Report on Bezymianny (Russia) — 8 March-14 March 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
8 March-14 March 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, 8 March-14 March 2017. 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 an explosive eruption at Bezymianny began at about 1330 on 9 March. Based on webcam observations, at 1454 an ash plume rose to altitudes of 6-7 km (20,000-23,000 ft) a.s.l. and drifted 20 km NE. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale). About 30 minutes later, at 1523, an ash plume rose to altitudes of 7-8 km (23,000-26,200 ft) a.s.l. and drifted 60 km NW. KVERT raised the Aviation Color Code to Red. Satellite data showed a 14-km-wide ash plume drifting 112 km NW at an altitude of 7 km (23,000 ft) a.s.l. Later that day a 274-km-long ash plume identified in satellite images drifted NW at altitudes of 4-4.5 km (13,100-14,800 ft) a.s.l.; the majority of the leading part of the plume contained a significant amount of ash. A lava flow traveled down the NW part of the lava dome. The Aviation Color Code was lowered to Orange. Ash plumes drifted as far as 500 km NW.
Geological Summary. 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.