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Report on Atka Volcanic Complex (United States) — June 1998

Atka Volcanic Complex

Bulletin of the Global Volcanism Network, vol. 23, no. 6 (June 1998)
Managing Editor: Richard Wunderman.

Atka Volcanic Complex (United States) Low eruption plume seen in June, dusting of ash in Atka

Please cite this report as:

Global Volcanism Program, 1998. Report on Atka Volcanic Complex (United States) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 23:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199806-311160

Atka Volcanic Complex

United States

52.331°N, 174.139°W; summit elev. 1518 m

All times are local (unless otherwise noted)

At about 1000 on 30 June, the Alaska Volcano Observatory (AVO) received a report of an eruption at Korovin from an observer in the village of Atka, near the volcano. The crew of a Coast Guard C-130 airplane confirmed that a low-level eruption plume had risen to almost 5 km above sea level by 1030, and late in the afternoon a pilot reported the plume at 9 km. The low-level ash-and-steam plume was not visible on satellite imagery due to meteorological clouds. Local winds at the time were light and to the SSW. A dusting of ash was reported in Atka. Poor weather on 1 July prohibited both direct and satellite observations.

Korovin volcano is located on the north end of Atka Island in the central Aleutians (figure 1), 538 km W of Dutch Harbor. It is 21 km N of the village of Atka, which has a population of about 100. The last reported eruption was in March 1987. AVO does not maintain seismic monitoring equipment on Atka Island.

Figure (see Caption) Figure 1. Location of Korovin [Atka] volcano in the Aleutians. Map courtesy of AVO.

Geological Summary. The Atka Volcanic Complex consists of a central shield and Pleistocene caldera with several post-caldera volcanoes. A major dacitic explosive eruption accompanied formation of the caldera about 500,000 to 300,000 years ago. The most prominent of the post-caldera stratovolcanoes are Kliuchef and Sarichef, both of which may have been active in historical time. Sarichef has a symmetrical profile, but the less eroded Kliuchef is the source of most if not all historical eruptions. Kliuchef may have been active on occasion simultaneously with Korovin volcano to the north. Hot springs and fumaroles are located on the flanks of Mount Kliuchef and in a glacial valley SW of Kliuchef. Korovin, at the NE tip of Atka Island, is the most frequently active volcano of the complex, and contains a double summit with two craters. The NW summit has a small crater, but the 1-km-wide crater of the SE cone has an open cylindrical vent of widely variable depth that sometimes contains a crater lake or a high magma column. A fresh-looking cinder cone lies on the flank of the partially dissected Konia volcano, located on the SE flank of the dominantly basaltic Korovin. Some late-stage dacitic lava flows are present on both Korovin and Konia.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.