ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Wednesday, September 21, 2022, 12:01 PM AKDT (Wednesday, September 21, 2022, 20:01 UTC)
Seismicity was very low over the past day, with only one local event observed. No explosions or ash emissions were detected or observed. Typical steaming was seen in web camera images during brief periods of clear weather over the past day.
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. Typical slightly elevated surface temperatures in vent region of the lava flow were observed in satellite data over the past day. A temporary data outage is affecting the local seismic network and webcams, but no significant activity was observed on regional geophysical networks.
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 from the vent just below the summit on the east flank. Seismic and infrasound tremor, accompanied by occasional small explosions, were detected in local seismic data and regional infrasound data. No ash emissions were observed in web camera or satellite images. Incandescence in the summit crater was seen in nighttime web camera images and satellite images over the past day showed elevated surface temperatures. These observations are due to the continued low-level eruption of lava near the vent. No active lava flows extend down the flanks from the vent.
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 quiet over the past day and no activity was observed in partly cloudy satellite images.
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
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.