An explosive eruption at Bezymianny began at 0310 on 15 March, producing ash plumes. KVERT raised the Aviation Color Code to Orange (the second highest level on a four-color scale). Activity intensified at 0053 on 16 March and remained elevated for about 30 minutes. During this phase pyroclastic flows descended the S, W, and N flanks, and ash plumes rose as high as 12 km (39,400 ft) a.s.l. that ultimately drifted more than 1,300 km NW and then NE. A large thermal anomaly over the volcano was visible through 18 March, indicating continuing lava-dome growth. Steam-and-gas emissions persisted though 23 March. The Aviation Color Code was lowered to yellow on 23 March.

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)