On 2 April a fumarolic plume rose 800-1,000 m above the crater and extended more than 10 km E. At 1100 on 3 April an ash explosion created a plume that rose 2,000 m above the dome. Coincident with this explosion, a shallow seismic event was registered under the volcano beginning at 1056. The ash cloud dissipated by 1130. That evening and the next day, a gas-and-steam plume rose 600 m above the dome. Fumarolic plumes were observed during most of the following week, including a gas-and-steam plume on 6 April that rose 1,000 m above the dome.

At 1900 on 12 April an ash explosion was observed and a plume rose 1,000 m above the dome. Shallow seismicity under the volcano had started at 1855. Explosions sent ash up to 200 m above the dome every 2-3 minutes during the hour following the initial blast. The ash plume extended 10 km to the E. Satellite imagery taken at 2052 on 12 April showed a 30-km-long, ash-poor, low-altitude plume extending SE. Another satellite image on 13 April, taken at 0750, indicated a possible thermal anomaly at the volcano. A series of shallow seismic events continued to be recorded during 14-15 April. Gas-and-steam plumes were seen on 13, 17-18, and 20 April.

Geological Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Olga Chubarova, 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.