ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, July 27, 2023, 1:41 PM AKDT (Thursday, July 27, 2023, 21:41 UTC)
Low-level eruptive activity is occurring at Shishaldin Volcano. Seismicity remains low following the eruptive activity on the morning of July 26. Low-frequency earthquakes indicative of moving magma are being detected but at reduced levels. A sulfur dioxide cloud associated with eruptive activity early on July 26 was observed in satellite data drifting NE of the volcano. Strongly elevated surface temperatures continue to be observed in satellite data over the past day.
Shishaldin has had five periods of elevated eruptive activity resulting in significant ash plumes during the current eruption which started on July 12. It is unknown how long this eruption will last, but previous eruptions of Shishaldin Volcano have lasted weeks to months with repeated cycles of activity similar to those seen in the last two weeks.
Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered 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 at Great Sitkin Volcano, where it is producing a thick lava flow within the summit crater. Earthquake activity remains slightly elevated. Weakly elevated surface temperatures were observed in satellite data consistent with cooling lava. Clouds obscured web camera views over the past day.
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.
Seismicity was low at Cleveland volcano over the last day with a single earthquake detected. No activity was observed in partly clear satellite views and steaming from the summit was observed in web camera views.
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 with a five-station real-time seismic network and three nearby web cameras. 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.
Seismic activity near Trident Volcano remained elevated over the past day. Clouds obscured views of the volcano in satellite 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.
A few earthquakes, including one with a magnitude of 2.7 were detected at Aniakchak volcano over the past day. Cloudy conditions obscured views of the volcano by satellite and web camera.
The current period of seismic unrest began in October 2022. Increases in seismic activity have been detected previously at other similar volcanoes, with no subsequent eruptions. We expect additional shallow seismicity and other signs of unrest, such as gas emissions, elevated surface temperatures, and additional surface deformation to precede any future eruption, if one were to occur.
Aniakchak volcano is monitored by local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data.
Seismicity was quiet at Semisopochnoi Island over the last day. No activity was observed in partly cloudy satellite views and low-level steaming from the north crater of Mount Young was observed in web camera views.
Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Young and ash clouds usually under 10,000 ft. (3 km) above sea level have characterized recent periods of eruption since 2018. The last evidence of ash emission from the volcano was on May 5, 2023, and consisted of a minor dusting of ash on the northwest flank of the north crater of Mount Young. Additional ash-producing events could occur again with little or no warning.
Semisopochnoi volcano is monitored by local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data.
Matt Loewen, Acting 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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