Report on Sheveluch (Russia) — 19 February-25 February 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
19 February-25 February 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Sheveluch (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 19 February-25 February 2003. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
During 14-21 February, seismicity remained above background levels at Shiveluch and many shallow earthquakes were recorded. Seismic data indicated that 17 ash-and-gas explosions reached heights of 1.5 km above the lava dome, and hot avalanches possibly occurred. Video footage showed several ash-and-gas clouds, with the highest cloud rising to 6.5 km a.s.l on 15 February accompanied by pyroclastic flows. Volcanic spasmodic tremor occurred and gas-and-steam plumes rose to 1 km above the crater. Shiveluch remained at Concern Color Code Yellow.
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.