Report on Bezymianny (Russia) — 7 March-13 March 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 March-13 March 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 7 March-13 March 2012. 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 a strong explosive eruption from Bezymianny was detected by seismic instruments on 9 March. Ash plumes rose to altitudes of 3.5-5 km (11,500-16,400 ft) a.s.l. and drifted NE. During the most intense phase of the eruption ash plumes from pyroclastic flows rose to an altitude of 8 km (26,200 ft) a.s.l. Satellite imagery showed the plume drifting 700 km NE. Ashfall was reported in Ust-Kamchatsk Village (120 km ENE). Later that day activity decreased significantly and the Aviation Color Code was lowered to Orange. During 9-13 March strong gas-and-steam emissions were noted, a viscous lava flow effused onto the lava-dome flank, and a thermal anomaly continued to be detected in satellite imagery. The Aviation Color Code was lowered to Orange on 14 March.
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.