Strong eruption at Bezymianny volcano, ash up to 9.5 km (31 000 feet) a.s.l., Russia

A strong eruption started at the Russian Bezymianny volcano at 20:22 UTC on October 21, 2020, ejecting ash up to 9.5 km (31 000 feet) above sea level.

The Aviation Color Code was raised to Red at 21:51 UTC and lowered back to Orange at 03:19 UTC on October 21 after the eruption has finished.

Satellite data at 23:00 UTC showed a large ash cloud moving about 75 km (46 miles) west of the volcano, KVERT reported.

Image credit: KB GS RAS

The large ash cloud was present in the area of the Klyuchevskoy group of volcanoes, but its height has decreased to 5 – 5.5 km (16 400 – 18 000 feet) a.s.l. by 03:19 UTC. 

The cloud has divided on the northern part (105 x 57 km / 65 x 25 miles in size) and the southern (36 x 67 km / 22 x 41 miles in size), KVERT said.

A powerful eruption took place at the volcano at 17:29 UTC on March 15, 2019, with volcanic ash rising up to 15.2 km (50 000 feet) above sea level. 

Image credit: KB GS RAS

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 11000 – 7000 years ago. 

Three periods of intensified activity have occurred during the past 3 000 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. (GVP)

Featured image credit: KB GS RAS