Amchitka was selected by the United States Atomic Energy Commission to be the site for underground detonations of nuclear weapons. Three such tests were carried out: Long Shot, an 80-kiloton (330 TJ) blast in 1965, Milrow, a 1-megaton (4.2 PJ) blast in 1969, and Cannikin in 1971 at 5 Mt. Cannikin was detonated on November 6, 1971, as the thirteenth test of the Operation Grommet (1971-72) underground nuclear test series. The ground lifted 20 feet, caused by an explosive force almost 400 times the power of the Hiroshima bomb. Subsidence and faulting at the site created a new lake, over a mile wide. The explosion caused a seismic shock of 7.0 on the Richter scale, causing rockfalls and turf slides of a total of 35, 000 square feet. |