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Snow cover highlights the calderas and volcanic cones that form the northern and southern ends of Onekotan Island, part of the Russian Federation in the western Pacific Ocean. Calderas are depressions formed when a volcano empties its magma chamber in an explosive eruption and then the overlaying material collapses into the evacuated space.

In this astronaut photograph from the International Space Station, the northern end of the island (image right) is dominated by the Nemo Peak volcano, which began forming within an older caldera approximately 9,500 years ago. The last recorded eruption at Nemo Peak occurred in the early 18th century.

The southern end of the island was formed by the 7.5 kilometer (4.6 mile) wide Tao-Rusyr Caldera. The caldera is filled by Kal’tsevoe Lake and Krenitzyn Peak, a volcano that has only erupted once in recorded history (in 1952).

Extending between northeastern Japan and the Kamchatka Peninsula of Russia, the Kurils are an island arc located along the Pacific “Ring of Fire.” Island arcs form along an active boundary between two tectonic plates, where one plate is being driven beneath the other (subduction). Magma generated by the subduction process feeds volcanoes—which eventually form volcanic islands over the subduction boundary.

Astronaut photograph ISS026-E-16287 was acquired on January 9, 2011, with a Nikon D2Xs digital camera using an 180 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 26 crew. The image has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, NASA-JSC.