Weak shallow seismic activity (1-4 events/day) continued to be registered beneath the volcano throughout July and August. Average duration of volcanic tremor was less than 30 minutes/day. The gas-and-steam plume (up to 500 m above the extrusive dome) observed during 7-14 July was blown E for about 30 km. Clouds frequently prevented observations in July and early August. Normal fumarolic activity was observed above the extrusive dome during mid-August. In late August and early September a gas-and-steam plume was observed up to ~3 km above the extrusive dome. Shallow seismicity remained at normal levels (1-5 events/day) through 12 September, with an average of 0.3 hours of tremor/day.

A strong eruption in April 1993 has been followed by a plume visible during clear weather (18:4-8 & 10-12, and 19:1-4 & 6). Prior to that eruption, the most recent explosive activity was in April 1991 (16:3). The largest historical eruptions from Shiveluch occurred in 1854 and 1964.

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: V. Kirianov, IVGG.