Report on Bezymianny (Russia) — 23 June-29 June 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 June-29 June 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Bezymianny (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 23 June-29 June 2004. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
An eruption at Bezymianny produced an ash cloud that during 18-19 June extended more than 1,000 km E and SE from the volcano and possible ash deposits extended 190 km SE from the lava dome. Seismicity at Bezymianny did not exceed background levels during 20-23 June. The Concern Color Code at Bezymianny was reduced from Orange to Yellow around 25 June.
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.