Report on Sheveluch (Russia) — 25 April-1 May 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 April-1 May 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Sheveluch (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 25 April-1 May 2001. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
Following the sharp increase in seismic activity on 22 April the number and magnitude of seismic events continued to increase at Shiveluch until 27 April. The largest earthquake occurred on 27 April (M 4) and the number and magnitude of earthquakes began to slightly decrease on 28 April. Several gas-and-steam plumes that reached a maximum height of 700 m above the volcano were observed starting on 28 April. As of 1 May seismic activity was still significantly above background levels. KVERT stated that the trend of the seismic activity is similar to the increase that preceded the violent 1993 eruption. The Concern Color Code at Shiveluch 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.