Tinakula is a remote stratovolcano in the SE part of the Solomon Islands. Recent activity began with an ash explosion in October 2017, followed in December 2018 by dense gas-and-steam plumes and weak thermal anomalies (BGVN 44:07, 47:02), which continued into 2022. The current report summarizes activity during January-September 2022 using satellite data, as ground observations are rarely available.

Infrared MODIS satellite data processed by MIROVA (Middle InfraRed Observation of Volcanic Activity) detected intermittent low-power thermal anomalies each month except for September 2022 when none were detected (figure 50). More frequent anomalies were detected from mid-February through March 2022.

Figure 50. Graph of thermal anomalies (Log Radiative Power) at Tinakula from the MIROVA system through September 2022. Courtesy of MIROVA.

Sentinel-2 satellite imagery showed persistent white gas-and-steam plumes rising from Tinakula during January through September 2022. Almost all observed plumes drifted W or SW and were usually profuse and dense. On the few viewing days when not obscured by the plumes or weather clouds, a thermal anomaly was visible at the summit area (figure 51); three small thermal anomalies were visible on 23 September.

Figure 51. Selected Sentinel-2 infrared satellite images of Tinakula showing a thermal anomaly at the summit and associated steam plumes on 27 March (left) and 23 September (right) 2022. Images with Atmospheric penetration (bands 12, 11, 8a) rendering. Courtesy of Sentinel Hub Playground.

Geologic Background. The small 3.5-km-wide island of Tinakula is the exposed summit of a massive stratovolcano at the NW end of the Santa Cruz islands. Similar to Stromboli, it has a breached summit crater that extends from the summit to below sea level. Landslides enlarged this scarp in 1965, creating an embayment on the NW coast. The satellitic cone of Mendana is located on the SE side. The dominantly andesitic volcano has frequently been observed in eruption since the era of Spanish exploration began in 1595. In about 1840, an explosive eruption apparently produced pyroclastic flows that swept all sides of the island, killing its inhabitants. Frequent historical eruptions have originated from a cone constructed within the large breached crater. These have left the upper flanks and the steep apron of lava flows and volcaniclastic debris within the breach unvegetated.

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).

Recent activity at Ibu, an Indonesian stratovolcano about 35 km SW of Dukono volcano, has included occasional low-level ash plumes, light ashfall, and thermal anomalies. This report covers similar activity during March-September 2022, using information from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM) and various satellite data. The Volcano Alert Level remained at 2 (on a scale of 1-4), 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.

According to daily reports from MAGMA Indonesia (a platform developed by PVMBG), gray-and-white ash plumes rising 200-1,000 m above the summit were observed almost every day during the reporting period, with a few plumes reaching up to 3 km above the summit (figure 39). Plume heights were variable, though higher plumes were noted during 21-29 April.

Figure 39. Webcam photo of Ibu on 16 May 2022 at 1646 local time showing an ash plume that might have risen as high as 2.5 km above the summit. Photo has been color corrected. Courtesy of MAGMA Indonesia.

Frequent thermal hotspots were detected by the MIROVA system during the reporting period (figure 40). In contrast, only a few scattered hotspots were identified by the MODIS-MODVOLC thermal alert system, and none in March or June. Satellite imagery continued to show thermal anomalies at both summit craters (figure 41), though the volcano was obscured by weather clouds on all but a few days.

Figure 40. The MIROVA (Log Radiative Power) thermal data for Ibu during the year ending in October 2022 showed numerous low-power thermal signals during March-September 2022, except for early April. Courtesy of MIROVA.

Figure 41. Sentinel-2 infrared satellite images of Ibu taken on 14 June (left) and 19 July 2022 (right) showing gray-and-white ash plume drifting W (top) and thermal signals from summit craters. Images taken with Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

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); 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).

Dukono has been erupting continuously since 1933, with frequent ash explosions, ash plumes, and sulfur dioxide plumes (BGVN 46:11). After a period of diminished volcanism during October 2021-March 2022 (BGVN 47:04), activity resumed its more usual heightened pattern through September 2022. The data below were primarily provided by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), also known as the Center for Volcanology and Geological Hazard Mitigation (CVGHM), the Darwin Volcanic Ash Advisory Centre (VAAC), and satellite sensors. Since 15 June 2008, the Alert Level has remained at 2 (on a scale of 1-4) and the public has been warned to remain outside of the 2-km exclusion zone (BGVN 46:11).

According to almost daily images from MAGMA Indonesia (a platform developed by PVMBG), white, gray, or dark plumes were observed almost every day during the reporting period (figure 30). According to the Darwin VAAC, plumes reached an altitude of 2.1-2.7 km (900-1,500 m above the summit) during the last week of May. PVMBG reported that during July-September 2022 plumes often rose 200-1,000 m above the summit.

Figure 30. Photo of an ash plume rising from Dukono on 28 August 2022. Courtesy of MAGMA Indonesia.

During the few days when the volcano was not obscured by weather clouds, Sentinel-2 satellite images recorded ash plumes and an occasional thermal anomaly in the summit crater (figure 31). The MIROVA system also recorded a few scattered, low-strength hotspots. Strong sulfur dioxide plumes above the volcano were detected on numerous days every month of the reporting period (figure 32), but their intensity appeared to diminish during August and September 2022.

Figure 31. Sentinel-2 satellite image of ash plume blowing W from Dukono on 24 June 2022. Sentinel-2 images with natural rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

Figure 32. Example of a sulfur dioxide plume from Dukono on 5 May 2022, as detected by the TROPOMI instrument aboard the Sentinel-5P satellite. 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, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

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

Activity began to subside at Turrialba after 2019, following a period of weak ash explosions and emissions, allowing for the reappearance of a hydrothermal system. Thereafter, occasional weak explosions at this Costa Rican stratovolcano were thought to be phreatic (steam-driven), with associated minor passive ash emissions (BGVN 46:09, 47:04). The following report summarizes activity from March-August 2022 and is based primarily on information from periodic reports published by the Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA) and satellite data.

Overall activity was at a low level during this reporting period. Occasional small rumblings were recorded, some associated with minor ash emissions. Seismicity remained low, eventually returning to the pre-June 2021 level, and geodetic monitoring showed that the Irazú-Turrialba massif continued to subside and contract, especially around the active Turrialba crater.

In early April 2022 an inspection of the bottom of the West Crater (or Bat Crater) with a drone revealed some fumaroles, mainly in the eastern sector, releasing steam and sulfur gases. The fumaroles registered temperatures of at least 113°C according to remote measurement with an infrared thermograph.

According to OVSICORI-UNA, at 0749 on 17 July a brief phreatic eruption was recorded. An ash emission rose less than 500 m above the crater and drifted SW, with minor ashfall in Irazú Volcano National Park. This was the only eruption during the reporting period, and the first since 27 February 2022. Seismic activity continued to decrease.

A sulfur dioxide plume was detected originating from Turrialba on 30 August, using the TROPOMI instrument on the Sentinel-5P satellite. According to OVSICORI-UNA, the plume contained 108 tons of SO₂.

Geologic Background. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive edifice covers an area of 500 km2. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

Information Contacts: Observatorio Vulcanologico Sismologica de Costa Rica-Universidad Nacional (OVSICORI-UNA), Apartado 86-3000, Heredia, Costa Rica (URL: http://www.ovsicori.una.ac.cr/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard MD, USA (URL: https://so2.gsfc.nasa.gov/).

Recent activity at Yasur, which has been erupting since at least 1774 and possibly the past 750 years, includes frequent Strombolian explosions and ash and gas plumes from several vents in the 400 m-diameter summit crater (BGVN 44:02, 45:03). This report summarizes activity during September 2021-August 2022, using information from monthly bulletins of the Vanuatu Meteorology and Geo-Hazards Department (VMGD), the Wellington Volcanic Ash Advisory Center (VAAC), and various satellite data. According to VMGD, Yasur (also called Tanna, after the island on which it is located) has remained on Alert Level 2 (major unrest state, on a scale of 0-5), since 18 October 2016, and VMGD reminded the public not to enter the restricted area within a radius of 600 m around the cone (1 km radius 22 October-24 November 2021).

VMGD reported that seismic data and visual observations confirmed ongoing strong explosions with gas and/or ash plumes during the reporting period, with bombs falling in and around the crater, and infrequently on the flanks (figures 84-85). According to VMGD and the Wellington VAAC, emissions generally rose 1.2-1.8 km in altitude (0.8-1.4 km above the crater), sometimes depositing ash on nearby villages. The intensified activity caused VMGD to expand the restricted area to a 1-km radius around the cone. The heightened emissions had ceased by 1845 on 24 October.

Figure 84. Webcam image of Yasur on 22 October 2021 showing an ash plume rising as high as 800 m above the summit. Courtesy of VMGD.

Figure 85. Webcam image of Yasur on 27 November 2021. According to VMGD and the Wellington VAAC, multiple gas-and-ash emissions that day rose to 1.5-1.8 km altitude and drifted W. Courtesy of VMGD.

Sentinel-2 satellite images showed persistent strong thermal anomalies in the summit crater during the few days of the reporting period the volcano was not obscured by weather clouds (figure 86). The MODIS-MODVOLC thermal alerts system recorded only occasional hotspots for Yasur during the reporting period. The number of days with recorded hotspots ranged from 0 (October and November 2021; January, March, and July 2022) to 3 to 6 during other months. A high of 4 pixels was recorded on 12 April. In contrast, the MIROVA (Middle InfraRed Observation of Volcanic Activity) system recorded numerous hotspots during the year beginning in February 2022 (figure 85).

Figure 86. Sentinel-2 infrared satellite images of Yasur showing various configurations of the thermal anomalies in the summit crater during September 2021-May 2022. Images use Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

Strong sulfur dioxide plumes were often detected by the TROPOMI instrument (figure 87) on the Sentinel-5P satellite (i.e., those plumes exceeding 2 Dobson Units). The number of days with plumes was highest during November and December 2021 (most days) but dropped to one day each for July and August 2022.

Figure 87. Strong sulfur dioxide plumes from Yasur were frequently detected, as seen here in representative images on 23 October, 9 December, and 23 December 2021, and 17 February 2022. The southern plumes on 9 December and 17 February are from Yasur, and the northern plumes originated from Ambae. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Geologic Background. Yasur has exhibited essentially continuous Strombolian and Vulcanian activity at least since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Located at the SE tip of Tanna Island in Vanuatu, this pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone is largely contained within the small Yenkahe caldera, and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide open feature associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century.

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 Center (VAAC), MetService, PO Box 722, Wellington, New Zealand (URL: http://vaac.metservice.com/); 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).

Nyamulagira (also known as Nyamuragira) is a shield volcano in the Democratic Republic of the Congo that hosts a lava lake in the summit crater. Recent activity has been characterized by lava effusion, thermal anomalies, seismicity, and gas-and-steam emissions (BGVN 45:12). The current report summarizes activity during December 2021-August 2022 and is based on satellite data.

The MODIS thermal sensors aboard the Aqua and Terra satellites processed using the MODVOLC algorithm (MODIS-MODVOLC) detected numerous hotspots at the volcano, consistent with the persistent lava lake in the summit crater. Days with hotspots increased during the reporting period, with 1-4 days per month during December 2021 through February, 7-8 days during March and April, and 10-12 days during May-August. Every month from May-August had at least one day with 4 pixels. The MIROVA (Middle InfraRed Observation of Volcanic Activity) system also detected numerous hotspots, with the frequency noticeably increasing starting in January 2022 (figure 91).

Figure 91. Numerous thermal anomalies at Nyamulagira during December 2021 through August 2022, according to the MIROVA graph (Log Radiative Power). Stronger pulses were apparent after May. Courtesy of MIROVA.

Throughout the reporting period, hotspots were observed in every Sentinel-2 infrared image during the infrequent days when cloud conditions allowed an observation. Images showed that activity generally intensified over the reporting period, especially beginning in late April when effusive activity and surface lava was detected outside the NE pit crater. Infrared satellite imagery showed multiple areas of lava effusion and flows throughout the S and W parts of the caldera that changed with every available image (figure 92). This increased activity continued through the reporting period.

Figure 92. Sentinel-2 satellite images of Nyamulagira showed persistent strong thermal anomalies in 2022 through August. Thermal signals on 1 February 2022 were in the NE pit crater, typical of activity during December 2021-February 2022. Satellite images from 6 June, 6 July, and 21 July reveal multiple vent locations and lava flows across the S and W parts of the caldera, both in and around the large crater in that area. Images use false color (urban) rendering (bands 12, 11, 4). Courtesy of Sentinel Hub Playground.

Geologic Background. Africa's most active volcano, Nyamulagira (also known as Nyamuragira), is a massive high-potassium basaltic shield about 25 km N of Lake Kivu and 15 km NE of the steep-sided Nyiragongo volcano. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Documented eruptions have occurred within the summit caldera, as well as from the numerous flank fissures and cinder cones. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Recent lava flows extend down the flanks more than 30 km from the summit as far as Lake Kivu; extensive lava flows from this volcano have covered 1,500 km2 of the western branch of the East African Rift.

Information Contacts: MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

Volcán El Reventador is located 100 km E of the main axis of active volcanoes in Ecuador, and has dated eruptions extending into the 16th century, characterized by explosive events and lava flows. The current eruption began in late July 2008 and has more recently consisted of daily explosions, ash plumes, incandescent block avalanches, and lava flows (BGVN 47:03). This report covers similar activity during February through July 2022, based on daily reports from Ecuador's Instituto Geofisico (IG-EPN), the Washington Volcano Ash Advisory Center (VAAC), and infrared satellite data.

During February through July 2022, IG-EPN reported daily explosions, gas-and-steam and ash plumes 400-1,900 m above the crater, and frequent crater incandescence, often accompanied by incandescent block avalanches and lava flows. The average number of explosions gradually increased since February, with the highest average numbers of explosions per day in June (57) and July (52) (table 15). At night and early morning, frequent crater incandescence was visible and block avalanches descended all flanks, occasionally accompanied by gas-and-steam and ash emissions. Occasional lava flows were reported traveling down the N, NE, and NW flanks.

Table 15. Monthly summary of explosions and plume heights recorded at Reventador from February through July 2022. Data courtesy of IG-EPN (February-July 2022 daily reports).

The summit crater activity was often obscured by clouds during February. There were 4-160 daily explosive events, which generated gas-and-ash plumes that rose 400-1,300 m above the crater and drifted NW, W, SW, S, NE, and SE. Intermittent nighttime crater incandescence was observed in the upper part of the volcano. There were also 14-97 large period (LP) earthquakes and 3-30 emission tremors (signals indicating steam) detected. On 4 February an infrared image showed a lava flow descending the NE flank, which may have started earlier, but was not visible due to cloud coverage (figure 155). During 8-10 February incandescent block avalanches traveled down all flanks as far as 700 m below the crater, in addition to the active lava flow on the NW flank. During 17-18 February an incandescent avalanche of material descended 300 m on the S flank. During 21-22 February the number of daily explosions increased to 160 and 97 LP events were detected. Crater incandescence and the active flow on the NE flank persisted during 28 February-1 March.

Figure 155. Webcam infrared image of Reventador showed crater incandescence, an ash plume, and a lava flow descending the NE flank on 4 February 2022. Courtesy of IG-EPN (INFORME DIARIO DEL VOLCAN REVENTADOR No. 2022-036, 05 de febrero de 2022).

Similar activity was reported during March, with 3-68 daily explosions producing gas-and-ash plumes 500-1,300 m high that drifted in various directions. Intermittent nighttime incandescence was observed in the upper part of the volcano, though clouds would often cover clear views of the summit. LP-type events ranged from 23 to 80 and emission tremor events occurred 1-54 times. An incandescent block avalanche was reported during 2-3 March that traveled as far as 500 m down the W flank. A pyroclastic flow on 2 March descended the S and SE flanks (figure 156). On 5 March an incandescent lava flow moved 800 m down the SE flank. During 6-7 March a lava flow was reported on the NE flank and incandescent block avalanches descended the E flank 800 m below the crater. On 8 March the lava flow continued to be active down the NE flank, while at night in thermal images traces of pyroclastic material was visible in the E flank. During the morning of 9 March ashfall was reported by IG personnel. The emitted mass of sulfur dioxide was measured as 18.4 tons by the MOUNTS system on 10 March; during the next day 1,373 tons were detected by the MOUNTS system. At night during 10-11 March, incandescent block avalanches descended all flanks 400 m below the crater. On 24 March a lava flow was identified in a thermal image as it descended the NNE flank.

Figure 156. Webcam image showed an ash plume rising about 1 km above the crater from Reventador. A pyroclastic flow also accompanied this activity, which descended the S and SE flanks. Courtesy of IG-EPN (INFORME DIARIO DEL VOLCAN REVENTADOR No. 2022-062, 03 de marzo de 2022).

During April, there were 9-72 daily explosions detected, which generated ash plumes 500-1,600 m above the crater that drifted in multiple directions. LP-type events continued and ranged from 25-87 each day. Emission tremor events occurred 5-59 times each day. Intermittent nighttime and early morning incandescence was also observed in the crater, although occasionally cloud cover prevented clear views of the summit. During 4-5 April incandescent block avalanches were observed descending up to 400 m on all flanks. On 9 April an infrared image showed an active lava flow descending the NE flank. Incandescent block avalanches continued to occur throughout the month, descending multiple flanks (figure 157). During 20-21 April incandescent block avalanches moved 500 m below the summit crater. On 23 April a strong ash plume rose higher than 600 m and drifted NE, NW, and W, according to IG-EPN (figure 158). There was no seismic data recorded during 25-31 April. During the night of 27-28 April incandescent block avalanches descended 400 m down all flanks of the volcano, and the next night descended to 600 m below the summit.

Figure 157. Webcam infrared image showed incandescent block avalanches descending all the flanks of Reventador on 14 April 2022. Courtesy of IG-EPN (INFORME DIARIO DEL VOLCAN REVENTADOR No. 2022-104, 14 de abril de 2022).

Figure 158. Webcam image of a strong ash plume drifting NE from Reventador on 23 April 2022. Courtesy of IG-EPN (INFORME DIARIO DEL VOLCAN REVENTADOR No. 2022-113, 23 de abril de 2022).

Activity during May consisted of occasional nighttime crater incandescence. There were 10-79 daily explosions detected throughout the month, which produced gas-and-ash plumes that rose 600-1,900 m above the crater and drifted NW, W, NE, N, SW, and S. Intermittent nighttime crater incandescent persisted, though was not always visible due to cloud cover. There were 12-95 LP-type events and 3-25 tremor emission events detected daily. A lahar was detected during 3-4 May due to rainfall. During the night and early morning of 3-7 May incandescent block avalanches descended 400-600 m below the crater on all flanks. On 3 May the MOUNTS system recorded 50 tons of sulfur dioxide emissions. According to the Washington VAAC a gas-and-ash plume rose 1.9 km above the crater and drifted W during 5-6 May. On 9 May a new lava flow was observed in a thermal image that descended 600 m below the crater on the NE flank, which persisted at least through 19 May. IG-EPN reported lahars occurred due to rainfall during 15-16 May. On 29 May a strong ash plume rose 700-1,000 m above the crater and drifted NW (figure 159).

Figure 159. Webcam image of a strong ash plume drifting NW from Reventador on 28 May 2022. Courtesy of IG-EPN (INFORME DIARIO DEL VOLCAN REVENTADOR No. 2022-149, 29 de mayo de 2022).

During June, 11-98 daily explosions produced gas-and-ash plumes that rose 388-1,900 m high and drifted W, SW, NW, NE, N, and SE. LP-type events continued at a rate of 37-102 per day and emission tremor events of 2-35 throughout the month. Nighttime and early morning incandescence was occasionally visible throughout the month, though sometimes clouds covered the summit. On 7 June incandescent material was observed descending all the flanks.

Similar activity persisted during July with 14-105 daily explosions. There were 22-104 LP-type events, and 2-31 emission tremor events detected each day throughout the month. Gas-and-ash plumes rose 500-1,600 m high and drifted W, NW, SW, S, NE (figure 160). Intermittent crater incandescence was reported during the night and early morning. On 1 July, crater incandescence was visible, accompanied by ash emissions up to 700 m high that drifted N on 1 July. Intermittent crater incandescence continued to be visible throughout the month. On 5 July an infrared image showed a new lava flow descending the N flank, which continued the next day down the NE flank. During 7-15 and 28-31 July IGP-EN reported an incandescent block avalanche descending all flanks for 300-600 m below the crater. During 13-14 July an incandescent avalanche descended the S flank and was accompanied by continuous gas-and-steam and ash emissions that rose 900 m high that drifted W. During 21-31 July a lava flow was reported descending the NE flank, though it remained confined to the upper part of the volcano.

Figure 160. Webcam image of a strong ash plume rising from Reventador on 19 July 2022. Courtesy of IG-EPN (INFORME DIARIO DEL VOLCAN REVENTADOR No. 2022-200, 19 de julio de 2022).

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed intermittent thermal anomalies of varying intensity during February through July 2022, which was most likely represented by incandescent block avalanches and lava flows throughout that time (figure 161). In comparison, 13 thermal anomalies were detected by the MODVOLC thermal algorithm on 18 and 25 March, 10, 21, and 30 May, 6, 9, and 15 June, and 8 and 31 July. Although the summit was often obscured by clouds, Sentinel-2 infrared satellite images showed some of this incandescence at the summit and NE flanks (figure 162).

Figure 161. Intermittent thermal activity was detected at Reventador at varying levels during January through July 2022, based on this MIROVA graph (Log Radiative Power). A small cluster of anomalies were recorded during late May and mid-June. Courtesy of MIROVA.

Figure 162. Sentinel-2 infrared satellite images of Reventador on 15 June and July (left and right, respectively) showing a small thermal anomaly at the summit crater and on the NE flank. Images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

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 about 1,300 m 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 constructed a debris plain on the eastern floor of the scarp. 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-EPN), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); 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).

Popocatépetl, located 70 km SE of Mexico City, Mexico, contains a 400 x 600 m wide summit crater. Records of activity date back to the 14th century. The current eruption period has been ongoing since January 2005 and has included numerous episodes of lava-dome growth and destruction within the summit caldera. Recent activity has consisted of continuous minor ash emissions and crater incandescence (BGVN 47:04). This report covers the period from February through July 2022, characterized by daily low-intensity gas-and-ash emissions, volcano-tectonic tremors, and crater incandescence, based on information from México's Centro Nacional de Prevención de Desastres (CENAPRED) and various satellite data.

Gas-and-steam emissions, some of which contained ash, continued from February through July 2022. CENAPRED reported the number of low-intensity gas-and-ash emissions or “exhalations” and the number of minutes of tremor in their daily reports (figure 192). A total of 120 volcano-tectonic (VT) tremors were detected throughout the reporting period. The average number of gas-and-ash emissions was 26 per day, with a maximum number of 86 on 24 February. Strong sulfur dioxide plumes were often visible in satellite data from the TROPOMI instrument on the Sentinel-5P satellite (figure 193).

Figure 192. CENAPRED reported the number of daily “exhalations” (in blue, left scale), and the number of minutes of tremor (in gold, right scale) at Popocatépetl each day during February through July 2022. The number of daily exhalations fluctuated throughout the period, reaching as high as 86 on 24 February 2022 and continuing to fluctuate. There were five distinct periods of tremor that occurred during late February to mid-March, late March, mid-April, late April to early May, and June through July. On 6 March a maximum duration of 1,265 minutes of tremor was detected. Data from CENAPRED daily reports.

Figure 193. Moderate to strong sulfur dioxide plumes were detected at Popocatépetl and drifted in different directions, as seen on 5 February 2022 (top left), 13 March 2022 (top middle), 15 April 2022 (top right), 5 May 2022 (bottom left), 7 June 2022 (bottom middle), and 3 July 2022 (bottom right). Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

During February through March, daily gas-and-steam and minor ash emissions were reported, along with intermittent tremor starting in late February. There were 42 VT-type events detected during the two months. On average, 32 exhalations occurred each day, which consisted mostly of water vapor, volcanic gases, and a small amount of ash. On 17 February at 0715 a minor explosion was detected (figure 194). On 23 February personnel from the Institute of Geophysics of the National Autonomous University of Mexico (UNAM) and the Center National for Disaster Prevention (CENAPRED), with the support of the National Guard, conducted an overflight of the volcano. They reported that the interior of the crater had an approximate diameter of 390-410 m and a depth of 160-200 m (figure 194). Remains of lava domes were also visible on the bottom of the crater. Slight ashfall was reported during 23-24 February in Atlautla, Ozumba, and Tepetlixpa. A moderate explosion was reported on 4 March at 0959 (figure 195). On 8 March, three low-intensity exhalations recorded at 0617, 0620, and 0623 were accompanied by an increase in ash emissions that drifted NE. A moderate explosion was reported on 29 March, which resulted in slight ashfall was reported in San Pedro Benito Juárez, a municipality of Atlixco on 30 March.

Figure 194. Webcam image showing a strong gas-and-ash plume rising above Popocatépetl on 17 February 2022. Courtesy of CENAPRED daily report.

Figure 195. Webcam image showing an ash plume rising about Popocatépetl on 4 March 2022. Courtesy of CENAPRED daily report.

During April through July, activity remained consistent with daily gas-and-steam emissions that sometimes contained minor amounts of ash, and occasional tremor events. There were 78 VT-type events that occurred during this time and an average of 23 daily exhalations were reported. Two minor explosions were reported on 21 April at 0152 and 0559. On 30 April some nighttime incandescence was visible (figure 196). An exhalation reported at 0728 on 1 June ejected some ash that rose 500 m high and drifted SW. A small exhalation occurred on at 0913 on 28 June that ejected minor ash emissions to 1 km high and drifted WNW. A low intensity exhalation at 1826 on 1 July ejected small amounts of ash that rose 2.5 km high and drifted NW.

Figure 196. Webcam image showing nighttime crater incandescence from Popocatépetl on 30 April 2022. Courtesy of CENAPRED daily report.

MODIS thermal anomaly data provided through MIROVA (Middle InfraRed Observation of Volcanic Activity) showed low- to moderate-level intermittent thermal activity during February through July, with a period of low activity during March through mid-April (figure 197). According to data from MODVOLC thermal alerts, a total of five hotspots were detected at the summit on 7 April, 29 May, 30 June, and 12, 19, and 23 July. Hotspots were also visible in the summit crater in infrared satellite data from Sentinel-2 (figure 198).

Figure 197. The MIROVA graph of thermal anomalies at Popocatépetl from 29 January through July 2022 shows low- to moderate-level, intermittent activity during February through July, with a period of low activity during March through mid-April. Courtesy of MIROVA.

Figure 198. Sentinel-2 infrared satellite images showing thermal anomalies in the summit crater of Popocatépetl on 5 February (top left), 2 March (top right), 1 April (middle left), 26 May (middle right), 30 June (bottom right), and 10 July 2022 (bottom right). Occasional gas-and-steam emissions accompanied these anomalies. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Geologic Background. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.

Information Contacts: Centro Nacional de Prevención de Desastres (CENAPRED), Av. Delfín Madrigal No.665. Coyoacan, México D.F. 04360, México (URL: http://www.cenapred.unam.mx/, Daily Report Archive https://www.gob.mx/cenapred/archivo/articulos); 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).

The Santiaguito lava-dome complex of Guatemala's Santa María volcano has been actively erupting since 1922. It formed within a large crater on the SW flank which was created during the 1902 eruption. Ash explosions, pyroclastic flows, and lava flows have emerged from Caliente, the youngest of the four vents in the complex, for more than 40 years. The Caliente vent has an elevation of about 2.5 km, and the summit of Santa Maria is at about 3.7 km elevation. A lava dome that appeared within the summit crater of Caliente in October 2016 has continued to grow, producing frequent block avalanches down the flanks. Recent activity, including frequent explosions, ash plumes, and block avalanches (BGVN 47:04), continued during February through July 2022, described here using information from Guatemala's INSIVUMEH (Instituto Nacional de Sismologia, Vulcanologia, Meterologia e Hidrologia) and satellite data.

Activity during February consisted of white-to-gray gas-and-steam emissions that rose to 200-800 m above the dome and drifted N, W, and SW. Moderate avalanches were reported down the SW, W, S, and NE flanks. Many of these avalanches reached the base of the lava dome and caused ashfall to the W and SW of the volcano, which primarily affected Loma Linda (6 km WSW) and San Marcos Palajunoj (8 km SW). The Caliente lava dome continued to grow and show nighttime and early morning crater incandescence as lava effusions occurred to the WSW. Resulting block-and-ash avalanches occurred frequently throughout the month. On 2 February ashfall was reported in Loma Linda Palajunoj and San Marcos Palajunoj. On 3 February pyroclastic flows were recorded at 0303, 0327, and 0633 that descended the SW and W flanks. As a result, fine ash particles were also generated, moving W and SW, some of which was reported in San Martin Sacatepéquez (11 km NW), Llanos del Pinal (6 km NNE), Xecaracoj (7 km NNE), Loma Linda, and El Palmar (12 km SSW), all in the department of Quetzaltenango. A distinct sulfur smell was detected 7 and 8 km SW of the volcano on 3 and 4 February, respectively. During the night and early morning of 4-5 February weak incandescence was visible from the Caliente dome and lava flows were reported on the W flank. Avalanches remobilized ash to 4 km altitude, which drifted as far as 30 km to the SSW. Two lava flows were reported on the W and SW flanks on 6 February, measuring 500 and 700 m long, respectively. Ashfall was reported in San Marcos Palajunoj, San Luis, and San Sebastián. Crater incandescence at the Caliente dome persisted. A lahar descended the San Isidro River, a SSW-flank tributary of the Tambor River, on 8 February. By 11 February the two lava flows on the W and SW flank reached 600 and 800 m long, respectively, and ash that was generated by frequent avalanches was deposited in Loma Linda Palajunoj and San Marcos Palajunoj. On 26 February incandescence was visible as high as 75 m above the dome.

During March, gas-and-steam emissions that rose 100-1,000 m high over the Caliente dome drifted in different directions. Weak to moderate block avalanches affected the SW, W, and S flanks, causing fine ashfall around the perimeter of the volcano. Nighttime and early morning crater incandescence was consistently visible; lava effusions in the WSW direction persisted in the lava dome. Lava flows remained active on the W and SW flanks. The front of the lava flow in the San Isidro river showed signs of collapse on 24 and 29 March, which generated an ash plume 300 m high.

Similar eruptive activity continued during April, with gas-and-steam emissions rising 50-800 m above the crater and drifted dominantly W and SW. Nighttime crater incandescence in the vicinity of the lava dome persisted, as the lava flows on the W and SW flanks remained active. Fine ash deposits were visible on the SW flank on 1 April. A sulfur odor was intermittently during the month. Avalanches of variable strength were recorded in the front of the lava flows on mainly the W and SW flanks, as well as on the SE, S, and N flanks. The avalanches also generate ash plumes that move W, depositing ashfall on San Marcos Palajunoj and Loma Linda Palajunoj during 2-3 April. Residents also reported the smell of sulfur in Las Marias. Collapses from the lava flow front into the San Isidro river on 4, 10, and 16 April generated ash plumes up to 300 m high. By 14 April the lava flow had reached 2,100 m elevation, with material piling up at the front of the flow as well as around the Caliente dome. Ashfall was reported in San Marcos Palajunoj and Loma Linda Palajunoj that same day.

White-to-gray gas-and-steam emissions continued to rise 400-800 m above the crater and drifted in various directions during May. Nighttime and early morning incandescence was observed from the growing Caliente lava dome and the active lava flows on the W and SW flanks. Weak to moderate avalanches were recorded at the front of the flows on the W and SW flanks, as well as down the S flank. Occasional ashfall deposits and the smell of sulfur were reported in communities around the volcano. During 9-15 May suspended ash was reported in multiple locations. On 14 and 20 May incandescence was visible at night 75 m above the Caliente dome; the lava flow remained active on the W and SW flanks. On 22 May collapses at the front of the lava flow, which measured 3 km long, produced an ash plume 300 m high. Ash deposits were reported during 22-23 May near the summit, including in El Faro, La Florida, and San José. By 24 May the lava flow reached 3.3 km long in the San Isidro river and continued to generate ash plumes to the S and SW from avalanches. On 27 May ashfall was detected in San Marcos Palajunoj and Loma Linda Palajunoj. Cement-like lahars descended the Cabello de Ángel drainage (a tributary of Nimá I on the SE flank) during 27-28 May, carrying tree trunks, branches, and blocks up to 1 m in diameter. On 29 May an ash plume was reported to 3 km altitude and weak-to-moderate avalanches and lava flows continued on the WSW and S flank.

Activity continued during June with constant gas plumes rising 200-700 m above the Caliente dome that drifted as far as 5 km E and 8 km SW. Weak avalanches were constantly observed on the W, SW, and S flanks, as well as in the dome. A lava flow continued to descend the SW and W flanks, which resulted in weak avalanches, incandescence, and some ashfall deposits. On 3 and 9 June the active lava flow in the San Isidro river produced avalanches that caused ash to rise 300 m above the crater. Occasionally a weak sulfur odor was noted around the volcano. Fine ashfall was reported in Santa Mara and Viejo Palmar on 4 June. Ashfall was also visible on 7 June in San Marcos Palajunoj, on 11 and 16 June deposits were reported in the upper part of Finca El Faro and San José Patzulin, and on 12 and 27 June deposits were visible in San Marcos Palajunoj and Loma Linda Palajunoj. Weak to moderate avalanches generated 1-km-high ash plumes that drifted SW as far as 5 km.

Activity persisted during July. White gas-and-steam emissions rose 100-700 m above the crater and drifted SW and W; on 22 and 23 July the emissions drifted as far as 6 km SW and W. Incandescence continued to be visible above the Caliente dome. Block avalanches descended the W, SW, S, and SE flanks, generating ash emissions. The active lava flow measured 3 km long on the SW and W flanks on 1 July, and by 7 July it was 3.5 km long. On 6 July an ash plume rose 1 km above the crater due to the constant avalanches down the W, SW, and S flanks. Ashfall was reported in San Marcos Palajunoj and Loma Linda Palajunoj on 9 July. By 15 July the active lava flows measured 3.8 km long, moving down the San Isidro and Tambor drainages. On 23 and 28 July the avalanches generated ash emissions that rose 800 m above the crater that extended 3 km E. Some lava flow deposits were observed in the Seco river. Ashfall deposits were reported in La Florida and Santa Marta farms on 25 July. INSIVUMEH reported that on 31 July the block avalanches generated moderate pyroclastic flows that burned parts of nearby vegetation.

Persistent thermal activity was recorded during February through July 2022, as reported by MIROVA (figure 132). The rate of the anomalies was higher during January through March, though the levels at which they occurred were relatively consistent. There was a brief gap in activity during late March through late April, where few low- to moderate-power anomalies were detected. During late April the anomalies continued at a slightly higher rate. The MODVOLC thermal algorithm detected a total of 59 hotspots on 3, 5, 9, 12, 14, 15, 16, 18, 20, 21, 23, 26, and 28 February, 2, 4, 6, 7, 13, 14, 15, 16, 19, and 25 March, 2, 17, 19, and 24 April, 3 May, 23 June, and 1, 5, 13, 18, and 25 July. On clear weather days, Sentinel-2 infrared satellite imagery showed a small thermal anomaly over the Caliente vent on 21 February and 7 April 2022 (figure 133).

Figure 132. Moderate-power thermal anomalies were common at Santa María during 10 January 2022 through July 2022, as seen on this MIROVA graph (Log Radiative Power). Anomalies were more frequent during January through March 2022 and remained at a relatively consistent level. There was a short gap in activity during late March through late April, when fewer anomalies were detected. Then, during late April anomalies continued, though at a lower frequency compared to January-March. Courtesy of MIROVA.

Figure 133. Sentinel-2 infrared satellite imagery showed small thermal anomalies over the Caliente vent of Santa María on 21 February and 7 April 2022 (left and right, respectively). Clouds often covered the summit. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Geologic Background. Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing W towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

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).

Kīlauea is the southeastern-most volcano in Hawaii and overlaps the E flank of the Mauna Loa shield volcano. Its East Rift Zone (ERZ) has been intermittently active for at least 2,000 years. An extended eruption period began in January 1983 and was characterized by open lava lakes and lava flows from the summit caldera and the East Rift Zone. During May 2018 lava migrated into the Lower East Rift Zone (LERZ) and opened 24 fissures along a 6-km-long NE-trending fracture zone that produced lava flows traveling in multiple directions. Lava fountaining was reported in these fissures and the lava lake in Halema’uma’u crater drained (BGVN 43:10).

The current eruption period started during September 2021 and has included seismicity, new fissures on the Halema’uma’u crater that generated lava flows, lava fountaining, and an active lava lake (BGVN 47:01). Similar activity with intermittent pauses continued during this reporting period of January through June 2022 using daily reports, volcanic activity notices, and abundant photo, map, and video data from the US Geological Survey's (USGS) Hawaiian Volcano Observatory (HVO).

Summary of activity during January-June 2022. Activity at Kīlauea consisted of intermittent lava effusions from the western vent in the Halema’uma’u crater and ooze-outs along margins of the crusted over eastern side of the lake (figure 509). The lake had risen about 70 m since lava was first detected on 29 September 2021 and measurements from a helicopter overflight on 30 December 2021 indicated that the total erupted volume of lava since September was approximately 40 million cubic meters. Activity remained confined to the crater. Summit tiltmeters and nearby seismometers detected inflation and deflation events and volcanic tremors that rose and declined in frequency, reflective of pauses in the eruption. Sulfur dioxide emissions were frequently measured, reaching as much as 4,500 t/d on 1 February.

Figure 509. Reference map of the summit eruption at Kīlauea on 7 January 2022. One eruptive vent (orange color) is intermittently active in the Halema’uma’u crater along the western edge of the lava lake, which frequently effuses lava that moves into the active portion of the lake (red color). During eruptive pauses, the only active lava is within a pond just N of the vent (purple color). The eruption statistics listed at the bottom of the map were updated on 30 December 2021. Courtesy of USGS, HVO.

Activity during January 2022. The lava lake at the Halema’uma’u crater remained active during January, showing several large overflows onto older ones and strong crater incandescence. Lava was visible at the western vent of the crater at 1445 on 31 December and remained confined to the crater. Seismicity in the summit region remained below background levels, and the sulfur dioxide emission rate was approximately 5,000 tons/day (t/d), based on measurements from 28 December. Pause events occurred throughout much of the reporting period and were characterized by lower effusion rates, deflation events, and lower volcanic tremor events. HVO issued a notice on 2 January at 0914 stating that the eruption was entering a pause, meaning that lava effusions continued, but at a much lower rate. Summit tiltmeters tracked rapid deflation during the early morning of 2 January. In addition, volcanic tremor associated with the eruption and recorded by nearby seismometers, also rapidly decreased. The lava lake began to cool at the same time. A large breakout along the northern margin of the crusted-over lava lake was observed during the morning; no effusions were reported from the western vent.

At approximately 0400 on 5 January the summit eruption at Halema’uma’u crater resumed, beginning with volcanic tremors detected at 0340 and then lava erupting from the western vent. On 6 January the sulfur dioxide emission rate was 3,300 t/d. Following another short pause, lava effused from the western vent at 1840 on 11 January, and lava ooze-outs were observed along the margins of the crusted over eastern side of the lake. The lava lake rose approximately 13 m, which was then followed by decreases in the summit tilt, tremor, and lake level. The total volume of lava erupted measured on 14 January was 45 million cubic meters. On 16 January HVO reported that lava had stopped erupting from the western vent and the level of the lake surface had dropped about 10 m. Occasional minor activity was reported at the vent on the N side of the spatter cone, as well as small lava ooze-outs along the margins of the crusted over eastern side of the lake.

After another multi-day pause, lava returned to the western vent at 1045 on 18 January and by 1630 the lava lake level had increased by about 12 m (figure 510). There were also several ooze-outs along the SE and NW margins of the lake. The active lava lake was confined to a small pond north of the western vent overnight during 20 January. Just after 0400 on the morning of 21 January the rate of effusion had increased, and the lava lake remained confined to the western half of the crater. Two overflow events were reported during the night of 21 January, with lava flowing NW, SW, and SE out of the lava lake. In addition, several ooze-out events occurred along the NW, N, SE, and S margins of the lake. By this time, the lava lake level had increased about 83 m since the beginning of the eruption period in late September 2021. Again, activity was confined to a small pond N of the western vent and several long-lived ooze-outs occurred along the margins of the E and NW side of the crater. Lava effusions into the pond were intermittent, with several hours in between short-lived periods of lava input. On 19 January the rate of sulfur dioxide emissions was 2,100 t/d and another measurement taken on 24 January showed that the rate had decreased to 58 t/d.

Figure 510. Comparison of two images of the active lava lake at Kīlauea on 18 January 2022 at 1230 (top) and 1345 (bottom). The two photos compare the active portion of the lava lake shortly after the eruption restarted when the lake level was lower (top) to when it had refilled with lava (bottom). The white arrows point to approximately the same spot on both images, the level of which is different by about one meter. Courtesy of K. Mulliken, USGS.

During the morning of 25 January at 0552 a lava flow from the top of the western vent was observed that traveled W and N along the crater margin. The lava lake began to rise around 0630 and by 0820, it had risen 11 m. Overflows from the lava lake and the small pond N of the western vent, the largest of which were on the W and S margins, continued until the afternoon. A small lava flow was noted along the N margin of the larger inactive lava lake surface during the early morning of 27 January, and a small spatter zone that was active in the E section of the crater had produced a small and steep cone. Field crews working in the caldera on 27 January noted loud gas-jetting from the new cone that had developed earlier that morning. The sulfur dioxide emission rate was measured at 2,800 t/d on 25 January, during which time lava was being erupted from the western vent.

HVO reported that on at 0800 on 29 January there was no active lava visible in the Halema’uma’u crater, which indicated a pause in activity. The lava lake depth had very gradually decreased less than one meter. Some overturning during the afternoon was observed in the eastern part of the crater, which briefly exposed surficial lava, and circulating lava was occasionally visible in the small pond N of the western vent. Then, just before 2130 on 30 January, a lava overflow in the western vent occurred, moving NW. The small pond also began to quickly fill with lava, which flowed into the lava lake and occupied the W part of the crater by 2200. The lake began to rise and was overflowing by midnight. Lava flows travel to the S and then E along the margin of the crater. Lava also began to ooze out along the N margin of the larger inactive lava lake surface just after 0500 on 31 January.

Activity during February 2022. Lava continued to intermittently erupt from the western vent in the Halema’uma’u crater during February, with overflows feeding a lava flow to the SE along the S margin of the crater until 1100 on 31 January. Multiple ooze-outs occurred intermittently along the N, E, and S margins of the crater, some of which remained weakly active, with substantial portions of the inactive E lava lake being resurfaced by these flows. A small pond to the N of the western vent also fed the active part of the lava lake via a small lava flow (figure 511). The level of the lava lake continued to fluctuate, depending on the lava supply and summit inflation or deflation. The small spatter cone near the E end of the crater was less than 6 m tall and was erupting lava fountains up to approximately 10 m high for several hours during the night of 1 February and into early the next morning. These fountains fed a short lava flow that was contained near the E margin of the crater. The sulfur dioxide emission rate was approximately 4,500 t/d measured on 1 February and during an eruptive pause they were around 330 t/d on 8 February. A particularly vigorous ooze-out was observed at the far E side of the crater during 4-5 February. Heavy rain at the summit occurred between 1320 and 1800 on 13 February, which triggered spattering in the lava lake. As a result, there were brief decreases in the level of the lake during 1330 and 1557; the lake level returned to its pre-spatter measurement within an hour of each spattering episode. The sulfur dioxide emission rate was 2,800 t/d measured on 14 February.

Figure 511. Photo of the small 20-m-wide pond to the N of the western vent in Kīlauea’s Halema’uma’u crater taken at 0930 on 1 February 2022. A small lava flow is shown feeding the active part of the lava lake. Photo was taken from the western rim of the crater. Courtesy of D. Downs, USGS.

Short-lived overflows of the active western lava lake to the W started around 1000 on 20 February, and were followed by lava flows coming from the western vent and flowing to the S and W an hour later, at 1100. Minor ooze-outs also continued intermittently along the crater floor margins. Lava continued to erupt from the western vent and move to the S, W, and into the western lava lake through the rest of the month. The sulfur dioxide emission rate was 2,500 t/d on 25 February. The Halema’uma’u crater floor had risen about 96 m since the eruption began in September 2021.

Activity during March 2022. Activity continued to fluctuate at the summit crater during March. Throughout February, the main western cone had broken down and by 4 March, lava effused from multiple vents, including the tallest cone (19 m high). The eruption was paused at 0130 on 1 March, meaning that the effusions from the western vent into the lava lake had diminished, though short-lived minor flows continued to be observed. These flows moved S, W, and into the western part of the lake, although they had stopped by the morning. Little to no ooze-outs along the crater margins were also reported. At 0100 on 2 March the eruption resumed, consisting of increased tremor that began 30 minutes earlier and continuous flows from the western vent moved to the S, W, and into the western lava lake (figure 512). During 4-5 March several ooze-outs were reported along the E and N margins of the crater floor. Spatter was also observed from the western vents on 4 March (figure 513). The total measured volume of the effusions since the start of the eruption was 53.6 million cubic meters on 4 March. During the early morning of 9 March, a small lava flow breakout began on the SE margin of the crater floor, but was already crusting over by 0900. The sulfur dioxide emission rate was approximately 2,200 t/d on 8 March and 1,900 t/d on 10 March. A sustained breakout from the NE edge of the crater began at around 1700 on 10 March and lasted until about 0630 the next day. On 11 March, HVO reported that lava was supplied from an embayment just N of the tallest cone in the western part of the crater, which had since grown to 27 m high (figure 514). Another small breakout occurred on the NW side of the crater floor from about 1700 on 12 March to 0500 the next day. Minor and slow crustal overturning occurred on the NW side of the crater floor during 13-14 March and began on the SE side of the crater floor edge, lasting for several hours.

Figure 512. A helicopter overflight on 2 March 2022 allowed for aerial visual and thermal imagery to be taken of the Halema’uma’u crater at Kīlauea’s summit crater. The active part of the lava lake is confined to the western part of the crater. The scale of the thermal map ranges from blue to red, with blue colors indicative of cooler temperatures and red colors indicative of warmer temperatures. Courtesy of USGS, HVO.

Figure 513. Photo of spatter erupting from the western vents in the Halema’uma’u crater at Kīlauea, near where the main cone used to be. On 4 March the tallest of these vents, at 19 m high, was seen characterized by spattering activity. Courtesy of L. Gallant, USGS.

Figure 514. Telephoto view looking east of the active lava lake in the Halema’uma’u crater at Kīlauea on 11 March 2022. The broken down remains of the main western vent cone is visible in the lower right (through the volcanic gas plume). Lava supplies the lake through a small embayment and spillway (bottom center) just N of the western vent area. Some lava spills over a narrow divide into a second smaller lake to the SE (upper right). Courtesy of N. Deligne, USGS.

At around 0700 on 16 March a lava flow that originated from the N part of the western vent area started to advance NW onto the crater floor and remained active for several hours into the early afternoon. At least one ooze-out occurred on the E crater floor. A lava flow advanced onto the NW crater floor from during noon to midnight on 18 March and 2100 to 0700 during 19-20 March. Measurements taken on 17 March showed that the total volume of lava erupted since the eruption began was 57.7 million cubic meters and the lava lake level had risen 89 m. HVO reported a notable ooze-out along the N margin of the crater floor at 0345 on 21 March and continued into the next day. Some ooze-outs were also observed along the N and S crater margins during 23-24 March. The sulfur dioxide emission rate measured on 23 March as approximately 1,400 t/d, which increased to 3,100 t/d on 29 March. Numerous and sustained ooze-outs along the margins of the crater floor continued but showed decreasing activity; by 29 March the volume of the lava effused measured 64 million cubic meters. During 30-31 March a hornito forming on the E side of the lake had a few periods of spattering throughout the day (figure 515).

Figure 515. Telephoto view looking north of the active lava lake in the Halema’uma’u crater at Kīlauea on 30 March 2022. Minor spattering is shown on the eastern margin (left) of the lava lake while circulation in the lake primarily moves from west to east (left to right). Sometimes lava can spatter up when it encounters the active lake margin, as shown in this image (right). Courtesy of N. Deligne, USGS.

Activity during April 2022. Intermittent activity continued during April with numerous and sustained ooze-outs along the NW, NE, and E half of the crater floor, occasional crustal overturning on the NW margin, and lava effusions from the western vent into the lava lake. On 6 April ooze-outs were observed along the NW margin of the crater floor, as well as the E half. The active part of the lava lake showed continuous surface activity and had risen about 1 m. The sulfur dioxide emission rate was 3,400 t/d on 5 April and 3,200 t/d on 6 April. The crater floor had risen about 99 m since the beginning of the eruption, and approximately 66 million cubic meters of lava had been erupted. Overnight on 8 April a small breakout from the active western part of the lava lake was observed, in addition to a small ooze-out along the E lake margin. Small ooze-outs were also detected during 9-10 April along the NW, E, and SE lake margins. Shortly after 2315 on 10 April a surface flow emerged from the S side of the western vent. The flow traveled S on the crater floor and covered the SW and W lake margin and remained active through 14 April. The sulfur dioxide emission rate measured 1,300 t/d on 8 April. Sporadic lava breakouts also occurred along the E, NE, S, and N lake margins. By 17 April lava flowed from the breakouts along the margins of the crater: N to the NE, and a smaller one to the S. During the morning of 27 April and into the next day, HVO reported increased roiling and spattering in the SE portion of the lake, particularly to the E. Sporadic breakouts also continued along the crater margins, particularly to the E. On 27 April the sulfur dioxide emission rate increased to 4,300 t/d, but dropped to 1,800 t/d by the next day.

Activity during May 2022. Lava continued to effuse into the lava lake and onto the crater floor during May; the active part of the lake showed continuous surface activity. The level of the lake fluctuated as a result of inflation, sporadic to continuous breakouts along the margins of the crater, and lava effusions. A particularly vigorous and expansive ooze-out began along the NW margin after 0200 on 5 May, accompanying relatively sluggish lava ooze-outs along the NE and S margins of the crater floor. Around 0700 on 7 May a new lava flow effused from the western vent onto the crater floor, but had stalled an hour later. The sulfur dioxide emission rate was 2,600 t/d on 4 May and 2,800 t/d on 12 May. Overflight measurements taken on 10 May indicated that the crater floor had risen about 106 m and 77 million cubic meters of lava had been effused since the September 2021. On 18 May HVO reported that the lake was draining into a small pond while spatter occurred along the margins of the crater (figure 516). This activity was also accompanied by loud whooshing and roiling noises, sometimes audible from the Keanakako‘i public overlook. On 31 May the sulfur dioxide emissions rate was 3,900 t/d.

Figure 516. Photo of the active lava lake in the Halema’uma’u crater at Kīlauea during the morning of 18 May 2022. The active lake is shown draining into a small pond to the right while spattering along the margins occurred (top center). Courtesy of L. Gallant, USGS.

Activity during June 2022. During June, lava effusions persisted from the Halema’uma’u western vent into the active lava lake, in addition to frequent ooze-outs along the E, NE, NW, W, S, and N crater floor margins and some spattering activity at the margins. Minor fluctuations in the lava lake level were also recorded throughout the month due to consistent surface activity. The sulfur dioxide emission rate was approximately 2,500 t/d on 2 June and 1,350 t/d on 10 June. On 10 June an overflow from the western vent produced a lava flow that moved onto the W side of the crater floor. Overflight measurements made on 17 June indicated that the crater floor had risen about 120 m and that 93 million cubic meters of lava had been effused since the start of the eruption (figure 517). On 24 June there was a small zone of weak ooze-outs effusing from the crater floor (figure 518). The sulfur dioxide emission rates were measured again on 23 and 29 June that were 3,000 t/d and 1,200 t/d, respectively.

Figure 517. Reference map of the summit eruption at Kīlauea on 17 June 2022. One eruptive vent (orange color) was active in the Halema’uma’u crater along the western edge of the lava lake, which frequently effused lava that moved into the active portion of the lake (red color). An adjacent pond (purple color) fed lava to a larger lake (light red), though at times the lava level declined and circulation decreased. Lava was visible from three public visitor overlooks in Hawai‘i Volcanoes National Park: Keanakako‘i Overlook and Kupina‘i Pali (Waldron Ledge) can see the eruptive vent and lava lake, while Kīlauea Overlook occasionally saw lava ooze-outs in the southeast part of the crater. The eruption statistics listed at the bottom of the map were updated on 21 June 2022. Courtesy of USGS, HVO.

Figure 518. Photo looking just north of the main lava lake in Halema’uma’u crater at Kīlauea showing a small zone of weak ooze-outs effusing from the crater floor on 24 June 2022. Courtesy of M. Patrick, USGS.

Geologic Background. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.

Information Contacts: Hawaiian Volcano Observatory (HVO), U.S. Geological Survey, PO Box 51, Hawai'i National Park, HI 96718, USA (URL: http://hvo.wr.usgs.gov/).

Masaya comprises a 6.5 x 11.5 km caldera consisting of the Nindirí, San Pedro, San Juan, and Santiago craters. The Santiago crater is currently the most active and contains a small lava lake that emits weak gas-and-steam plumes. It is located about 20 km SE of Managua, the capital of Nicaragua. The current eruption period began in October 2015 and has more recently consisted of an active lava lake and gas-and-steam emissions (BGVN 47:01). This report covers activity during January through July 2022, characterized by weak thermal activity in the lava lake, gas-and-steam emissions, and seismicity based on Instituto Nicaragüense de Estudios Territoriales (INETER) monthly reports and satellite data.

MIROVA (Middle InfraRed Observation of Volcanic Activity) analysis of MODIS satellite data showed nine low-power thermal anomalies during January 2022, which then decreased to one anomaly in late February, two in March, three in May, and one in June (figure 104). A weak hotspot was also reflected in Sentinel-2 infrared satellite images during January through July in the Santiago crater’s lava lake (figure 105). Few weak sulfur dioxide plumes drifted generally W during mid-January, late April, and May, based on data from the TROPOMI instrument on the Sentinel-5P satellite.

Figure 104. Low-power thermal anomalies were intermittently detected at Masaya during January through early June 2022, as shown on this MIROVA graph (Log Radiative Power). Nine anomalies were recorded throughout January, one in late February, two in late March, three in May, and one in early June. No hotspots were reported during April and July. Courtesy of MIROVA.

Figure 105. Sentinel-2 infrared satellite imagery showed small thermal anomalies (bright yellow-orange) at the active lava lake in Masaya’s Santiago crater during 3 January 2022 (top left), 7 February 2022 (top right), 3 April 2022 (bottom left), 28 May 2022 (bottom right). Occasional gas-and-steam emissions were also visible. Images with "Atmospheric penetration" (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

Activity was relatively low throughout the reporting period. Seismic tremor continued to be detected, varying between 80-100 RSAM units; roughly 21,352 seismic events, some of which were low frequency (LF), were recorded between January and July 2022, the most of which occurred in April (6,637). On 7 February, INETER measured the temperature of the Santiago crater, in addition to taking thermal images and Multigas measurements. Landslides and erosion were also recorded on the internal walls of the crater and lava lake, accompanied by white gas-and-steam emissions. The maximum temperature was 904.3°C, which INETER reported was higher than previous months, based on data from FLIR (forward-looking infrared) images. Sulfur dioxide measurements made during March were an average of 1,001 tons/day (t/d), based on data from several transects using a mobile DOAS spectrometer, which was lower than the measurements taken during February (1,844 tons/day). On 2 March INETER observed that the lava lake level had decreased, which obscured clear views. The temperature of the lava lake remained between the typical range of 500-800°C. During April the sulfur dioxide emissions measured 1,206 t/d, which had increased slightly from the previous month.

During 2-18 May a seismic swarm occurred in the Ticuantepe, which is located to the NW of the Santiago crater (figure 106). There were 43 earthquakes that were detected and on 10 May, a strong Mw 3.5 earthquake was felt by the entire population of Ticuantepe, some in Masaya, and some in Managua. The typical range of the magnitude of these earthquakes was 1.1-3.5 with a depth ranging 4-7 km. On 25 May at 1258 an Mw 5.2 earthquake was detected at a depth of 24 km, located 102 km SW of Managua. On 10 May temperature measurements made in the Santiago crater were 657°C and there was subsidence of about 2 m. The volume of sulfur dioxide emissions continued to decrease to an average of 661 t/d during June.

Figure 106. Location map of the epicenters of the earthquakes that occurred near Masaya during 2-18 May 2022. The red dots represent the earthquakes. The Santiago crater is labeled. Courtesy of INETER (Boletin Sismológico, Vulcanológico y Geológico Mayo, 2022).

Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras caldera and is itself a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The Nindirí and Masaya cones, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6,500 years ago. Historical lava flows cover much of the caldera floor and there is a lake at the far eastern end. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals have caused health hazards and crop damage.

Information Contacts: Instituto Nicaragüense de Estudios Territoriales (INETER), Apartado Postal 2110, Managua, Nicaragua (URL: http://www.ineter.gob.ni/); 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/); 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).

Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia, covering more than 200 km². It contains the 1-km-wide, 240-m-deep Arenas crater that occupies the summit. Eruptions are dated to 8,600 years before present, including observed activity since 1570. This current eruption period has been ongoing since November 2014 and has more recently consisted of continued dome growth, ash emissions, ashfall, and seismicity. This report covers intermittent ash emissions, ashfall, thermal activity, and seismicity during January through July 2022 based on information from the Servicio Geologico Colombiano (SGC) and the Observatorio Vulcanológico y Sismológico de Manizales and various satellite data.

Occasional thermal anomalies were recorded during January through July 2022, with the highest number of anomalies detected during January through February, according to the MIROVA graph (Log Radiative Power) (figure 137). Some of these anomalies were detected in the summit crater in Sentinel-2 infrared satellite imagery, accompanied by gas-and-steam emissions (figure 138). Small-to-moderate-sized sulfur dioxide plumes were often recorded with the TROPOMI instrument on the Sentinel-5P satellite (figure 139). Many of these plumes had maximum mass burdens in excess of 2 Dobson Units (DU) and drifted in multiple directions. The Washington VAAC reported that ash plumes rose to 5.8-8.5 km altitude and drifted in multiple directions. The highest plume occurred on 11 April.

Figure 137. Intermittent thermal anomalies were detected at Nevado del Ruiz during December 2021 through July 2022, according to this MIROVA graph (Log Radiative Power). A larger number of anomalies occurred during January through February, after which the frequency of the anomalies declined. Courtesy of MIROVA.

Figure 138. Sentinel-2 infrared satellite images showed occasional small thermal anomalies at the summit crater of Nevado del Ruiz on 28 January 2022 (top left), 2 February 2022 (top right), 9 March 2022 (bottom left), and 3 May 2022 (bottom right). White gas-and-steam emissions were intermittently observed in these images as well. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Figure 139. Sulfur dioxide emissions from Nevado del Ruiz were frequently recorded throughout January through July 2022 with the TOPOMI instrument on the Sentinel-5P satellite. Plumes drifted in different directions and often exceeded 2 Dobson Units (DU) on 24 January 2022 (top left), 20 February 2022 (top middle), 9 March 2022 (top right), 24 April 2022 (bottom left), 15 June 2022 (bottom middle), and 7 July 2022 (bottom right). Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Activity during January and February was relatively low and mainly consisted of seismicity in the Arenas crater. Seismic events included continuous volcanic tremor, tremor pulses, harmonic tremor, long period, and very long period earthquakes of variable intensity; these events indicated fluid movements. Drumbeat type seismicity was reported on 3, 25, 28, and 30 January and 2, 3, 4, 10, 19, 23, 26, and 28 February. According to SGC, this type of seismicity is related to the continued lava dome growth at the bottom of the crater. Gas-and-steam plumes were intermittently reported, the highest of which rose as 2.2 km above the crater on 24 January and drifted in various directions. Some of the seismic signals were associated with ash emissions and incandescence was observed in webcam images. During the night of 3 and 4 February two small explosions were observed with a FLIR camera. Gas-and-steam emissions rose as high as 2.9 km above the crater on 23 February and drifted in multiple directions. Another small explosion was reported on 11 February, which included an ash plume that rose above the crater; the Washington VAAC issued a notice that reported an ash plume that rose to 7 km altitude and drifted N at 1130.

During March and April low activity consisting of dome growth, ash emissions, and seismicity persisted. Seismicity included continuous volcanic tremor, tremor pulses, long period, and very long period earthquakes, all of which varied in intensity. Intermittent gas-and-ash emissions were also reported. Drumbeat type events were recorded on 1, 8, 9, 10, 11, 13, 16, and 22 March. Gas-and-steam emissions rose as high as 2.2 km above the crater on 13 March and drifted in multiple directions. During 9-10 April gas-and-ash emissions rose 3.3 km and 3.2 km high above the crater at 1713 and 0858 and drifting N and SW, respectively. Minor ashfall around the volcano was reported by Parque Nacional Natural Los Nevados staff. It was also visible in webcam images and from the city of Manizales (25 km N). During 25-26 April ashfall deposits were reported in Manizales and Villamaría (28 km NW), relating to gas-and-ash emissions.

Seismicity and dome growth continued during May, June, and July with continuous volcanic tremor, tremor pulses, long period, and very long period earthquakes each of variable intensities. An ash plume at 0536 on 3 May rose 2.1 km above the crater and drifted W. Resulting ashfall was detected in the municipalities of Santa Rosa de Cabal (33 km W), Dosquebradas (40 km W), Pereira (40 km WSW), and Manizales. Continued gas-and-steam emissions rose as high as 3 km above the crater on 10 May and drifted in different directions. Drumbeat type events were detected on 5, 8, and 12 May and 2, 3, 6, 7, 11, 13, 14, 15, 18, 22, and 26 June. A gas-and-ash plume rose 3 km above the volcano at 0857 on 9 May and resulted in ashfall in Manizales, Villamaría, Chinchiná (30 km WNW), Pereira, Dosquebradas, and Santa Rosa. Ashfall deposits were also detected during 25 and 26 May in Manizales and other towns located to the W and NW of the volcano. On 22 June, ashfall was reported in Manizales. During July, drumbeat-type events occurred on 11, 12, 16, and 22 July.

Geologic Background. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than 200 km2. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.

Information Contacts: Servicio Geologico Colombiano (SGC), Diagonal 53 No. 34-53 - Bogotá D.C., Colombia (URL: https://www.sgc.gov.co/volcanes); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); 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/).

Dukono has been erupting continuously since 1933, with frequent ash explosions, ash plumes, and sulfur dioxide plumes (BGVN 46:11). After a period of diminished volcanism during October 2021-March 2022 (BGVN 47:04), activity resumed its more usual heightened pattern through September 2022. The data below were primarily provided by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), also known as the Center for Volcanology and Geological Hazard Mitigation (CVGHM), the Darwin Volcanic Ash Advisory Centre (VAAC), and satellite sensors. Since 15 June 2008, the Alert Level has remained at 2 (on a scale of 1-4) and the public has been warned to remain outside of the 2-km exclusion zone (BGVN 46:11).

According to almost daily images from MAGMA Indonesia (a platform developed by PVMBG), white, gray, or dark plumes were observed almost every day during the reporting period (figure 30). According to the Darwin VAAC, plumes reached an altitude of 2.1-2.7 km (900-1,500 m above the summit) during the last week of May. PVMBG reported that during July-September 2022 plumes often rose 200-1,000 m above the summit.

Figure 30. Photo of an ash plume rising from Dukono on 28 August 2022. Courtesy of MAGMA Indonesia.

During the few days when the volcano was not obscured by weather clouds, Sentinel-2 satellite images recorded ash plumes and an occasional thermal anomaly in the summit crater (figure 31). The MIROVA system also recorded a few scattered, low-strength hotspots. Strong sulfur dioxide plumes above the volcano were detected on numerous days every month of the reporting period (figure 32), but their intensity appeared to diminish during August and September 2022.

Figure 31. Sentinel-2 satellite image of ash plume blowing W from Dukono on 24 June 2022. Sentinel-2 images with natural rendering (bands 4, 3, 2). Courtesy of Sentinel Hub Playground.

Figure 32. Example of a sulfur dioxide plume from Dukono on 5 May 2022, as detected by the TROPOMI instrument aboard the Sentinel-5P satellite. 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, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

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

Recent activity at Ibu, an Indonesian stratovolcano about 35 km SW of Dukono volcano, has included occasional low-level ash plumes, light ashfall, and thermal anomalies. This report covers similar activity during March-September 2022, using information from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM) and various satellite data. The Volcano Alert Level remained at 2 (on a scale of 1-4), 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.

According to daily reports from MAGMA Indonesia (a platform developed by PVMBG), gray-and-white ash plumes rising 200-1,000 m above the summit were observed almost every day during the reporting period, with a few plumes reaching up to 3 km above the summit (figure 39). Plume heights were variable, though higher plumes were noted during 21-29 April.

Figure 39. Webcam photo of Ibu on 16 May 2022 at 1646 local time showing an ash plume that might have risen as high as 2.5 km above the summit. Photo has been color corrected. Courtesy of MAGMA Indonesia.

Frequent thermal hotspots were detected by the MIROVA system during the reporting period (figure 40). In contrast, only a few scattered hotspots were identified by the MODIS-MODVOLC thermal alert system, and none in March or June. Satellite imagery continued to show thermal anomalies at both summit craters (figure 41), though the volcano was obscured by weather clouds on all but a few days.

Figure 40. The MIROVA (Log Radiative Power) thermal data for Ibu during the year ending in October 2022 showed numerous low-power thermal signals during March-September 2022, except for early April. Courtesy of MIROVA.

Figure 41. Sentinel-2 infrared satellite images of Ibu taken on 14 June (left) and 19 July 2022 (right) showing gray-and-white ash plume drifting W (top) and thermal signals from summit craters. Images taken with Atmospheric penetration rendering (bands 12, 11, 8A). Courtesy of Sentinel Hub Playground.

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); 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).

Raung, located in easternmost Java, Indonesia, was constructed SW of the Ijen caldera rim. The summit is truncated by a steep-walled, 2-km-wide caldera that has been the site of frequent eruptions in the past. Over 60 eruptions have been recorded since the late 16th century, consisting of explosions with ash plumes, Strombolian activity, and lava flows. The most recent eruption ended during April 2021 and was characterized by thermal and explosive activity, ash plumes, and sulfur dioxide plumes (BGVN 46:07). This report describes a new eruption during July that consisted of an ash plume and intermittent thermal anomalies that occurred through September 2022, based on reports from Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as the Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM) and various satellite data.

Activity at Raung has been relatively low since the January-April 2021 eruption, but has included occasional sulfur dioxide emissions between June 2021 and early July 2022, detected by the TROPOMI instrument on the Sentinel-5P satellite (figure 49). The emissions during 4 and 5 July 2022 formed more distinctive and stronger plumes. According to the MIROVA graph, there was a cluster of strong thermal anomalies detected during early January 2021, during March-May 2021, and May-September 2022; a period of no thermal activity followed the early January 2021 activity during November 2021-April 2022 (figure 50). Thermal activity resumed in May, which gradually increased in power in early June, and then began to decline in late June. This activity was also observed in Sentinel-2 infrared satellite imagery at the summit crater on 15 and 30 May, 9, 14, 19, 24, and 29 June, and 9, 19, and 24 July (figure 51).

Figure 49. Intermittent sulfur dioxide emissions were captured rising from Raung on 29 June 2021 (top left), 5 October 2021 (top right), 17 May 2022 (middle left), and 2 June 2022 (middle right) by the TROPOMI instrument on the Sentinel-5P satellite. Each of the plumes shown here exceed 2 DUs (Dobson Units) and drift in different directions. Stronger defined sulfur dioxide plumes were detected on 4 and 5 July 2022 (bottom left and right, respectively), and drifted SE and NE. Emissions originating further W are from Semeru. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Figure 50. Moderate to strong clusters of thermal anomalies (red dots) were detected in the summit area of Raung during early January 2021, March-May 2021, and May-September 2022 as recorded by the Sentinel-2 MODIS Thermal Volcanic Activity data (bands 12, 11, 8A). There was a break in thermal activity were also shown during November 2021-early April 2022. Courtesy of MIROVA.

Figure 51. Sentinel-2 satellite imagery showed intermittent thermal anomalies in the summit crater of Raung on 30 May 2022 (top left), 19 June 2022 (top right), 29 June 2022 (bottom left), and 9 July 2022 (bottom right). Images use “atmospheric penetration” rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

According to PVMBG, a short-lived eruption occurred at 1719 on 27 July 2022, which produced a gray ash plume that rose 1-1.5 km above the summit and drifted W and NW. A thermal anomaly was observed on 28 July in satellite images, and data from the GPS network indicated inflation. Continuous tremor events were reported during 29 July. As a result of these events, the Volcano Alert Level (VAL) was raised to 2 (on a scale of 1-4) that same day.

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

Information Contacts: 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); 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/); 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).

Tinakula is a remote stratovolcano in the SE part of the Solomon Islands. Recent activity began with an ash explosion in October 2017, followed in December 2018 by dense gas-and-steam plumes and weak thermal anomalies (BGVN 44:07, 47:02), which continued into 2022. The current report summarizes activity during January-September 2022 using satellite data, as ground observations are rarely available.

Infrared MODIS satellite data processed by MIROVA (Middle InfraRed Observation of Volcanic Activity) detected intermittent low-power thermal anomalies each month except for September 2022 when none were detected (figure 50). More frequent anomalies were detected from mid-February through March 2022.

Figure 50. Graph of thermal anomalies (Log Radiative Power) at Tinakula from the MIROVA system through September 2022. Courtesy of MIROVA.

Sentinel-2 satellite imagery showed persistent white gas-and-steam plumes rising from Tinakula during January through September 2022. Almost all observed plumes drifted W or SW and were usually profuse and dense. On the few viewing days when not obscured by the plumes or weather clouds, a thermal anomaly was visible at the summit area (figure 51); three small thermal anomalies were visible on 23 September.

Figure 51. Selected Sentinel-2 infrared satellite images of Tinakula showing a thermal anomaly at the summit and associated steam plumes on 27 March (left) and 23 September (right) 2022. Images with Atmospheric penetration (bands 12, 11, 8a) rendering. Courtesy of Sentinel Hub Playground.

Geologic Background. The small 3.5-km-wide island of Tinakula is the exposed summit of a massive stratovolcano at the NW end of the Santa Cruz islands. Similar to Stromboli, it has a breached summit crater that extends from the summit to below sea level. Landslides enlarged this scarp in 1965, creating an embayment on the NW coast. The satellitic cone of Mendana is located on the SE side. The dominantly andesitic volcano has frequently been observed in eruption since the era of Spanish exploration began in 1595. In about 1840, an explosive eruption apparently produced pyroclastic flows that swept all sides of the island, killing its inhabitants. Frequent historical eruptions have originated from a cone constructed within the large breached crater. These have left the upper flanks and the steep apron of lava flows and volcaniclastic debris within the breach unvegetated.

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).