Report on Sheveluch (Russia) — 22 July-28 July 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 July-28 July 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Sheveluch (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 July-28 July 2009. Smithsonian Institution and US Geological Survey.
56.653°N, 161.36°E; summit elev. 3283 m
All times are local (unless otherwise noted)
KVERT reported that during 17-18 and 20-24 July seismic activity from Shiveluch was above background levels. During 17-20 and 22 July, gas-and-steam plumes seen on a video camera rose to an altitude of 3.7 km (12,100 ft) a.s.l. Based on interpretations of seismic data, ash plumes possibly rose to an altitude of 5.2 km (17,000 ft) a.s.l. on 20, 21, and 22 July, and steam-and-gas plumes with some ash content were noted on other days. Analyses of satellite imagery revealed a large daily thermal anomaly over the lava dome, and steam plumes that drifted as far away as 40 km on 18 and 20 July. The Level of Concern Color Code remained at Orange.
Based on analyses of satellite imagery and information from KEMSD, the Tokyo VAAC reported that during 23-24 and 27-28 July eruptions produced plumes that rose to altitudes of 4.6-6.1 km (15,000-20,000 ft) a.s.l. According to news sources, an ash plume rose to an altitude of 7 km (23,000 ft) a.s.l. late on 25 July. Increased seismicity, powerful ash bursts, and avalanches were also reported.
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.