USGS Volcano Notice - DOI-USGS-AVO-2023-08-26T12:12:23-07:00

A large ash-producing explosive event – the eighth to occur during the ongoing eruption – started late yesterday morning and ended just after midnight this morning. Satellite data during the event showed an ash cloud rising as high as 30,000–32,000 ft (9–10 km) above sea level and drifitng northeast, eventually reaching a length of at least 250 miles (400 km). Based on seismic and infrasound data, low-level explosive activity within the volcano's summit crater has resumed, and satellite views continue to show elevated surface temperatures.

Shishaldin has now had eight periods of elevated eruptive activity resulting in significant ash emissions and mass flows of volcanic debris on the volcano's flanks. The ongoing eruptive period started on July 12, and it is unknown how long this eruptive episode will last. However, previous eruptions of Shishaldin Volcano have lasted weeks to months with repeated cycles of activity similar to those seen over the last month.

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 continues within the summit crater of Great Sitkin Volcano. Earthquake activity was slightly elevated over the past day. No eruptive activity was seen in satellite and webcam views, which were cloudy.

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.

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

Seismic activity near Trident Volcano remained slightly elevated over the past day. No activity was observed in satellite images and webcam views, which were cloudy.

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.   AVO issued an Information Statement on July 25 providing a more detailed update on the volcanic unrest at Trident Volcano and the broader Katmai volcanic cluster (https://www.avo.alaska.edu/news.php?id=1595).

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