Report on Sheveluch (Russia) — 27 June-3 July 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 June-3 July 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, 27 June-3 July 2001. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
Increases in both seismic activity and explosions at Shiveluch led KVERT to raise the Concern Color Code on 2 July from Yellow to Orange. On 26 June, prior to an increase in seismic activity, a possible thermal anomaly was observed on satellite imagery. The volcanic activity increase may have begun on 28 June at 1500 when the level of volcanic tremor and the number of shallow earthquakes increased. According to reports from observers in the town of Klyuchi (46 km from the volcano) on 29 June at 1150 a short-lived explosion sent an ash-and-gas plume to a height of ~4.5 m a.s.l. During the eruption pyroclastic flows traveled 2.5 to 3 km down the slopes of the volcano. Later in the day and during the next day seismic data suggested that six possible gas-and-ash explosions occurred that produced ash to a maximum height of 8.5 km a.s.l. According to the Tokyo VAAC the largest 30 June explosion began at 0300 and produced an ash plume that ascended to 7.3 km a.s.l. Later during 30 June and 1 July, GOES and other satellite's imagery showed a possible ash cloud drifting over the Bering Sea that may have originated in Kamchatka. According to visual observations from the town of Klyuchi, on 1 July explosions produced ash plumes that rose to 1.5 km above the dome, and at 1250 a short-lived explosion produced an ash-and-gas plume that rose to ~8 km a.s.l and drifted to the E. Pyroclastic flows extended 5 km down the Baidarnaya River.
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.