Tolbachik is a volcanic complex on the Kamchatka Peninsula in the far east of Russia. It consists of two volcanoes, Plosky (flat) Tolbachik (3,085 m) and Ostry (sharp) Tolbachik (3,682 m), which as the names suggest are respectively a flat-topped shield volcano and a peaked stratovolcano. As Ostry is the mountain's highest point, the entire mountain is often referred to as "Ostry Tolbachik", not to be confused with Ostry a separate volcano to the north also on the Kamchatka Peninsula.
Its eruptive history stretches back thousands of years, but the most notable eruption occurred in 1975, commonly known as "The Great Tolbachik Fissure Eruption". It was preceded by an earthquake swarm, which led to a successful prediction of the eruption by scientists from the Russian Institute of Volcanology. The eruption created several new cinder cones, and in terms of volume of lava emitted was Kamchatka's largest basaltic eruption in historic times.
On November 27, 2012 an eruption started from 2 fissures of a strombolian type. Basaltic lava flows move relatively fast and already flooded some buildings 4 km away. Eruption continued for more than a month, as lava continued to flow from the fissures. Lava flowed up to 20 kilometers (12 miles) from a line of fissures on the volcano’s southern flank. This satellite image was collected on December 22, 2012. According to the Kamchatka Volcanic Eruption Response Team (KVERT), the eruption is ongoing.
The slag deposits of Tolbachik are rich in exotic minerals and 39 were first described from here (e.g. Alarsite and Tolbachite).