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 13 December-19 December 2023
Name	Location	Eruption Start Date	Report Status
Ioto	Volcano Islands	2023 Oct 18	New
Kanaga	Andreanof Islands (USA)	—	New
Lewotobi	Flores Island	2023 Dec 23	New
Marapi	Central Sumatra	2023 Dec 3	New
Raung	Eastern Java	—	New
Reykjanes	Reykjanes Peninsula	2023 Dec 18	New
Tengger Caldera	Eastern Java	—	New
Aira	Kyushu (Japan)	2017 Mar 25	Continuing
Ebeko	Paramushir Island (Russia)	2022 Jun 11	Continuing
Great Sitkin	Andreanof Islands (USA)	2021 May 25	Continuing
Ibu	Halmahera	2008 Apr 5	Continuing
Krakatau	Sunda Strait	—	Continuing
Lewotolok	Lembata Island	2020 Nov 27	Continuing
Mayon	Luzon (Philippines)	2023 Apr 27 ± 2 days	Continuing
Merapi	Central Java	2020 Dec 31	Continuing
Poas	Costa Rica	2023 Dec 1	Continuing
Popocatepetl	Mexico	2005 Jan 9	Continuing
Reventador	Ecuador	2008 Jul 27	Continuing
Sabancaya	Peru	2016 Nov 6	Continuing
Sangay	Ecuador	2019 Mar 26	Continuing
Semeru	Eastern Java	2017 Jun 6	Continuing
Sheveluch	Central Kamchatka (Russia)	1999 Aug 15	Continuing
Shishaldin	Fox Islands (USA)	—	Continuing
Suwanosejima	Ryukyu Islands (Japan)	2004 Oct 23	Continuing
Ubinas	Peru	—	Continuing
Whakaari/White Island	North Island (New Zealand)	—	Continuing

All times are local unless otherwise stated.

Ioto | 13 December-19 December 2023 | New Activity / Unrest Cite this Report

Ioto
Volcano Islands

The Japan Coast Guard conducted an overflight on 14 December of Ioto (Iwo-jima) to inspect the new island formed by an eruption from a submarine vent about 1 km off the SE coast at Okinahama. No eruptive activity was detected, but the shape of the island had notably changed due to erosion and wave action. During the previous 10 days deposits at the N part of the “J” shaped island had separated and migrated N, connecting to the Okinahama coast, and the curved part of the “J” had eroded into two smaller islands.

Sources: Japan Coast Guard, Copernicus Browser

Kanaga | 13 December-19 December 2023 | New Activity / Unrest Cite this Report

Kanaga
Andreanof Islands (USA)

AVO reported that a small explosion at Kanaga was detected in local infrasound and seismic data at 2231 on 18 December, and was followed by elevated seismicity. No ash emissions were detected in partly cloudy satellite images. The next day the Volcano Alert Level was raised to Advisory (the second level on a four-level scale) and the Aviation Color Code was raised to Yellow (the second color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Lewotobi | 13 December-19 December 2023 | New Activity / Unrest Cite this Report

Lewotobi
Flores Island

On 17 December seismicity at Lewotobi increased significantly, prompting PVMBG to raise the Alert Level to 2 (on a scale of 1-4). Seismicity had been increasing during the previous week and was characterized by greater numbers of both deep and shallow volcanic earthquakes, and the emergence of tornillo-type earthquakes which indicated fluid movement. The public was warned to stay 2 km away from the craters at each summit.

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

Marapi | 13 December-19 December 2023 | New Activity / Unrest Cite this Report

Marapi
Central Sumatra

PVMBG reported that eruptive activity at Marapi (on Sumatra) was ongoing during 13-19 December, though foggy and raining weather conditions often prevented visual observations of the summit. White-and-gray ash plumes that were sometimes dense rose 400-600 m and drifted S, SW, NW, and NE during 13-15 and 18 December. The Alert Level remained at 2 (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)

Raung | 13 December-19 December 2023 | New Activity / Unrest Cite this Report

Raung
Eastern Java

PVMBG reported that during 1-17 December the maximum height of steam-and-gas plumes at Raung was 500 m above the summit. An M 2.6 local tectonic earthquake was detected on 18 December and afterwards plumes rose as high as 1 km. Seismicity during December indicated that fluid movement was concentrated at shallow depths; signals indicating emissions significantly increased on 18 December. Deformation data indicated a trend of deflation. On 18 December PVMBG raised the Alert Level to 2 (on a scale of 1-4) noting that the visual observations and seismic data indicated unstable conditions. The pubic was warned to stay 3 km away from the summit crater.

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

Reykjanes | 13 December-19 December 2023 | New Activity / Unrest Cite this Report

Reykjanes
Reykjanes Peninsula

IMO reported that a new eruption on the Reykjanes peninsula began at 2217 on 18 December from fissures that opened in a location close to the older Sundhnúkagígar crater row, about 3 km NE of the town of Grindavík. A magmatic dike began intruding beneath the area in late October based on seismic and deformation data; magma continued to flow into the dike causing ground cracking in areas along its axis. The eruption was immediately preceded by an earthquake swarm that began at 2100 on 18 December and the opening of the fissure was accompanied by significant ground deformation.

Increased seismicity and a burst of incandescence indicating the start of the eruption was seen in webcam images. IMO raised the Aviation Color Code to Red (the highest level on a four-color scale) until the situation was able to be evaluated and in case ash was present in any emissions. After the first fissure opened, it propagated S in a series of four additional segments, slightly offset from each other but aligned with the previous dike intrusion. The total length of the fissure was estimated to be 4 km, with the north end just E of the Stóra-Skógfell cones and the south end E of the Sundhnúk cone. Large lava fountains possibly rose hundreds of meters high along the fissures, feeding lava flows in multiple directions. The rate of lava discharge during the first two hours of the eruption was about 100-200 cubic meters per second. The tallest lava fountains were located on the N end of the fissure. The largest earthquake, a M 4.1, was recorded at 2325. The Aviation Color Code was lowered to Orange. By midnight seismicity had declined and the eruption was less intense.

During a second overflight with the Iceland Coast Guard at around 0400 on 19 December scientists noted that the fissure had stopped extending and that most of the activity was concentrated in the central portion. There was minor activity at the S end, near the Hagafell cone, and most of the lava was advancing E towards Fagradalsfjall. Two branches traveled W, remaining N of Stóra-Skógfell. Gas plumes drifted W and NW. Residents of Grindavík, evacuated in November due to ground cracking and unsafe conditions, had recently been allowed to return and allowed to stay until 2100, but not overnight; they again fully evacuated the town due to the eruption. The recently reopened Blue Lagoon resort closed again. Some area roads were also temporarily closed.

Eruptive activity concentrated at five vents during the early part of 19 December. By 1430 the lava discharge rate was about one-fourth the rate measured at the beginning of the eruption and about one-third of the fissure was active. Lava fountains were lower, rising as high as about 30 m. The eruption intensity continued to decline and by 1830 only three vents were erupting. About 5 cm of deflation was detected in Svartsengi; a total of 35 cm of uplift had been recorded there since the beginning of the dike intrusion in November. The power plant in Svartsengi, W of the fissure, was not threatened by the current lava flows, though construction of an earthen barrier around it and the Blue Lagoon continued.

Sources: Icelandic Meteorological Office (IMO), Icelandic National Broadcasting Service (RUV)

Tengger Caldera | 13 December-19 December 2023 | New Activity / Unrest Cite this Report

Tengger Caldera
Eastern Java

PVMBG reported increased activity at Tengger Caldera’s Bromo cone in a 13 December press release. Emissions that day were white, gray, and brown, had variable densities, and rose as high as 900 m above the summit. The plumes drifted in multiple directions. The report noted that tremor was continuous and accompanied in December by three volcanic earthquakes. Deformation data indicated inflation in December. Daily white emissions that rose as high as 700 m above the summit and drifted in multiple directions were visible through 18 December. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.

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

Aira | 13 December-19 December 2023 | Continuing ActivityCite this Report

Aira
Kyushu (Japan)

JMA reported ongoing activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 11-18 December, with incandescence at the crater observed nightly. Small eruptive events were occasionally recorded through the week. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 km away from both craters.

Source: Japan Meteorological Agency (JMA)

Ebeko | 13 December-19 December 2023 | Continuing ActivityCite this Report

Ebeko
Paramushir Island (Russia)

KVERT reported that moderate explosive activity was ongoing at Ebeko during 7-14 December. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 7 and 11-12 December generated ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l and drifted NE. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are UTC; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Great Sitkin | 13 December-19 December 2023 | Continuing ActivityCite this Report

Great Sitkin
Andreanof Islands (USA)

AVO reported that an 11 December radar image of Great Sitkin showed continuing growth of a thick flow in the summit crater; effusion likely continued during 12-19 December. Weather clouds often obscured views of the volcano, though no notable activity was visible in a few clear webcam images on 15 December. Seismicity was low. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Ibu | 13 December-19 December 2023 | Continuing ActivityCite this Report

Ibu
Halmahera

PVMBG reported that Ibu continued to erupt during 13-19 December. Daily white-and-gray ash emissions that were sometimes dense rose 200-1,300 m above the summit and drifted in multiple directions during 13-16 December. The Alert Level remained at a 2 (the second highest level on a four-level scale), with the public advised to stay outside of the 2 km hazard zone and 3.5 km away from the N area of the active crater.

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

Krakatau | 13 December-19 December 2023 | Continuing ActivityCite this Report

Krakatau
Sunda Strait

PVMBG reported that the eruption at Krakatau continued during 13-19 December. White-and-gray ash plumes that were sometimes dense rose as high as 1 km above the summit and drifted NE and N during 13-16 December. Some webcam images posted with the daily reports showed incandescence at the vent. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay at least 5 km away from the crater.

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

Lewotolok | 13 December-19 December 2023 | Continuing ActivityCite this Report

Lewotolok
Lembata Island

PVMBG reported that the eruption at Lewotolok continued during 13-19 December. White-and-gray ash plumes rose 100 m on 13 December and drifted E. White steam-and-gas plumes rose 100-200 m above the summit on the other days and drifted E, NE, and NW. Incandescence lava was ejected 200 m from the vent on 15 and 18 December and summit incandescence was visible in webcam images on 16 and 19 December. The 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 summit crater.

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

Mayon | 13 December-19 December 2023 | Continuing ActivityCite this Report

Mayon
Luzon (Philippines)

PHIVOLCS characterized activity at Mayon as “decreased unrest” during 12-19 December. The seismic network recorded 1-4 daily volcanic earthquakes and 1-2 rockfall events during 12-15 December. The summit was occasionally obscured by weather conditions, though on most days emissions were visible drifting in multiple directions. The Tokyo VAAC reported that at 1447 on 17 December an ash emission was identified in a satellite image rising to 2.4 km (8,000 ft) a.s.l. and drifting WSW based on satellite data and information from PHIVOLCS. The Alert Level remained at 2 (on a 0-5 scale). Residents were reminded to stay away from the 6-km-radius Permanent Danger Zone (PDZ) and pilots were advised to avoid flying close to the summit.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Merapi | 13 December-19 December 2023 | Continuing ActivityCite this Report

Merapi
Central Java

BPPTKG reported that the eruption at Merapi (on Java) continued during 8-14 December. A series of pyroclastic flows traveled 3.8 km SW down the Bebeng and Krasak drainages on 8 December. Minor amounts of ash fell in the districts of Dukun, Sawangan, Magelang, and Selo. During the week the SW lava dome produced a total of 243 lava avalanches; 22 traveled as far as 2 km down the Boyong drainage and 221 traveled as far as 1.9 km down the Bebeng drainage. Minor morphological changes to the SW lava dome were identified in webcam images due to continuing lava effusion and collapses of material. Both the number and intensity of shallow volcanic earthquakes and hybrid events significantly decreased during the week. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit, based on location.

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

Poas | 13 December-19 December 2023 | Continuing ActivityCite this Report

Poas
Costa Rica

OVSICORI-UNA reported that at 0646 on 16 December a small phreatic eruption at Poás ejected material 20 m above the lake’s surface and produced a steam plume that rose 200 m. Additionally, two small eruptions were recorded at 1436 on 17 December and 0022 on 18 December.

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

Popocatepetl | 13 December-19 December 2023 | Continuing ActivityCite this Report

Popocatepetl
Mexico

CENAPRED reported that eruptive activity continued at Popocatépetl during 11-19 December. Long-period events totaling 34-280 per day were accompanied by steam-and-gas plumes that occasionally contained minor amounts of ash. The plumes mainly drifted ENE. The seismic network recorded 1.5-15.5 daily hours of tremor, as well as two volcano-tectonic earthquakes during 14-15 December and one M 1.9 volcano-tectonic earthquake on 16 December. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

Reventador | 13 December-19 December 2023 | Continuing ActivityCite this Report

Reventador
Ecuador

IG-EPN reported that the eruption at Reventador was ongoing during 12-19 December. Seismicity was characterized by 23-51 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions; data reception was interrupted during 13-14 December. Several daily ash-and-gas plumes rose as high as 1 km above the crater rim and drifted in multiple directions, though cloudy conditions prevented views at times during 18-19 December. Crater incandescence was often visible during both overnight and morning hours, and avalanches of incandescent material frequently descended the flanks to distances as far as 800 m from the summit. Weather conditions sometimes prevented views of the volcano. Secretaría de Gestión de Riesgos maintained the Alert Level at Orange (the second highest level on a four-color scale).

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)

Sabancaya | 13 December-19 December 2023 | Continuing ActivityCite this Report

Sabancaya
Peru

Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued at moderate levels during 11-17 December with a daily average of 55 explosions. Gas-and-ash plumes rose as high as 3.5 km above the summit and drifted E and SE. Thermal anomalies over the lava dome in the summit crater were identified in satellite data. Minor inflation was detected near the Hualca Hualca sector (4 km N). The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12 km radius.

Source: Instituto Geofísico del Perú (IGP)

Sangay | 13 December-19 December 2023 | Continuing ActivityCite this Report

Sangay
Ecuador

IG-EPN reported a high level of eruptive activity at Sangay during 12-19 December, with seismic stations recording 109-613 daily explosions. Daily ash-and-gas plumes were visible in webcam and satellite images, rising as high as 2 km above the crater rim and drifting SW, W, and NW; ash plumes rose as high as 3 km during 18-19 December. Webcam images showed incandescence at the summit vent and incandescent material descending the SE flank as far as 1.8 km from the crater. Weather clouds often prevented observations of the summit area. Secretaría de Gestión de Riesgos maintained the Alert Level at Yellow (the second highest level on a four-color scale).

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)

Semeru | 13 December-19 December 2023 | Continuing ActivityCite this Report

Semeru
Eastern Java

PVMBG reported that eruptive activity continued at Semeru during 13-19 December. White-and-gray ash plumes that were sometimes dense rose 500-700 m above the summit and drifted in multiple directions during 13 and 15-18 December. The Alert Level remained at 3 (third highest on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km from the summit, and to avoid other drainages 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)

Sheveluch | 13 December-19 December 2023 | Continuing ActivityCite this Report

Sheveluch
Central Kamchatka (Russia)

KVERT reported that the eruption at Sheveluch continued during 7-14 December. A daily thermal anomaly was identified in satellite images. The Aviation Color Code remained at Orange (the third 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)

Shishaldin | 13 December-19 December 2023 | Continuing ActivityCite this Report

Shishaldin
Fox Islands (USA)

AVO reported that unrest continued at Shishaldin during 12-19 December. Seismicity remained low and was characterized by small low-frequency earthquakes recorded daily and tremor recorded during 15-19 December. Barely elevated surface temperatures identified in satellite images during 13-14 December were likely associated with cooling deposits on the upper flanks. Minor steaming at the summit was visible in webcam images on 15 December. Infrasound signals indicating weak explosions were detected during 17-18 December but did not produce ash emissions; only minor steaming at the summit was visible in clear webcam images. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Suwanosejima | 13 December-19 December 2023 | Continuing ActivityCite this Report

Suwanosejima
Ryukyu Islands (Japan)

JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 11-18 December and crater incandescence was visible nightly. No explosions were detected, though eruption plumes rose as high as 800 m above the crater rim and large blocks were ejected as far as 200 m from the vent. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1 km away from the crater.

Source: Japan Meteorological Agency (JMA)

Ubinas | 13 December-19 December 2023 | Continuing ActivityCite this Report

Ubinas
Peru

Instituto Geofísico del Perú (IGP) reported that activity at Ubinas was at low levels during 1-15 December. Seismicity was low with daily averages of 143 volcano-tectonic earthquakes indicating rock fracturing and 23 earthquakes signifying the movement of gas and magma. Additionally, there was a total of more than 16 hours of seismic signals associated with ash emissions. During 10-15 December webcam images recorded emissions of gas, steam, and ash that rose as high as 2.5 km above the summit and drifted NW and W. The Alert Level remained at Yellow (the second level on a four-color scale) and the public was warned to stay 2 km away from the crater.

Source: Instituto Geofísico del Perú (IGP)

Whakaari/White Island | 13 December-19 December 2023 | Continuing ActivityCite this Report

Whakaari/White Island
North Island (New Zealand)

On 19 December GeoNet reported that activity at Whakaari/White Island remained low based on gas and observation flights conducted over the previous two months. Minor steam-and-gas emissions rose from a cluster of fumarolic vents located on the W shore of the lake; there has been no evidence of ash in the emissions. The discharge rates of the emissions during the year were characterized by low-to-moderate levels which were typical. Temperatures at the larger vents generally declined. The level of the lake had dropped, isolating a small pool from the main body of the lake. The Volcanic Alert Level remained at 2 (on a scale of 0-5) and the Aviation Color Code remained at Yellow (the second level on a four-color scale). GeoNet noted that Alert Levels reflect the level of unrest at the volcano but also consider the greater level of uncertainty due to the current lack of consistent and useful real-time data.

Source: GeoNet

Weekly Reports Archive

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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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Acronyms and Abbreviations

a.s.l. - above sea level

AVO - Alaska Volcano Observatory

AVHRR - Advanced Very High Resolution Radiometer

CENAPRED - Centro Nacionale de Prevencion de Desastres (México)

CONRED - Coordinadora Nacional para la Reducción de Desastres

COSPEC - Correlation Spectrometer

CVGHM (formerly VSI) - Center of Volcanology and Geological Hazard Mitigation

CVO - Cascades Volcano Observatory (USGS)

GMS - Geostationary Meteorological Satellite

GOES - Geostationary Operational Environmental Satellite

GVO - Goma Volcano Observatory

GVP - Global Volcanism Program (Smithsonian Institution)

HVO - Hawaiian Volcano Observatory (USGS)

ICE - Instituto Costarricense de Electricidad (Costa Rica)

IG - Instituto Geofísico (Ecuador)

IGNS - Institute of Geological and Nuclear Sciences (New Zealand) - now GNS Science

INETER - Instituto Nicaragüense de Estudios Territoriales (Nicaragua)

INGEMMET - Instituto Geológical Minero y Metalúrgico (Peru)

INGEOMINAS - Instituto Colombiano de Geología y Minería (Colombia)

INGV-CT - Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (Italy)

INSIVUMEH - Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (Guatemala)

IRD - Institut de Recherche pour le Développement (France)

JMA - Japanese Meteorological Agency

KEMSD - Kamchatkan Experimental and Methodical Seismilogical Department

KVERT - Kamchatkan Volcanic Eruption Response Team

M - magnitude

METEOSAT - Meteorological Satellite

MEVO - Mount Erebus Volcano Observatory

MODIS - Moderate Resolution Imaging Spectroradiometer

MVO - Montserrat Volcano Observatory

MWO - Meteorological Watch Office

NEIC - National Earthquake Information Center

NIED - National Research Institute for Earth Science and Disaster Prevention (Japan)

NOAA - National Oceanic and Atmospheric Administration

NOTAM - Notice to Airmen

OVDAS - Observatorio Volcanologico de los Andes del Sur (Chile)

OFDA - Office of US Foreign Disaster Assistance

ONEMI - Oficina Nacional de Emergencia - Ministerio del Interior (Chile)

OVPDLF - Observatoire Volcanologique du Piton de la Fournaise (France)

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

PHIVOLCS - Philippine Institute of Volcanology and Seismology (Philippines)

RSAM - Real-time Seismic Amplitude Measurement

RVO - Rabaul Volcano Observatory

SERNAGEOMIN - Servicio Nacional de Geologia y Mineria (Chile)

SIGMET - Significant Meteorological Information

SNET - Servicio Nacional de Estudios Territoriales (El Salvador)

SVERT - Sakhalin Volcanic Eruption Response Team (Russia)

USAID - US Agency for International Development

USGS - United States Geological Survey

UTC - Coordinated Universal Time

VAAC - Volcanic Ash Advisory Center

VAFTAD - Volcanic Ash Forecast Transport And Dispersion

VDAP - Volcano Disaster Assistance Program (USGS)

VHP - Volcano Hazards Program (USGS)

VRC - Volcano Research Center (Japan)

Report for Ioto
The Japan Coast Guard conducted an overflight on 14 December of Ioto (Iwo-jima) to inspect the new island formed by an eruption from a submarine vent about 1 km off the SE coast at Okinahama. No eruptive activity was detected, but the shape of the island had notably changed due to erosion and wave action. During the previous 10 days deposits at the N part of the “J” shaped island had separated and migrated N, connecting to the Okinahama coast, and the curved part of the “J” had eroded into two smaller islands.
Sources: Japan Coast Guard, Copernicus Browser

Report for Kanaga
AVO reported that a small explosion at Kanaga was detected in local infrasound and seismic data at 2231 on 18 December, and was followed by elevated seismicity. No ash emissions were detected in partly cloudy satellite images. The next day the Volcano Alert Level was raised to Advisory (the second level on a four-level scale) and the Aviation Color Code was raised to Yellow (the second color on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Lewotobi
On 17 December seismicity at Lewotobi increased significantly, prompting PVMBG to raise the Alert Level to 2 (on a scale of 1-4). Seismicity had been increasing during the previous week and was characterized by greater numbers of both deep and shallow volcanic earthquakes, and the emergence of tornillo-type earthquakes which indicated fluid movement. The public was warned to stay 2 km away from the craters at each summit.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Marapi
PVMBG reported that eruptive activity at Marapi (on Sumatra) was ongoing during 13-19 December, though foggy and raining weather conditions often prevented visual observations of the summit. White-and-gray ash plumes that were sometimes dense rose 400-600 m and drifted S, SW, NW, and NE during 13-15 and 18 December. The Alert Level remained at 2 (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)

Report for Raung
PVMBG reported that during 1-17 December the maximum height of steam-and-gas plumes at Raung was 500 m above the summit. An M 2.6 local tectonic earthquake was detected on 18 December and afterwards plumes rose as high as 1 km. Seismicity during December indicated that fluid movement was concentrated at shallow depths; signals indicating emissions significantly increased on 18 December. Deformation data indicated a trend of deflation. On 18 December PVMBG raised the Alert Level to 2 (on a scale of 1-4) noting that the visual observations and seismic data indicated unstable conditions. The pubic was warned to stay 3 km away from the summit crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Reykjanes
IMO reported that a new eruption on the Reykjanes peninsula began at 2217 on 18 December from fissures that opened in a location close to the older Sundhnúkagígar crater row, about 3 km NE of the town of Grindavík. A magmatic dike began intruding beneath the area in late October based on seismic and deformation data; magma continued to flow into the dike causing ground cracking in areas along its axis. The eruption was immediately preceded by an earthquake swarm that began at 2100 on 18 December and the opening of the fissure was accompanied by significant ground deformation.

Increased seismicity and a burst of incandescence indicating the start of the eruption was seen in webcam images. IMO raised the Aviation Color Code to Red (the highest level on a four-color scale) until the situation was able to be evaluated and in case ash was present in any emissions. After the first fissure opened, it propagated S in a series of four additional segments, slightly offset from each other but aligned with the previous dike intrusion. The total length of the fissure was estimated to be 4 km, with the north end just E of the Stóra-Skógfell cones and the south end E of the Sundhnúk cone. Large lava fountains possibly rose hundreds of meters high along the fissures, feeding lava flows in multiple directions. The rate of lava discharge during the first two hours of the eruption was about 100-200 cubic meters per second. The tallest lava fountains were located on the N end of the fissure. The largest earthquake, a M 4.1, was recorded at 2325. The Aviation Color Code was lowered to Orange. By midnight seismicity had declined and the eruption was less intense.

During a second overflight with the Iceland Coast Guard at around 0400 on 19 December scientists noted that the fissure had stopped extending and that most of the activity was concentrated in the central portion. There was minor activity at the S end, near the Hagafell cone, and most of the lava was advancing E towards Fagradalsfjall. Two branches traveled W, remaining N of Stóra-Skógfell. Gas plumes drifted W and NW. Residents of Grindavík, evacuated in November due to ground cracking and unsafe conditions, had recently been allowed to return and allowed to stay until 2100, but not overnight; they again fully evacuated the town due to the eruption. The recently reopened Blue Lagoon resort closed again. Some area roads were also temporarily closed.

Eruptive activity concentrated at five vents during the early part of 19 December. By 1430 the lava discharge rate was about one-fourth the rate measured at the beginning of the eruption and about one-third of the fissure was active. Lava fountains were lower, rising as high as about 30 m. The eruption intensity continued to decline and by 1830 only three vents were erupting. About 5 cm of deflation was detected in Svartsengi; a total of 35 cm of uplift had been recorded there since the beginning of the dike intrusion in November. The power plant in Svartsengi, W of the fissure, was not threatened by the current lava flows, though construction of an earthen barrier around it and the Blue Lagoon continued.
Sources: Icelandic Meteorological Office (IMO), Icelandic National Broadcasting Service (RUV)

Report for Tengger Caldera
PVMBG reported increased activity at Tengger Caldera’s Bromo cone in a 13 December press release. Emissions that day were white, gray, and brown, had variable densities, and rose as high as 900 m above the summit. The plumes drifted in multiple directions. The report noted that tremor was continuous and accompanied in December by three volcanic earthquakes. Deformation data indicated inflation in December. Daily white emissions that rose as high as 700 m above the summit and drifted in multiple directions were visible through 18 December. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Aira
JMA reported ongoing activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 11-18 December, with incandescence at the crater observed nightly. Small eruptive events were occasionally recorded through the week. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 km away from both craters.
Source: Japan Meteorological Agency (JMA)

Report for Ebeko
KVERT reported that moderate explosive activity was ongoing at Ebeko during 7-14 December. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 7 and 11-12 December generated ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l and drifted NE. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are UTC; specific events are in local time where noted.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Report for Great Sitkin
AVO reported that an 11 December radar image of Great Sitkin showed continuing growth of a thick flow in the summit crater; effusion likely continued during 12-19 December. Weather clouds often obscured views of the volcano, though no notable activity was visible in a few clear webcam images on 15 December. Seismicity was low. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Ibu
PVMBG reported that Ibu continued to erupt during 13-19 December. Daily white-and-gray ash emissions that were sometimes dense rose 200-1,300 m above the summit and drifted in multiple directions during 13-16 December. The Alert Level remained at a 2 (the second highest level on a four-level scale), with the public advised to stay outside of the 2 km hazard zone and 3.5 km away from the N area of the active crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Krakatau
PVMBG reported that the eruption at Krakatau continued during 13-19 December. White-and-gray ash plumes that were sometimes dense rose as high as 1 km above the summit and drifted NE and N during 13-16 December. Some webcam images posted with the daily reports showed incandescence at the vent. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay at least 5 km away from the crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Lewotolok
PVMBG reported that the eruption at Lewotolok continued during 13-19 December. White-and-gray ash plumes rose 100 m on 13 December and drifted E. White steam-and-gas plumes rose 100-200 m above the summit on the other days and drifted E, NE, and NW. Incandescence lava was ejected 200 m from the vent on 15 and 18 December and summit incandescence was visible in webcam images on 16 and 19 December. The 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 summit crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Mayon
PHIVOLCS characterized activity at Mayon as “decreased unrest” during 12-19 December. The seismic network recorded 1-4 daily volcanic earthquakes and 1-2 rockfall events during 12-15 December. The summit was occasionally obscured by weather conditions, though on most days emissions were visible drifting in multiple directions. The Tokyo VAAC reported that at 1447 on 17 December an ash emission was identified in a satellite image rising to 2.4 km (8,000 ft) a.s.l. and drifting WSW based on satellite data and information from PHIVOLCS. The Alert Level remained at 2 (on a 0-5 scale). Residents were reminded to stay away from the 6-km-radius Permanent Danger Zone (PDZ) and pilots were advised to avoid flying close to the summit.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Report for Merapi
BPPTKG reported that the eruption at Merapi (on Java) continued during 8-14 December. A series of pyroclastic flows traveled 3.8 km SW down the Bebeng and Krasak drainages on 8 December. Minor amounts of ash fell in the districts of Dukun, Sawangan, Magelang, and Selo. During the week the SW lava dome produced a total of 243 lava avalanches; 22 traveled as far as 2 km down the Boyong drainage and 221 traveled as far as 1.9 km down the Bebeng drainage. Minor morphological changes to the SW lava dome were identified in webcam images due to continuing lava effusion and collapses of material. Both the number and intensity of shallow volcanic earthquakes and hybrid events significantly decreased during the week. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit, based on location.
Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)

Report for Poas
OVSICORI-UNA reported that at 0646 on 16 December a small phreatic eruption at Poás ejected material 20 m above the lake’s surface and produced a steam plume that rose 200 m. Additionally, two small eruptions were recorded at 1436 on 17 December and 0022 on 18 December.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Report for Popocatepetl
CENAPRED reported that eruptive activity continued at Popocatépetl during 11-19 December. Long-period events totaling 34-280 per day were accompanied by steam-and-gas plumes that occasionally contained minor amounts of ash. The plumes mainly drifted ENE. The seismic network recorded 1.5-15.5 daily hours of tremor, as well as two volcano-tectonic earthquakes during 14-15 December and one M 1.9 volcano-tectonic earthquake on 16 December. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

Report for Reventador
IG-EPN reported that the eruption at Reventador was ongoing during 12-19 December. Seismicity was characterized by 23-51 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions; data reception was interrupted during 13-14 December. Several daily ash-and-gas plumes rose as high as 1 km above the crater rim and drifted in multiple directions, though cloudy conditions prevented views at times during 18-19 December. Crater incandescence was often visible during both overnight and morning hours, and avalanches of incandescent material frequently descended the flanks to distances as far as 800 m from the summit. Weather conditions sometimes prevented views of the volcano. Secretaría de Gestión de Riesgos maintained the Alert Level at Orange (the second highest level on a four-color scale).
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)

Report for Sabancaya
Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued at moderate levels during 11-17 December with a daily average of 55 explosions. Gas-and-ash plumes rose as high as 3.5 km above the summit and drifted E and SE. Thermal anomalies over the lava dome in the summit crater were identified in satellite data. Minor inflation was detected near the Hualca Hualca sector (4 km N). The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12 km radius.
Source: Instituto Geofísico del Perú (IGP)

Report for Sangay
IG-EPN reported a high level of eruptive activity at Sangay during 12-19 December, with seismic stations recording 109-613 daily explosions. Daily ash-and-gas plumes were visible in webcam and satellite images, rising as high as 2 km above the crater rim and drifting SW, W, and NW; ash plumes rose as high as 3 km during 18-19 December. Webcam images showed incandescence at the summit vent and incandescent material descending the SE flank as far as 1.8 km from the crater. Weather clouds often prevented observations of the summit area. Secretaría de Gestión de Riesgos maintained the Alert Level at Yellow (the second highest level on a four-color scale).
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)

Report for Semeru
PVMBG reported that eruptive activity continued at Semeru during 13-19 December. White-and-gray ash plumes that were sometimes dense rose 500-700 m above the summit and drifted in multiple directions during 13 and 15-18 December. The Alert Level remained at 3 (third highest on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km from the summit, and to avoid other drainages 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)

Report for Sheveluch
KVERT reported that the eruption at Sheveluch continued during 7-14 December. A daily thermal anomaly was identified in satellite images. The Aviation Color Code remained at Orange (the third 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)

Report for Shishaldin
AVO reported that unrest continued at Shishaldin during 12-19 December. Seismicity remained low and was characterized by small low-frequency earthquakes recorded daily and tremor recorded during 15-19 December. Barely elevated surface temperatures identified in satellite images during 13-14 December were likely associated with cooling deposits on the upper flanks. Minor steaming at the summit was visible in webcam images on 15 December. Infrasound signals indicating weak explosions were detected during 17-18 December but did not produce ash emissions; only minor steaming at the summit was visible in clear webcam images. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Suwanosejima
JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 11-18 December and crater incandescence was visible nightly. No explosions were detected, though eruption plumes rose as high as 800 m above the crater rim and large blocks were ejected as far as 200 m from the vent. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1 km away from the crater.
Source: Japan Meteorological Agency (JMA)

Report for Ubinas
Instituto Geofísico del Perú (IGP) reported that activity at Ubinas was at low levels during 1-15 December. Seismicity was low with daily averages of 143 volcano-tectonic earthquakes indicating rock fracturing and 23 earthquakes signifying the movement of gas and magma. Additionally, there was a total of more than 16 hours of seismic signals associated with ash emissions. During 10-15 December webcam images recorded emissions of gas, steam, and ash that rose as high as 2.5 km above the summit and drifted NW and W. The Alert Level remained at Yellow (the second level on a four-color scale) and the public was warned to stay 2 km away from the crater.
Source: Instituto Geofísico del Perú (IGP)

Report for Whakaari/White Island
On 19 December GeoNet reported that activity at Whakaari/White Island remained low based on gas and observation flights conducted over the previous two months. Minor steam-and-gas emissions rose from a cluster of fumarolic vents located on the W shore of the lake; there has been no evidence of ash in the emissions. The discharge rates of the emissions during the year were characterized by low-to-moderate levels which were typical. Temperatures at the larger vents generally declined. The level of the lake had dropped, isolating a small pool from the main body of the lake. The Volcanic Alert Level remained at 2 (on a scale of 0-5) and the Aviation Color Code remained at Yellow (the second level on a four-color scale). GeoNet noted that Alert Levels reflect the level of unrest at the volcano but also consider the greater level of uncertainty due to the current lack of consistent and useful real-time data.
Source: GeoNet