USGS Volcano Notice - DOI-USGS-AVO-2023-03-03T09:33:51-09:00

Lava likely continued to erupt within the summit crater of Great Sitkin at a low rate over the past week. The most recent imagery showed the lava flow advancing to the east and south within the summit crater. Seismicity was at very low levels throughout the week. Slightly elevated surface temperatures were observed on one day in satellite imagery and nothing significant was seen in web camera views.

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

Over the past week, seismicity continued at an elevated level beneath Trident Volcano, with over 60 earthquakes located. The earthquakes over the past week have been small, with magnitudes below M1.0. No significant activity was seen in cloudy to mostly clear satellite and web camera views. 

The current period of seismic unrest began on August 24, 2022. Earthquake depths at the beginning of the swarm were mostly deep, around 25 km (16 miles) below sea level and became progressively shallower to around 5 km (3 miles) over the following four days. Since late August 2022, most earthquakes have been located in the shallow crust, with depths less than 6 km below sea level. Since January 1, 2023, earthquakes under Trident are occurring at an average rate of about ten per day.   

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. 

Earthquake activity beneath Aniakchak volcano continued over the past week, with over 120 earthquakes located. Magnitudes reached as high as M3.1 and several earthquakes had magnitudes between M2 and M3. The earthquakes are occurring at shallow depths (< 5 km) and below the southern part of the caldera and to the east of the volcano. No significant activity was observed in partly clear to cloudy web camera and satellite views. 

There is no indication that an eruption of Aniakchak is imminent, or that one will occur. 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 consists of six seismometers, a web camera, and a single infrasound sensor, as well as satellite remote sensing data and regional infrasound and lightning networks. 

A few short episodes of weak volcanic tremor were detected in seismic data over the past week. No unusual activity was observed in infrasound data. Steam emissions were seen from the north cone of Mount Young in partly cloudy web camera views twice during the week. Nothing significant was observed in mostly cloudy to partly cloudy satellite views. 

Although the active north cone of Mount Young continues to produce a robust steam plume when views are clear, no ash emissions or explosive activity have been detected at Semisopochnoi volcano since late January. The level of seismic activity has also decreased over the past month. 

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 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. 

The ongoing earthquake swarm near Takawangha volcano continues, with over 120 earthquakes located during the past week. The number of events per day was highest on Tuesday and Wednesday, with over 50 earthquakes located on each of those days. Three earthquakes had magnitudes greater than M3.0 and occurred at shallow depths (< 6 km) about 6 km to the east of the volcano. No eruptive signals were detected in seismic or satellite data. Weather conditions were mostly cloudy all week obscuring satellite views of the volcano. 

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 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 is monitored with a local seismic network, a single local infrasound sensor, regional infrasound and lightning sensors, and satellite imagery.