Background:Ushkovsky volcano (formerly known as Plosky) is a large compound volcanic massif located at the NW end of the Kliuchevskaya volcano group. It consists of the flat-topped 3943-m-high Ushkovsky volcano (Daljny Plosky), which is capped by an ice-filled 4.5 x 5.5 km caldera, and the adjacent slightly higher peak of 4108 m Krestovsky (Blizhny Plosky) volcano. Two glacier-clad cinder cones with large summit craters form a high point within the Ushkovsky caldera. Linear zones of cinder cones are found on the SW and NE flanks and on lowlands to the west. The younger caldera at the summit of Plosky Daljny (Ushkovsky) was formed in association with the eruption of large lava flows and pyroclastic material from the Lavovy ShIsh cinder cones at the foot of the volcano about 8600 years ago. The only known historical activity at Ushkovsky was an explosive eruption from the summit cone in 1890.
Smithsonian / GVP volcano information