Alaska Volcano Observatory

Lava continues to erupt slowly within the summit crater at Great Sitkin Volcano. Weakly elevated surface temperatures were observed during a break in the cloud cover on December 4. Otherwise, most views of the lava dome were obscured by clouds. Seismicity has been low, with occasional small earthquakes and rockfalls detected in seismic data. Only a single earthquake was large enough to be located over the past week. Overall, the rate of lava effusion appears to be declining gradually. 

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 continued this week. Vigorous steaming from the summit crater was observed in web-camera and satellite images yesterday, December 4. Views the rest of the week were blocked by clouds. Low-level seismicity is ongoing, with frequent small earthquakes occurring daily. Infrasound signals were also detected throughout the week. These are likely caused by gas bubbles bursting through magma deep within the volcanic vent. Satellite data show no evidence of elevated temperatures or other changes within the summit crater, indicating no lava at or near the surface. 

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 images to monitor the volcano.