Report on Bezymianny (Russia) — November 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 11 (November 1986)
Managing Editor: Lindsay McClelland.
Bezymianny (Russia) Lava extrusions; explosions feed pyroclastic flows
Please cite this report as:
Global Volcanism Program, 1986. Report on Bezymianny (Russia) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 11:11. Smithsonian Institution.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
Renewed extrusion of rigid blocks onto the summit lava dome was first observed on 9 December. Lava outflow started during the night of 16-17 December, accompanied by explosions that fed pyroclastic flows ~4 km long. The eruption cloud reached 5-6 km height and extended 40-50 km to the SE. The eruption ended 17 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.
Information Contacts: G. Bogoyavlenskaya, IV.