Report on Sheveluch (Russia) — August 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 8 (August 1987)
Managing Editor: Lindsay McClelland.
Sheveluch (Russia) Ash plumes and base surges from extrusive dome
Please cite this report as:
Global Volcanism Program, 1987. Report on Sheveluch (Russia). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 12:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198708-300270.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
Gas and ash plumes from the extrusive dome were sighted more frequently in 1987. Four or five plumes were seen each month March-June and 6 in July. Seismic activity also intensified and each explosion was accompanied by volcanic tremor. Vertical columnar ash plumes with a maximum height of 5 km were often accompanied by base surges that extended 300 m. Explosion products included ash and andesitic sand-sized tephra with rare blocks as large as 1 m.
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.
Information Contacts: G. Bogoyavlenskaya and V. Beloussov, IV.