Volcanos

Roundup of Global Volcanic Activity - Ongoing activity for the week 29 March - 4 April 2023

Ahyi - Mariana Islands (USA) : Unrest at Ahyi Seamount continued during 28 March-4 April. Underwater events were detected by pressure sensors on Wake Island, 2,270 km E, on 29 and 31 March and during 1-2 April. The events were possibly related to underwater explosions or earthquakes at the volcano.

Aira - Kyushu (Japan) : JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera's Sakurajima volcano) during 27 March-4 April with nightly crater incandescence. Five eruptive events were recorded during 27-31 March producing plumes that rose 1.5 km above the crater rim. A few small eruptive events occasionally occurred during the rest of the week.

Asamayama - Honshu (Japan) : JMA reported that inflation on Asamayama's W flank persisted during 29 March-4 April, and the number of shallow volcanic earthquakes continued to increase. There were 95 events on 29 March, 91 on 30 March, 94 on 31 March, 77 on 1 April, 68 on 2 April, 104 on 3 April, and 149 on 4 April. Sulfur dioxide measurements were 1,600 tons per day on 29 March, which had increased compared to the previous measurement of 100 tons per day on 17 March. On 3 April the sulfur dioxide concentration was 1,000 tons per day.

Bezymianny - Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Bezymianny persisted in satellite images at least through 31 March, local time. On 2 April an ash plume rose 4.3 km (14,000 ft) a.s.l. and drifted SE according to the Tokyo VAAC.

Cotopaxi - Ecuador : IG reported that eruptive activity at Cotopaxi was ongoing during 29 March-4 April. Gas-and-ash plumes visible in webcam images and reported by the Washington VAAC during 28-29 March rose as high as 2 km above the summit and drifted SE and N. Minor ashfall was reported in Machachi (23 km NW), El Chasqui (17 km W), and Latacunga (34 km SW). Gas-and-steam plumes were seen rising 100-300 m during 30-31 March. Ash-and-gas plumes rose as high as 1 km and drifted W during 1-2 April. Gas-and-steam plumes rose 1 km and drifted W on 3 April.

Ebeko - Paramushir Island (Russia) : KVERT reported that moderate activity at Ebeko was ongoing during 23-30 March. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions during 23, 26, and 29-30 March generated ash plumes that rose as high as 2.8 km (9,200 ft) a.s.l. and drifted NE and E.

Fuego - South-Central Guatemala : INSIVUMEH reported that 4-12 explosions per hour recorded at Fuego during 29 March-4 April generated ash plumes that rose as high as 4.8 km above sea level (15,700 ft a.s.l.) and drifted at least 10 km W, NW, SE, SW. Weak to moderate rumbling accompanied the explosions, vibrating the roofs and windows of nearby houses. During the night and early morning incandescent material was ejected 100-200 m above the crater. Daily block avalanches descended all the flanks toward the Seca (W), Taniluya (SW), Ceniza (SSW), Trinidad (S), Las Lajas (SE), El Jute (ESE), Honda (E), and Santa Teresa drainages, sometimes reaching vegetated areas. Some avalanches resuspended ash to 100 m high. Ashfall was reported almost daily in areas downwind.

Great Sitkin - Andreanof Islands (USA) : AVO reported that lava likely continued to slowly effuse at the summit of Great Sitkin during 29 March-4 April, producing a thick lava flow. Minor earthquakes and seismic events were noted during 1-2 April.

Karangetang - Sangihe Islands : During 29 March-4 April a webcam image of Karangetang captured in the PVMBG daily reports showed incandescent material at the summit Main Crater (S crater) and on the flanks at 0016 on 1 April.

Krakatau - Sunda Strait : PVMBG reported that daily white steam-and-gas plumes rose as high as 300 m above Anak Krakatau’s summit during 29 March-4 April. White-and-gray plumes rose 50-200 m above the summit and drifted NE on 2 April.

Lewotolok - Lembata Island : PVMBG reported that the eruption at Lewotolok was ongoing during 29 March-4 April. White gas plumes rose as high as 700 m above the summit and drifted in multiple directions during 29 March and 1-2 April. White-and-gray ash plumes of variable densities rose 100-750 m above the summit and drifted in multiple directions during 30-31 March and during 3-4 April. A webcam image from 0050 on 4 April showed summit incandescence.

Merapi - Central Java : BPPTKG reported that the eruption at Merapi (on Java) continued during 24-30 March and seismicity remained at high levels. The SW lava dome produced 176 lava avalanches that traveled as far as 2 km down the SW flank (upstream in the Bebeng and Boyong drainages). Two pyroclastic flows traveled 1 km down the SW flank, upstream of the Boyong drainage. Morphological changes to the SW lava dome were evident in webcam images due to continuing collapses of material.

Reventador - Ecuador : IG described the ongoing eruption at Reventador as moderate during 29 March-4 April. Seismicity was characterized by explosions, long-period earthquakes, periods of harmonic tremor, and signals that indicated emissions. The number of daily explosions ranged from 24 to 45; though the daily seismic data transmission was sometimes interrupted. Steam, gas, and ash plumes were observed in IG webcam images and described in Washington VAAC advisories during 29-31 March; weather conditions occasionally prevented views. The plumes rose as high as 1.3 km above the summit and drifted W. Crater incandescence was visible during the night of 29 and 30 March. Incandescent blocks were seen rolling as far as 700 m down the flanks in all directions during 30-31 March.

Sangay - Ecuador : IG reported a high level of activity at Sangay during 29 March-4 April, which included daily explosions, periods of tremor, and gas, steam, ash emissions. The daily count of explosions ranged from 7-72, though the daily seismic data transmission was sometimes interrupted. Almost daily gas, steam, and ash plumes were either observed in IG webcam images or described in Washington VAAC volcanic activity notifications; weather clouds often prevented observations of the summit. The plumes rose as high as 1.4 km above the volcano and drifted W. TROPOMI data from the Sentinel-5P satellite showed that sulfur dioxide plumes contained 183-2,049 tons/day. Multiple thermal anomalies were identified in satellite images on most days. Incandescence from the crater and an avalanche of material on the SE flank were visible during the night of 30 March; only crater incandescence was visible during the night of 31 March.

Santa Maria - Southwestern Guatemala : INSIVUMEH reported that the Santa Maria-Santiaguito lava dome complex remained highly active during 29 March-4 April. Seismic stations and webcams recorded weak-to-moderate explosions which produced ash plumes to 4.3 km altitude (14,100 ft a.s.l.). Incandescence from the dome and along lava flow margins was visible most nights or early mornings. Weak-to-moderate block-and-ash flows were recorded around the crater, on the S, W, SE, SW, and E flanks, and at the front of the western lava flow. Ash plumes rose 3.5 km above the crater and drifted W on 31 March. Avalanches traveled down the S, SW, E, and N flanks; on 31 March the avalanches were accompanied by small pyroclastic flows. The active lava flow measured 4.3 km long in the WSW direction down the San Isidro and Zanión Seco drainages on 1 April, with some block collapses that generated ash clouds several hundred meters high. On 4 April ash plumes rose 3.5 km above the crater and drifted W and the active lava flow generated avalanches and moderate-to-strong pyroclastic flows.

Semeru - Eastern Java : PVMBG reported that the eruption at Semeru continued during 29 March-4 April, with almost daily emissions of dense ash plumes; weather conditions prevented views on 30 March. Several Volcano Observatory Notices for Aviation (VONAs) were issued through the week. At 0714 on 29 March a dense gray ash plume rose 500 m above the summit and drifted N and NE. At 0517, 0605, and 0704 on 31 March dense white-to-gray ash plumes rose as high as 1 km and drifted NE, N, and NW. At 0552 and 0804 on 1 April and 0532, 0622, and 1630 on 2 April white-to-gray ash plumes rose 500-800 m and drifted N, SE, S, and SW. At 0538 and 0630 white-to-gray ash plumes rose as high as 1.2 km and drifted S and SE.

Semisopochnoi - Aleutian Islands (USA) : AVO reported that low-level unrest continued at Semisopochnoi during 28 March-4 April. Steam emissions from the N crater of Mount Young were visible in webcam images during 29-30 March; weather clouds obscured webcam and satellite views during most of the week. Minor seismic and infrasound signals were recorded during 31 March-1 April that may or may not have been related to activity at N crater. Local earthquakes and periods of tremor occurred during 1-2 April. A 200-km-long gas-and-steam emission was visible at low altitudes during the night of 3 April; no ash signatures were detected in the cloud.

Sheveluch - Central Kamchatka (Russia) : KVERT reported that the ongoing eruption at Sheveluch was generally characterized by explosions, hot avalanches, lava-dome extrusion, and strong fumarolic activity. A daily thermal anomaly was identified in satellite images during 23-30 March. Ash plumes drifted 80 km E during 25-26 and 28-30 March.

Stromboli - Aeolian Islands (Italy) : INGV reported that both explosive and effusive activity at Stromboli occurred during 27 March-2 April, though inclement weather conditions often prevented views on most days. Activity was centered at three vents (two at crater N1 and one at crater N2) in Area N, within the upper part of the Sciara del Fuoco, and from three vents in the Area C-S (South-Central Crater area) in the crater terrace area. Explosions at two vents in the N1 crater and one vent in the N2 crater in Area N were low to medium in intensity levels and ejected coarse material (bombs and lapilli) 80-150 m at a rate of 7-9 explosions per hour. Explosive activity at three active vents at the S2 sector in the Central-South area (CS) ejected coarse material generally as high as 150 m above the vent at a rate of 4-7 explosions per hour. No activity was recorded at sectors C and S1.

Suwanosejima - Ryukyu Islands (Japan) : JMA reported that the eruption at Suwanosejima’s Ontake Crater continued during 27 March-3 April. Two eruption events on 31 March and 3 April ejected large volcanic blocks 300-400 m from the crater and the accompanying eruption plumes rose 1.7-2 km above the crater rim. Crater incandescence was visible nightly. Ashfall was reported in Toshima village (3.5 km SSW).

Ulawun - New Britain (Papua New Guinea) : RVO reported that after a short-lived eruption at Ulawun on 28 March seismicity decreased and was characterized by very low levels of volcanic tremor at least through 31 March. In addition, small high-frequency volcanic earthquakes were recorded mainly during 29-30 March. White steam plumes of variable densities rose above the summit.

Yasur - Vanuatu : According to the Wellington VAAC a pilot saw an ash plume rising from Yasur to an altitude below 3 km (10,000 ft) and drifting W at 1752 on 4 April. Ash was not identified in satellite images.