Report on Sheveluch (Russia) — 21 May-27 May 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 May-27 May 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Sheveluch (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 May-27 May 2008. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
KVERT reported that seismic activity at Shiveluch was at background levels during 15-17 and 21 May and above background levels the other days during 16-23 May; gas-and-ash explosions may have occurred on 18, 19, and 20 May. According to video footage and visual observations, small hot avalanches descended the lava dome every day and fumarolic activity was noted. A large hot avalanche caused an ash plume to rise to an altitude of 4 km (13,100 ft) a.s.l. on 20 May. The plume drifted E. Observations of satellite imagery revealed that a thermal anomaly was present in the crater daily and an ash-and-steam plume drifted more than 100 km SE on 20 May.
Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. 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 dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. 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.