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Report on Sheveluch (Russia) — 20 February-26 February 2002

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 February-26 February 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, 20 February-26 February 2002. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (20 February-26 February 2002)


Sheveluch

Russia

56.653°N, 161.36°E; summit elev. 3283 m

All times are local (unless otherwise noted)


Volcanic unrest continued at Shiveluch during 15-22 February, with several ash-and-gas explosions occurring and seismicity remaining above background levels. An eruption on 15 February at 1501 produced an ash cloud accompanied by pyroclastic flows that traveled 2.5 km down the SE slope of the dome. The highest rising observed ash cloud was produced by an eruption on 19 February at 0800; it reached a height of 3.5-4 km above the lava dome. Seismicity included earthquakes with magnitudes less than 2.4 at depths of 0-5 km, many local shallow seismic signals (from possible avalanches or weak gas-ash explosions), and episodes of weak intermittent volcanic tremor. Thermal anomalies and ash clouds were visible on satellite imagery. The volcano remained at Color Concern Code Orange ("volcano is in eruption or eruption may occur at any time").

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.

Sources: Anchorage Volcanic Ash Advisory Center (VAAC), Kamchatkan Volcanic Eruption Response Team (KVERT)