ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Sunday, August 21, 2022, 11:08 AM AKDT (Sunday, August 21, 2022, 19:08 UTC)
Low-level eruption of lava probably continues at Great Sitkin but clouds obscured satellite and webcam images of the volcano over the last day. Seismic activity remains very low with only a few small earthquake events detected.
The terrain is steep near the terminus of the current eruption's lava flows, and blocks of lava could detach without warning and form small rock avalanches in these valleys. These avalanches may liberate ash and gas and could travel several hundred meters beyond the lava flows; they would be hazardous to anyone in those areas.
Great Sitkin is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.
Pavlof Volcano continues to erupt from the vent on the volcano’s east flank just below the summit. Seismic tremor and small explosions were detected in local seismic and infrasound data. Elevated surface temperature at this vent were observed in satellite images.
Small explosions associated with the current eruption could happen at any time and may be accompanied by small ash plumes within the immediate vicinity of the volcano. The level of unrest at Pavlof can change quickly and the progression to more significant eruptive activity can occur with little or no warning.
Pavlof is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.
Low-level unrest continues with detection of a periods of tremor and small earthquakes and steam emissions from North Cerberus visible in local webcams. No explosions or ash emissions were detected during the past day.
There have been no observations of ash emissions from the north crater of Mount Cerberus since mid-June 2022, although steam emissions continue. Small explosions and associated ash emissions could resume, and may be difficult to detect during periods of high winds and/or when thick cloud cover obscures the volcano. Ash emissions over the past several years of activity have typically reached altitudes of less than 10,000 ft (3 km) above mean sea level.
Semisopochnoi is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.
Unrest continues at Cleveland but clouds obscured satellite views of the volcano. One small local earthquake was detected in the last day. No explosive activity was detected on local or regional networks.
Episodes of lava effusion and explosions can occur without advance warning. Explosions from Cleveland are normally short duration and only present a hazard to aviation in the immediate vicinity of the volcano. Larger explosions that present a more widespread hazard to aviation are possible but are less likely and occur less frequently.
When operational, Cleveland volcano is monitored by only two seismic stations, which restricts AVO's ability to precisely locate earthquakes and detect precursory unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data.
OTHER ALASKA VOLCANOES
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Michelle Coombs, Scientist-in-Charge, USGS, email@example.com, (907) 786-7497
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