Alaska Volcano Observatory

Lava continues to erupt slowly within the summit crater at Great Sitkin Volcano. Weakly elevated surface temperatures were observed frequently this week in satellite views during breaks in the cloud cover, and a few clear webcam views showed weak steaming from the summit lava dome. Satellite data also confirms that the lava dome continues to slowly inflate upwards, with minor advance on the edges of the flow. Otherwise, most views of the volcano were obscured by clouds. Seismicity has been low, with occasional small earthquakes and rockfalls detected in seismic data.

The current lava eruption began in July 2021 and has filled most of the summit crater and advanced into valleys below. There have been no explosions at Great Sitkin Volcano since an event in May 2021. The volcano is monitored using local seismic and infrasound sensors, satellite data and web cameras, and regional infrasound and lightning networks. 

Signs of volcanic unrest at Shishaldin Volcano continued to be observed this week. Webcam images, when clear, showed a gas plume rising from the summit crater. Additionally, satellite images captured the plume on several occasions. There has been ongoing low-level seismic activity, with frequent small earthquakes occurring each day. Infrasound signals, likely caused by gas bubbles bursting through magma deep within the volcanic vent, were also detected throughout the week, when the conditions were not too windy. There is no indication, though, that lava is present at or near the surface. The strong winds early in the week caused resuspension of ash and other fine particles from the ground surface around Shishaldin Volcano and neighboring peaks on Unimak Island. This ash resuspension was not related to the current unrest.

Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite data to monitor the volcano.