Report on Sheveluch (Russia) — 16 January-22 January 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 January-22 January 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Sheveluch (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 16 January-22 January 2002. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
On 17 January, increased seismic energy release prompted KVERT to increase the Color Concern Code at Shiveluch to Orange ("volcano is in eruption or eruption may occur at any time") from Yellow ("volcano is restless"). During 11-18 January the total number of earthquakes within Shiveluch's edifice decreased, but the energy of individual earthquakes increased (up to ~M 3). In addition, weak, shallow seismic signals (possible collapses and avalanches) were registered. Seismic data indicated the occurrence of more intense possible gas-and-ash explosions than occurred during previous weeks. During 13-14 and 15-16 January, gas-and-steam plumes rose 1-1.5 km above the lava dome. On 14 January, a plume extended more than 10 km SE, and rock avalanches were visible continuously rolling down the dome. Thermal anomalies were visible on satellite imagery, but ash was not.
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.