ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Sunday, November 20, 2022, 11:18 AM AKST (Sunday, November 20, 2022, 20:18 UTC)
Weak eruptive activity continues from a vent on the east flank of Pavlof Volcano, just below the summit. Seismic tremor was recorded throughout the past 24 hours but no explosions were detected. Elevated surface temperatures 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 Volcano can change quickly and the progression to more significant eruptive activity can occur with little or no warning.
Pavlof Volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.
Unrest continues at Semisopochnoi volcano. Mild seismic tremor and occasional small earthquakes were detected over the past day. Nothing significant was observed in cloudy satellite imagery or webcam views.
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 volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.
Lava continues to erupt in the summit crater of Great Sitkin Volcano. Seismicity was low over the past day, and nothing noteworthy was observed in cloudy satellite and webcam views.
Great Sitkin Volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and regional infrasound and lightning networks.
The ongoing earthquake swarm near Takawangha volcano waxed and waned in intensity over the past day. The earthquakes are generally shallow, having preliminary depths of about 2 to 4 miles (3 to 6 km) below sea level. This activity may be due to the movement of magma beneath the volcano. No eruptive activity has been detected in satellite views or other monitoring data.
Local instruments detected no significant seismic activity over the past day. No activity was observed in cloudy satellite and webcam data.
Episodes of lava effusion and explosions can occur without advance warning. Explosions from Mount 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 the seismic network is operational, Mount Cleveland is monitored by only three local 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, firstname.lastname@example.org, (907) 786-7497
David Fee, Coordinating Scientist, UAFGI, email@example.com, (907) 378-5460
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