Report on Bezymianny (Russia) — 26 December-1 January 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 December-1 January 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Bezymianny (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 26 December-1 January 2002. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
A reduction in volcanic and seismic activity during 21-28 December at Bezymianny led KVERT to reduce the Concern Color Code from Yellow ("volcano is restless") to Green ("volcano is dormant"). Seismicity under the volcano decreased to background levels, with weak, shallow earthquakes continuing within the volcano's edifice. Several small gas-and-steam plumes rose above the lava dome and a one-pixel thermal anomaly became less intense.
Geologic Background. Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped 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.