt drop in surface activity with no eruptive columns or crater incandescence observed.

Figure 103. Photo of an ash plume rising 2.4 km above the crater of Nevados de Chillán that drifted NNW on 9 October 2022. Courtesy of SERNAGEOMIN (Reporte Especial de Actividad Volcanica (REAV) Region De Nuble, Complejo Volcanico Nevados de Chillan, 9 de octubre de 2022, 1930 Hora local (Chile continental)).

Geologic Background. The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The dominantly andesitic Cerro Blanco (Volcán Nevado) stratovolcano is located at the NW end of the massif. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The Volcán Nuevo lava-dome complex formed during 1906-1945 on the NW flank of Viejo. The Volcán Arrau dome complex was then constructed on the SE side of Volcán Nuevo between 1973 and 1986, and eventually exceeded its height. Smaller domes or cones are present in the 5-km valley between the two major edifices.

Information Contacts: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Observatorio Volcanológico de Los Andes del Sur (OVDAS), Avda Sta María No. 0104, Santiago, Chile (URL: http://www.sernageomin.cl/, https://twitter.com/Sernageomin); 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).

Klyuchevskoy is one of the most active stratovolcanoes in Russia’s northern Kamchatka Peninsula. After almost three months of inactivity, renewed eruptions in October 2020 included Strombolian activity, explosions, lava flows, and ash plumes (BGVN 45:09). Strong activity continued through January 2021, but then decreased in February, although lava flows, Strombolian activity, and gas-and steam emissions were still present through mid-March (BGVN 46:04). This report covers activity from April 2021 through December 2022, including a short eruption in November, and is based on information provided by the Kamchatkan Volcanic Eruption Response Team (KVERT) and satellite data. During this period, the volcano was inactive until November 2022 when a new eruption phase began.

On several occasions during the reporting period, high winds resuspended unconsolidated ash from the flanks to form plumes (table 18), prompting KVERT to raise the Aviation Color Code (ACC) to Orange (the second highest level on a four-color scale). Each time, the ACC was lowered to Green over the next one to three days, as conditions quieted. These events were not renewed volcanic activity.

Table 19. Dates reported by KVERT during September 2021-September 2022 when high winds resuspended loose ash on Klyuchevskoy’s flanks, prompting an Aviation Color Code increase.

On 17 November 2022 at 2330 local time, an explosive Strombolian eruption began, along with gas-and-steam plumes. A thermal anomaly had been detected starting on 13 November, and intensified when the Strombolian activity began. Lava fountaining at the summit was visible and a thermal anomaly over the summit was identified in satellite images during 17-20 and 24 November. The eruption persisted, and on 20 November (figure 74), KVERT raised the ACC to Yellow (the second lowest level). The eruption continued through at least 26 November and possibly until 5 December. On 1 December, possible ash plumes rose 150 m above the summit. KVERT began to characterize the activity as moderate on 6 December, and on the 22nd KVERT lowered the ACC to Green. On their volcano summary page KVERT listed the eruption dates as 16-26 November 2022.

Figure 74. Image of incandescence above the crater from renewed eruptive activity at Klyuchevskoy on 20 November 2022. Photo by Y. Demyanchuk, courtesy of KVERT.

The MIROVA thermal detection system recorded a few low-power thermal anomalies within 5 km of the summit, some of which included November 2022 eruption period. Sentinel-2 thermal data compiled by MIROVA also showed summit thermal anomalies during the November activity. The HIGP MODVOLC Thermal Alerts System recorded one weak anomaly on 20 November.

Geologic Background. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); 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/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

Chikurachki is the highest volcano on Paramushir Island in the northern Kuriles. It is a small cone constructed on a high Pleistocene edifice. Reported eruptions date back to 1690, with the most recent eruption period beginning in January 2022 that consisted of ash explosions, ash plumes, thin ash deposits on the flank, and thermal activity (BGVN 47:05). This report covers activity during May through October 2022 characterized by occasional explosions, ash plumes, and thermal anomalies. Information primarily comes from the Kamchatka Volcanic Eruptions Response Team (KVERT), the Tokyo Volcanic Ash Advisory Center (VAAC), and satellite information.

No activity was reported during May through the first half of June 2022. Sentinel-2 satellite imagery captured some dark brown to black ash deposits near the summit and flanks of the volcano on 5, 7, 10, 17, 22, 25, 27, and 30 May (figure 15). Possible gas-and-steam emissions containing some ash were visible on 22, 25, and 27 May.

Figure 15. Sentinel-2 satellite images showing brown-to-black ash deposits on the flanks of Chikurachki on 10 May 2022 (top left), 22 May 2022 (top right), 25 May 2022 (bottom left), and 27 May 2022 (bottom right). Brown plumes were visible in images captured on 22, 25, and 27 May and drifted SW, S, and E. Images use “Natural color” rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

A thermal anomaly was first identified in satellite imagery on 21 June. KVERT reported that an explosive eruption began around 0730 on 24 June; explosions were recorded during 0730-2100 (local time), which generated ash plumes that rose to 4.5 km altitude and drifted 45 km SE (figure 16). The large ash cloud was visible in satellite images at 0850 and drifted 25 km SE (figure 17). A VONA (Volcano Observatory Notice for Aviation) that was issued at 1445 on 25 June stated that only gas-and-steam emissions were rising from the volcano. The ash cloud from 24 June had drifted about 790 km SE by the next day. Another explosive eruption was reported on 30 June at 1230. The resulting ash plumes rose to 4.5 km altitude and drifted 300 km W and 50 km SSE. A thermal anomaly was also reported over the area on 30 June. Ongoing ash plumes rose to 3-4.6 km altitude and drifted E through 1 July, based on satellite data, according to the Tokyo VAAC. Activity declined by 1230 on 1 July. During 2-5 July only gas-and-steam emissions were visible, according to KVERT. Sentinel-2 satellite imagery captured gray plumes on 1, 4, and 11 July (figure 18). No further activity was reported for the remainder of the month.

Figure 16. Photo of a strong ash plume rising to 3 km altitude and drifting SE from Chikurachki at 0730 on 24 June 2022 (local time). Photo has been color corrected. Courtesy of D. Bobyrev, KVERT.

Figure 17. Sentinel-2 satellite image showing the strong brown ash plume drifting E from the explosive eruption at Chikurachki on 24 June 2022. Images use “Natural color” rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

Figure 18. Sentinel-2 satellite images showing strong gray plumes rising from Chikurachki on 1 July (left), 4 July (middle), and 11 July (right) 2022. The plumes drift SE, SE, and SW, respectively. Images use “Natural color” rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

The first half of August was similarly quiet; a single plume was visible on 5 August that drifted NW from the summit crater, based on a Sentinel-2 satellite image. Observers reported that on 22 August an ash emission rose to 2 km altitude and drifted E (figure 19). During 23-25 August occasional ash plumes rose as high as 2 km altitude and drifted as far as 20 km E and 8 km SE. A thermal anomaly was detected in satellite images on 25 August. On 26 August an ash plume drifted 94 km ESE. Activity during September declined and became relatively low again. According to the Tokyo VAAC, an ash plume that was identified in satellite images rose to 3.7 km altitude and drifted NE at 1730 on 2 September. A thermal anomaly was visible on 4 September. Gas-and-steam emissions continued to be detected at the summit crater.

Figure 19. Photo of ash emissions rising from Chikurachki and drifting E on 22 August 2022. Courtesy of S. Samoylenko, KVERT.

Gas-and-steam emissions persisted during October and two explosive eruptions were reported. An explosive eruption began around 0310 on 16 October. Satellite images showed a dense ash plume rose to 4.3-4.6 km altitude and drifted 240-344 km ESE (figure 20). A thermal anomaly was also visible in satellite data. At 1011 and 1620 that same day ash plumes rose as high as 3.5 km altitude and drifted ESE; by 1620 ash plumes had extended as far as 523-780 km (figure 21). Ongoing ash emissions rose to 4.3 km altitude on 17 October and drifted SE, according to the Tokyo VAAC. KVERT reported that ash emissions were last observed at 0130 on 17 October and a thermal anomaly was visible at 0432.

Figure 20. Satellite image showing a dense ash plume extending several hundred kilometers SE and E from Chikurachki on 15 October 2022 (UTC) due to a strong explosive eruption. Courtesy of FEC SRC Planeta, KVERT.

Figure 21. Photo of a strong ash plume rising above Chikurachki on 16 October 2022. Photo has been color corrected. Courtesy of D. Bobylev, KVERT.

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/); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Manam is a 10-km-wide island located 13 km off the northern coast of mainland Papua New Guinea. It consists of two active summit craters: the Main summit crater and the South summit crater, although activity is more frequently observed from the South summit crater. Frequent mild-to-moderate eruptions have been recorded since 1616. The current eruption period has been ongoing since June 2014 and has more recently been characterized by strong Strombolian explosions, ash plumes, and thermal activity (BGVN 47:08). This report covers activity during May through October 2022 using information primarily from the Darwin Volcanic Ash Advisory Center (VAAC), and various satellite data.

Intermittent ash plumes were reported by the Darwin VAAC throughout May. Continuous low-level ash plumes during 1-7 May rose to 1.8-2.7 km altitude and drifted SE, NW, ESE, and WNW, based on information from RVO, satellite images, and weather models. On 13 May an eruption was visible in satellite imagery that rose to 3.7 km altitude and drifted SW. A continuous ash plume was still visible in satellite imagery during 14-16 May at 2.4-3.7 km altitude and drifting SW and NE. During 17-19 May ash plumes rose to 2.4 km altitude and drifted NW and W, based on satellite images. Daily ash plumes were reported by the Darwin VAAC during 25-31 May that rose to 2.1-3 km altitude and drifted in different directions. An eruptive event at 0657 on 27 May generated an ash plume that rose to 2.4 km altitude, according to observations from RVO and webcam images.

Low activity was reported during June and July and mainly consisted of occasional ash plumes. During 1-3 and 5 June ash plumes rose to 2.4-3 km altitude and drifted NW, W, and SW, based on satellite and webcam images and information from RVO. On 14 July ash plumes rose to 2.1 km altitude and drifted NW. Activity during August through October was relatively quiet. On 29 October an ash plume rose to 1.5 km altitude and drifted NW; the plume dissipated within three hours.

Occasional sulfur dioxide plumes were detected using the TROPOMI instrument on the Sentinel-5P satellite, some of which exceeded at least two Dobson Units (DU) and drifted in different directions (figure 90). Intermittent low-to-moderate-power thermal anomalies were recorded during May through mid-September, as recorded by the MIROVA (Middle InfraRed Observation of Volcanic Activity) system (figure 91). Thermal activity was particularly strong during late May and early-to-mid-July. A single anomaly was detected during early October. A total of nine thermal hotspots were detected by the MODVOLC thermal alerts system on 23, 25, and 28 May, and 1, 13, 19, and 23 July. On clear weather days some of that stronger thermal activity was captured in Sentinel-2 infrared satellite imagery; the stronger hotspot was detected in the South summit crater, but occasionally, anomalies were visible in both the Main and South craters (figure 92). Distinct anomalies were detected in both the Main and South craters on 17 August, 6 September, and 1 October.

Figure 90. Small but distinct sulfur dioxide plumes rising from Manam were detected using data from the TROPOMI instrument on the Sentinel-5P satellite on 7 May 2022 (top left), 22 July 2022 (top right), 16 August 2022 (bottom left), and 25 October 2022 (bottom right). Plumes generally drifted in different directions, and the ones shown here exceeded 2 Dobson Units (DUs). Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

Figure 91. Intermittent low-to-moderate-power thermal anomalies were detected at Manam during May through September 2022, as shown in this MIROVA graph (Log Radiative Power). Anomalies were particularly strong during late May and early-to-mid-July. A single anomaly was detected during early October. Courtesy of MIROVA.

Figure 92. Sentinel-2 infrared satellite images show a persistent thermal anomaly (bright yellow-orange) dominantly at the South summit crater on 24 May 2022 (top left), 3 July 2022 (top right), 17 August 2022 (bottom left), and 6 September 2022 (bottom right). The hotspot was notably strong during 24 May and 3 July. The Main summit crater (the northern crater) also showed a hotspot on 17 August and 6 September. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

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), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea; 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/); 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).

Krakatau volcano in the Sunda Strait between Java and Sumatra, Indonesia, had a major caldera collapse around 535 CE; this event formed a 7-km-wide caldera ringed by the three islands of Verlaten, Lang, and Rakata. A new island grew that was then destroyed in the 1883 caldera-forming eruption. Anak Krakatau (Child of Krakatau), constructed beginning in late 1927 (BGVN 44:03, figure 56), was the site of over 40 smaller eruptions until 22 December 2018 when a large explosion destroyed most of the 338 m above sea level edifice and generated a deadly tsunami (BGVN 44:03). Intermittent ash-bearing explosions from the sea-level crater since May 2021 have contributed to the growth of a new pyroclastic cone to about 150 m elevation. The current eruption period began in May 2021 and has more recently consisted of explosions, gas-and-ash plumes, and thermal activity (BGVN 47:05). This report updates similar activity during May through October 2022 using information provided by the Indonesian Center for Volcanology and Geological Hazard Mitigation, referred to as Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), MAGMA Indonesia, the Darwin Volcanic Ash Advisory Center (VAAC), and several sources of satellite data.

Activity during May was relatively low and consisted of white gas-and-steam emissions that rose 25-200 m above the summit and drifted in different directions. On 2 May incandescent lava flows in and around the crater that advanced into the sea. According to the Darwin VAAC, continuous gas-and-ash emissions were reported during 5 and 8-20 May rising to 2.4 km altitude and drifting in various directions, based on satellite images and weather models. On 13 May satellite images showed a narrow ash plume that rose to 2.4 km altitude and drifted SE and E. A dense gas-and-steam plume with some amount of ash rose to 2.4 km altitude and drifted NE, N, NW, W, and WNW during 14-16 and 18-19 May.

White gas-and-steam emissions during June rose 25-400 m above the summit and drifted in various directions. According to VONAs (Volcano Observatory Notice for Aviation) from MAGMA Indonesia, eruptive events at 1159, 1305, and 2359 on 8 June generated ash plumes that rose 500 m above the summit and drifted SW and S. Incandescence was visible above the summit during the night of 8 June. A faint plume observed in satellite imagery during 11-12 June that rose to 1.5 km altitude and drifted W, according to Darwin VAAC notices. Ground reporters recorded several eruptive events during 15-17 June that generated dense gray-to-black plumes that rose 300-700 m above the summit and drifted N, SW, W, and S. Webcam images showed that incandescent ejecta accompanied these eruptive events. Eruptive events at 1712 on 25 June and at 0209 on 29 June produced ash plumes that rose 400 m and 2,000 m above the summit and slowly drifted SW and N, respectively. Another event occurred at 1817 on 30 June that generated an ash plume that rose as high as 1 km above the summit and drifted slowly NE.

Similar activity with intermittent eruptive events continued during July; white gas-and-steam emissions rose 25-100 m above the summit and drifted in different directions, though the summit was often obscured by weather clouds. A discrete eruption was observed in satellite imagery, with an ash plume that rose to 900 m altitude and drifted W on 1 July. Nighttime crater incandescence was visible during 2-5 July. Several eruptive events were detected during 16-18 July that rose 1-2.5 km above the summit and drifted NE, S, SW, and W. A webcam image during the night of 16 July showed incandescence at the vent (figure 131). The Darwin VAAC issues noted that during 19-25 July ash plumes rose to 2.6-3 km altitude and drifted in different directions based on satellite and webcam images, as well as weather models.

Figure 131. Webcam image showing a plume rising above Krakatau accompanied by incandescence on 16 July 2022. Courtesy of MAGMA Indonesia.

During August and September, cloudy weather often obscured clear views of the summit and activity was relatively low. On clear weather days, white gas-and-steam emissions rose 25-100 m above the summit. Frequent nighttime incandescence was visible at or near the vent (figure 132). MAGMA Indonesia reported several eruptive events during 2-4 August that generated black ash plumes that rose as high as 1.5 km above the summit and drifted NE, SW, and N. During 5-6 August a continuous ash emission was reported rising to 2.4 km altitude and drifted W, though it could not be confirmed in satellite images. Diffuse white gas-and-steam plumes were observed during 7-8 August. A discrete ash emission that rose to 1.2 km altitude and was reported by Darwin VAAC on 24 August.

Figure 132. Webcam image of an eruptive event at Krakatau during the night on 16 August 2022 showing strong nighttime incandescence. Courtesy of MAGMA Indonesia.

Low activity continued during October, with white gas-and-steam emissions rising 15-250 m above the summit accompanied by occasional nighttime incandescence. Multiple ash plumes were reported in webcam views and by ground observations during 24-28 October. The ash plumes rose 150-480 m above the summit and drifted NE and E. An eruptive event was recorded at 1845 by the seismic network; a webcam image showed incandescent material ejected above the crater rim. Ash plumes during 26-28 October rose as high as 300 m above the summit and drifted NE.

The MIROVA (Middle InfraRed Observation of Volcanic Activity) graph of MODIS thermal anomaly data showed frequent moderate-to-strong thermal anomalies during May through October (figure 133). Many of those thermal hotspots were detected by the MODVOLC thermal algorithm, with MODVOLC thermal alerts issued on 1 and 8 May, 4, 7, 11, 21, and 27 July, 1, 17, 19, 20, and 28 August, and 4, 12, and 21 September. Sentinel-2 infrared also showed occasional thermal anomalies in the crater accompanied by gas-and-steam plumes that drifted in different directions (figure 134).

Figure 133. Frequent moderate-to-strong thermal anomalies were detected at Anak Krakatau during May through October 2022, based on this MIROVA graph (Log Radiative Power). Courtesy of MIROVA.

Figure 134. A persistent thermal anomaly was detected at Krakatau in Sentinel-2 infrared satellite imagery on clear weather days throughout May-October 2022 . Occasionally, gas-and-steam plumes would accompany this activity and drifted in different directions. Images were captured on 14 May 2022 (top left), 8 June 2022 (top right), 18 July 2022 (middle left), 17 August 2022 (middle right), 9 September 2022 (bottom left), and 1 October 2022 (bottom right). Images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

Geologic Background. The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of that volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption caused more than 36,000 fatalities, most as a result of tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Home Reef is a submarine volcano located in the central Tonga islands between Lateiki (Metis Shoal) and Late Island. The first recorded eruption occurred in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12-km-high eruption plume, a large volume of floating pumice, and an ephemeral island 500 x 1,500 m wide, with cliffs 30-50 m high that enclosed a water-filled crater. Another island-forming eruption in 2006 produced widespread pumice rafts that drifted as far as Australia; by 2008 the island had eroded below sea level. Activity during November 2008 included a hydrothermal plume in addition to discolored water that spanned roughly 1-2 km² (BGVN 33:12). This report covers a new island-forming eruption during 10 September through 17 October 2022 that consisted of lava effusion, ash plumes, discolored water, and gas-and-steam plumes using information from the Tonga Geological Services (TGS) and satellite data.

Starting on 22 May 2022 up until the start of the new eruption in early September 2022, discolored water plumes were visible in Sentinel-2 satellite images on clear weather days that originated from a single point (figure 26). Water discoloration was yellow-green in color and extended in different directions.

Figure 26. Sentinel-2 satellite images showing light yellow-green discolored plumes originating from a single point (white arrow) at Home Reef during 22 May 2022 (top left), 16 June 2022 (top right), 16 July 2022 (bottom left), and 20 August 2022 (bottom right). Images using “Natural Color” rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

According to the Volcano Watch Team from the TGS, the summit rose above sea level at 0139 on 10 September 2022, based on a volcanic gas plume that was detected in satellite images (figure 27). Then, at 1259 a Sentinel-2 satellite image showed a small island about 70 m in diameter and an estimated 10 m above the ocean surface due to lava effusion. The new island was consistently surrounded by yellow-green discolored water (figure 28). Near-daily gas-and-steam emissions mostly rose to 1 km altitude and rose as high as 2 km altitude. Hydrothermal submarine activity was detected during 12-13 September, and a thermal anomaly was identified in a satellite image acquired at 1400 on 13 September. Thermal activity was captured in HIMAWARI-8 satellite imagery at 1340 on 14 September, at 0730 on 15 September, and at 0220 on 16 September. By 16 September the island had grown to 170 m in diameter and reached 182 m N-S and 173 m E-W by 18 September (figure 29).

Figure 27. Sentinel-2 satellite image showing the emergence of a new island (black circle) at Home Reef on 9 September 2022 (UTC time). A gas-and-steam plume drifts W, with distinct yellow-green discolored submarine plumes surrounding the island and dispersing generally NE. Image using “Natural Color” rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

Figure 28. Sentinel-2 satellite image showing the new island that emerged at Home Reef taken on 14 September 2022 (UTC time). The island (black circle) is 170 m in diameter and yellow-green discolored water surrounds the island. Distinct gas-and-steam plumes are also visible drifting SW. Image using “Natural Color” rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

Figure 29. Worldview-3 satellite image acquired at 2148 (UTC time) on 15 September 2022 showing the lava surface of the newly emerged island at Home Reef. The island measured 182 m N-S and 173 m E-W. Strong white gas-and-steam emissions and yellow-green discolored water surround the newly formed island. A fumarolic plume drifts W. Courtesy of USGS and Tonga Geological Services.

During 19-20 September gas-and-steam plumes containing some amount of ash rose to 3 km above sea level (figure 30). New measurements made on 19 September showed that the island had grown to 211 m N-S and 218 m E-W and was an estimated height of 15 m above sea level. During 0040-0250 on 25 September gas-and-ash plumes rose to 2-4 km altitude and drifted 30 km W, S, and SE. At 0030 on 27 September an ash plume rose to 6-8 km altitude and drifted 25 km SSE. On 28 September the island was 268 m N-S, 283 m E-W, and 15-18 m above sea level. Discolored water plumes continued to circulate the island within about 200 m from the shore and generally drifted S due to the current direction. Ash was no longer detected in the eruptive plumes on 29 September, and according to a Skysat satellite, the volcanic plume thinned within 1 km of the island.

Figure 30. Sentinel-2 satellite images showing the evolution of the new island (black circle) at Home Reef due to persistent lava effusion during 19 September 2022 (top left), 24 September 2022 (top right), 29 September 2022 (bottom left), and 9 October 2022 (bottom right). White gas-and-steam emissions sometimes containing ash were occasionally visible and drifted NW and SW, as shown on 19 and 24 September, respectively. Yellow-green discolored water was also observed surrounding the island and extending to the SW, W, and N. Images using “Natural Color” rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

Eruptive activity continued during October, with persistent lava effusion, fumarolic activity, and discolored water areas. On 5 October at 0036 an ash plume rose to 3 km altitude and drifted 5 km SE. Satellite imagery showed that the island had not grown on 10 October, with measurements of 268 m N-S and 283 m E-W, and an estimated height of 15-18 m. An ash plume was visible at 0040 on 6 October that rose to 3 km altitude and drifted 5 km SE. A thermal anomaly was detected in satellite imagery at 0146 on 17 October; TGS reported on 22 October that the anomaly on the 17th was the last recorded activity.

Geologic Background. Home Reef, a submarine volcano midway between Metis Shoal and Late Island in the central Tonga islands, was first reported active in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12-km-high eruption plume, copious amounts of floating pumice, and an ephemeral island 500 x 1500 m wide, with cliffs 30-50 m high that enclosed a water-filled crater. Another island-forming eruption in 2006 produced widespread dacitic pumice rafts that reached as far as Australia.

Information Contacts: Tonga Geological Services, 51 Vaha'akolo Road, Nuku’alofa, Tonga (URL: https://www.facebook.com/tongageologicalservice); US Geological Survey, Volcano Hazards Program (USGS-VHP), 12201 Sunrise Valley Drive, Reston, VA, USA, https://volcanoes.usgs.gov/index.html; Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Erebus, Antarctica’s best known and world’s southernmost active volcano, overlooks the McMurdo research station on Ross Island. It has a lava lake in the summit crater that has been active since at least 1972. Because of the remote location, activity is primarily monitored by satellites. This report covers activity during 2022.

During 2022 the Sentinel-2 satellite only captured images of Erebus during 1 January-8 March and 27 September-26 December (figure 31). The images showed at least three distinct thermal sources within the summit crater. The HIGP MODVOLC Thermal Alerts System recorded more thermal activity during January-May, and lower activity during June-December compared to 2021 (table 8).

Figure 31. Sentinel-2 infrared satellite images showing the active lava lake in the summit crater of Erebus during 2022. The image on 17 February shows a single lava lake, while the image on 4 December shows a larger lake and at least two smaller thermal areas immediately SW. Images use Atmospheric Penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

Table 8. Number of monthly MODIS-MODVOLC thermal alert pixels recorded at Erebus during 2017-2022. See BGVN 42:06 for data from 2000 through 2016. The table was compiled using data provided by the HIGP – MODVOLC Thermal Alerts System.

Geologic Background. Mount Erebus, the world's southernmost historically active volcano, overlooks the McMurdo research station on Ross Island. It is the largest of three major volcanoes forming the crudely triangular Ross Island. The summit of the dominantly phonolitic volcano has been modified by one or two generations of caldera formation. A summit plateau at about 3,200 m elevation marks the rim of the youngest caldera, which formed during the late-Pleistocene and within which the modern cone was constructed. An elliptical 500 x 600 m wide, 110-m-deep crater truncates the summit and contains an active lava lake within a 250-m-wide, 100-m-deep inner crater; other lava lakes are sometimes present. The glacier-covered volcano was erupting when first sighted by Captain James Ross in 1841. Continuous lava-lake activity with minor explosions, punctuated by occasional larger Strombolian explosions that eject bombs onto the crater rim, has been documented since 1972, but has probably been occurring for much of the volcano's recent history.

Information Contacts: 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).

Sabancaya, located in Peru NE of Ampato and SE of Hualca Hualca, has had Holocene activity that consisted of Plinian eruptions and lava flow effusions, which have formed an extensive apron around the volcano on all sides except the south. Eruptions date back to 1750, with the most recent beginning in November 2016 characterized by frequent, low-energy explosions and gas-and-ash plumes (BGVN 47:05). This report covers activity during April through October 2022 using information from Instituto Geophysico del Peru (IGP) that use weekly activity reports and various satellite data.

Frequent low-to-moderate power thermal anomalies were reported by the MIROVA project during April through October 2022 (figure 116). There was a small gap in detected activity during mid-to-late October. According to data recorded by the MODVOLC thermal algorithm, there was a total of 34 thermal hotspots: 7 in April, 5 in May, 5 in June, 3 in July, 5 in August, 5 in September, and 4 in October. On clear weather days, some of this thermal activity was visible in Sentinel-2 infrared satellite data that showed the active summit crater (figure 117). Moderate-to-strong sulfur dioxide plumes were recorded almost daily during the reporting period by the TROPOMI instrument on the Sentinel-5P satellite (figure 118). Many of these plumes exceeded 2 Dobson Units (DU) and drifted in multiple directions.

Figure 116. Frequent low-to-moderate strength thermal anomalies were detected during April through October 2022 at Sabancaya, as shown in this MIROVA graph (Log Radiative Power). There was a small gap in detected activity during mid-to-late October. Courtesy of MIROVA.

Figure 117. Sentinel-2 infrared satellite imagery showed persistent thermal activity at the summit crater of Sabancaya on 19 April 2022 (top left), 9 May 2022 (top right), 8 June 2022 (middle left), 28 July 2022 (middle right), 27 August 2022 (bottom left), and 26 September 2022 (bottom right). Occasionally, gas-and-steam emissions accompanied this activity, as shown on 19 April and 27 August, which drifted SW and SE, respectively. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Figure 118. Strong sulfur dioxide plumes were detected rising from Sabancaya by the TROPOMI instrument on the Sentinel-5P satellite during the entire reporting period; the DU (Dobson Unit) density values were frequently greater than 2. Plumes from 18 April 2022 (top left), 20 May 2022 (top right), 15 June 2022 (bottom left), and 2 July 2022 (bottom right) that drifted SE, SE, SW, and SW, respectively. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

IGP reported that moderate levels of eruptive activity continued during April and May 2022; the weekly averages of explosions were 41, 52, 46, 37, and 40 during April, and 53, 54, 21, and 15 during May. Gas-and-ash plumes in April rose 2-3.4 km above the summit and drifted in different directions. During May gas-and-ash plumes rose 2-3 km above the summit and drifted E, SE, N, NE, and S. There were 1,125 volcanic earthquakes recorded during April and 1,337 during May. Seismicity also included volcano-tectonic-type events that indicate rock fracturing events. Thermal activity was frequently reported in the crater due to an active lava dome.

Similar explosive activity continued during June and July. The weekly averages of explosions were 9, 8, 17, and 18 during June, and 22, 20, 28, 30, and 27 during July. Gas-and-ash plumes rose 1.5-2.5 km above the summit and drifted E, SE, and NE during June and rose 1.5-2.7 km above the summit and drifted SE, E, S, N, NW, and SW during July. IGP also detected 945 volcanic earthquakes during June and 1,444 during July; VT-type earthquakes were also reported. Satellite imagery showed persistent thermal anomalies within the crater due to the active lava dome.

The weekly averages of explosions were 19, 25, 33, 48 during August and 58, 44, 47, 50, 46 during September. Accompanying gas-and-ash plumes rose 2.4-2.7 km above the summit and drifted in multiple directions during August and 1.6-3 km above the summit and drifted E, SE, SW, and NE during September. Frequent seismic events continued to be detected; there were 1,378 events reported during August and 1,817 events during September. VT-type events persisted. Satellite data identified several thermal anomalies in the crater due to the active lava dome.

The weekly averages of explosions during October were 45, 56, 40, and 28. The accompanying gas-and-ash plumes rose 2.5-3 km above the summit and drifted W, NE, E, and SE. Seismicity continued, with 1,346 events detected throughout the month, in addition to VT-type events. Thermal activity at the summit crater was commonly detected in satellite imagery.

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

Information Contacts: Observatorio Volcanologico del INGEMMET (Instituto Geológical Minero y Metalúrgico), Barrio Magisterial Nro. 2 B-16 Umacollo - Yanahuara Arequipa, Peru (URL: http://ovi.ingemmet.gob.pe); Instituto Geofisico del Peru (IGP), 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Taal is a stratovolcano with a crater lake on a 5-km-wide volcanic island within a large caldera (Lake Taal) in the SW part of Luzon, Philippines, about 65 km S of Manila. Since at least 1968, episodes of increased seismicity, elevated lake temperatures, steaming, significant sulfur dioxide plumes, and deformation have been reported, both during and independent of eruptive periods. A series of phreatic and phreatomagmatic explosions began in January 2020, and subsequent explosions occurred in July and November 2021, and January-March 2022 (NSEB 02:10, SEAN 03:02, BGVN 45:06, 46:10, 47:04). This report describes activity during April-October 2022 using reports from the Philippine Institute of Volcanology and Seismology (PHIVOLCS), the Tokyo Volcanic Ash Advisory Center (VAAC), and satellite data.

PHIVOLCS reported that hot volcanic fluids circulated and upwelled in Taal’s crater lake during 30 March through 6 April 2022, producing plumes that rose as high as 2 km above the lake’s surface and drifted SW. Tremor persisted daily until 5 April. Three phreatomagmatic bursts from the Main Crater were detected at 1039, 1047, and 1055 on 1 April, based on seismic data and webcam images, which produced plumes 500-900 m above the lake that drifted SW.

The Alert Level for Taal was lowered to 2 (on a scale of 0-5) by PHIVOLCS on 9 April 2022, noting a significant decrease in activity during the previous two weeks. Sulfur dioxide emissions that had peaked at 21,211 metric tons per day (t/d) on 16 March, dropped significantly during the first half of April and on 11 April were below detection limits; this was the lowest number recorded since unrest began in 2021. Diffuse plumes from the lake had also decreased in frequency, though they rose 600-900 m above the surface during 10-12 April. On 11 July PHIVOLCS lowered the Alert Level to 1, noting that during the previous two months activity had returned to baseline levels of volcanic earthquakes, weak gas emissions, and minor surface activity.

In May and June 2022, sulfur dioxide emissions increased, then increased more beginning on 15 July. Another significant increase was measured during early August, peaking on 7 August (table 1). Vog, dense in some locations, was present over the W part of the caldera during 2-3 August and caused vegetation damage. Upwelling gas and hot fluids in the lake, and voluminous steam-rich plumes rising as high as 3 km above the lake, were visible during 1-15 August. Low-frequency earthquakes and tremor increased above background levels. Strong sulfur dioxide plumes were detected during the last third of April; none were detected in May or June, a few were scattered in July, about half the days consisted of plumes in August, and intermittent plumes occurred during September and October (figure 29).

Table 1. Sulfur dioxide levels measured at Taal during 15 July through October 2022. Compiled from PHIVOLCS reports.

Figure 29. Typical examples of strong sulfur dioxide plumes from Taal, shown here on 13 August and 22 October 2022, as detected by the TROPOMI instrument aboard the Sentinel-5P satellite. Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

PHIVOLCS reported increased unrest during 5-29 October, with a series of phreatomagmatic explosions (table 2). The explosions were accompanied by volcanic earthquakes and tremor. In addition to phreatomagmatic explosions, upwellings of gas and hot fluid in the lake were typically visible in October, with white steam emissions rising 600-3,000 m above the lake.

Table 2. Phreatomagmatic explosions at Taal recorded during October 2022. The lake is about 300 m above sea level. Data courtesy of PHIVOLCS and the Tokyo VAAC.

Thermal measurements made by MODIS satellite instruments and processed by MIROVA showed numerous hotspots throughout the reporting period (figure 30). The MODVOLC thermal alerts system recorded only occasional hotspots during the reporting period. The number of days with hotspots during April-October 2022 ranged from 2 to 6 (April: 6, May: 3, June: 4, July: 5, August: 3, September: 5, October: 2). During the series of phreatomagmatic explosions in October, only two hotspots were recorded by MODVOLC.

Figure 30. Log Radiative Power graph of thermal anomalies at Taal during 2022, as recorded by the MIROVA system, showing numerous low to moderate power hotspots during April-October 2022. Courtesy of MIROVA.

Geologic Background. Taal is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. Though not topographically prominent, its prehistorical eruptions have greatly changed the landscape of SW Luzon. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities.

Information Contacts: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Department of Science and Technology, University of the Philippines Campus, Diliman, Quezon City, Philippines (URL: http://www.phivolcs.dost.gov.ph/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); 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, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Ambae is a large basaltic shield volcano in Vanuatu that has had periodic phreatic and pyroclastic explosions since the 16th century. A large eruption more than 400 years ago resulted in a volcanic cone within the summit crater that is now filled by Lake Voui; approximately the same size, Lake Manaro fills the western third of the caldera. The September 2017-October 2018 eruption included large ash explosions with heavy ashfall and plumes that rose to 13.7 km altitude, lava fountaining, minor lava flows, incandescence, lahars, sulfur dioxide plumes, and thermal anomalies (BGVN 43:02, 43:07). The currently active vent is within the pyroclastic cone that grew in the lake in mid-September 2017 (BGVN 43:02), eventually splitting Lake Voui into two sections (BGVN 43:07). A new explosive eruption period began on 5 December 2021 (BGVN 47:03). This report covers activity from January-September 2022, with information provided by the Vanuatu Meteorology and Geo-Hazards Department (VMGD) and satellite data.

During the reporting period, the Alert Level remained at 2 (on a scale of 0-5), which signifies “Danger around the crater rim and specific area, notable/large unrest, considerable possibility of eruption and also chance of flank eruption”. According to VMGD, during January-September 2022 weather clouds often prevented observations, but the cone in Lake Voui continued to grow and produce gas-and-steam and ash emissions, and plumes occasionally caused light ashfall on nearby villages. Explosions of wet tephra rose above the lake surface but remained within the caldera.

VMGD reported that on 2 January 2022 ash plumes were seen drifting ENE at 1730 and 1830. On 3 January at 0600, a gas-and-ash plume rose 5 km, though only the lower portion of the plume contained ash (figure 96); at 0730 another ash plume rose almost 1.6 km. Additional significant ash plumes were observed on 16 January and at 0845 on 5 February. The Wellington Volcanic Ash Advisory Centre reported that webcam images on 17 February showed ash emissions rising to an altitude of 3 km and drifting WSW. A notable sulfur dioxide plume was also detected that day by the TROPOMI instrument aboard the Sentinel-5P satellite (figure 97).

Figure 96. A gas-and-ash plume rises above Ambae on 3 January 2022 at 0600, as seen in this webcam image annotated by VMGD. Courtesy of VMGD.

Figure 97. Image showing a strong sulfur dioxide plume from Ambae (center) on 17 February 2022, as detected by the TROPOMI instrument aboard the Sentinel-5P satellite. Yasur (bottom) was also venting a strong sulfur dioxide plume on the same day. Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

Sentinel-2 images show that the growing pyroclastic cone divided the W section of Lake Voui into two parts by 24 March 2022 (figure 98). During the reporting period, the MIROVA system recorded several hotspots, mostly in early January 2022, and one in early May 2022. VMGD did not issue reports about Ambae after 27 May, noting continuing gas-and-ash emissions, until 31 August 2022, when they noted gas emissions with “possible ashes” included. Satellite imagery on 10 September showed no morphological changes to the lakes since late March.

Figure 98. Sentinel-2 images of Ambae show the changing features and sections of Lake Voui (center), with Lake Manaro to the E (right) and smaller Lake Ngoru to the W (left). The image from 30 October 2021 shows Lake Voui divided into two sections from earlier activity. The 8 January 2022 image shows a new pyroclastic cone in the western section from activity since early December 2021. By 24 March 2022 ongoing eruptions had divided the western part of Lake Voui into at least two smaller lakes. Images use natural color rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

Geologic Background. The island of Ambae, also known as Aoba, is a massive 2,500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Information Contacts: Geo-Hazards Division, Vanuatu Meteorology and Geo-Hazards Department (VMGD), Ministry of Climate Change Adaptation, Meteorology, Geo-Hazards, Energy, Environment and Disaster Management, Private Mail Bag 9054, Lini Highway, Port Vila, Vanuatu (URL: http://www.vmgd.gov.vu/, https://www.facebook.com/VanuatuGeohazardsObservatory/); Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Ethiopia's Erta Ale is an active shield volcano with a large oval-shaped summit caldera containing two smaller pit craters (North and South) that have exhibited lava lake activity for many decades. During October 2021-May 2022, the S pit crater had almost persistent thermal anomalies of varying intensity, while activity in the N pit crater was more intermittent (BGVN 47:05). This status continued through November 2022, although thermal intensities diminished after mid-June 2022. The volcano is monitored by satellites and visiting tour groups occasionally share their observations and images online. This report covers activity from May through November 2022 and is based on satellite infrared data.

Sentinel-2 images show the variation in heat signal intensity from the N and S pit craters during May-November 2022 (figure 115). Hotspots in the N crater were visible during two brief periods, while they persisted in the S crater. On 3 May there was a strong hotspot in the S pit crater along with a weak hotspot in the SSE part of the N pit crater. The hotspot in the S crater persisted throughout the reporting period, although by the end of June it had faded. On 16 August, after two weeks of heavy clouds, a strong thermal signal in the N pit crater was recorded; by 31 August it had vanished while the S crater anomaly remained weak.

Figure 115. Sentinel-2 infrared images of Erta Ale during May-November 2022 show the variations in strength and extent of the heat signatures in the N and S pit craters. All images are in “False color (urban)” rendering (bands 12, 11, 4). Courtesy of Sentinel Hub Playground.

During the reporting period, the MIROVA thermal detection system recorded numerous low-to-moderate power thermal anomalies during May through mid-June 2022, but none thereafter, except for one in mid-August (figure 116). Similarly, the MODVOLC thermal detection system registered four anomalies during 7 May-1 June, but none thereafter. These data are consistent with the Sentinel-2 infrared imagery (figure 117) that showed that intermittent weak summit thermal anomalies continued after mid-June, then became more consistent again after mid-August.

Figure 116. The MIROVA graph (Log Radiative Power) for the year ending on 19 December 2022 shows that moderate thermal activity at Erta Ale decreased in early June and was not detected after about the middle of the month. Brief low-power anomalies were detected in mid-August and early November. Courtesy of MIROVA.

Figure 117. Graph of Sentinel-2 (red dots) and MODIS (blue bars) thermal anomalies at Erta Ale for the 2-year period ending 19 December 2022. Courtesy of MIROVA.

Geologic Background. The Erta Ale basaltic shield volcano in Ethiopia has a 50-km-wide edifice that rises more than 600 m from below sea level in the Danakil depression. The volcano includes a 0.7 x 1.6 km summit crater hosting steep-sided pit craters. Another larger 1.8 x 3.1 km wide depression elongated parallel to the trend of the Erta Ale range is located SE of the summit and is bounded by curvilinear fault scarps on the SE side. Basaltic lava flows from these fissures have poured into the caldera and locally overflowed its rim. The summit caldera usually also holds at least one long-term lava lake that has been active since at least 1967, and possibly since 1906. Recent fissure eruptions have occurred on the N flank.

Information Contacts: 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); 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/).

Erebus, Antarctica’s best known and world’s southernmost active volcano, overlooks the McMurdo research station on Ross Island. It has a lava lake in the summit crater that has been active since at least 1972. Because of the remote location, activity is primarily monitored by satellites. This report covers activity during 2022.

During 2022 the Sentinel-2 satellite only captured images of Erebus during 1 January-8 March and 27 September-26 December (figure 31). The images showed at least three distinct thermal sources within the summit crater. The HIGP MODVOLC Thermal Alerts System recorded more thermal activity during January-May, and lower activity during June-December compared to 2021 (table 8).

Figure 31. Sentinel-2 infrared satellite images showing the active lava lake in the summit crater of Erebus during 2022. The image on 17 February shows a single lava lake, while the image on 4 December shows a larger lake and at least two smaller thermal areas immediately SW. Images use Atmospheric Penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

Table 8. Number of monthly MODIS-MODVOLC thermal alert pixels recorded at Erebus during 2017-2022. See BGVN 42:06 for data from 2000 through 2016. The table was compiled using data provided by the HIGP – MODVOLC Thermal Alerts System.

Geologic Background. Mount Erebus, the world's southernmost historically active volcano, overlooks the McMurdo research station on Ross Island. It is the largest of three major volcanoes forming the crudely triangular Ross Island. The summit of the dominantly phonolitic volcano has been modified by one or two generations of caldera formation. A summit plateau at about 3,200 m elevation marks the rim of the youngest caldera, which formed during the late-Pleistocene and within which the modern cone was constructed. An elliptical 500 x 600 m wide, 110-m-deep crater truncates the summit and contains an active lava lake within a 250-m-wide, 100-m-deep inner crater; other lava lakes are sometimes present. The glacier-covered volcano was erupting when first sighted by Captain James Ross in 1841. Continuous lava-lake activity with minor explosions, punctuated by occasional larger Strombolian explosions that eject bombs onto the crater rim, has been documented since 1972, but has probably been occurring for much of the volcano's recent history.

Information Contacts: 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).