|Urataman consists of an impressive 7.5-km-wide Pleistocene caldera that forms the NE tip of the island. Caldera walls rise 450 m above a 250-m-deep caldera bay. A narrow gap in the northern caldera rim provides sea-water access into the half-moon-shaped Brouton Bay, which fills the NW half of the caldera. A central cone, andesitic Urataman volcano, has grown to a height of 678 m during the Holocene in the SE part of the caldera. Two cinder cones are located along the northern flank of Urataman, and a lava dome was formed on its NW flank along Brouton Bay. No historical eruptions are known from Urataman [Gorshkov, 1970].
Gorshkov G.S. Volcanism and the Upper Mantle: Investigations in the Kurile Island Arc. 1970. 385 p.