Global Volcanism Program | Image GVP-10821
The 1.6-km-wide caldera of Ushishur volcano opens towards the south and formed during an eruption about 9,400 years ago. Two post-caldera lava domes that erupted sometime after a 1769 visit of Captain Snow form islands in the caldera bay. Two older domes in front of the islands are joined by a sand bar to the SE caldera wall. A northern island (top) consists of a portion of the flanks.
Photo by R. Bulgakov, 1990 (Institute of Marine Geology and Geophysics, Yuzhno-Sakhalin).