Report on Bezymianny (Russia) — 20 August-26 August 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
20 August-26 August 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 20 August-26 August 2008. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
KVERT reported that seismic activity at Bezymianny was slightly above background levels during 14 and 16-18 August and at background levels during 15 and 20-21 August. Analysis of satellite imagery revealed a thermal anomaly over the lava dome during 14-15 and 18-21 August. The thermal anomaly enlarged just before an explosion on 19 August. The explosion produced an ash plume that rose to an altitude of 9 km (29,500 ft) a.s.l. and drifted 1,200 km W. Staff at a seismic station about 50 km W reported ashfall and the smell of volcanic gas. The Level of Concern Color Code was lowered to Yellow.
Geological Summary. The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.