Day: August 19, 2021

Roundup of Global Volcanic Activity – New Activity for the Week 11 August – 17 August 2021

Atka – Andreanof Islands (USA) : The number of small shallow earthquakes increased at Atka during 10-11 August, prompting AVO to raise the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. The earthquakes were located at a depth of 3-6 km and around 7 km SW of Korovin, though may be related to the several vents that are part of the Atka volcanic complex. Seismicity declined afterwards but remained above background levels through 16 August, and was near baseline levels by 17 August.

Chirinkotan – Kuril Islands (Russia) : KVERT reported that the eruption at Chirinkotan continued during 11-17 August. An explosion at 1315 on 14 August produced a 15 x 17 km ash plume that rose 3-3.5 km (10,000-11,500 ft) a.s.l. and drifted 13 km SSE. Ash plumes from an explosion at 0945 on 15 August rose 2.5-3 km (8,200-10,000 ft) a.s.l. and drifted 8 km S. KVERT and SVERT noted that another explosive event at 1010 on 16 August generated ash plumes that rose 3.5-5 km (11,500-16,400 ft) a.s.l. and drifted 23 km E.

Fukutoku-Oka-no-Ba – Volcano Islands (Japan) : JMA reported that a large eruption at Fukutoku-Oka-no-Ba commenced around 0620 on 13 August based on satellite data. Ash plumes rose as high as 16 km (54,000 ft) a.s.l. and drifted W. The eruption was also confirmed during an overflight later that day. Video showed Surtseyan explosions ejecting black material above the ocean’s surface, and ash plumes drifted W. Ash plumes identified in satellite images rose 12.2-16 km (40,000-54,000 ft) a.s.l. during 13-15 August; the height of the plume decreased afterwards though the eruption intermittently continued. The Japan Coast Guard observed a new horseshoe-shaped island that was about 1 km in diameter during an overflight on 15 August. They also observed and photographed a notable pumice raft swirling with the currents as far as 60 km NW. JMA noted that the volcano last erupted in 2010 and frequent episodes of discolored seawater had been observed since then.

Great Sitkin – Andreanof Islands (USA) : AVO reported that the lava dome at Great Sitkin continued to be active, growing in diameter from 250 m on 6 August, to 380 m three days later, and to 700 m by 16 August. Steam-and-gas plumes were periodically observed in webcam images, in satellite data, and by observers on the ground during 11-17 August. Elevated surface temperatures and small earthquakes detected daily were consistent with the growing dome.

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 11-17 August. According to the Institute of Earth Sciences photographs of the flow field captured on 8 August suggested that the lava effusion rate averaged 9.3 cubic meters per second over the previous 12 days. The area of the flow field had grown to 4.4 square kilometers, and the total volume erupted was 119 million cubic meters. New ground cracks were observed in Gónhóll, a hill S of the main crater (the fifth vent) that was a former vantage point but is now surrounded by lava, though they had likely formed sometime in the previous two weeks and may not have been caused by rising magma. A new vent that opened on 9 August was not confirmed to be separate from the nearby main vent until about a week later. The new cone quickly grew from intense spattering and by 17 August was around the same height as the main crater. Spattering from the new vent was at times ejected higher than spatter from the main vent.

Nishinoshima – Japan : JMA reported that ash plumes from Nishinoshima were visible in satellite images on 14 August rising about 1.9 km and drifting N. The Japan Coast Guard conducted an overflight the next day and did not observe eruptive activity or new deposits from the day before. The Tokyo VAAC noted that a period of continuous ash emissions was visible in satellite data on 15 August.

Pacaya – Guatemala : INSIVUMEH reported that gas emissions rose as high as 1.1 km above Pacaya’s summit and drifted as far as 1 km S and SW during 10-17 August. Two explosions produced ash plumes that drifted S on 13 August.

Pavlof – United States : AVO reported that several small daily explosions at Pavlof were recorded by seismic and infrasound sensors during 10-17 August. The vent producing the explosions was possibly near the 2007 vent location on the upper SE flank. Small ash emissions, visible in webcam images and occasionally observed by pilots, dissipated quickly and likely deposited ash no further on the upper flanks.

Sarychev Peak – Matua Island (Russia) : SVERT reported that an emission of sulfur dioxide from Sarychev Peak was identified in satellite data on 15 August.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that an eruption at Semisopochnoi’s North Cerberus crater was ongoing during 11-17 August, characterized by daily explosions, ash plumes, and occasional sulfur dioxide emissions identified in satellite images. Multiple energetic explosions were detected daily in seismic and infrasound data, and strong seismic tremor was occasionally recorded. Daily steam-and-ash plumes identified in webcam and satellite data rose no higher than 3 km (10,000 ft) a.s.l. and drifted 200-300 km W. Daily ashfall likely occurred on the island.