USGS Volcano Notice - DOI-USGS-AVO-2023-07-16T11:57:26-08:00

The eruption of Shishaldin Volcano continues with a possibility of low-level ash emissions. Strongly elevated surface temperatures were observed in satellite data from last night and this morning. Seismicity is currently low although aftershocks from a regional earthquake (unrelated to the eruption) continue to be observed in seismic data. There have been no new explosions observed at the volcano since last night's explosive episode which produced an ash cloud to 16,000 ft that drifted to the southeast of the volcano for nearly 311 miles (500 km) before dissipating. The Aviation Color Code was raised to Red and the Volcano Alert Level was raised  to Warning at 11:57 pm AKDT (7:57 UTC) July 16 in response to this episode. Activity then declined and the Aviation Color Code/Volcano Alert Level was lowered to Orange/Watch at 7:35 am AKDT (15:35 UTC) this morning. Explosions from Shishaldin can occur with little warning. 

Shishaldin is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. The local monitoring network is partially impaired, therefore AVO is also using nearby geophysical networks, satellite data and regional infrasound and lighting data.

Slow eruption of lava continues at Great Sitkin Volcano, where it is producing a thick lava flow within the summit crater. Several local earthquakes were detected over the past day. Cloudy weather conditions prevented clear views of the volcano in satellite and web camera imagery. 

An eruption of lava began at Great Sitkin Volcano in July 2021 and has continued to slowly erupt since, but no explosive events have occurred. An explosive event occurred in May 2021, before the current eruption of lava. The volcano is monitored by local seismic and infrasound sensors, satellite data, webcams, and regional infrasound and lightning networks.

Seismic activity near Trident Volcano remained elevated over the past 24 hours.  No activity was observed in cloudy satellite and web camera views over the past day. 

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.

Seismicity was low at Aniakchak volcano over the past day. No activity was observed in partly cloudy satellite and web camera views over the past 24 hours.

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.

AVO currently monitors Aniakchak with satellite remote sensing data, regional infrasound and lightning networks and several regional seismometers. The local seismic network has been struggling with power issues during the past week. 

Seismicity was low at Semisopochnoi over the past day. No evidence of explosive activity was observed in geophysical or remote sensing data. 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. Additional ash-producing events could occur again with little warning. 

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

Several earthquakes were observed at Tanaga Island over the past day. No activity was observed in cloudy satellite and web camera images.

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

Takawangha volcano and Tanaga Volcano are monitored with a local seismic and infrasound network, regional infrasound and lightning detection networks, and satellite data. Tanaga Volcano is about 5 miles (8 km) west of Takawangha volcano on Tanaga Island.

Several local earthquakes were observed at Tanaga Island over the past day. No activity was observed in cloudy satellite and web camera images.

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

Tanaga Volcano and Takawangha volcano are monitored with a local seismic and infrasound network, regional infrasound and lightning detection networks, and satellite data. Takawangha volcano is about 5 miles (8 km) east of Tanaga Volcano on Tanaga Island.