USGS Volcano Notice - DOI-USGS-AVO-2025-11-28T18:52:51+00:00

ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, November 28, 2025, 11:52 AM AKST (Friday, November 28, 2025, 20:52 UTC)

GREAT SITKIN (VNUM #311120)
52°4'35" N 176°6'39" W, Summit Elevation 5709 ft (1740 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Lava continues to erupt within the summit crater at Great Sitkin Volcano. Satellite radar observations show continued growth of the lava dome toward the southwest and southeast, with minor advancement of the flow front over the past week. Weakly elevated surface temperatures were observed during occasional breaks in the cloud cover. 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.

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.

Great Sitkin Volcano is a basaltic andesite volcano that occupies most of the northern half of Great Sitkin Island, a member of the Andreanof Islands group in the central Aleutian Islands. It is located 26 miles (42 km) east of the community of Adak. The volcano is a composite structure consisting of an older dissected volcano and a younger parasitic cone with a ~1 mile (1.6 km)-diameter summit crater. A steep-sided lava dome, emplaced in the crater during an eruption in 1974, has been mostly buried by the ongoing eruption. The 1974 eruption produced at least one ash cloud that likely exceeded an altitude of 25,000 ft (7.6 km) above sea level. A poorly documented eruption also occurred in 1945, producing a lava dome that was partially destroyed in the 1974 eruption. Within the past 280 years a large explosive eruption produced pyroclastic flows that partially filled the Glacier Creek valley on the southwest flank.

SHISHALDIN (VNUM #311360)
54°45'19" N 163°58'16" W, Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Signs of volcanic unrest at Shishaldin continued this week. Vigorous steaming from the summit crater was observed in web cameras and satellite images over the past several days but there was no evidence of ash emissions. Pilot reports from November 27 estimated the steam plume reached an altitude of 15,000 ft (4.6 km) above sea level. Low-level seismicity is ongoing, with frequent small earthquakes occurring daily. Infrasound signals were detected throughout the week, and the amplitude increased late in the week during the period of increased steam emissions. The infrasound signals 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. 

Shishaldin Volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a conical stratovolcano with a base diameter of approximately 10 miles (16 km). It is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 28 confirmed eruptions since 1824. Most eruptions are relatively small, although activity during July – November 2023 generated ash columns that reached between 30,000 ft (9 km) and 42,000 ft (13 km) above sea level.

CONTACT INFORMATION:

Chris Waythomas, Acting Scientist-in-Charge, USGS cwaythomas@usgs.gov (907) 786-7497

David Fee, Coordinating Scientist, UAFGI dfee1@alaska.edu (907) 378-5460

Contact AVO: https://avo.alaska.edu/contact

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.