Report on Sheveluch (Russia) — 19 December-25 December 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 19 December-25 December 2007
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2007. Report on Sheveluch (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 19 December-25 December 2007. 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 14-21 December. Based on seismic interpretation, a series of explosions during 18-19 December produced ash plumes that rose to altitudes of 6.5-8.7 km (21,300-29,000 ft) a.s.l. Ash plumes were observed on satellite imagery and drifted more than 130 km W on 18 December and 300 km to the NW and SW on 19 December. Ashfall was reported in the town of Klyuchi, about 30 km SW on 19 December. Based on visual observations, large pyroclastic flow deposits 8-9 km from the lava dome were noted on the S flank. On 20 December, KVERT reported that the Level of Concern Color Code was raised to Red. On 21 December, the Level of Concern Color Code was lowered back to 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.