ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, August 25, 2022, 12:00 PM AKDT (Thursday, August 25, 2022, 20:00 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.
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 were detected in local seismic data. An explosion was detected in infrasound data followed by low-level ash emissions. 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.
Unrest continues with low-level seismicity detected over the past day. No unusual activity detected in cloudy satellite and web camera views over the past day.
Ash emissions have declined significantly 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. Seismicity remains low, yet above background levels. No explosive activity was detected on local or regional networks. No unusual activity observed in cloudy satellite views over the past day.
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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