Activity at Bezymianny increased during 22-23 October characterized by incandescence at the summit, sometimes strong fumarolic activity, and an increasing temperature of a thermal anomaly identified in satellite images. KVERT raised the Aviation Color Code to Orange (the second highest level on a four-color scale). A strong explosive phase commenced and by 2340 local time on 23 October satellite images showed ash plumes rising to 10 km (32,800 ft) a.s.l. and drifting 10 km ENE. The Aviation Color Code was raised to Red. By 1005 local time on 24 October the phase was over, and the Aviation Color Code was lowered to Orange. Satellite images showed gas-and-steam plumes drifting NE and an intense thermal anomaly. The ash plumes from the day before had drifted as far as 1,915 km NE. At 2028 local time on 25 October KVERT lowered the Aviation Color Code to Yellow and noted that the intense thermal anomaly persisted. Dates are based on UTC times; specific events are in local time where noted.

Geological Summary. The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)