ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Saturday, August 19, 2023, 11:38 AM AKDT (Saturday, August 19, 2023, 19:38 UTC)
Low-level explosive activity is occurring at Shishaldin Volcano. Seismicity is at low levels. Small explosions were detected in infrasound data this morning and are consistent with pilot observations of small, short-lived ash clouds up to about 14,000 ft above sea level. Steam and ash emissions were visible in clear web camera images obtained yesterday and this morning, but the plumes were small, and any ash present likely fell out on the volcano's flanks. 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 flanks of the volcano. 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.
Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a geodetic network. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions.
Slow eruption of lava continues within the summit crater of Great Sitkin Volcano. Earthquake activity remains slightly elevated over the past day. No significant activity was observed in cloudy webcam and satellite views of the volcano.
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.
The volcano is monitored by local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data.
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.
Seismicity was quiet at Cleveland volcano over the past day. Clouds obscured satellite views of the volcano and steaming from the summit crater was seen in web camera images.
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.
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.
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