USGS Volcano Notice - DOI-USGS-AVO-2023-03-25T11:15:53-08:00

Low-level unrest continued at Semisopochnoi volcano during the past 24 hours. No explosive activity was detected in seismic or infrasound data. Nothing was observed in cloudy satellite and web camera imagery.

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 the recent periods of activity. Additional ash-producing events could occur again with little warning. 

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

Lava likely continued to slowly erupt at the summit of Great Sitkin Volcano, producing a thick lava flow within the summit crater. No significant local seismicity was observed during the past 24 hours—events recorded on the seismic network there are principally from the earthquake swarm at Tanaga Island. No activity was detected in cloudy satellite and web camera imagery.

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

Earthquake activity beneath Tanaga Volcano and nearby Takawangha volcano, which is about 5 miles (8 km) east of Tanaga Volcano on Tanaga Island, continued over the past 24 hours with no significant change in rate or size of earthquakes. No activity was observed in cloudy satellite data. AVO continues to closely monitor the ongoing seismicity.

Increases in seismic activity have been detected previously at Tanaga Volcano and other similar volcanoes, with no subsequent eruptions. We expect additional shallow seismicity and possibly other signs of unrest, such as gas emissions, elevated surface temperatures, and surface deformation to precede any future eruption, if one were to occur.   

Tanaga Volcano is monitored with a local seismic and infrasound network, regional infrasound and lightning detection networks, and satellite data.

Earthquake activity beneath Takawangha volcano and nearby Tanaga Volcano, which is about 5 miles (8 km) west of Takawangha volcano on Tanaga Island, continued over the past 24 hours with no significant change in rate or size of earthquakes. No activity was observed in cloudy satellite data. AVO continues to closely monitor the ongoing seismicity.

Increases in seismic activity have been detected previously at Takawangha volcano and other similar volcanoes, with no subsequent eruptions. We expect additional shallow seismicity and possibly other signs of unrest, such as gas emissions, elevated surface temperatures, and surface deformation to precede any future eruption, if one were to occur.   

Takawangha volcano is monitored by local seismic and infrasound sensors, satellite data, and regional infrasound and lightning networks.

Shallow earthquakes continued at Aniakchak volcano including one M2.6 over the past 24 hours. No eruptive activity was observed in cloudy satellite data. 

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 surface deformation to precede any future eruption, if one were to occur. 

AVO monitors Aniakchak with a local network, which currently consists of two functional seismometers, as well as satellite remote sensing data and regional infrasound and lightning networks.

Occasional small, shallow earthquakes continued to occur in the vicinity of Trident Volcano over the past 24 hours. No activity was seen in satellite or web camera imagery.

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, with no subsequent eruptions. We expect additional shallow seismicity and other signs of unrest, such as gas emissions, elevated surface temperatures, and surface deformation to precede any future eruption, if one were to occur. 

AVO monitors Trident Volcano with a local network of seismometers, a webcam, remote sensing data, and regional infrasound and lightning networks.