Report on Sheveluch (Russia) — 18 February-24 February 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 February-24 February 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Sheveluch (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 18 February-24 February 2004. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
During 13-20 February, seismicity was slightly above background levels at Shiveluch. A large number of weak, shallow earthquakes was recorded daily at depths of 0-5 km beneath the active lava dome. Spasmodic tremor was recorded the entire week. Based on interpretations of seismic data, two ash-and-gas explosions on 12 February, and one on 16 February, produced ash plumes to ~4 km a.s.l. Visual and video observations revealed that two ash plume rose to ~5 km a.s.l. and drifted E on 12 February. Shiveluch remained at Concern Color Code 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.