ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Sunday, August 20, 2023, 12:11 PM AKDT (Sunday, August 20, 2023, 20:11 UTC)
Based on seismic and infrasound data, low-level explosive activity is likely occurring within the summit crater of Shishaldin Volcano. No noticeable emissions were apparent in clear web camera images this morning, and the explosions do not appear to produce much, if any, ash. Elevated surface temperatures were observed in satellite images over the past day, indicating hot material on the upper parts of the volcano.
Shishaldin has had seven periods of elevated eruptive activity resulting in significant ash emissions and mass flows of volcanic debris on the volcano's flanks. The ongoing eruptive period started on July 12, and it is unknown how long this eruptive episode will last. However, previous eruptions of Shishaldin Volcano have lasted weeks to months with repeated cycles of activity similar to those seen over the last month.
Local seismic and infrasound sensors, web cameras, and a geodetic network monitor Shishaldin Volcano. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions.
Cleveland volcano remained relatively quiet over the past day. The level of seismic activity was low and nothing was detected in infrasound data. Clouds obscured the volcano for most of the day, although slightly elevated surface temperatures were observed in a few clear satellite images. Steaming from the summit crater and a vapor plume were also observed in web camera and satellite 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.
Cleveland volcano is currently monitored by a local seismic network, infrasound sensors, and web cameras. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite observations to detect eruptions. Based on past events, explosive eruptions of Cleveland may occur with little or no warning. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, web camera, lightning, and satellite data.
Slow eruption of lava likely continues within the summit crater of Great Sitkin Volcano. Earthquake activity was slightly elevated over the past day. No significant activity was observed in webcam and satellite views.
The current lava flow at Great Sitkin Volcano began erupting in July 2021. No explosive events have occurred since a single event in May 2021.
Local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data are used to monitor the volcano.
Seismic activity near Trident Volcano remained slightly elevated over the past day. No activity was observed in clear to cloudy satellite images and web camera views.
The current period of seismic unrest began on August 24, 2022. Increases in seismic activity have been detected previously at Trident Volcano and other similar volcanoes and did not result in eruptions. We expect additional shallow seismicity and other signs of unrest, such as gas emissions, elevated surface temperatures, and ground movement, to precede any future eruption if one were to occur. AVO issued an Information Statement on July 25 providing a more detailed update on the volcanic unrest at Trident Volcano and the broader Katmai volcanic cluster (https://www.avo.alaska.edu/news.php?id=1595).
Trident Volcano is monitored by local seismic sensors, web cameras, regional infrasound and lightning networks, and satellite data.
Matt Haney, Scientist-in-Charge, USGS firstname.lastname@example.org (907) 786-7497
David Fee, Coordinating Scientist, UAFGI email@example.com (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.