Bezymianny ("unnamed") was considered extinct until it erupted violently in 1955-56, after a slumber of probably 1000 years. It is one of the most active volcanoes in Kamchatka. The eruption followed a massive flank failure (similar to Mt. St. Helens eruption in 1980) which removed a 0.5 sq km sector of the volcano.

The present-day Bezymianny volcano, lying next to its massive sisters Kamen and Kliuchevskoi, is a young and relatively small volcano only about 4700 years old. It was formed on top of an older volcano built between about 11,000-7000 years ago. 3 periods of intensified activity have been recognized in the geologic history during the past 3000 years. The present-day activity started with the eruption in 1955-56 after a 1000 year interval of repose. At the beginning of the eruption, the summit and a large sector of its flank failed and resulted in a catastrophic landslide followed by a powerful blast. The event left a large horseshoe-shaped crater. Since then, the volcano has been one of Kamchatka's most active. A new lava dome has been growing inside the 1956 crater, frequently producing explosive activity and pyroclastic flows. As of 2011, the lava dome has already largely filled the 1956 crater.