Roundup of Global Volcanic Activity – Ongoing Activity for the week of 26 April – 2 May 2023
Aira – Kyushu (Japan) : JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 24 April-2 May, with crater incandescence visible nightly. Very small eruptive events occasionally occurred during the week. On 28 April sulfur dioxide emissions were somewhat high at 1,800 tons per day. An explosion at 0422 on 2 May ejected large blocks 500-700 m from the crater and generated an ash plume that rose 1.8 km above the crater rim and drifted SW.
Cotopaxi – Ecuador : IG reported ongoing moderate eruptive activity at Cotopaxi during 26 April-2 May. Cloudy weather sometimes prevented webcam and satellite views, but emissions of steam-and-ash were visible on most days. On 26 April a gas plume with minor amounts of ash rose 500 m above the crater rim and drifted E. On 28 April an ash plume rose 800 m and drifted SE and W; ashfall was reported in the S part of Parque Nacional Cotopaxi. Gas-and-ash plumes rose 800 m and drifted W on 29 April, and two ash emissions rose 200-800 m and drifted SW and W on 30 April. At 0130 on 1 May the seismic network began recording a high-frequency signal that corresponded to the descent of a very small secondary lahar that remained within the bounds of Parque Nacional Cotopaxi. Gas-and-ash emissions rose 300 m and drifted W during 1-2 May.
Ebeko – Paramushir Island (Russia) : KVERT reported that moderate activity at Ebeko was ongoing during 20-27 April and a thermal anomaly was identified in satellite images on 20 and 26 April. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) and satellite data explosions during 22 and 25-26 April generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l. and drifted E.
Fuego – South-Central Guatemala : INSIVUMEH reported that a range of 5-14 weak and moderate explosions per hour were recorded at Fuego during 26 April-2 May. The explosions generated ash plumes, weak to moderate rumbling sounds, and shockwaves that vibrated the roofs and windows of nearby houses. Ash plumes rose 1.1 km above the crater and sometimes dispersed as far as 15 km S, SW, SE, and W. Ash fall was reported in Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), El Porvenir (11 km SW), Finca La Asunción, La Rochela (8 km SSW), Finca Ceilán (9 km S), and San Andres Osuna. Incandescent material was ejected as high as 350 m above the crater almost daily. Weak and moderate avalanches descended multiple drainages including the Seca (W), Ceniza (SSW), Taniluyá (SW), Trinidad (S), Las Lajas (SE), Santa Teresa (ESE), and Honda (SE); sometimes reaching the edges of vegetation. In the evening on 27 April a weak-to-moderate lahar descended the Ceniza, a tributary of the Achiguate River, and consisted of fine-grain, hot material, branches, tree trunks, and blocks that ranged from 30 cm to 1.5 m in diameter.
Great Sitkin – Andreanof Islands (USA) : AVO reported that lava continued to slowly erupt at the summit of Great Sitkin during 26 April-2 May. Weather clouds obscured satellite and webcam views during most of the week. Seismicity was low, and during 27-28 April only a few small events were detected. Satellite data last acquired up to 24 April showed that the thick lava continued to expand toward the E and remained confined to the summit crater.
Lewotolok – Lembata Island : PVMBG reported that the eruption at Lewotolok was ongoing during 26 April-2 May. Almost daily white-and-gray plumes rose as high as 500 m above the summit and drifted NW, W, and SW. White gas-and-steam plumes rose 300 m and drifted SW on 28 April. Crater incandescence was visible in webcam images posted with the 27 April report.
Merapi – Central Java : BPPTKG reported that the eruption at Merapi (on Java) continued during 21-27 April and seismicity remained at elevated levels. The SW lava dome produced 148 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.
Popocatepetl – Mexico : CENAPRED reported that there were 65-288 daily steam-and-gas emissions, sometimes containing ash, and daily explosions at Popocatépetl during 26 April-2 May. Ash-and-gas plumes drifted ENE. On most days webcam images showed nighttime incandescence in the crater and from material that had been deposited on the upper flanks. A moderate explosion at 0109 on 26 April ejected material that landed on the N flank as far as 1 km from the crater rim. A minor explosion was recorded later that day at 1817. A moderate explosion at 0116 on 27 April ejected incandescent material onto the upper flanks. Another moderate explosion was recorded at 1147 and minor explosions were recorded at 0348, 0606, 0857, and 1059. Minor explosions continued to be detected during the rest of the week: at 0857 and 1750 on 28 April, 0150 and 2350 on 29 April, at 2205, 2220, 2256, and 2345 on 30 April, and at 0000, 0130, 0356, 0454, and 0506 on 1 May. A moderate explosion occurred at 1249 on 30 April. On 2 May minor explosions occurred at 0335 and 0942. According to the Washington VAAC ash plumes were identified in satellite images daily rising 5.8-7.3 km (19,000-24,000 ft) a.s.l. (0.4-1.9 km above the crater rim) and drifting NE, E, and SE.
Ruapehu – North Island (New Zealand) : On 3 May GeoNet reported that temperatures in Ruapehu’s cater lake had declined from 32 to 21 degrees Celsius since January, and other monitoring parameters indicated that volcanic unrest remained low. Weak volcanic tremor persisted and very few earthquakes were located beneath the volcano. Gas emissions were at low-to-moderate levels during the previous three months, and only minor changes to the lake water chemistry were identified over the past several months and most recently on 6 April.
Sangay – Ecuador : IG reported a high level of activity at Sangay during 25 April-2 May. Gas, steam, and ash plumes were occasionally observed in IG webcam images or described in Washington VAAC volcanic activity notifications, though weather clouds prevented observations on most days. On 25 April an ash-and-gas plume rose as high as 6 km above the crater rim and drifted SW. That same day notifications issued by the Washington VAAC indicated that ash plumes rose to 4.7 km (22,000 ft) a.s.l. (1.4 km above the crater rim) and drifted E, SE, SW, and W. IG noted that minor amounts of ash fell in the Province of Chimborazo in the Matriz and Juan de Velasco parishes, and in the Guamote canton. The VAAC reported that ash plumes rose as high as 1.4 km above the crater rim and drifted in multiple directions during 26-27 and 29 April. IG noted that a minor ash plume was visible in satellite images drifting W on 28 April. On 1 May an ash plume rose 1 km above the crater rim and drifted W.
Santa Maria – Southwestern Guatemala : INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 26 April-2 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. Daily weak-to-moderate explosions generated ash-and-steam plumes that rose as high as 1 km above the dome and drifted W and SW. The explosions were also accompanied by block-and-ash flows that descended multiple flanks of the dome. Avalanches of material were also generated from the lava-flow front and margins. During 28-29 April quiet rumbling sounds were barely heard on nearby farms. Incandescence from the dome and the lava flows was visible nightly. On 28 April a lahar descended the Cabello de Angel River, a tributary of the Nimá I and Samalá rivers, on the E flank and was registered by the nearby seismic stations. The lahar consisted of volcanic material, water, volcanic blocks up to 1 m in diameter, and tree trunks and branches. On 30 April at 0920 a moderate explosion generated a pyroclastic flow that traveled 5 km SW and produced an ash cloud that rose 100 m along the flow. Seismic data confirmed that the event lasted 40 minutes.
Semeru – Eastern Java : PVMBG reported that the eruption at Semeru continued during 26 April-2 May and frequent Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued through the week. On 28 April at 0739, 0822, and 2035 dense white-and-gray or gray-to-brown ash plumes rose 500-1,000 m above the summit and drifted S and SW. On 29 April at 0551 and 0734 dense white-and-gray ash plumes rose 800-1,000 m and drifted S. At 0624 and 0738 on 30 April white-and-gray ash plumes of variable densities rose 500-800 m and drifted NE. At 0611 on 1 May a dense white-and-gray ash plume rose 700 m and drifted S and SW, and at 0705 on 2 May a dense white-and-gray ash plume rose 500 m and drifted N.
Semisopochnoi – Aleutian Islands (USA) : AVO reported that low-level unrest continued at Semisopochnoi during 26 April-2 May. Seismicity was at low levels, and a few small local earthquakes were recorded during 28-29 April. Daily minor steam emissions were seen rising from Mount Young, though cloudy weather sometimes prevented webcam and satellite views. Ash deposits near the crater rim were visible during 27-28 April, though it was unclear if they were recent.
Stromboli – Aeolian Islands (Italy) : INGV reported ongoing Strombolian activity at Stromboli during 24-30 April. Activity was centered at two vents (one each at craters N1 and 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 intensity and ejected coarse material (bombs and lapilli), sometimes mixed with ash, 80-150 m high at a rate of 3-8 explosions per hour. Explosions at the three vents in sector S2 (Area C-S) ejected ash sometimes mixed with coarse material at an average rate of 4-7 explosions per hour. Sectors C and S1 in Area C-S did not show significant activity. Although thermal activity was generally low and the summit was often clouded by weather, a thermal anomaly was detected at 0150 on 29 April.
Suwanosejima – Ryukyu Islands (Japan) : JMA reported that the eruption at Suwanosejima’s Ontake Crater continued during 24 April-1 May. No explosions were recorded, but eruptive activity produced periodic ash plumes, and during 28 April-1 May blocks were ejected as far as 200 m from the vent. On 28 April at 0643 an ash-and-gas plume rose 1.5 km above the crater rim and drifted NW.
Yasur – Vanuatu : On 27 April the Vanuatu Meteorology and Geohazards Department (VMGD) reported that activity at Yasur continued at a high level of “major unrest,” as defined by the Alert Level 2 status (the middle level on a scale of 0-4). Recent observations confirmed that low-to-moderate explosions continued, ejecting bombs that landed back into the crater and producing gas-and-ash emissions. The larger explosions occasionally ejected material outside of the crater.