Report on Bezymianny (Russia) — 25 April-1 May 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 April-1 May 2007
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2007. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 April-1 May 2007. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
Based on [a pilot report to the] Petropavlovsk-Kamchatsky Flight Information Region (FIR) [at 0725], the Tokyo VAAC reported that on 29 April an ash plume from Bezymianny rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted W. [Ash was not seen in MTSAT-IR satellite data about 26 minutes prior to the pilot report.]
[Later information regarding this reported event provided by KVERT noted that no satellite data reviewed by volcanologists contained ash plumes, there were no strong seismic events, and no explosions were seen on the video camera. Meteorological clouds were present at 4.5-5.0 km altitude overnight and through 0900 local time. No ash fell in the village of Kozyrevsk, which would have been expected had an ash plume drifted W.]
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.