Report on Bezymianny (Russia) — 20 April-26 April 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 April-26 April 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 20 April-26 April 2011. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
In addition to producing ashfall 45 km to the NNW on 14 April, KVERT reported that the explosive eruption from Bezymianny also generated a viscous lava flow on the SE flank. Incandescence from the lava flow was visible on 19 April. Satellite imagery showed a thermal anomaly during 15-22 April, and small ash-and-gas plumes on 16 April. The Aviation Color Code remained at Orange.
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.