Volcanos

Roundup of Global Volcanic Activity - Ongoing Activity for the week of 17 May - 23 May 2023

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.

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.

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.

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.

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.

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.

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. T

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.

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.

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.

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.

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.

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.

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.

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.

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. 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.

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.

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.