Report on Sheveluch (Russia) — 25 April-1 May 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 April-1 May 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Sheveluch (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 April-1 May 2012. 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 explosive activity at Shiveluch continued during 20-27 April. Ground-based observers and satellite imagery indicated that a viscous lava flow continued to effuse in the crater formed during a 2010 eruption and was accompanied by fumarolic activity. Seismic data and visual observations showed that ash plumes rose to an altitude greater than 10 km (32,800 ft) a.s.l. on 24 April and were slight on the other days. Satellite imagery showed a weak thermal anomaly on the lava dome during 20-22 April, and ash plumes that drifted 396 km NE on 24 April. 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.