Report on Sheveluch (Russia) — 28 September-4 October 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 September-4 October 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, 28 September-4 October 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 23-30 September, and indicated that possible ash plumes rose to an altitude of 4.6 km (15,100 ft) a.s.l. during 23 and 26-27 September. Ground-based observers noted that ash plumes rose to altitudes of 5.5 and 4.5 km (18,000 and 14,800 ft) a.s.l. on 23 and 27 September, respectively. Ash plumes observed in satellite imagery during 23-24 September drifted 45 km E. Seismicity increased on 3 October. Ash plumes rose to altitudes of 6-9 km (19,700-29,500 ft) a.s.l. during 3-5 October. Ground-based observers noted on 5 October a brightly incandescent lava dome, which was also detected as a large and bright thermal anomaly in satellite imagery. The Aviation Color Code was raised to Red.
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.