During the interval from mid-November to mid-December gas-and-steam plumes rose 0.3-1.5 km above the crater rim; these blew toward the S or SE and remained conspicuous for over 40 km. . . . tremor peaked in the week ending 18 November (21-24 hours/day) and dropped steadily for the subsequent weeks. By the weeks ending on 15 and 22 December, tremor registered for less than 1 hour/day.

For late-November to mid-December, 2-8 earthquakes/day were recorded near the volcano. This level of seismicity is similar to that in the first half of October. The second half of October and some periods in September saw sharp increases in earthquakes to over 40 events/day.

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.