Report on Sheveluch (Russia) — 26 November-2 December 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 November-2 December 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, 26 November-2 December 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 above background levels during 21-28 November. Based on interpretations of seismic data, ash plumes rose to an altitude of 5.6 km (18,400 ft) a.s.l. Ashfall was reported in the town of Klyuchi, about 30 km SW, on 22 November. Visual observations confirmed that ash plumes rose to an altitude of 5.5 km (18,000 ft) a.s.l. on 25 November. Fumarolic activity was visible on the web camera during 26-28 November. Analysis of satellite imagery revealed a daily thermal anomaly on the lava dome and a gas-and-steam plume that drifted about 30 km SE on 26 November. The Level of Concern Color Code remained at Orange.
Based on information from KEMSD and analysis of satellite imagery, the Tokyo VAAC reported that on 1 December eruptions produced plumes to an altitude of 4.9 km (16,000 ft) a.s.l.
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.