Amchitka (ămchĭtˈkə) [key], island, 40 mi (64 km) long, in the Rat group of the Aleutian Islands, W Alaska. It was a site in 1965 and 1971 for the underground detonation of nuclear devices, its small population having been relocated. In the 1990s, radiation from the test caves was detected at the surface.
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