Tao-Rusyr volcano is an impressive basaltic-to-andesitic stratovolcano located on the southern end of Onekotan Island in the northern Kuriles. It contains a 7.5 km wide caldera and a large symmetrical new central cone, Krenitzyn Peak which is the vent of young activity. A lava dome was formed in eruptions in 1952. The caldera contains the beautiful, deep blue 7-km-wide Kal'tsevoe lake and is famous for its spectacular scenery.

The caldera had been formed about 7500 years ago during a massive eruption, one of the largest known from the Kurile Islands. Volcanic activitiy after the caldera formation has built a large new summit cone, the andesitic Krenitzyn Peak, which rises high above the caldera rims.

Krenitzyn has grown about 1000 meters in 7500 years and now forms a 4 km wide island and fills the NW part of the caldera.

The summit contains a 350-m-wide and 100-m-deep crater, and there is a large lateral crater on the upper NE side.

(Source: Smithsonian / GVP Tao-Rusyr volcano information)