Volcanos

Roundup of Global Volcanic Activity - Ongoing Activity for the week of 12 April - 18 April 2023

Aira - Kyushu (Japan) : JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 10-17 April, with crater incandescence visible nightly. Very small eruptive events occasionally occurred during 10-14 April. Two eruptive events on 17 April produced ash plumes that rose as high as 1.5 km and drifted S.

Aniakchak - Alaska Peninsula, Alaska : On 13 April AVO issued an Information Statement about the ongoing unrest at Aniakchak. Measurements of the earthquake rate in the ongoing swarm were disrupted by a partial network outage that began on 4 March and reduced the ability to detect smaller earthquakes. Earthquake activity continued to be above background levels with a M 3.3 on 6 April as the largest recent event. In addition to the earthquake swarm, high rates of deformation were detected in radar data. A zone of uplift centered within the W side of the caldera was first detected between 4 and 27 February. The ground uplift rates were about 4 cm per week during February-March and about 3 cm per week during 23 March-4 April. These uplift rates are at the high end of those observed for restless volcanoes worldwide. Seismic and deformation data suggested that magma was intruding beneath the caldera at a depth of 3-4 km below sea level. AVO noted that unrest at calderas such as Aniakchak sometimes lasts for many months or even years and could be variable . If an eruption were to occur, it could be after a period of months or years and would likely be preceded by additional signals that would allow AVO to provide advance warning. Aniakchak has a local monitoring network consisting of six seismometers, a web camera, and an infrasound sensor, as well as with satellite remote sensing data and regional infrasound and lightning networks. AVO recently installed an additional seismic station and web camera in Port Heiden, 26 km NW.

Asamayama - Honshu (Japan) : JMA reported that minor inflation on Asamayama's W flank persisted during 10-17 April. The daily number of shallow volcanic earthquakes was 40-80 during 10-14 April and around 40 during 14-17 April. Sulfur dioxide emissions were high at 700 tons per day on 14 April.

Cotopaxi - Ecuador : IG reported that eruptive activity at Cotopaxi was ongoing during 11-18 April, though cloudy weather often prevented webcam and satellite views. A small secondary lahar descended the Agualongo drainage on the SW flank on 11 April. Ash-and-gas plumes on 12 April rose as high as 1.5 km above the crater rim and drifted W and SW. Muddy water in a drainage on the NW flank was visible on 15 April. Daily gas-and-steam emissions were visible during 13-18 April, rising as high as 300 m and drifted W.

Dukono - Halmahera : PVMBG reported that the eruption at Dukono was ongoing during 12-17 April. Daily dense white-and-gray ash plumes rose as high as 400 m above the summit and drifted E. No ash plumes were reported by PVMBG on 12 April, but according to the Darwin VAAC an ash plume rose to 2.1 km (7,000 ft) a.s.l., or about 900 m above the summit, and drifted E.

Ebeko - Paramushir Island (Russia) : According to the Tokyo VAAC a possible ash plume at Ebeko was visible in a satellite image at 0920 on 14 April rising to 2.4 (8,000 ft) a.s.l. and drifted NE. The plume had dissipated by 1120. Another plume from a possible eruption was identified in satellite images at 1300, rising to 3.7 (12,000 ft) a.s.l. and drifting N. The plume was no longer visible or had dissipated by 1720. At 1452 on 16 April an ash plume rose to 3 km (10,000 ft) a.s.l. and drifted NE.

Fuego - South-Central Guatemala : INSIVUMEH reported that 4-13 explosions per hour were generally recorded at Fuego during 11-18 April, generating daily ash plumes that rose as high as 1.1 km above the crater rim and drifted as far as 30 km SW, S, SE, and E. Daily ashfall was recorded in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), La Rochela, San Andrés Osuna, Ceylon, Finca La Asunción, El Zapote (10 km S), Alotenángo (8 km ENE), and other areas to the N and NE. Daily block avalanches descended multiple drainages including the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Honda, Las Lajas (SE), and El Jute (ESE), and often reached vegetated areas. Daily shock waves rattled structures in communities around the volcano and rumbling was often heard. Explosions ejected incandescent material as high as 350 m above the summit on most days.

Great Sitkin - Andreanof Islands (USA) : AVO reported that lava continued to slowly erupt at the summit of Great Sitkin during 11-17 April, producing a thick lava flow that expanded mostly to the E. Seismicity was low, and during 11-13 April only a few small events were detected. Elevated surface temperatures were identified in satellite images during 16-17 April, and steam emissions were visible in webcam views during 17-18 April. Weather clouds often obscured satellite and webcam views during most of the week.

Ibu - Halmahera : PVMBG reported that the eruption at Ibu continued during 12-18 April. White-and-gray plumes of variable densities rose as high as 800 m above the summit and drifted NE, S, SW, and NW.

Karangetang - Sangihe Islands : Webcam images of Karangetang captured in the PVMBG daily reports periodically showed small areas of incandescence at the summit craters during 11-17 April.

Lewotolok - Lembata Island : PVMBG reported that the eruption at Lewotolok was ongoing during 12-17 April. White steam-and-gas plumes of variable densities were seen on most days rising as high as 700 m above the summit and drifting NE, E, and SE. On 13, 15, and 17 April white-and-gray plumes rose as high as 500 m and drifted NW, NE, E, and SE.

Merapi - Central Java : BPPTKG reported that the eruption at Merapi (on Java) continued during 7-13 April and seismicity remained at high levels. The SW lava dome produced 132 lava avalanches that traveled as far as 2 km down the SW flank (upstream in the Bebeng and Boyong drainages). Morphological changes to the SW lava dome were evident in webcam images due to continuing collapses of material.

Rincon de la Vieja - Costa Rica : OVSICORI-UNA reported that small phreatic eruptions, often in association with observed emissions, occurred at Rincón de la Vieja during 11-17 April. A small phreatic eruption on 11 April consisted of several pulses of activity recorded during 0653-0700 and at 0743. Gas-and-steam plumes rose 500 m above the crater rim. A small phreatic event was recorded late in the evening. An event at 0450 on 12 April produced a gas-and-steam plume that rose 500 m and another was recorded at 1920 with no visual observations reported. Gas-and-steam emissions from a phreatic event were seen at 0632 on 13 April; an event was recorded at 1826 with no visual observations reported. At 0936 on 14 April an event produced a gas-and-steam plume that rose as high as 2 km and was seen from Curubandé. The event was preceded by a swarm of long-period earthquakes five hours prior to the eruption; sediments were possibly ejected from the crater lake and deposited on the crater floor. A small phreatic eruption at 0647 on 16 April ejected material out of the crater and produced a gas-and-steam plume that rose 2 km. A smaller emission rose 500 m at 0957 and at 2235 an event generated a plume that rose 500 m. At 1237 on 17 April a phreatic event produced a plume that rose 1.5 km above the crater rim and a brief event was recorded at 0722 on 18 April.

Sabancaya - Peru : Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 10-16 April with a daily average of 41 explosions. Gas-and-ash plumes rose as high as 2.5 km above the summit and drifted NW, W, SW, and S. Six thermal anomalies originating from the lava dome in the summit crater were identified in satellite data.

Santa Maria - Southwestern Guatemala : INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 12-18 April. 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. Incandescence from the dome and the lava flows was frequently visible at night. Avalanches down the N, E, S, and SW flanks of the dome were sometimes generated from the lava-flow front and margins. Daily weak or weak-to-moderate explosions were recorded by the seismic network and on most days the explosions generated ash plumes that rose as high as 1 km above the complex and drifted mainly E, S, and SW. Weak rumbling was barely heard on nearby farms during 16-17 April. Residents were reminded to stay at least 6 km away from the complex.

Semeru - Eastern Java : PVMBG reported that the eruption at Semeru continued during 12-18 April and daily Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued through the week. At 0747 on 12 April a dense white-to-gray plume rose 600 m above the summit and drifted N. On 13 April at 1135 a gray-to-brown ash plume rose 400 m and drifted NE, at 1249 a dense gray ash plume rose 500 m and drifted N and NE, and at 1709 a dense white-to-gray ash plume rose 600 m and drifted E. At 0529 on 14 April a white-to-brown ash plume rose 500 m and drifted S. White-to-gray ash plumes at 0606 and 0731 on 15 April rose 600-700 m and drifted N and NE. At 0551 on 16 April a dense white-to-gray ash plume rose 1 km and drifted N. On 17 April at 0614 a medium-density white-to-brown ash plume rose 700 m and drifted S and at 0847 a white-to-gray ash plume rose 600 m and also drifted S. At 0540 and 0708 on 18 April dense white-to-gray ash plumes rose 500-600 m and drifted S and W.

Semisopochnoi - Aleutian Islands (USA) : AVO reported that low-level unrest continued at Semisopochnoi during 12-18 April. No eruptive activity was observed, though some weak seismicity was recorded. Cloudy weather often prevented webcam and satellite views during most of the week.

Suwanosejima - Ryukyu Islands (Japan) : JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 10-17 April. Eruptive activity produced ash plumes during 12-14 and 17 April that rose as high as 1.5 km above the crater rim and drifted NW, S, SE, and E. Large blocks were ejected as far as 500 m from the vent. Crater incandescence was visible nightly.