USGS Volcano Notice - DOI-USGS-AVO-2024-09-20T17:34:46+00:00

ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, September 20, 2024, 11:32 AM AKDT (Friday, September 20, 2024, 19:32 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

There have been no significant changes in the ongoing eruption at Great Sitkin Volcano this week. Slow eruption of lava in the summit crater continues, leading to frequent small volcanic earthquakes. Occasional clear satellite images have shown slightly elevated surface temperatures due to the active lava flow. 

Since the single explosive event in May 2021, there have been no other explosions at the Great Sitkin Volcano. The ongoing lava eruption began in July 2021, and the lava has filled most of the summit crater and advanced over the crater rim into valleys below. The Alaska Volcano Observatory (AVO) monitors Great Sitkin using seismic, infrasound, and satellite data.

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 (43 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 (1.5 km)-diameter summit crater. A steep-sided lava dome, emplaced during the 1974 eruption, occupies the center of the crater. That 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 occurred in 1945, also 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.

CONTACT INFORMATION:

Hannah Dietterich, Acting Scientist-in-Charge, USGS hdietterich@usgs.gov (907) 786-7497

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

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.