Report on Sheveluch (Russia) — 13 October-19 October 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
13 October-19 October 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, 13 October-19 October 2004. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
Seismicity was above background levels at Shiveluch during 8-15 October, with weak shallow earthquakes occurring beneath the active lava dome. Two relatively strong shallow earthquakes, M 1.75 and 2.1, were recorded on 8 and 11 October, respectively. Spasmodic tremor was recorded during 7-12 October. Based on interpretations of seismic data, weak ash-and-gas explosions and hot avalanches may have occurred all week. Visual observations from the town of Klyuchi revealed that ash plumes rose to 3.5 km a.s.l. on 7 and 12 October and extended more than 10 km E. Weak gas-and-steam activity occurred on 11 and 12 October. Clouds obscured the volcano at other times. Shiveluch remained at Concern Color Code Orange.
Geological Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. 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 occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. 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.