Report on Sheveluch (Russia) — 6 December-12 December 2000
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 December-12 December 2000
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2000. Report on Sheveluch (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 6 December-12 December 2000. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
For most of the period during 1-8 December weak seismicity was registered at the volcano, however two seismic events occurred that were above normal levels. First, at 1853 on 6 December seismic data indicated that a gas-and-ash explosion may have occurred. The possible explosion was registered as a shallow seismic event and was followed by volcanic tremor. Then, at 1556 on 7 December another shallow seismic event and possible gas-and-ash explosion occurred. The height of the cloud was estimated on the basis of seismicity at about 4-4.5 km a.s.l. The Concern Color Code at the volcano remained at Yellow.
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.