USGS Volcano Notice - DOI-USGS-AVO-2023-10-25T11:02:47-08:00

Volcanic unrest continues at Shishaldin Volcano. Seismic activity remains elevated and consists of seismic tremor and small, low-frequency earthquakes. Satellite observations were obscured over the past day. Minor steam emissions were observed in web camera images from beneath the cloud cover.  

Twelve significant explosive events have occurred at Shishaldin since July 12 through October 3, 2023. These events have been preceded by increases in seismicity in the hours to days before they occur. It is unknown how long this period of ongoing activity will last. However, previous eruptions of Shishaldin Volcano have lasted weeks to months with repeated cycles of eruptive activity like those seen since July.

Local seismic and infrasound sensors, web cameras, and a geodetic network monitor Shishaldin Volcano. 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 in the summit crater of Great Sitkin Volcano likely continues. Small earthquakes detected over the past day and typical elevated surface temperatures indicative of eruption of lava were observed in satellite images. Web camera observations were obscured by clouds. 

The current lava flow began erupting in July 2021. No explosive events have occurred since a single event in May 2021.

Local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data are used to monitor the volcano.

The  Aviation Color Code and the Volcano Alert Level were increased to YELLOW/ADVISORY at Bogoslof volcano yesterday due to an increase in earthquake activity that began on October 22. Over the past day, an additional 10 earthquakes were observed, bringing the total since unrest began to more than 100 in the vicinity of the volcano.  Increases in seismic activity typically precede eruptions, but many volcanoes have exhibited similar behavior that did not result in eruptions. There have been no other signs of unrest observed in mostly cloudy satellite data over the past day. 

Bogoslof volcano is monitored using a single local seismic station, distant seismic and infrasound instruments, satellite data and lightning networks.  At least nine historical eruptions have been documented at Bogoslof volcano. The most recent occurred from December 2016 to August 2017 and produced seventy main explosive events that generated volcanic ash clouds that rose as high as 13 km (42,500 ft) above sea level, and that greatly modified the topography of Bogoslof Island.

Small earthquakes continue to occur near Trident and neighboring volcanoes. No volcanic activity was observed in clear webcam or satellite images over the past day. 

The current period of seismic unrest began in August 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.