Report on Bezymianny (Russia) — 13 December-19 December 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 December-19 December 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 December-19 December 2017. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
On 18 December hot avalanches on the SE flank of Bezymianny’s lava dome were recorded by a webcam, prompting KVERT to raise the Aviation Color Code to Orange (the second highest level on a four-color scale). A strong explosion that started at 1555 on 20 December generated ash plumes that rose 10-15 km (32,800-49,200 ft) a.s.l., prompting KVERT to raise the Aviation Color Code to Red. Ash plumes were identified in satellite data drifting 85 km NE. Later that day satellite images indicted decreased activity; the Alert level was lowered back to 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.