Report on Sheveluch (Russia) — 23 May-29 May 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 May-29 May 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Sheveluch (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 23 May-29 May 2001. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
On 22 May at 0209 an explosive eruption produced a mushroom-shaped ash column that rose to a height of more than 10 km a.s.l. (preliminary reports stated ~20 km). The high-pressure system over N Kamchatka caused the plume to remain fairly stationary over the region as it spread out to cover an area of ~50,000 km2. Observations from the town of Klyuchi, 46 km from the volcano, revealed that the new lava dome (first observed on 12 May) and the W part of the old dome were destroyed during the eruption. After the 22 May eruption several small eruptions produced ash-and-gas clouds that rose up to 2 km a.s.l. On 23 May a large thermal anomaly was observed at Shiveluch. In satellite imagery the anomaly consisted of ten pixels ranging in temperature from 30 to 49 °C with two pixels near saturation. The anomaly may have represented a pyroclastic flow that originated from the dome area. Seismic activity remained above background levels. On 24 May the Concern Color Code was reduced from Red to Orange.
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.