Report on Bezymianny (Russia) — 16 December-22 December 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 December-22 December 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 16 December-22 December 2009. 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 from Bezymianny increased on 8 December. After a significant thermal anomaly was detected in satellite imagery on 17 December, the Level of Aviation Color Code was raised to Red. A few hours later a large explosive eruption produced ash plumes that were seen drifting as far as 350 km W and NW in satellite imagery. Ash plumes likely rose to altitudes greater than 10 km (32,800 ft) a.s.l.; clouds in the area prevented visual observations. Ashfall up to 3 mm thick was noted in Kozyrevsk, 45 km W, and other surrounding villages. The Level of Aviation Color Code was lowered to Orange after seismic activity significantly decreased. On 18 December another large thermal anomaly was seen over the volcano and on the SE flank. Gas-and-steam activity was also noted. During 19-20 December, a thermal anomaly continued to be detected in satellite imagery. KVERT lowered the Level of Aviation Color Code to Yellow on 21 December.
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.