Tolbachik(redirected from Ostry Tolbachik)
a volcanic cluster on the Kamchatka Peninsula. Located in the southwestern part of the Kliuchevskaia volcanic group, Tolbachik consists of a cone, Ostryi Tolbachik, which lacks a crater and has an elevation of 3,682 m; a flat dome; the active volcano Ploskii Tolbachik, which has an elevation of 3,140 m; and more than 120 parasitic cones. Tolbachik is composed of basalts and partly of andesites. Ploskii Tolbachik is a Hawaiian-type volcano with a crater 2 km in diameter at its summit. Both central and fissure eruptions have occurred. Ploskii Tolbachik erupted in 1740, 1769, 1788 to 1790, 1793, 1904, 1931, 1939 to 1941, and 1954. An eruption in 1975 and 1976 was accompanied by the formation of a number of new volcanic cones and domes along fissures on the volcano’s periphery.