The previous report on Bezymianny (BGVN 22:04) described an early May eruption. That event spawned aviation reports, including ash-cloud dispersion observations and forecasts that showed the 9 May plume moving hundreds of kilometers ENE- NE.

In one case (at 0832 GMT), satellite imagery disclosed two clouds at different altitudes. One cloud was still attached to the volcano; it reached ~500 km E-W; it spread both E and W from the volcano but was offset slightly to the N. The other cloud was detached and higher; it lay over the Bering Sea centered ~600 km NE of the summit.

About an hour later (at 0932 GMT), the lower cloud detached and moved N. The higher cloud covered a larger area and moved NE to assume a position with its N margin overlying the mainland. The lower cloud shifted N and detached from the source.

An aviation report on 15 May mentioned ash erupted from the volcano before 2015 GMT. This was confirmed by AVO and satellite imagery. Ash, however, was not detected the next day on satellite images.

Several gas-and-steam plumes were noted in July. On the 14th one rose to 1 km above the crater and moved 25 km E. During 15-20 July, others rose 100-400 m above the crater and blew 5-10 km to the E and SE. On 21 July one rose 50 m above the crater; yet another on 27 July rose 300 m above the crater and moved 20 km to the W.

Geological Summary. The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Information Contacts: Vladimir Kirianov, Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanic Geology and Geochemistry, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia; Tom Miller, 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; Bureau of Meteorology, Northern Territory Regional Office, P.O. Box 735, Darwin NT 0801, Australia; NOAA/NESDIS Satellite Analysis Branch (SAB), Room 401, 5200 Auth Road, Camp Springs, MD 20746, USA.