Report on Sheveluch (Russia) — 22 October-28 October 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 October-28 October 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, 22 October-28 October 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 17-24 October. Based on interpretations of seismic data, a large number of hot avalanches were inferred to have descended the lava dome and produced ash plumes that rose to an altitude of 6.7 km (22,000 ft) a.s.l. Significant hot avalanches that produced ash plumes to altitudes of 5 km (16,400 ft) a.s.l. were seen on 16 and 20 October. Fumarolic activity was visible on the web camera during 17-20 and 22-23 October. Analysis of satellite imagery revealed a daily thermal anomaly on the lava dome, and ash plumes drifted 60 km E on 20 October. Ash plumes about 10 by 11 km and 10 by 5 km in horizontal dimensions drifted about 30-40 km SE on 19 and 22 October, respectively. The Level of Concern Color Code remained at Orange.
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.