ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Monday, September 26, 2022, 12:12 PM AKDT (Monday, September 26, 2022, 20:12 UTC)
Seismicity was low over the past day, with occasional short periods of tremor observed. Satellite and webcam observations were obscured by clouds over the past day. No ash emissions observed.
Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Cerberus and ash clouds usually under 10,000 ft (3 km) above sea level have characterized the recent activity. 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.
Low-level eruption of lava likely continues at Great Sitkin. Seismicity was low, with a local events detected. No activity observed in web camera images during periods of clear weather. Satellite observations were obscured by clouds over the past day.
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 continues to erupt minor amounts of lava from the vent just below the summit on the east flank. Seismic tremor was variable over the past day. No explosions or ash emissions were detected. A small gas plume was sometimes visible in web camera images during periods of clear weather.
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 at Cleveland. Seismicity was very low over the past day. Satellite observations were obscured by clouds.
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
Information on all Alaska volcanoes is available at: http://www.avo.alaska.edu.
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Michelle Coombs, Scientist-in-Charge, USGS, email@example.com, (907) 786-7497
David Fee, Coordinating Scientist, UAFGI, firstname.lastname@example.org, (907) 378-5460
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