Report on Sheveluch (Russia) — 17 August-23 August 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 August-23 August 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Sheveluch (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 17 August-23 August 2011. 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 moderate during 12-19 August, and indicated that possible ash plumes rose to an altitude of 6.8 km (22,300 ft) a.s.l. on 13 August and to an altitude of 7.8 km (25,600 ft) a.s.l. on 15 August. Ash plumes may have risen to an altitude of 5 km (16,400 ft) a.s.l. on the other days. Gas-and-steam plumes containing ash observed in satellite imagery drifted 30 km SW on 12 August. Ground-based observers noted that an ash plume rose to an altitude of 6.5 km (21,300 ft) a.s.l. on 16 August. The Aviation 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.