USGS Issues Volcano Notice for Great Sitkin
The Alaska Volcano Observatory has issued a notice for Great Sitkin Volcano, where lava has filled most of the summit crater since July 2021.
Updated on Nov. 6, 2026 in Geology
The USGS Alaska Volcano Observatory issued a volcano notice for Great Sitkin Volcano in the central Aleutian Islands. The ongoing lava eruption, which began in July 2021, has filled most of the summit crater, and there have been no explosions since May 2021.
Why it matters
Great Sitkin Volcano lies 26 miles (42 km) east of the community of Adak, and the volcano has a history of significant explosive activity, including a 1974 eruption that produced an ash cloud likely exceeding 25,000 ft (7.6 km). The notice reflects continued monitoring of volcanic activity across Alaska's Aleutian Island chain.
Monitoring relies on local seismic, geodetic and infrasound sensors, satellite data and web cameras, with the summit crater about 1 mile (1.6 km) across and the 1974 ash cloud reaching at least 25,000 ft (7.6 km). Whether the ongoing lava effusion will resume explosive activity remains unknown.
The players
USGS Alaska Volcano Observatory
The Alaska Volcano Observatory is a USGS program that monitors and reports on volcanic activity across Alaska and the Aleutian Islands.
The details
The current lava eruption began in July 2021 and has filled most of the summit crater, with no explosions recorded since May 2021. Great Sitkin is a basaltic andesite volcano on Great Sitkin Island in the Andreanof Islands, and its 1974 eruption produced both an ash cloud and a lava dome in the summit crater.
Timeline
May 2021: Last explosion at Great Sitkin Volcano.
July 2021: Current lava eruption began at Great Sitkin Volcano.
1974: Eruption produced an ash cloud and a lava dome in the summit crater.
Seasonal Patterns
Great Sitkin's 1974 eruption, which produced an ash cloud likely above 25,000 ft (7.6 km) and a summit lava dome, sets a benchmark against which the current effusive eruption, underway since July 2021, can be compared. The volcano's present activity without explosions since May 2021 contrasts with that earlier explosive episode.
Ongoing monitoring of Great Sitkin lets officials track whether the current lava eruption changes character, which matters for residents and air travelers in the region. Understanding volcanic hazards helps the public interpret future notices from the Alaska Volcano Observatory.
The takeaway
Volcano notices reflect ongoing scientific monitoring rather than an immediate emergency, and residents can follow updates from the Alaska Volcano Observatory. Watching for changes in activity helps the public understand how a volcano's behavior is evolving.
Further reading
Explore more on Geology to see how volcanoes like Great Sitkin are studied and monitored.
Source note: This article includes information reported by Usgs.
