Report on Bezymianny (Russia) — 9 May-15 May 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 May-15 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, 9 May-15 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)
KVERT reported on 11 May that the level of Concern Color Code for Bezymianny was raised to Orange due to a large thermal anomaly noted on satellite imagery. During 0330-0400 on 12 May, an explosive eruption may have occurred according to seismic data from Kozyrevsk. Ash plumes were visible on satellite imagery drifting multiple directions. Ashfall was reported from the town of Klyuchi, about 47 km NE. A slight amount of the ash originated from Kliuchevskoi, an active volcano directly N of Bezymianny. Hot avalanches were observed and an ash plume rose to an altitude of 4 km (13,100 ft) a.s.l. On 13 May, an elongated thermal anomaly was seen on satellite imagery to the SE of the lava dome.
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.