USGS Volcano Notice - DOI-USGS-AVO-2023-07-24T12:53:47-08:00

Low-level eruptive activity is occuring at Shishaldin Volcano. Seismicity is currently at low-levels. Earthquakes and volcanic tremor are being detected but at much reduced levels since the explosive eruption yesterday. Strongly elevated surface temperatures were observed in satellite data over the past day. A vigorous steam and gas plume to about 10,000 ft (3 km) above sea level was reported by pilots flying by the volcano. Minor amounts of ash may be present in the plume currently being emitted from the volcano. 

Shishaldin has had four 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. The local monitoring network has been partially impaired over the last few weeks due to telecommunications issues but seismic stations and web cameras south of the volcano were brought back online on July 19. 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. Web camera images showed steaming of the lava flow surface over the past day. Earthquake activity remains slightly elevated. 

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.

Earthquakes continue to be detected at Cleveland volcano over the last day. Cloudy conditions obscured views of the volcano in satellite but weak steaming from the summit 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 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. No volcanic activity or unrest was observed in clear satellite and web camera images. 

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.     

Trident Volcano is monitored by local seismic sensors, web cameras, regional infrasound and lightning networks, and satellite data.

Seismicity was low at Aniakchak volcano over the past day with 2 local earthquakes detected. No volcanic activity was observed in partly cloud satellite and web camera views over the past day.

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.

Low-level seismicity was detected over the last day at Semisopochnoi Island. No activity was observed in partly cloudy satellite and web camera images.

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.