Soboliny is a stratovolcano of Maly Semiachik. It is about 12.5 by 9.5 miles (20 by 15 km) across. It has a long oval shape. There are many faults around this structure. They are found over a volcanic plateau which is partially overlapped by ignimbrites and central volcanoes. This area was formed before Soboliny. Total movement along these faults near Soboliny so far is not less than 1300 ft (400 m). Northern and western boundaries of the volcano are overlapped by younger volcanic formations. The southern boundary is hidden under lava flows and partially by pyroclastics of younger stages of volcano formation. Tuff ignimbrites covering the formation of this volcano are up to 650 ft (200 m) thick. Soboliny was formed in middle Pleistocene times during several strong eruptions.
Erlich, Edward, "Geology of the Calderas of Kamchatka and Kurile Islands with Comparison to Calderas of Japan and the Aleutians, Alaska," United States Department of the Interior Geological Survey, Geoexplorers International, Inc., Denver, Colorado, 300 pp., 1986.
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