Report on Sheveluch (Russia) — 2 May-8 May 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 2 May-8 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, 2 May-8 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)
Volcanic activity continued at high levels at Shiveluch, with an increase in seismic activity, a thermal anomaly visible in satellite imagery, several small explosions, and a small pyroclastic-flow-producing eruption. An increase in seismic activity occurred on 1 May following the initial increase on 22 April and subsequent slight decrease on 28 April. The seismic activity increase on 1 May consisted of many shallow earthquakes and episodes of weak spasmodic tremor. Several small eruptions produced gas-and-steam plumes that rose up to 1.5 km. AVO reported that on 2 May a weak thermal anomaly (3 pixels) that was originally detected on 30 April was visible on satellite imagery. By 3 May the thermal anomaly had increased in intensity, with 2 of the 3-4 pixels at or near saturation on the imagery. At 0958 on 7 May an eruption produced an ash-and-gas plume that rose ~4.5 km a.s.l. and extended to the NW. Small pyroclastic flows were visible traveling down the volcano's SW slope. The Concern Color Code at Shiveluch remained at 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.