Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 19 May – 25 May 2021

Aira – Kyushu (Japan) : JMA reported that during 21-24 May incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. A very small eruptive event was recorded on 23 May. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 18-23 and 25 May ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Ebeko – Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 14-20 May that sent ash plumes to 3.5 km (11,500 ft) a.s.l. and drifted N, NE, E, and SE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Etna – Sicily (Italy) : INGV reported episodes of lava fountaining at Etna’s Southeast Crater (SEC) on 19 and 22 May that continued the recent pattern of Strombolian explosions followed by lava fountaining and lava flows. Strombolian activity began at 2340 on 19 May and produced ash plumes that drifted E. Activity intensified and lava fountains formed at 0234 on 20 May. At the same time lava overflowed the SEC and traveled SW, and within a few hours had reached 2,800 m elevation. The activity lasted about three and a half hours and then abruptly ended. The next episode during 0134-0454 on 22 May included Strombolian explosions and ash plumes that drifted SE; lava fountaining began at 0302 and flows traveled SW, overlapping the flows from 19 May. Explosions produced ash plumes that drifted SE around 0830 and 1014. Strombolian explosions intensified around 2031, producing dense ash plumes that drifted E. Lava fountains formed about two hours later, sending flows down the E and SW flanks; fountaining was over by 0038 on 23 May. A series of explosions were visible during 0351-0403, producing dense ash plumes that drifted E. Two ash plumes were observed rising from SEC’s E crater during the night and the day on 23 May. Intense explosive activity at SEC began at 1820 on 25 May, producing ash plumes that rose to 3.5 km (11,500 ft) a.s.l. and drifted E. Strombolian activity commenced at 1845 and lava fountains were visible around 2023. Lava flows were visible at 2244 and ash plumes drifted E at an altitude of 6 km (19,700 ft) a.s.l. Activity ceased by 0026 on 26 May.

Karymsky – Eastern Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Karymsky was visible in satellite images on 13-14 and 19 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Kilauea – Hawaiian Islands (USA) : HVO reported that lava at Kilauea’s Halema`uma`u Crater lava lake circulated in a 20-m-diameter area on 19 May but was stagnant and crusted over on other days through 25 May. A few minor oozes of lava between the W vent and main island were occasionally visible. The depth of the lava lake was 229 m and had remained unchanged since 11 May. Sulfur dioxide emissions were 100-150 tons per day during 19-23 May, close to the less than 50 tonnes per day measured during the non-eruptive period from late 2018 to late 2020. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Krysuvik-Trolladyngja – Iceland : The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 19-25 May. Lava fountains rose from the fifth vent and continued to feed the lava flows. According to news sources, lava during 20-21 May overtook the eastern earthen dam that had been constructed at the head of Nátthaga valley in an attempt to prevent flows from descending towards Highway 427 (Suðurstrandarvegur) to the S, and burying fiber optic cables. By 22 May the lava was about 2.5 km from the road. The Aviation colour Code remained at Orange due to the lack of ash and tephra emissions. Authorities warned of increased gas emissions hazards.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that white-and-gray plumes from Lewotolok rose as high as 800 m and drifted W and E during 18-24 May. Rumbling was heard almost daily. Crater incandescent was visible on 18 May and on 22 May incandescent material was ejected 400-700 m to the SE. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Merapi – Central Java (Indonesia) : BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both continued to extrude lava during 14-20 May. The SW rim lava-dome volume was an estimated 1.284 million cubic meters, with a growth rate of about 11,700 cubic meters per day, and continued to shed material down the flank. A total of seven pyroclastic flows traveled a maximum of 2 km down the SW flank. Incandescent avalanches, recorded 58 times, traveled as far as 2 km down the SW flank and once went 800 m SE. The summit lava dome had not changed since the previous week. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Pacaya – Guatemala : In a special 15 May bulletin INSIVUMEH noted that lava effusion at Pacaya ceased and activity instead was characterized by explosive activity at the summit crater. Ash-and-gas plumes rose 1 km and drifted downwind, causing ashfall in San Francisco de Sales, Concepción El Cedro, Aldea El Patrocinio, and San Miguel Petapa. Explosions ejected material up to 100 m above the summit. Ash plumes rose around 500 m above the summit and drifted 5-10 km N, NW, SW, and S during 18-21 and 24-25 May. Some explosions were recorded by the seismic network during 22-23 May; white-and-blue gas plumes rose 300-700 m and drifted 5 km W during 23-24 May.

Piton de la Fournaise – Reunion Island (France) : OVPF reported that gas emissions rose from the cones at Piton de la Fournaise during 18-19 and 22-23 May; inclement weather conditions prevented visual observations on days in between. The eruption likely ceased around 0200 on 24 May, when tremor subsided, though inclement weather again prevented visual confirmation. The Alert Level remained at 2-2.

Semeru – Eastern Java (Indonesia) : PVMBG reported that Semeru continued to erupt during 18-25 May. Gray-and-white plumes rose 100-700 m above the summit and drifted S, SW, and N during 18-23 May. Avalanches of material occurred four times on 18 May, traveling as far as 500 m down the Kobokan drainage. Ash plumes rose 600 and 400 m and drifted N on 21 and 22 May, respectively. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that sulfur dioxide and steam plumes from Semisopochnoi were possibly visible in satellite images during 19-20 May. Satellite images on 21 May showed a sulfur dioxide gas plume drifting 160 km SE. Steam plumes rose from Cerberus on 24 May. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 14-21 May. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 19-25 May. Pyroclastic flows traveled 3 km down the E and SE flanks at 0448 on 19 May. A dense gray ash plume rose as high as 3.5 km above the summit and drifted E and S. White-and-gray plumes rose 100-400 m and drifted NE, E, SE, and S on 20 May. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.

Soufriere St. Vincent – St. Vincent : University of the West Indies Seismic Research Centre (UWI-SRC) and National Emergency Management Organisation (NEMO) reported that seismicity at Soufrière St. Vincent (often simply referred to as “La Soufriere”) remained low during 17-24 May, with a few long-period and volcano-tectonic earthquakes occasionally recorded. Persistent steaming from the crater was visible on days when weather permitted views, and thermal anomalies continued to be identified in satellite data. Sulfur dioxide emissions were 461 tons per day on 20 May. NEMO noted that the total number of displaced people was 22,759 on 15 May though the number continued to fluctuate as people arrived at shelters while others returned home or changed locations. The Alert Level remained at Orange.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that intermittent eruptive activity at Suwanosejima’s Ontake Crater produced plumes that rose as high as 1.6 km above the crater rim during 14-21 May. Large volcanic bombs were ejected 300 m from the crater. Crater incandescence was visible overnight during 18-19 May. The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Taal – Luzon (Philippines) : PHIVOLCS reported that unrest at Taal continued during 19-25 May. Low-level background tremor that had begun at 0905 on 8 April continued. During 19-21 May there were 2-30 daily low-frequency events, 10-169 daily volcanic earthquakes, and 8-139 periods of volcanic tremor with variable durations (1-37 minutes); no earthquakes were recorded during 22-25 May. Most of the earthquakes were very shallow (less than 5 km deep) beneath Taal Volcano Island (TVI) and the NE part of Taal Lake. Daily upwelling of hot volcanic fluids in the crater lake was accompanied by sometimes voluminous steam plumes that were as tall as 2 km. Sulfur dioxide emissions were 2,811-3,611 tonnes/day. Slow and steady inflation of the Taal region was recorded by multiple instruments after the January 2020 eruption. PHIVOLCS noted the continuing state of elevated unrest, reminding the public that the Alert Level for Taal remained at 2 (on a scale of 0-5). PHIVOLCS strongly recommended no entry onto the island, and access to the Main Crater, Daang Kastila fissure (along the walking trail), and boating on Taal Lake was strictly prohibited.

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