Atka volcano alert levels raised after brief eruption, Alaska

A small explosive event was recorded at the Atka volcanic complex in the Aleutian Islands, U.S., at 04:26 UTC on February 21. The explosion, detected through local seismic and infrasound monitoring, lasted for less than 10 seconds.

The event likely produced a small amount of volcanic ash, but direct satellite observations were obstructed by a meteorological cloud layer at an altitude of 2 400–3 000 m (8 000–10 000 feet) above sea level (a.s.l). No ash emissions were observed above this cloud cover. Since the explosion, no additional explosive events have been recorded, and seismic activity remains unchanged.

As a result, the Aviation Color Code and Volcano Alert Level have been raised to Orange/Watch, indicating heightened unrest with the potential for further activity.

The Atka Volcanic Complex is continuously monitored by local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data. The instruments provide real-time analysis of volcanic activity in the region.

The Alaska Volcano Observatory (AVO) downgraded the Atka Volcanic Complex to the lowest alert levels, Normal for the Alert Level and Green for the Aviation Color Code on April 9, 2024. The decision followed a decrease in activity after a minor explosion at the summit crater of Korovin volcano on March 27, 2024. While small earthquakes and weak volcanic tremors continued after the event, they remained at background levels.

The Atka Volcanic Complex is located within a UNESCO Biosphere Reserve, an area recognized for its ecological significance. The nearest human settlements are situated within a 30 km (18.6 miles) radius, with approximately 207 people residing in the region. No populations are present within 10 km (6.2 miles) of the complex.

The Complex, part of the Aleutian Ridge Volcanic Arc, consists of a central shield, a Pleistocene caldera, and multiple stratovolcanoes. The complex has a summit elevation of 1 518 m (4 980 feet). Its most frequently active volcano is Korovin, situated at the northeastern end of Atka Island, approximately 5 km (3.1 miles) north of Kliuchef stratovolcano.

A major dacitic eruption occurred between 500 000 and 300 000 years ago, forming the complex’s caldera, which remains open to the northwest. The Kliuchef stratovolcano, positioned within the caldera, features five active vents along a northeast-trending fissure, with two located at its summit. A 700 m (2 296 feet) crater northeast of the summit may have been the vent for an eruption in 1812 CE.

The volcanic complex consists of basalt, andesite, and dacite. It is positioned in a subduction zone with an intermediate crust thickness of 15–25 km (9.3–15.5 miles), where the Pacific Plate subducts beneath the North American Plate. The tectonic environment contributes to the region’s volcanic and seismic activity.

References:

¹ Atka volcanic complex – AVO – February 21, 2025

² Atka Volcanic Complex – GVP – Accessed on February 21, 2025

Rishika Yadav

Rishika holds a Master’s in International Studies from Stella Maris College, Chennai, India, where she earned a gold medal, and an MCA from the University of Mysore, Karnataka, India. Previously, she served as a Research Assistant at the National Institute of Advanced Studies, Indian Institute of Science, Bengaluru, India. During her tenure, she contributed as a Junior Writer for Europe Monitor on the Global Politics website and as an Assistant Editor for The World This Week. Her work has also been published in The Hindu newspaper, showing her expertise in global affairs. Rishika is also a recipient of the Women Empowerment Award at the district level in Haryana, India, in 2022.

This author does not have any more posts.