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 17 May-23 May 2023
Name	Location	Eruption Start Date	Report Status
Ahyi	Mariana Islands (USA)	2024 Jan 1	New
Etna	Sicily (Italy)	2022 Nov 27	New
Karangetang	Sangihe Islands	2018 Nov 25	New
Nyamulagira	DR Congo	2018 Apr 18	New
Popocatepetl	Mexico	2005 Jan 9	New
Aira	Kyushu (Japan)	2017 Mar 25	Continuing
Bulusan	Luzon (Philippines)	—	Continuing
Cotopaxi	Ecuador	—	Continuing
Ebeko	Paramushir Island (Russia)	2022 Jun 11	Continuing
Fuego	South-Central Guatemala	2002 Jan 4	Continuing
Great Sitkin	Andreanof Islands (USA)	2021 May 25	Continuing
Ibu	Halmahera	2008 Apr 5	Continuing
Lewotolok	Lembata Island	2020 Nov 27	Continuing
Merapi	Central Java	2020 Dec 31	Continuing
Nevado del Ruiz	Colombia	2014 Nov 18	Continuing
Rincon de la Vieja	Costa Rica	2021 Jun 28	Continuing
Sabancaya	Peru	2016 Nov 6	Continuing
Sangay	Ecuador	2019 Mar 26	Continuing
Santa Maria	Southwestern Guatemala	1922 Jun 22	Continuing
Semeru	Eastern Java	2017 Jun 6	Continuing
Semisopochnoi	Aleutian Islands (USA)	—	Continuing
Sheveluch	Central Kamchatka (Russia)	1999 Aug 15	Continuing
Suwanosejima	Ryukyu Islands (Japan)	2004 Oct 23	Continuing

All times are local unless otherwise stated.

Ahyi | 17 May-23 May 2023 | New Activity / Unrest Cite this Report

Ahyi
Mariana Islands (USA)

The U.S. Geological Survey reported that unrest at Ahyi Seamount was again detected, after activity paused in early April. Signals consistent with eruptive activity were recorded by underwater pressure sensors on Wake Island, 2,270 km E, beginning at about 2210 on 21 May and were continuing. A plume of discolored sea water was observed above the area of the vent in a satellite image on 22 May. On 23 May the Aviation Color Code was changed to Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level was changed to Advisory (the second lowest level on a four-level scale).

Source: US Geological Survey

Etna | 17 May-23 May 2023 | New Activity / Unrest Cite this Report

Etna
Sicily (Italy)

Strong explosive eruptions were reported at Etna by INGV starting on 18 May after continuous degassing and moderate seismicity over the previous few days, with significant Strombolian activity and a paroxysmal event at SE Crater on 21 May. Views were often obscured by persistent weather cloud cover. Strombolian activity from SE Crater at 0456 on 18 May was seen in webcam images from the camera located at Montagnola. The Aviation Color Code was raised to Yellow (second lowest level on a four-color scale) at 1242 following a sudden increase in volcanic tremor amplitude that began at 1210. The signal amplitude decreased for a short time but then increased to an even higher level at 1330. A seismic swarm in the summit area at 1644 was immediately followed by ground deformation recorded at the Punta Lucia and Pizzi Deneri summit stations. At 1656 weak intra-crater Strombolian activity at SE Crater was observed in images taken by the INGV thermal camera at La Montagnola (3 km S). Explosive activity from Bocca Nuova crater starting at 1700 was visible in thermal images from the Bronte (13 km WNW) webcam, concurrent with infrasonic signals. The Aviation Color Code was raised to Orange at 1751. The activity likely persisted for a few hours based on satellite images; weather conditions prevented confirmation with webcams. Tremor fluctuated and by 0927 on 19 May levels had begun to decrease.

Intermittent explosive activity persisted at SE Crater during 19-20 May, with pulsating gas emissions rising from the crater. A sharp increase in volcanic tremors at 0720 on 21 May was a precursor to significant tall lava fountaining during 0730-1140, with ash plumes that rose to 10 km and drifted SW, S, and SE. At 0937 the Aviation Color Code was raised to Red after INGV field personnel observed ash and lapilli fall on the SW flank and ashfall in Adrano at 560 m elevation. Lava flows from SE Crater descended the W part of the Valle del Bove as far as 1.9 km E and the S flank as far as 2 km. Satellite data showed a large sulfur dioxide plume drifting E. Weather clouds prevented views of the activity. Tremor levels sharply decreased starting at 1135 and had stabilized by 1200. Ashfall was also reported in Catania and Aci Castello. According to news reports the ashfall caused the Catania-Fontanarossa Airport in Sicily to close until 0900 on 22 May. The runway had been covered in ash and at least 68 flights to and from the airport were cancelled.

The Aviation Color Code was lowered to Orange at 0601 on 22 May, though lava flows were still active. By 0832 on 23 May monitoring data indicated that eruptive activity had ceased, and webcam images showed that the lava flows were cooling. The Aviation Color Code was lowered to Yellow at 0840 and then to Green at 1051.

Sources: Sezione di Catania - Osservatorio Etneo (INGV), Advanced geospatial Data Management Platform (ADAM), MSN

Karangetang | 17 May-23 May 2023 | New Activity / Unrest Cite this Report

Karangetang
Sangihe Islands

PVMBG reported that activity at Karangetang had intensified in May, leading to a change in the Alert Level status. During 1-17 May white gas-and-steam plumes were sometimes dense and rose as high as 250 m above the summit, slightly higher than the 200 m maximum height noted in April. Incandescence at North Crater was visible at night 10-25 m above the lava dome. Incandescence also emanated from Main Crater though the glow was less intense, reaching about 10 m above the dome. Sounds of falling rocks at Main Crater were heard on 15 May, the seismic network recorded 32 rockfall events in the crater on 17 May, and rock avalanches on 18 May traveled as far as 1.5 km down the SW and S flanks accompanied by rumbling sounds. On 19 May the Alert Level was raised to 3 (on a scale of 1-4) and the public was warned to stay 2.5 km away from the craters on the S and SW flanks and 1.5 km away on the other flanks. A webcam image from 2025 on 19 May showed incandescent material traveling down the flanks. On 21 May white gas-and-steam plumes rose 400 m above the summit.

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

Nyamulagira | 17 May-23 May 2023 | New Activity / Unrest Cite this Report

Nyamulagira
DR Congo

The Observatoire Volcanologique de Goma (OVG) reported that lava continued to erupt from vents in Nyamulagira’s summit crater during 17-23 May. Lava flows began moving into the N and NW parts of the crater beginning on 9 May, towards the low point of the crater rim. Intense incandescence from the summit was visible from Goma (27 km S) during the evenings of 17 and 19 May. Satellite images showed a notable sulfur dioxide plume drifting NW and W during 19-20 May. Drone footage acquired on 20 May captured images of narrow lava flows traveling about 100 m down the W flank. Intense incandescence emanating from the summit was again visible from Goma at around 1830. Data from the Rumangabo seismic station indicated a downward trend in activity during 17-20 May and a significant decrease during 20-21 May. Though weather clouds were dense over the summit, hot lava on the NW flank was visible in a 22 May Sentinel-2 infrared (SWIR) image.

Sources: Observatoire Volcanologique de Goma (OVG), Sentinel Hub

Popocatepetl | 17 May-23 May 2023 | New Activity / Unrest Cite this Report

Popocatepetl
Mexico

CENAPRED reported that activity at Popocatépetl intensified during 16-23 May after recent activity characterized by the formation of small to medium lava domes on the summit crater floor and their subsequent destruction. There were 154-168 daily steam, gas, and ash emissions and minor-to-moderate explosions during 16-19 May. Periods of high-frequency tremor lasted more than 12 hours during 16-17 May and more than 10 hours during 17-18 May. Minor ashfall was reported on 18 May in the municipalities of Atlixco (25 km SE) and Cholula (35 km E), Puebla. Six volcano-tectonic earthquakes with magnitudes as high as 1.8 were recorded along with over 2 hours of high-frequency tremor on 19 May. Residents of Tétela del Volcán (18 km SW), Morelos, noted minor ashfall. According to the Washington VAAC ash plumes rose 6.7-7 km (22,000-23,000 ft) a.s.l., or 1.3-1.6 km above the summit, during 16-19 May.

A period of high-frequency tremor that began at around 1800 on 19 May and lasted about 10 hours until about 0400 on 20 May was accompanied by steam, gas, and ash plumes that drifted NNW and continuous ejection of incandescent tephra onto the flanks as far as 1.5 km from the crater. On 20 May the Benito Juárez International Airport closed during about 0430-1000 and the Felipe Ángeles International Airport closed during 0600-1100 in order to clear ash from runways. Ash fell in multiple areas downwind including in the municipalities of Venustiano Carranza (66 km NW), Gustavo A. Madero (73 km NW), Azcapotzalco (78 km NW), Tlalpan (62 km NW), Iztapalapa (58 km NW), Amecameca (18 km NW), Ayapango (21 km NW), Ozumba (18 km W), Ecatzingo (15 km SW), Atlautla (16 km W), Valle de Chalco (44 km NW), La Paz (50 km NW), Chalco (38 km NW), Nezahualcóyotl (56 km NW), Temamatla (32 km NW), Tenango del Aire (29 km NW), Tlalmanalco (27 km NW), Juchitepec (28 km NW), Cocotitlán (34 km NW), and Tepetlixpa (21 km W). Ashfall in Puebla municipalities included Huejotzingo (28 km NE), Nealtican (21 km E), Chignahuapan (108 km NE), Puebla Capital (44 km E), San Martín Texmelucan (35 km NE), and San Felipe Teotlalcingo (26 km NE).

Additional explosions were recorded at 1047, 1247, 1454, 2136, 2238, and 2253 on 20 May. Almost 19 hours of high-frequency tremor recorded during 20-21 May was accompanied by continuous emissions of steam, gas, and ash and occasional ejections of incandescent material short distances onto the flanks. The Washington VAAC reported that activity intensified at 1453 on 20 May as a large, dense ash plume was visible in webcam images. By 1551 the ash plume was visible in satellite images rising to 8.2 km (27,000 ft) a.s.l., or 2.8 km above the summit. By 2041 the dense ash plume had risen to 9.1 km (30,000 ft) a.s.l., or 3.7 km above the summit, and drifted ENE far over the Gulf of Mexico. The plume rose as high as 9.7 km (32,000 ft) a.s.l., or 4.3 km above the summit by 2136 and remained at that altitude at least through 0341 on 21 May as it fanned out to the NE and ENE. By 0951 on 21 May ash plumes were rising to 9.1 km and at 1436 plumes were reaching 8.5 km (28,000 ft) a.s.l., or 3.1 km above the summit. Satellite images showed a large dense ash plume drifting 388 km NE over the Bay of Campeche, but emissions were most dense within 65 km of the summit. Webcam images showed that continuing dense ash emissions.

According to CENAPRED the Scientific Advisory Committee of the Popocatépetl Volcano announced on 21 May that the Alert Level was raised from Yellow, Phase 2, to Yellow, Phase 3, the highest of the three sub-phases based on the intensifying activity over the previous few days. The National Coordination of Civil Protection (CNPC) announced actions to be implemented by the state civil protection units including preparing evacuation routes and evacuation teams and shelters. Ashfall was reported in Puebla state, in the municipalities of San Andrés Cholula (36 km E), San Pedro Cholula (34 km E), Cuautlancingo (38 km E), Amozoc (61 km E), Puebla Capital (44 km E), Zacatlán (121 km NE), Tetela de Ocampo (121 km NE), and Chignahuapan (108 km NE). The Hermanos Serdán International Airport, in Puebla (30 km NE), closed at 2300 on 21 May until 0700 on 22 May according to Gobierno de Puebla.

High-frequency tremor was almost constant for over 23 hours during 21-22 May. Steam, gas, and ash emissions were continuous with occasional ejections of incandescent material short distances onto the flanks. Explosions occurred at 1355 on 21 May and 0533 on 22 May. According to the Washington VAAC satellite images acquired at 0236, 0821, 1421, and 1936 revealed continuing ash emissions to 3.7 km above the summit, drifting E and ENE. An accompanying very large sulfur dioxide plume drifted as far as Cancun, 1,295 km E. Ashfall occurred in the municipalities of San Andrés Cholula (36 km E), San Pedro Cholula (34 km E), Cuautlancingo (38 km E), Amozoc (61 km E), Zacatlán (121 km NE), Tetela de Ocampo (121 km NE), San Nicolás de los Ranchos (15 km NE), Palmar de Bravo (115 km SE), Tepeaca (76 km E), in Izúcar de Matamoros (51 km S), Epatlán (51 km SE), Teopantlán (52 km SE), Tlapacoya (144 km NE), Huatlatlauca Chignahuapan (72 km SE), and in the Puebla capital, in the state of Puebla. Ash also fell in Juchitepec (28 km W), State of Mexico, Hueyapan (17 km SW), Locality of Xochitepec (municipality of Jolalpan) (68 km SW), in Morelos, and in the capital of the state of Tlaxcala (50 km NE). At 1651 on 22 May the Hermanos Serdán International Airport suspended operations due to ash on the runway.

Tremor remained nearly continuous (more than 20 hours) during 22-23 May. Ongoing steam, gas, and ash emissions drifted NE, and occasional ejections of incandescent material short distances onto the flanks. Ash fell in the municipalities of Nealtican, Tianguismanalco, Atlixco, San Diego la Mesa, Huaquechula, and Atzizihuacán, State of Puebla. Ash plumes rose as high as 3.7 km above the summit and drifted E according to the Washington VAAC.

Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC), Simple Flying, Gobierno de Puebla, Cuenta Oficial de la Coordinación General de Protección Civil del Estado de Puebla

Aira | 17 May-23 May 2023 | Continuing ActivityCite this Report

Aira
Kyushu (Japan)

JMA reported ongoing activity at both Minamidake Crater and Showa Crater (Aira Caldera’s Sakurajima volcano) during 15-22 May. Crater incandescence was observed nightly at Minamidake Crater. At 1429 on 17 May an eruptive event at Showa Crater produced an ash plume that rose 1.2 km above the crater rim and drifted N. An explosion from Minamidake Crater at 2027 generated an ash plume that rose 400 m and ejected large blocks 600-900 m from the crater; another eruptive event at 2051 produced an ash plume that rose as high as 1 km and drifted N. An explosion at Minamidake was recorded at 1519 on 18 May. Showa Crater sent an ash plume 1.5 km high at 1125 on 22 May. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from both craters.

Source: Japan Meteorological Agency (JMA)

Bulusan | 17 May-23 May 2023 | Continuing ActivityCite this Report

Bulusan
Luzon (Philippines)

In a special advisory, PHIVOLCS reported that from 0500 on 21 May to 1600 on 22 May the seismic network at Bulusan recorded a total of 37 volcanic earthquakes. Out of those, 34 were volcano-tectonic earthquakes associated with rock fracturing and three were low-frequency volcanic earthquakes associated with movement of volcanic gas. Minor steam emissions from an active vent on the SE flank were occasionally visible. Ground deformation data from electronic tiltmeter stations continued to record short-term inflation of the SE flanks, first detected in December 2022. The Alert Level remained at 0 (the lowest level on a scale of 0-5) and PHIVOLCS reminded the public not to enter the 4-km-radius Permanent Danger Zone (PDZ).

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Cotopaxi | 17 May-23 May 2023 | Continuing ActivityCite this Report

Cotopaxi
Ecuador

IG reported that moderate eruptive activity continued at Cotopaxi during 17-23 May. Seismic activity was mainly characterized by long-period earthquakes and tremors associated with emissions that occurred almost daily; a total of six volcanic-tectonic earthquakes were recorded during the week. Emissions of steam, gas, and variable amounts of ash were observed on most days; clouds obscured views on 19 May. Weak steam-and-gas emissions that barely rose above the crater level were recorded during 17 and 20-22 May; the emissions drifted W on 22 May. Starting at 0510 on 18 May emissions of steam-and-ash rose 1-3 km above the crater and drifted N and NE; ashfall was reported in Machachi (23 km NW). During the morning of 23 May several steam-and-gas emissions with possible minor ash content were observed rising 1 km above the crater and drifting S. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).

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

Ebeko | 17 May-23 May 2023 | Continuing ActivityCite this Report

Ebeko
Paramushir Island (Russia)

KVERT reported that moderate activity at Ebeko was ongoing during 11-18 May. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions during 12-16 May generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l. and drifted in multiple directions. A thermal anomaly was identified in satellite images during 13-14 May. 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)

Fuego | 17 May-23 May 2023 | Continuing ActivityCite this Report

Fuego
South-Central Guatemala

INSIVUMEH reported that 1-4 weak explosions per hour were recorded at Fuego on most days during 16-23 May. The explosions generated ash plumes that rose 250-750 m above the crater; the plumes drifted S and SW during 18-20 May and as far as 10 km SW during 21-22 May. Slight incandescent at the crater was occasionally visible during dark hours a few times during the week. Very minor ashfall was reported in Morelia (9 km SW) and Panimaché (8 km SW) during 20-22 May.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Great Sitkin | 17 May-23 May 2023 | Continuing ActivityCite this Report

Great Sitkin
Andreanof Islands (USA)

AVO reported that slow lava effusion continued at Great Sitkin during 16-23 May. Satellite data acquired on 16 May showed that the thick lava continued to expand towards the E but remained confined to the summit crater. Elevated surface temperatures were identified in satellite images during 18 and 21-23 May. Seismicity was low with some variations; five small earthquakes occurred during 19-20 May and small low-frequency earthquakes that began at 1000 on 23 May were ongoing at least through 1206. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Ibu | 17 May-23 May 2023 | Continuing ActivityCite this Report

Ibu
Halmahera

PVMBG reported that Ibu continued to erupt during 18-23 May. An average of approximately 80 eruption-related earthquakes were recorded by the seismic network during 18-22 May. White-and-gray emissions of variable densities rose as high as 1 km above the summit and drifted N, E, SE, and W. At 2021 and 2140 on 21 May dense gray ash plumes rose 600 m and 1 km above the summit, respectively, and drifted W. The Alert Level remained at a 2 (the second highest level on a four-level scale), and the public was advised to stay outside of the 2 km hazard radius, and to stay 3.5 km away from the N area of the active crater.

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

Lewotolok | 17 May-23 May 2023 | Continuing ActivityCite this Report

Lewotolok
Lembata Island

PVMBG reported that the eruption at Lewotolok was ongoing during 17-23 May. Almost daily white-and-gray ash plumes rose as high as 700 m above the summit and drifted in variable directions; only white gas-and-steam plumes were visible on 19 May. A nighttime webcam image of incandescent material being ejected above the summit was captured at 1844 on 17 May. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the summit crater.

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

Merapi | 17 May-23 May 2023 | Continuing ActivityCite this Report

Merapi
Central Java

BPPTKG reported that the eruption at Merapi (on Java) continued during 12-18 May and seismicity remained at elevated levels. The SW lava dome produced 182 minor lava avalanches that traveled as far as 1.8 km down the SW flank (upstream in the Bebeng and Boyong drainages) and one that traveled 500 m NW (upstream of the Senowo River). Morphological changes to the SW lava dome due to continuing collapses of material were evident in webcam and drone images. 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)

Nevado del Ruiz | 17 May-23 May 2023 | Continuing ActivityCite this Report

Nevado del Ruiz
Colombia

Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that the eruption at Nevado del Ruiz continued during 17-23 May and was characterized by periodic gas, steam, and ash emissions, thermal anomalies at the lava dome in Arenas Crater, and elevated seismicity. Seismic signals indicating rock-fracturing events were located 3-8 km around the Arenas Crater at depths of 1-6 km. The largest event, a M 2.1, was recorded at 0341 on 21 May and was located 2 km below the Arenas crater. Gas-and-ash emissions rose as high as 1.5 km above the crater and drifted multiple directions. A thermal anomaly was observed within the crater on 18 May. The Alert Level was remained at Orange, Level II (the second highest level on a four-level scale).

Source: Servicio Geológico Colombiano (SGC)

Rincon de la Vieja | 17 May-23 May 2023 | Continuing ActivityCite this Report

Rincon de la Vieja
Costa Rica

OVSICORI-UNA reported that small phreatic eruptions periodically occurred at Rincón de la Vieja during 16-23 May. Four small events occurred during 16-17 May; the last one, recorded at 1255 on 17 May, produced a gas-and-steam plume that rose 700 m above the crater rim. Sulfur dioxide emissions were almost as high as 5,000 tonnes per day on 17 May; emissions averaged around 132 tonnes per day during the previous week. Events were recorded at 1537 on 18 May and at 0727 and 1025 on 19 May. Vigorous gas emissions were visible in the early morning of 20 May and a phreatic event occurred at 1648 that same day. At 1349 a phreatic event generated a plume mostly comprised of steam that rose 1 km above the crater rim.

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

Sabancaya | 17 May-23 May 2023 | Continuing ActivityCite this Report

Sabancaya
Peru

Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 15-21 May with a daily average of 37 explosions. Gas-and-ash plumes rose as high as 2.4 km above the summit and drifted NE, E, and SE. Eight thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Seismic sensors detected 232 volcanic activity-related earthquakes, in addition to volcano-tectonic earthquakes. 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 | 17 May-23 May 2023 | Continuing ActivityCite this Report

Sangay
Ecuador

IG reported a high level of activity at Sangay during 17-23 May, though weather clouds sometimes prevented visual observations. Incandescent material at the crater and along the lava flow extending 1 km down the SE flank was visible nightly. On 17 May steam-and-ash emissions rose 500 m above the summit and drifted SW. On 18 May an ash plume rose 1.7 km and drifted N and SW. At 2000 on 20 May ash plumes rose 2 km above the summit and drifted to the SW. Continuous ash emissions persisted during 21-22 May, drifting W and SW. Ashfall during 20-22 May was reported in Chauzan, Guamote, Tixán, Palmira, Cebadas, and Alausí cantons in the Province of Chimborazo. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).

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

Santa Maria | 17 May-23 May 2023 | Continuing ActivityCite this Report

Santa Maria
Southwestern Guatemala

INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 16-23 May. Effusion from the Caliente dome complex fed lava flows that descended the San Isidro and Zanjón Seco drainages on the W and SW flanks; the main lava flow was 4.3 km long and remained active. Avalanches of material from the growing dome and occasional explosions descended all sides of the dome and avalanches from the lava flow descended the S and SW flanks. Explosions generated gas, steam, and ash plumes that drifted S and SW on a few days. Incandescence from the dome and lava flows was visible during the nights and early mornings. An average of 40 explosions per day were recorded during 21-22 May, generating ash plumes that rose up to 1 km above the dome and drifted SW.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Semeru | 17 May-23 May 2023 | Continuing ActivityCite this Report

Semeru
Eastern Java

PVMBG reported that the eruption at Semeru continued during 17-23 May and several Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued during the week. Daily white-to-gray ash plumes that were sometimes dense rose 200-800 m above the summit and drifted in multiple directions. VONAs were issued as follows: 0501, 0646, and 0919 on 17 May; 0517 and 0822 on 18 May; 0547, 0911, and 0936 on 19 May; 0545, 0733, 0742, and 1054 on 20 May. 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, 100 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)

Semisopochnoi | 17 May-23 May 2023 | Continuing ActivityCite this Report

Semisopochnoi
Aleutian Islands (USA)

On 17 May AVO reported that eruptive activity at Semisopochnoi had declined during the previous week, though seismicity remained slightly elevated and low-level steaming continued from Mount Young. Ash emissions had last occurred on 5 May leaving minor deposits on the NW flank of Mount Young’s N crater. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level was lowered to Advisory (the second highest level on a four-level scale). Intense gas emissions were periodically visible in webcam images during 17-18 and 20-21 May. On 22 May a weak sulfur dioxide signal was detected, suggestive of low-level degassing.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Sheveluch | 17 May-23 May 2023 | Continuing ActivityCite this Report

Sheveluch
Central Kamchatka (Russia)

KVERT reported that the eruption at Sheveluch was ongoing during 11-18 May. A thermal anomaly over the active crater and Karan lava dome area was identified in satellite images all week. Intense fumarolic activity at the active crater was likely associated with dome growth. Plumes of ash, originally deposited during the 10-13 April eruption and resuspended by strong winds, were visible in satellite images drifting 400 km SE during 14-15 May. 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 | 17 May-23 May 2023 | Continuing ActivityCite this Report

Suwanosejima
Ryukyu Islands (Japan)

JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 15-22 May. Incandescence was visible nightly, and seismicity remained elevated during 15-19 May. On 16 May an ash plume rose 1.8 km above the crater rim and caused ashfall in Toshima village (3.5 km SSW). On 17 May, an ash plume rose to 1.1 km and drifted NW. Four eruptive events were observed during 21-23 May. On 21 May an eruptive event ejected volcanic blocks up to 200 m from the crater and produced an ash plume that rose 1.8 km above the crater and drifted E. On 22 May an ash plume rose to 1 km above the crater and drifted SE. Two eruptive events on 23 May generated ash plumes that rose 600 m above the crater and drifted SE and S. 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)

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Westdahl

Campi Flegrei del Mar di Sicilia

Whakaari/White Island

Palena Volcanic Group

Soufriere St. Vincent

South Sarigan Seamount

Colo

Hunga Tonga-Hunga Ha'apai

News Feeds and Google Placemarks

Download Smithsonian / USGS Weekly Volcanic Activity Report Network RSS Feed

The RSS (Really Simple Syndication) feed is identical to the Weekly Volcanic Activity Report minus some features including the header information (latitude and longitude and summit elevation), the Geologic Summary, and a link to the volcano's page from the Global Volcanism Program. At the end of each report is a list of the sources used. Each volcano report includes a link from the volcano's name back to the more complete information in the Weekly Volcanic Activity Report on the Smithsonian website. This feature was first made available on 5 March 2008.

Download Smithsonian / USGS Weekly Volcanic Activity Report Network CAP Feed

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Download Smithsonian / USGS Weekly Volcanic Activity Report Network Link

A Google Earth network link for the Weekly Volcanic Activity Report can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano profile page and to the complete Weekly Report for that week. This feature was first made available on 1 April 2009.

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.

4. Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.

5. USGS Disclaimer Statement for this Website:

Information presented on this website is considered public information and may be distributed or copied. Use of appropriate byline/photo/image credit is requested. We strongly recommend that USGS data be acquired directly from a USGS server and not through other sources that may change the data in some way. While USGS makes every effort to provide accurate and complete information, various data such as names, telephone numbers, etc. may change prior to updating. USGS welcomes suggestions on how to improve our home page and correct errors. USGS provides no warranty, expressed or implied, as to the accuracy, reliability or completeness of furnished data.

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U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
URL: https://volcano.si.edu/reports_weekly.cfm

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 Ahyi
The U.S. Geological Survey reported that unrest at Ahyi Seamount was again detected, after activity paused in early April. Signals consistent with eruptive activity were recorded by underwater pressure sensors on Wake Island, 2,270 km E, beginning at about 2210 on 21 May and were continuing. A plume of discolored sea water was observed above the area of the vent in a satellite image on 22 May. On 23 May the Aviation Color Code was changed to Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level was changed to Advisory (the second lowest level on a four-level scale).
Source: US Geological Survey

Report for Etna
Strong explosive eruptions were reported at Etna by INGV starting on 18 May after continuous degassing and moderate seismicity over the previous few days, with significant Strombolian activity and a paroxysmal event at SE Crater on 21 May. Views were often obscured by persistent weather cloud cover. Strombolian activity from SE Crater at 0456 on 18 May was seen in webcam images from the camera located at Montagnola. The Aviation Color Code was raised to Yellow (second lowest level on a four-color scale) at 1242 following a sudden increase in volcanic tremor amplitude that began at 1210. The signal amplitude decreased for a short time but then increased to an even higher level at 1330. A seismic swarm in the summit area at 1644 was immediately followed by ground deformation recorded at the Punta Lucia and Pizzi Deneri summit stations. At 1656 weak intra-crater Strombolian activity at SE Crater was observed in images taken by the INGV thermal camera at La Montagnola (3 km S). Explosive activity from Bocca Nuova crater starting at 1700 was visible in thermal images from the Bronte (13 km WNW) webcam, concurrent with infrasonic signals. The Aviation Color Code was raised to Orange at 1751. The activity likely persisted for a few hours based on satellite images; weather conditions prevented confirmation with webcams. Tremor fluctuated and by 0927 on 19 May levels had begun to decrease.

Intermittent explosive activity persisted at SE Crater during 19-20 May, with pulsating gas emissions rising from the crater. A sharp increase in volcanic tremors at 0720 on 21 May was a precursor to significant tall lava fountaining during 0730-1140, with ash plumes that rose to 10 km and drifted SW, S, and SE. At 0937 the Aviation Color Code was raised to Red after INGV field personnel observed ash and lapilli fall on the SW flank and ashfall in Adrano at 560 m elevation. Lava flows from SE Crater descended the W part of the Valle del Bove as far as 1.9 km E and the S flank as far as 2 km. Satellite data showed a large sulfur dioxide plume drifting E. Weather clouds prevented views of the activity. Tremor levels sharply decreased starting at 1135 and had stabilized by 1200. Ashfall was also reported in Catania and Aci Castello. According to news reports the ashfall caused the Catania-Fontanarossa Airport in Sicily to close until 0900 on 22 May. The runway had been covered in ash and at least 68 flights to and from the airport were cancelled.

The Aviation Color Code was lowered to Orange at 0601 on 22 May, though lava flows were still active. By 0832 on 23 May monitoring data indicated that eruptive activity had ceased, and webcam images showed that the lava flows were cooling. The Aviation Color Code was lowered to Yellow at 0840 and then to Green at 1051.
Sources: Sezione di Catania - Osservatorio Etneo (INGV), Advanced geospatial Data Management Platform (ADAM), MSN

Report for Karangetang
PVMBG reported that activity at Karangetang had intensified in May, leading to a change in the Alert Level status. During 1-17 May white gas-and-steam plumes were sometimes dense and rose as high as 250 m above the summit, slightly higher than the 200 m maximum height noted in April. Incandescence at North Crater was visible at night 10-25 m above the lava dome. Incandescence also emanated from Main Crater though the glow was less intense, reaching about 10 m above the dome. Sounds of falling rocks at Main Crater were heard on 15 May, the seismic network recorded 32 rockfall events in the crater on 17 May, and rock avalanches on 18 May traveled as far as 1.5 km down the SW and S flanks accompanied by rumbling sounds. On 19 May the Alert Level was raised to 3 (on a scale of 1-4) and the public was warned to stay 2.5 km away from the craters on the S and SW flanks and 1.5 km away on the other flanks. A webcam image from 2025 on 19 May showed incandescent material traveling down the flanks. On 21 May white gas-and-steam plumes rose 400 m above the summit.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Nyamulagira
The Observatoire Volcanologique de Goma (OVG) reported that lava continued to erupt from vents in Nyamulagira’s summit crater during 17-23 May. Lava flows began moving into the N and NW parts of the crater beginning on 9 May, towards the low point of the crater rim. Intense incandescence from the summit was visible from Goma (27 km S) during the evenings of 17 and 19 May. Satellite images showed a notable sulfur dioxide plume drifting NW and W during 19-20 May. Drone footage acquired on 20 May captured images of narrow lava flows traveling about 100 m down the W flank. Intense incandescence emanating from the summit was again visible from Goma at around 1830. Data from the Rumangabo seismic station indicated a downward trend in activity during 17-20 May and a significant decrease during 20-21 May. Though weather clouds were dense over the summit, hot lava on the NW flank was visible in a 22 May Sentinel-2 infrared (SWIR) image.
Sources: Observatoire Volcanologique de Goma (OVG), Sentinel Hub

Report for Popocatepetl
CENAPRED reported that activity at Popocatépetl intensified during 16-23 May after recent activity characterized by the formation of small to medium lava domes on the summit crater floor and their subsequent destruction. There were 154-168 daily steam, gas, and ash emissions and minor-to-moderate explosions during 16-19 May. Periods of high-frequency tremor lasted more than 12 hours during 16-17 May and more than 10 hours during 17-18 May. Minor ashfall was reported on 18 May in the municipalities of Atlixco (25 km SE) and Cholula (35 km E), Puebla. Six volcano-tectonic earthquakes with magnitudes as high as 1.8 were recorded along with over 2 hours of high-frequency tremor on 19 May. Residents of Tétela del Volcán (18 km SW), Morelos, noted minor ashfall. According to the Washington VAAC ash plumes rose 6.7-7 km (22,000-23,000 ft) a.s.l., or 1.3-1.6 km above the summit, during 16-19 May.

A period of high-frequency tremor that began at around 1800 on 19 May and lasted about 10 hours until about 0400 on 20 May was accompanied by steam, gas, and ash plumes that drifted NNW and continuous ejection of incandescent tephra onto the flanks as far as 1.5 km from the crater. On 20 May the Benito Juárez International Airport closed during about 0430-1000 and the Felipe Ángeles International Airport closed during 0600-1100 in order to clear ash from runways. Ash fell in multiple areas downwind including in the municipalities of Venustiano Carranza (66 km NW), Gustavo A. Madero (73 km NW), Azcapotzalco (78 km NW), Tlalpan (62 km NW), Iztapalapa (58 km NW), Amecameca (18 km NW), Ayapango (21 km NW), Ozumba (18 km W), Ecatzingo (15 km SW), Atlautla (16 km W), Valle de Chalco (44 km NW), La Paz (50 km NW), Chalco (38 km NW), Nezahualcóyotl (56 km NW), Temamatla (32 km NW), Tenango del Aire (29 km NW), Tlalmanalco (27 km NW), Juchitepec (28 km NW), Cocotitlán (34 km NW), and Tepetlixpa (21 km W). Ashfall in Puebla municipalities included Huejotzingo (28 km NE), Nealtican (21 km E), Chignahuapan (108 km NE), Puebla Capital (44 km E), San Martín Texmelucan (35 km NE), and San Felipe Teotlalcingo (26 km NE).

Additional explosions were recorded at 1047, 1247, 1454, 2136, 2238, and 2253 on 20 May. Almost 19 hours of high-frequency tremor recorded during 20-21 May was accompanied by continuous emissions of steam, gas, and ash and occasional ejections of incandescent material short distances onto the flanks. The Washington VAAC reported that activity intensified at 1453 on 20 May as a large, dense ash plume was visible in webcam images. By 1551 the ash plume was visible in satellite images rising to 8.2 km (27,000 ft) a.s.l., or 2.8 km above the summit. By 2041 the dense ash plume had risen to 9.1 km (30,000 ft) a.s.l., or 3.7 km above the summit, and drifted ENE far over the Gulf of Mexico. The plume rose as high as 9.7 km (32,000 ft) a.s.l., or 4.3 km above the summit by 2136 and remained at that altitude at least through 0341 on 21 May as it fanned out to the NE and ENE. By 0951 on 21 May ash plumes were rising to 9.1 km and at 1436 plumes were reaching 8.5 km (28,000 ft) a.s.l., or 3.1 km above the summit. Satellite images showed a large dense ash plume drifting 388 km NE over the Bay of Campeche, but emissions were most dense within 65 km of the summit. Webcam images showed that continuing dense ash emissions.

According to CENAPRED the Scientific Advisory Committee of the Popocatépetl Volcano announced on 21 May that the Alert Level was raised from Yellow, Phase 2, to Yellow, Phase 3, the highest of the three sub-phases based on the intensifying activity over the previous few days. The National Coordination of Civil Protection (CNPC) announced actions to be implemented by the state civil protection units including preparing evacuation routes and evacuation teams and shelters. Ashfall was reported in Puebla state, in the municipalities of San Andrés Cholula (36 km E), San Pedro Cholula (34 km E), Cuautlancingo (38 km E), Amozoc (61 km E), Puebla Capital (44 km E), Zacatlán (121 km NE), Tetela de Ocampo (121 km NE), and Chignahuapan (108 km NE). The Hermanos Serdán International Airport, in Puebla (30 km NE), closed at 2300 on 21 May until 0700 on 22 May according to Gobierno de Puebla.

High-frequency tremor was almost constant for over 23 hours during 21-22 May. Steam, gas, and ash emissions were continuous with occasional ejections of incandescent material short distances onto the flanks. Explosions occurred at 1355 on 21 May and 0533 on 22 May. According to the Washington VAAC satellite images acquired at 0236, 0821, 1421, and 1936 revealed continuing ash emissions to 3.7 km above the summit, drifting E and ENE. An accompanying very large sulfur dioxide plume drifted as far as Cancun, 1,295 km E. Ashfall occurred in the municipalities of San Andrés Cholula (36 km E), San Pedro Cholula (34 km E), Cuautlancingo (38 km E), Amozoc (61 km E), Zacatlán (121 km NE), Tetela de Ocampo (121 km NE), San Nicolás de los Ranchos (15 km NE), Palmar de Bravo (115 km SE), Tepeaca (76 km E), in Izúcar de Matamoros (51 km S), Epatlán (51 km SE), Teopantlán (52 km SE), Tlapacoya (144 km NE), Huatlatlauca Chignahuapan (72 km SE), and in the Puebla capital, in the state of Puebla. Ash also fell in Juchitepec (28 km W), State of Mexico, Hueyapan (17 km SW), Locality of Xochitepec (municipality of Jolalpan) (68 km SW), in Morelos, and in the capital of the state of Tlaxcala (50 km NE). At 1651 on 22 May the Hermanos Serdán International Airport suspended operations due to ash on the runway.

Tremor remained nearly continuous (more than 20 hours) during 22-23 May. Ongoing steam, gas, and ash emissions drifted NE, and occasional ejections of incandescent material short distances onto the flanks. Ash fell in the municipalities of Nealtican, Tianguismanalco, Atlixco, San Diego la Mesa, Huaquechula, and Atzizihuacán, State of Puebla. Ash plumes rose as high as 3.7 km above the summit and drifted E according to the Washington VAAC.
Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC), Simple Flying, Gobierno de Puebla, Cuenta Oficial de la Coordinación General de Protección Civil del Estado de Puebla

Report for Aira
JMA reported ongoing activity at both Minamidake Crater and Showa Crater (Aira Caldera’s Sakurajima volcano) during 15-22 May. Crater incandescence was observed nightly at Minamidake Crater. At 1429 on 17 May an eruptive event at Showa Crater produced an ash plume that rose 1.2 km above the crater rim and drifted N. An explosion from Minamidake Crater at 2027 generated an ash plume that rose 400 m and ejected large blocks 600-900 m from the crater; another eruptive event at 2051 produced an ash plume that rose as high as 1 km and drifted N. An explosion at Minamidake was recorded at 1519 on 18 May. Showa Crater sent an ash plume 1.5 km high at 1125 on 22 May. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from both craters.
Source: Japan Meteorological Agency (JMA)

Report for Bulusan
In a special advisory, PHIVOLCS reported that from 0500 on 21 May to 1600 on 22 May the seismic network at Bulusan recorded a total of 37 volcanic earthquakes. Out of those, 34 were volcano-tectonic earthquakes associated with rock fracturing and three were low-frequency volcanic earthquakes associated with movement of volcanic gas. Minor steam emissions from an active vent on the SE flank were occasionally visible. Ground deformation data from electronic tiltmeter stations continued to record short-term inflation of the SE flanks, first detected in December 2022. The Alert Level remained at 0 (the lowest level on a scale of 0-5) and PHIVOLCS reminded the public not to enter the 4-km-radius Permanent Danger Zone (PDZ).
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Report for Cotopaxi
IG reported that moderate eruptive activity continued at Cotopaxi during 17-23 May. Seismic activity was mainly characterized by long-period earthquakes and tremors associated with emissions that occurred almost daily; a total of six volcanic-tectonic earthquakes were recorded during the week. Emissions of steam, gas, and variable amounts of ash were observed on most days; clouds obscured views on 19 May. Weak steam-and-gas emissions that barely rose above the crater level were recorded during 17 and 20-22 May; the emissions drifted W on 22 May. Starting at 0510 on 18 May emissions of steam-and-ash rose 1-3 km above the crater and drifted N and NE; ashfall was reported in Machachi (23 km NW). During the morning of 23 May several steam-and-gas emissions with possible minor ash content were observed rising 1 km above the crater and drifting S. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest 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 Ebeko
KVERT reported that moderate activity at Ebeko was ongoing during 11-18 May. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions during 12-16 May generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l. and drifted in multiple directions. A thermal anomaly was identified in satellite images during 13-14 May. 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)

Report for Fuego
INSIVUMEH reported that 1-4 weak explosions per hour were recorded at Fuego on most days during 16-23 May. The explosions generated ash plumes that rose 250-750 m above the crater; the plumes drifted S and SW during 18-20 May and as far as 10 km SW during 21-22 May. Slight incandescent at the crater was occasionally visible during dark hours a few times during the week. Very minor ashfall was reported in Morelia (9 km SW) and Panimaché (8 km SW) during 20-22 May.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Report for Great Sitkin
AVO reported that slow lava effusion continued at Great Sitkin during 16-23 May. Satellite data acquired on 16 May showed that the thick lava continued to expand towards the E but remained confined to the summit crater. Elevated surface temperatures were identified in satellite images during 18 and 21-23 May. Seismicity was low with some variations; five small earthquakes occurred during 19-20 May and small low-frequency earthquakes that began at 1000 on 23 May were ongoing at least through 1206. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Ibu
PVMBG reported that Ibu continued to erupt during 18-23 May. An average of approximately 80 eruption-related earthquakes were recorded by the seismic network during 18-22 May. White-and-gray emissions of variable densities rose as high as 1 km above the summit and drifted N, E, SE, and W. At 2021 and 2140 on 21 May dense gray ash plumes rose 600 m and 1 km above the summit, respectively, and drifted W. The Alert Level remained at a 2 (the second highest level on a four-level scale), and the public was advised to stay outside of the 2 km hazard radius, and to stay 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 Lewotolok
PVMBG reported that the eruption at Lewotolok was ongoing during 17-23 May. Almost daily white-and-gray ash plumes rose as high as 700 m above the summit and drifted in variable directions; only white gas-and-steam plumes were visible on 19 May. A nighttime webcam image of incandescent material being ejected above the summit was captured at 1844 on 17 May. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the summit crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Merapi
BPPTKG reported that the eruption at Merapi (on Java) continued during 12-18 May and seismicity remained at elevated levels. The SW lava dome produced 182 minor lava avalanches that traveled as far as 1.8 km down the SW flank (upstream in the Bebeng and Boyong drainages) and one that traveled 500 m NW (upstream of the Senowo River). Morphological changes to the SW lava dome due to continuing collapses of material were evident in webcam and drone images. 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 Nevado del Ruiz
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that the eruption at Nevado del Ruiz continued during 17-23 May and was characterized by periodic gas, steam, and ash emissions, thermal anomalies at the lava dome in Arenas Crater, and elevated seismicity. Seismic signals indicating rock-fracturing events were located 3-8 km around the Arenas Crater at depths of 1-6 km. The largest event, a M 2.1, was recorded at 0341 on 21 May and was located 2 km below the Arenas crater. Gas-and-ash emissions rose as high as 1.5 km above the crater and drifted multiple directions. A thermal anomaly was observed within the crater on 18 May. The Alert Level was remained at Orange, Level II (the second highest level on a four-level scale).
Source: Servicio Geológico Colombiano (SGC)

Report for Rincon de la Vieja
OVSICORI-UNA reported that small phreatic eruptions periodically occurred at Rincón de la Vieja during 16-23 May. Four small events occurred during 16-17 May; the last one, recorded at 1255 on 17 May, produced a gas-and-steam plume that rose 700 m above the crater rim. Sulfur dioxide emissions were almost as high as 5,000 tonnes per day on 17 May; emissions averaged around 132 tonnes per day during the previous week. Events were recorded at 1537 on 18 May and at 0727 and 1025 on 19 May. Vigorous gas emissions were visible in the early morning of 20 May and a phreatic event occurred at 1648 that same day. At 1349 a phreatic event generated a plume mostly comprised of steam that rose 1 km above the crater rim.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Report for Sabancaya
Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 15-21 May with a daily average of 37 explosions. Gas-and-ash plumes rose as high as 2.4 km above the summit and drifted NE, E, and SE. Eight thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Seismic sensors detected 232 volcanic activity-related earthquakes, in addition to volcano-tectonic earthquakes. 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 reported a high level of activity at Sangay during 17-23 May, though weather clouds sometimes prevented visual observations. Incandescent material at the crater and along the lava flow extending 1 km down the SE flank was visible nightly. On 17 May steam-and-ash emissions rose 500 m above the summit and drifted SW. On 18 May an ash plume rose 1.7 km and drifted N and SW. At 2000 on 20 May ash plumes rose 2 km above the summit and drifted to the SW. Continuous ash emissions persisted during 21-22 May, drifting W and SW. Ashfall during 20-22 May was reported in Chauzan, Guamote, Tixán, Palmira, Cebadas, and Alausí cantons in the Province of Chimborazo. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest 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 Santa Maria
INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 16-23 May. Effusion from the Caliente dome complex fed lava flows that descended the San Isidro and Zanjón Seco drainages on the W and SW flanks; the main lava flow was 4.3 km long and remained active. Avalanches of material from the growing dome and occasional explosions descended all sides of the dome and avalanches from the lava flow descended the S and SW flanks. Explosions generated gas, steam, and ash plumes that drifted S and SW on a few days. Incandescence from the dome and lava flows was visible during the nights and early mornings. An average of 40 explosions per day were recorded during 21-22 May, generating ash plumes that rose up to 1 km above the dome and drifted SW.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Report for Semeru
PVMBG reported that the eruption at Semeru continued during 17-23 May and several Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued during the week. Daily white-to-gray ash plumes that were sometimes dense rose 200-800 m above the summit and drifted in multiple directions. VONAs were issued as follows: 0501, 0646, and 0919 on 17 May; 0517 and 0822 on 18 May; 0547, 0911, and 0936 on 19 May; 0545, 0733, 0742, and 1054 on 20 May. 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, 100 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 Semisopochnoi
On 17 May AVO reported that eruptive activity at Semisopochnoi had declined during the previous week, though seismicity remained slightly elevated and low-level steaming continued from Mount Young. Ash emissions had last occurred on 5 May leaving minor deposits on the NW flank of Mount Young’s N crater. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level was lowered to Advisory (the second highest level on a four-level scale). Intense gas emissions were periodically visible in webcam images during 17-18 and 20-21 May. On 22 May a weak sulfur dioxide signal was detected, suggestive of low-level degassing.
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Sheveluch
KVERT reported that the eruption at Sheveluch was ongoing during 11-18 May. A thermal anomaly over the active crater and Karan lava dome area was identified in satellite images all week. Intense fumarolic activity at the active crater was likely associated with dome growth. Plumes of ash, originally deposited during the 10-13 April eruption and resuspended by strong winds, were visible in satellite images drifting 400 km SE during 14-15 May. 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)

Report for Suwanosejima
JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 15-22 May. Incandescence was visible nightly, and seismicity remained elevated during 15-19 May. On 16 May an ash plume rose 1.8 km above the crater rim and caused ashfall in Toshima village (3.5 km SSW). On 17 May, an ash plume rose to 1.1 km and drifted NW. Four eruptive events were observed during 21-23 May. On 21 May an eruptive event ejected volcanic blocks up to 200 m from the crater and produced an ash plume that rose 1.8 km above the crater and drifted E. On 22 May an ash plume rose to 1 km above the crater and drifted SE. Two eruptive events on 23 May generated ash plumes that rose 600 m above the crater and drifted SE and S. 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)