Report on Bezymianny (Russia) — 12 December-18 December 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 December-18 December 2001
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, 12 December-18 December 2001. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
KVERT increased the Concern Color Code at Bezymianny from Yellow ("volcano is restless") to Orange ("eruption may occur at anytime"). During 7-14 December seismicity under Bezymianny was above background levels, with the number of shallow earthquakes increasing near the end of the week. On 10 and 12-13 December gas-and-steam plumes rose to 300 m above the volcano and extended 40 km to the W, SW, and SE. Thermal anomalies were visible centered over the lava-dome area.
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.