指臼岳

The Sashiusudake (also known as Baransky) volcanic complex along the Pacific coast in the central part of Iturup Island consists of a Holocene stratovolcano built over an eroded Pleistocene edifice. A young summit lava dome is cut by a NW-trending chain of small explosion craters. A group of flank cones farther to the NW with a similar NW-SE orientation is partially surrounded by lava flows from the central crater of the andesitic-dacitic volcano. Lava flows descended 4-5 km SE to reach the Pacific Ocean along a broad front. The only observed eruption occurred in 1951, when local inhabitants reported weak explosive activity at the summit. Strong solfataric activity continues from the summit and several flank craters, and the SW flank geothermal field contains hot springs and geysers. A small hydrothermal explosion took place in 1992 at an exploratory well in the SW-flank geothermal field.