Smithsonian / USGS Weekly Volcanic Activity Report

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday and averaging 16 reported volcanoes, this is not a comprehensive list of all eruptions this week, but rather a summary of activity that meet criteria discussed in the "Criteria and Disclaimers" section below.

Volcanic activity reported here is preliminary and subject to change. Carefully reviewed, detailed narratives over longer time periods are published as reports of the Bulletin of the Global Volcanism Network available through volcano profile pages.

Smithsonian / USGS Weekly Volcanic Activity Report for the week of 22 December-28 December 2021
Name	Country	Volcanic Province	Eruption Start Date	Report Status
Ambae	Vanuatu	Vanuatu Volcanic Arc	—	New
Fagradalsfjall	Iceland	Iceland Neovolcanic Rift Zone	—	New
Hunga Tonga-Hunga Ha'apai	Tonga	Tofua Volcanic Arc	—	New
Piton de la Fournaise	France	Reunion Hotspot Volcano Group	—	New
Semeru	Indonesia	Sunda Volcanic Arc	2017 Jun 6	New
Aira	Japan	Ryukyu Volcanic Arc	2017 Mar 25	Continuing
Great Sitkin	United States	Aleutian Ridge Volcanic Arc	2021 May 25	Continuing
Karymsky	Russia	Eastern Kamchatka Volcanic Arc	—	Continuing
Kilauea	United States	Hawaiian-Emperor Hotspot Volcano Group	—	Continuing
Laguna del Maule	Chile	Andean Southern Volcanic Arc	—	Continuing
Lewotolok	Indonesia	Sunda Volcanic Arc	2020 Nov 27	Continuing
Manam	Papua New Guinea	Bismarck Volcanic Arc	2014 Jun 29	Continuing
Merapi	Indonesia	Sunda Volcanic Arc	2020 Dec 31	Continuing
Pavlof	United States	Aleutian Ridge Volcanic Arc	—	Continuing
Reventador	Ecuador	Andean Northern Volcanic Arc	2008 Jul 27	Continuing
Rincon de la Vieja	Costa Rica	Central America Volcanic Arc	2021 Jun 28	Continuing
Sangay	Ecuador	Andean Northern Volcanic Arc	2019 Mar 26	Continuing
Semisopochnoi	United States	Aleutian Ridge Volcanic Arc	—	Continuing
Sheveluch	Russia	Eastern Kamchatka Volcanic Arc	1999 Aug 15	Continuing
Suwanosejima	Japan	Ryukyu Volcanic Arc	2004 Oct 23	Continuing
Turrialba	Costa Rica	Central America Volcanic Arc	—	Continuing
Yasur	Vanuatu	Vanuatu Volcanic Arc	1270 ± 110 years	Continuing

All times are local unless otherwise stated.

Ambae (Vanuatu) | 22 December-28 December 2021 | New Activity / Unrest Cite this Report

Ambae
Vanuatu Volcanic Arc

The Vanuatu Meteorology and Geo-Hazards Department (VMGD) raised the Alert Level for Ambae to 2 (on a scale of 0-5) on 27 December, noting confirmation of a cone that has built up in Lake Voui and increasing activity. A vent in the lake had been emitting steam-and-gas emissions and ejecting wet tephra above the lake’s surface since 5 December. The public was warned to stay outside of the Danger Zone defined as a 2-km radius around the active vents in Lake Voui and away from drainages during heavy rains.

Source: Vanuatu Meteorology and Geohazards Department (VMGD)

Fagradalsfjall (Iceland) | 22 December-28 December 2021 | New Activity / Unrest Cite this Report

Fagradalsfjall
Iceland Neovolcanic Rift Zone

Icelandic Meteorological Office (IMO) reported that the earthquake swarm at the Krýsuvík-Trölladyngja volcanic system was ongoing at least through 26 December. The swarm began at 1800 on 21 December in an area 2-4 km NE of Geldingadalir. Around 3,000 daily earthquakes recorded by the seismic network were mostly located near Fagradalsfjall volcano at depths of 5-8 km, though some were located near the town of Grindavík and lake Kleifarvatn. The swarm was episodic with periods of intense activity. Three earthquakes over M 4 were recorded near Grindavík on 24 December; the largest was a M 4.8. Deformation during 20-26 December was clear in InSAR data, and similar to the deformation observed at the end of February as the dike intrusion was starting near Fagradalsfjall. The seismicity and deformation indicated that magma was moving at depth, likely along the same dyke system that fed the previous eruption at Geldingadalir. The Aviation Color Code remained at Orange.

Source: Icelandic Meteorological Office (IMO)

Hunga Tonga-Hunga Ha'apai (Tonga) | 22 December-28 December 2021 | New Activity / Unrest Cite this Report

Hunga Tonga-Hunga Ha'apai
Tofua Volcanic Arc

The eruption at Hunga Tonga-Hunga Ha'apai that began on 20 December continued through 28 December. According to the Wellington VAAC continuous gas-and-steam plumes with diffuse ash rose 6.1-12.2 km (20,000-40,000 ft) a.s.l. and drifted NE and NNE during 22-23 December, based on pilot observations, satellite images, information from the Tonga Meteorological Office, and weather models. On 22 December Tonga Navy crew sailing near the island recorded Surtseyan explosions ejecting tephra 350 m high. The video confirmed that the vent was in the same area as the 2014 activity. According to a news article plumes of sulfur dioxide spread NNE over the Ha'apai, Vava'u, and Niuatoutapu island groups with the highest concentrations affecting the ‘Otumu‘omu‘a islands on 23 December.

Plumes became intermittent by 24 December rising to 10.4 km (34,000 ft) a.s.l. and occasionally as high as 12.2 km. Tonga Geological Services warned the public to stay outside of a 5 km radius of the vents. According to Tonga’s Lead Geologist, satellite images from 25 December showed that the island had grown 300-600 m on the E side, and ash was falling within a 10 km radius. During 25-28 December the gas-and-steam plume rose 9.1-12.2 km (30,000-40,000 ft) a.s.l. and drifted N and NE; the lower part of the plume contained ash and rose as high as 3 km (10,000 ft) a.s.l. Ashfall was confined to the vicinity of the volcano. Tonga Geological Services reported that during 27-28 December clouds of gas and steam drifted E across the ‘Otu Mu’omu’a Islands of Ha’apai at altitudes of 1-18 km (3,300-59,000 ft) a.s.l.; they warned residents to protect water reservoirs because rain may be acidic or contain traces of ash, though the plumes were predominantly drifting at high levels. One flight to Tonga was canceled on 28 December, for the second time since the eruption started.

Sources: Wellington Volcanic Ash Advisory Center (VAAC), Tonga Meteorological Services, Government of Tonga, Tonga Geological Services, Government of Tonga, Kaniva Tonga, Kaniva Tonga, Matangi Tonga Online, Matangi Tonga Online, Matangi Tonga Online, Matangi Tonga Online, Matangi Tonga Online, Matangi Tonga Online

Piton de la Fournaise (France) | 22 December-28 December 2021 | New Activity / Unrest Cite this Report

Piton de la Fournaise
Reunion Hotspot Volcano Group

OVPF reported that an eruption at Piton de la Fournaise began at 0105 on 22 December on the S flank, SE of Piton Kala Pélé and SW of Château Fort. Four fissures opened and produced lava fountains, with the lowest point of the eruption at an elevation of 2,000 m. By the evening, the eruption was focused at 2,030 m elevation where a cone was forming around the vent. The lava effusion rate based on satellite data was an estimated 4-7 meters per second, with peak rates of 22 meters per second, during 22-23 December. By 0930 on 23 December the cone was 10 m high and low lava fountains intermittently rose above the crater rim. Lava flowed from an opening at the base of the cone, though a lava tube was beginning to form; lava had descended 2.2 km SSE from the main vent. During 24-25 December lava traveled from the base of the cone hundreds of meters through a tube before it emerged and advanced in a single channel; the front of the flow had advanced slowly, only traveling an additional 300 m by 25 December. During 25-26 December the lava tube broke open and lava was again visible emerging from the base of the cone. The flow rate was between 2 and 27 meters per second, averaging 5 meters per second. A second vent at the base of the cone was visible in the morning of 27 December and lava was again flowing through a tube and then emerging downstream. Lava fountaining continued with material occasionally ejected less than 15 m above the cone during 27-28 December. The effusion rate was an estimated 2-8 meters per second, based on satellite data. The end of the lava flow had not notably advanced since the day before.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)

Semeru (Indonesia) | 22 December-28 December 2021 | New Activity / Unrest Cite this Report

Semeru
Sunda Volcanic Arc

PVMBG reported that the eruption at Semeru continued during 21-28 December. Crater incandescence was visible overnight during 22-23 December and four block avalanches traveled 800 m down the Kobokan drainage on the SE flank. Two pyroclastic flows descended the Kobokan drainage a maximum distance of 5 km. Dense gray plumes rose 500 m above the summit during 23-24 December and three avalanches of material traveled 500 m down the SE flank. At 1706 on 25 December and at 0902 on 28 December ash plumes rose 300 m above the summit and drifted SW and N, respectively. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 500 m away from Kobokan drainages within 17 km of the summit, and other drainages originating on Semeru including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Aira (Japan) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Aira
Ryukyu Volcanic Arc

JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 20-27 December. The sulfur dioxide emission rate was 600 tons per day on 20 December. Two eruptive events during 20-24 December produced plumes that rose 1.1 km above the crater rim. Very small eruptive events were detected during 24-27 December. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)

Great Sitkin (United States) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Great Sitkin
Aleutian Ridge Volcanic Arc

AVO reported that slow lava effusion at Great Sitkin continued during 21-28 December with advancing lava flows on the N, W, and S flanks. Very low seismicity persisted. Elevated surface temperatures at the summit were detected overnight during 21-24 and 26-27 December; weather clouds prevented observations during 25-26 December. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Karymsky (Russia) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Karymsky
Eastern Kamchatka Volcanic Arc

KVERT reported that a thermal anomaly over Karymsky was visible in satellite images during 16-21 December. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Kilauea (United States) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Kilauea
Hawaiian-Emperor Hotspot Volcano Group

HVO reported that lava effusion intermittently continued at a vent in the lower W wall of Kilauea’s Halema`uma`u Crater during 21-28 December. Effusion paused for a period during 21-22, and sulfur dioxide emissions were 130 tonnes per day during the pause. Strong volcanic tremor began to be recorded at 1930 on 22 December and by 2000 lava again effused from the vent into the rejuvenated a portion of the lake. The lake overflowed and fed substantial lava flows that traveled SE over older crusted parts of the lake all day on 23 December until around midnight. Lava oozed out along the E margins of the lake during 24-25 December, including onto the lowermost down-dropped block from the 2018 caldera collapse, indicating a continuing supply of lava beneath the lake’s crust. The sulfur dioxide emission rate was about 5,300 tonnes per day on 24 December, much higher than during the pause. The surface of the lava lake had begun crusting over on 25 December and by 26 December lava had again ceased erupting from the vent. An area of the lake, 50 m in diameter, to the N of the vent remained molten on 27 December. The sulfur dioxide emission rate was 125 tonnes per day during the pause. Lava again erupted from the vent later that day, beginning at 1930. The lake was incandescent around the vent and lava overflowed the margins, feeding substantial lava flows to the N and S. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

Laguna del Maule (Chile) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Laguna del Maule
Andean Southern Volcanic Arc

SERNAGEOMIN reported that inflation at Laguna del Maule continued in an area SW of the lake during 1-15 December, though deformation had been decreasing since October with a with a maximum rate of 1.88 centimeters per month. Deformation rates during November and December were comparable to those recorded prior to 2019. The number of volcano-tectonic events had also decreased; the largest event was a M 2.3 located 4.1 km ESE from the center of the lake at a depth of 6.1 km. The Alert Level for Laguna del Maule was lowered to Green, the lowest level on a four-color scale, on 24 December. ONEMI canceled the Yellow Alert for San Clemente, and reminded the public to stay 1 km away from the area producing anomalous carbon dioxide emissions, about 5 km SW of the lake’s shore.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)

Lewotolok (Indonesia) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Lewotolok
Sunda Volcanic Arc

PVMBG reported that the eruption at Lewotolok continued during 21-25 December. White-and-gray ash plumes that were sometimes dense rose as high as 600 m above the summit. Incandescent material was ejected from the vent up to 300 m in multiple directions. Rumbling, roaring, and booming were often heard. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Manam (Papua New Guinea) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Manam
Bismarck Volcanic Arc

The Darwin VAAC reported that a large thermal anomaly over Manam was identified in satellite images during 21-22 December. A discrete ash plume rose to 3.4 km (11,000 ft) a.s.l. and drifted SE on 21 December. Ash plumes may have risen to 10.7 km (35,000 ft) a.s.l. during 0137-0300 on 22 December, though weather clouds and heavy rain obscured satellite views; the plumes were unconfirmed by ground observers. At 1200 on 22 December an ash plume rose to 4.9 km (16,000 ft) a.s.l., drifted E, and dissipated within four hours.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Merapi (Indonesia) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Merapi
Sunda Volcanic Arc

BPPTKG reported no notable morphological changes to Merapi’s summit lava dome, though the dome just below the SW rim had increased about 2 m in height during 17-23 December. The estimated dome volumes were over 1.65 million cubic meters for the SW dome and just over 3 million cubic meters for the summit dome. The intensity of the seismic signals remained at high levels. As many as 112 lava avalanches traveled a maximum of 2 km SW down the Bebeng drainage, and four pyroclastic flows traveled a maximum of 2.5 km SW. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-5 km away from the summit based on location.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)

Pavlof (United States) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Pavlof
Aleutian Ridge Volcanic Arc

AVO reported that seismicity at Pavlof was elevated during 22-28 December and was mainly characterized by periods of sustained tremor and discrete low-frequency events. Numerous small explosions were recorded almost daily, and strongly elevated surface temperatures were visible in satellite images, consistent with lava effusion. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Reventador (Ecuador) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Reventador
Andean Northern Volcanic Arc

IG reported that a high level of activity continued at Reventador during 21-28 December. Gas-and-ash plumes, often observed multiple times a day with the webcam or reported by the Washington VAAC, rose as high as 1.2 km above the summit crater and drifted mainly NW, W, and SW. Crater incandescence was visible nightly, and lava flows were active on the NE and N flanks. Explosions, crater incandescence, and incandescent blocks rolling 500 m down the N and NE flanks were observed at night during 27-28 November.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)

Rincon de la Vieja (Costa Rica) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Rincon de la Vieja
Central America Volcanic Arc

OVSICORI-UNA reported that at 1015 on 25 December a small eruption at Rincón de la Vieja was recorded for about four minutes but not visually observed due to weather clouds. Rains after the event and continuing early on 26 December washed the acidic sediment deposited from the volcano downstream in the Pénjamo, Azul, and Azufrada drainages, into the aquatic ecosystem. Phreatic events were recorded at 1402 and 1630 on 28 December though weather conditions prevented visual confirmation.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Sangay (Ecuador) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Sangay
Andean Northern Volcanic Arc

IG reported a high level of activity at Sangay during 21-28 December. Seismicity was characterized by daily explosions, long-period earthquakes, and signals indicating emissions. Weather clouds and rain sometimes prevented visual and webcam observations of the volcano, though almost daily ash-and-gas plumes were identified in satellite images by the Washington VAAC or in webcam views; plumes rose as high as 1.5 km above the volcano and drifted SE, S, SW, and W. Multiple (33-73 per day) daily thermal anomalies over the volcano were visible in satellite data. On 25 December volcano observers near Macas reported hearing noises coming from Sangay, possibly due to favorable weather conditions, though the intensity of explosions had slightly increased. Crater incandescence and an active lava flow on the SE flank were visible at night during 27-28 November.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)

Semisopochnoi (United States) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Semisopochnoi
Aleutian Ridge Volcanic Arc

AVO reported that low-level eruptive activity and elevated seismicity at Semisopochnoi's North Cerberus crater continued during 22-28 December. Small explosions were detected almost daily in seismic and infrasound data. Low-level ash-and-steam emissions were observed by webcams and in satellite images during 22-25 December, when weather conditions were clear. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Sheveluch (Russia) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Sheveluch
Eastern Kamchatka Volcanic Arc

KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 17-24 December. At 1210 local time on 23 December explosions produced ash plumes that rose to 6 km (19,700 ft) a.s.l. and drifted 70 km NE. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Suwanosejima (Japan) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Suwanosejima
Ryukyu Volcanic Arc

JMA reported that crater incandescence at Suwanosejima's Ontake Crater was visible nightly during 20-27 December. The number of explosions totaled 143 during 22-24 December. Plumes rose as high as 3.1 km above the crater rim and bombs were ejected 700 m from the crater. Explosive activity increased during 24-27 December with explosions totaling 361. Plumes rose as high as 1.5 km and bombs were ejected 800 m form the vent. The Alert Level remained at 3 and the public was warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)

Turrialba (Costa Rica) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Turrialba
Central America Volcanic Arc

OVSICORI-UNA reported that an area of incandescence on the NW inner wall of Turrialba’s West Crater had been periodically visible at least since mid-November, and was visible during 26-27 December, suggesting that fumarolic temperatures exceeded 300 degrees Celsius. At 0644 on 28 December a one-minute-long eruption produced an ash emission that rose 50 m above the crater rim and drifted W. Another small eruption that produced ash emissions was recorded at 1105 by the seismicity and infrasound networks. The event was heard by authorities in the Parque Nacional Volcán Turrialba.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Yasur (Vanuatu) | 22 December-28 December 2021 | Continuing ActivityCite this Report

Yasur
Vanuatu Volcanic Arc

The Wellington VAAC reported that during 27-28 December ash emissions from Yasur were visible in webcam images rising above the crater rim, to 1.5 km (5,000 ft) a.s.l. Plumes containing ash were not visible in satellite images, though they were also confirmed by Vanuatu Meteorology and Geohazards Department (VMGD).

Source: Wellington Volcanic Ash Advisory Center (VAAC)

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Criteria & Disclaimers

Criteria

The Weekly Volcanic Activity Report does not necessarily include all volcanic activity that occurred on Earth during the week. More than a dozen volcanoes globally have displayed more-or-less continuous eruptive activity for decades or longer, and such routine activity is typically not reported here. Moreover, Earth's sea-floor volcanism is seldom reported even though in theory it represents the single most prolific source of erupted material. The Weekly Volcanic Activity Report summarizes volcanic activity that meets one or more of the following criteria:

- A volcano observatory raises or lowers the alert level at the volcano.
- A volcanic ash advisory has been released by a volcanic ash advisory center (VAAC) stating that an ash cloud has been produced from the volcano.
- A verifiable news report of new activity or a change in activity at the volcano has been issued.
- Observers have reported a significant change in volcanic activity. Such activity can include, but is not restricted to, pyroclastic flows, lahars, lava flows, dome collapse, or increased unrest.

Volcanoes are included in the "New Activity/Unrest" section of the Weekly Volcanic Activity Report if the activity occurs after at least 3 months of quiescence. Once a volcano is included in the "New Activity/Unrest" section, updates will remain in that section unless the activity continues for more than 1 month without escalating, after which time updates will be listed in the "Continuing Activity" section. Volcanoes are also included in the "New Activity/Unrest" section if the volcano is undergoing a period of relatively high unrest, or increasing unrest. This is commonly equal to Alert Level Orange on a scale of Green, Yellow, Orange, Red, where Red is the highest alert. Or alert level 3 on a scale of 1-4 or 1-5.

It is important to note that volcanic activity meeting one or more of these criteria may occur during the week, but may not be included in the Weekly Volcanic Activity Report because we did not receive a report.

Disclaimers

1. The Weekly Volcanic Activity Report is intended to provide timely information about global volcanism on a weekly basis. Consequently, the report is generated rapidly by summarizing volcanic reports from various sources, with little time for fact checking. The accuracy of the Weekly Volcanic Activity Report is dependent upon the quality of the volcanic activity reports we receive. Reports published in the Bulletin of the Global Volcanism Network are cover longer time periods and are more carefully reviewed, although all of the volcanoes discussed in the Weekly Volcanic Activity Report are not necessarily reported in the Bulletin. Because of our emphasis on rapid reporting on the web we have avoided diacritical marks. Reports are updated on the Weekly Volcanic Activity Report web page as they are received, therefore information may be included regarding events that occurred before the current report period.

2. Rapidly developing events lead to coverage that is often fragmentary. Volcanoes, their eruptions, and their plumes and associated atmospheric effects are complex phenomena that may require months to years of data analysis in order to create a comprehensive summary and interpretation of events.

3. Preliminary accounts sometimes contain exaggerations and "false alarms," and accordingly, this report may include some events ultimately found to be erroneous or misleading.

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