Semiachik

the name of three volcanoes in the southeastern part of Kamchatka. The most active is Malyi Semiachik (elevation, 1,560 m), a caldera-type volcano with three craters; Lake Zelenoe is in the active crater. In the early 19th century, an explosion destroyed the peak. Eruptions of volcanic ash are known to have occurred in 1851, 1852, 1945–46, and 1952. Tsentral’nyi Semiachik (elevation, approximately 1,100 m) is a destroyed cone with active mud pots, solfataras, hot springs, and a lake. Bol’shoi Semiachik (elevation, 1,720 m) is a destroyed strato-volcano with no known eruptions. The volcanoes are composed of basalts and andesite-dacites and of the tuffs of these rocks.