Ushishur volcano, Russia
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Ushishur volcano, Russia
The small, but spectacular caldera of Ushishur volcano is breached on its southern side. The 1.6-km-wide caldera was formed during an eruption about 9400 years ago.
Two post-caldera lava domes, erupted sometime after the 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) to the north consists of a portion of the volcano's flanks.
The subaerial portion of Ushishur volcano in the central Kuriles is exposed in two small islands, the southern containing the summit caldera and the northern a portion of the volcano's flanks.
A small 1.6-km-wide caldera that formed about 9400 years ago is narrowly breached on the south, allowing sea water to fill the caldera.
Two andesitic lava domes occupy part of the caldera bay; two other older domes are joined by a sand bar to the SE caldera wall.
The two younger domes, erupted sometime after the 1769 visit of Captain Snow, form islands in the bay.
A cluster of strong fumaroles and hot springs along the SE caldera shoreline was a sacred place to 18th- and 19th-century Kurile Ainu peoples, and vigorous submarine hydrothermal activity has modified the geochemistry of sea water within the caldera bay.
Aside from growth of the two younger lava domes, only minor phreatic eruptions have occurred at Ushishur during historical time.
PHOTO SOURCE: Photo by R. Bulgakov, 1990 (Institute of Marine Geology and Geophysics, Yuzhno-Sakhalin) courtesy of the Global Volcanism Program, Smithsonian National Museum of Natural History, used with permission.
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