Report on Sheveluch (Russia) — 13 December-19 December 2000
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 December-19 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, 13 December-19 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)
KVERT reported that the character of volcanic activity at Shiveluch did not change during 9-16 December. Weak seismicity was registered at the volcano during most of the week. Much like the previous week, two seismic events occurred that were above normal levels. First, at 2147 on 9 December a shallow seismic event was likely accompanied by a gas-and-ash explosion that sent a cloud to an inferred 3.5 km a.s.l. The event was followed by volcanic tremor for ~0.5 hour. The second possible gas-and-ash explosion occurred at 0021 on 12 December. The cloud was again inferred from seismic data to have risen to ~4 km a.s.l. These inferred plume heights were determined by comparing the amplitude of the seismic wave caused by the eruption to the heights of ash clouds observed in the past associated with earthquakes with similar amplitudes. After the 12 December event, volcanic tremor was registered for 1 hour. 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.