Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the Week 31 March 2021 – 6 April 2021

Aira – Kyushu (Japan) : JMA reported that during 29-30 March explosions at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) produced ash plumes that rose as high as 2.7 km above the crater rim and ejected bombs 600-900 m away. An explosion was recorded on 4 April. An explosion at 0641 on 5 April ejected bombs 800-1,100 m away from the crater and generated an ash plume that rose up to 3 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Dukono – Halmahera (Indonesia) : Based on satellite and wind model data, the Darwin VAAC reported that during 31 March-6 April ash plumes from Dukono rose to 2.4 km (8,000 ft) a.s.l. and drifted E, SE, and SSE. 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 25 and 28-29 March that sent ash plumes up to 2.5 km a.s.l. (8,200 ft) and drifted in different directions. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Etna – Sicily (Italy) : INGV reported continuing episodes of lava fountaining, intra-crater explosive activity, and discontinuous ash emissions at Etna’s Southeast Crater (SEC) during the week of 29 March-4 April, though weather conditions often prevented visual observations. Gas emissions rose from the other summit craters and occasional explosive activity was visible; puffs of ash sometimes rose from Voragine Crater during 31 March-2 April. At 0707 on 31 March a loud explosion was followed by several ash puffs, marking the beginning of the 17th lava-fountaining episode since they began on 16 February. At around 1100 a thermal anomaly at the S base of SEC was visible during an overflight and in thermal camera images. Explosive activity increased by late afternoon and several lava flows effused from the S-base vent. The main part of the flow traveled towards the Valle del Bove with other smaller flows traveled S and SW. Two other vents at the S base had opened by evening and one ejected spatter a few tens of meters high. Periods of lava fountaining began through the night, and the main lava flow descended the W wall of the Valle del Bove. Strombolian activity intensified at 1950, with an eruption plume that rose to 1.2 km (4,000 ft) a.s.l. and drifted SSW. Lava fountaining began at around 0100 on 1 April. At 0218 lava overflowed the E rim of SEC and headed towards the Valle del Bove, running parallel to the flows from the S base. Lava fountains continued to be visible during the morning of 1 April and intense Strombolian activity produced dense ash plumes that drifted S. By 0940 the eruption plume had risen to 9 km (29,500 ft) a.s.l. and drifted SSW. Lava fountaining ceased around 1000 and the eruption plume rose to 5.5 km (18,000 ft) a.s.l. and drifted S. Ash fell in Milia, Nicolosi, and Catania and lapilli (1 cm in diameter) fell in Rifugio Sapienza. Lava effusion and flow advancement continued; lava from the S base of SEC spread out like a fan. A series of loud bangs were audible in the late morning and ash emissions continued until the afternoon. Lava overflowed the E rim of SEC at 1040, and a SSE flow entered the Valle del Bove at the SW wall. Explosive activity began to decline at 1320, and effusive activity waned overnight during 1-2 April.

Gareloi – United States : AVO reported that a loss of operation and communication with all seismic stations on Gareloi was likely due to snow cover. Both the Aviation colour Code and the Volcano Alert Level were changed to Unassigned, reflecting the lack of this data to detect unrest. The observatory noted that regional infrasound networks, lightning detection, and satellite images will be used to monitor and detected unrest.

Kilauea – Hawaiian Islands (USA) : HVO reported that the W vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 31 March-6 April. Lava flowed at a low rate from the main vent into the lake through crusted-over channels and submerged inlets. The total depth of the lake measured about 225 m and lava continued to circulate in the W part; the E half of the lake remained solidified and expanded toward the W. The sulfur dioxide emission rate was 1,200 tons/day on 1 April. HVO field crews observed weak spattering from two areas at the W vent during 1-2 April. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Langila – New Britain (Papua New Guinea) : Based on analyses of satellite imagery and wind model data, the Darwin VAAC reported that on 5 April an ash plume from Langila rose to 1.5 km (5,000 ft) a.s.l. and drifted SW.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the Strombolian eruption at Lewotolok continued during 30 March-6 April. Gray-and-white ash plumes rose as high as 700 m above the summit and drifted in multiple directions, though rainy weather conditions prevented visual observations during 2-3 and 5 April. Incandescent material was ejected 300-500 m above the summit and 500 m SE during 30-31 March; eruptive events were recorded by the seismic network on the other days but not visually confirmed. Rumbling was occasionally noted. According to news articles secondary lahars from Cyclone Seroja destroyed homes, and impacted as many as 300, in several villages to the SW; mud-and-debris flows and flooding severely impacted other parts of Indonesia and killed at least 70 people. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 4 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 grow during 26 March-1 April. The SW rim lava-dome volume was an estimated 1,060,000 cubic meters on 1 April, with a growth rate of about 13,400 cubic meters per day, and continued to shed material down the flank. A total of 14 pyroclastic flows traveled a maximum of 1.8 km down the SW flank. Incandescent avalanches, recorded 158 times, traveled as far as 1.1 km down the SW flank. The summit lava dome had grown to 70 m tall and produced one incandescent avalanche. Minor ashfall was reported in Ngadirojo, Stabelan (4 km NW), Takeran, Tlogolele (5 km NW), Selo (3 km NNW), Pos Babadan (4 km NW), and Pasar Talun (12 km W). 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.

Raung – Eastern Java (Indonesia) : PVMBG reported that daily gray-and-white ash plumes rose 50-500 m above Raung’s summit during 31 March-5 April and drifted N and S. 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.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 28 March-2 April. On 3 April a plume of re-suspended ash rose to 2.5 km (8,200 ft) a.sl. and drifted 250 km ESE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Shishaldin – Fox Islands (USA) AVO reinstated the Green Aviation colour Code and the Normal Volcano Alert Level for Shishaldin on 2 April, after several seismic stations again became operational following a months-long outage, thus improving the observatory’s monitoring capability.

Sinabung – Indonesia : PVMBG reported that the eruption at Sinabung continued during 31 March-6 April. Weather conditions sometimes prevented visual observations of the volcano, though daily white fumarolic plumes were visible rising as high as 500 m above the summit. Avalanches were detected daily by the seismic network and observed traveling 500-1,500 m down the E and SE flanks. An eruptive event produced a gray ash plume that rose 500 m above them summit on 1 April. Pyroclastic flows went as far as 1.5 km down the E and SE flanks. Ash plumes rose 0.7-2 km during 2-5 April and mainly drifted E and SE. 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 the lava dome in Soufrière St. Vincent’s main crater continued to slowly grow during 31 March-6 April, expanding to the N and S. Gas-and-steam continued to rise from the top of the dome, as well as along the contact with the pre-existing 1979 dome. A swarm of volcano-tectonic (VT) earthquakes began at 0638 on 5 April. The number and frequency of the VTs increased until about 0830 and then stabilized. The rate declined at around 1400 and then significantly dropped at 1600, though small VT events continued to be detected through 1800. The events were located at depths of 6 km, slightly deeper than the swarm events recorded during 22-25 March, located at revised depths of 3-5 km. Several reports of felt events came from nearby communities, including Fancy and Chateaubelair. The largest event, a M 3.5, was recorded at 0920 and felt by local residents. The swarm was more intense than the previous one, with an average rate of about 50 earthquakes per hour compared with 1.5 per hour during 22-25 March. The Alert Level remained at Orange (the second highest level on a four-colour scale).

Tanaga – Andreanof Islands (USA) : AVO reported a loss of operation and communication with all but two seismic stations on Tanaga, likely caused by snow cover. Both the Aviation colour Code and the Volcano Alert Level were changed to Unassigned, reflecting the inability to locate earthquakes to detect unrest. Monitoring will continue with the remaining seismic stations, regional infrasound networks, lightning detection, and satellite images.

Tengger Caldera – Eastern Java (Indonesia) : PVMBG reported that during 30 March-5 April white steam-and-gas plumes rose 50-700 m above the summit of Tengger Caldera’s Bromo cone. The plumes were white to gray during 1-2 April. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.

Ubinas – Peru : Instituto Geofísico del Perú (IGP) reported that during 29 March-4 April there were 11 volcano-tectonic earthquakes at Ubinas with magnitudes less than 1.8, and a few seismic signals indicated emissions. Sporadic steam-and-gas plumes rose as high as 200 m above the crater rim. On 5 April the Alert Level was lowered to Green (the lowest level on a four-colour scale).

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