Report on Bezymianny (Russia) — 21 October-27 October 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 October-27 October 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 October-27 October 2020. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
Based on Tokyo VAAC notices, KVERT reported that an explosive eruption at Bezymianny began at 0822 on 22 October and produced a large ash cloud that rose as high as 9 km (29,500 ft) a.s.l. The Aviation Color Code was raised to Red, the highest level on a four-color scale. The ash cloud identified in satellite images was 100 x 200 km in size. KVERT noted that by 1519 the eruption was over. A large ash cloud was still visible, though it had dropped to lower altitudes of 5-5.5 km (16,400-18,000 ft) a.s.l. and split into a N part (57 x 105 km) and a S part (36 x 67 km). The clouds shiftied direction and drifted as far as 811 km NW and SE. The Aviation Color Code was lowered to Orange. On 23 October a thermal anomaly over the summit was identified in satellite images and growth of a lava dome was noted. The Aviation Color Code was lowered to Yellow.
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.