Since July 1962 all nuclear tests conducted in the United States were conducted underground at the Nevada Test Site (NTS). Many of the underground tests left subsidences craters varying in diameter and depth. The blueish picture of Yucca Flat above show numerous subsidence craters in the main valley of the NTS. Overall there were just over 800 underground tests detonated at the NTS.

Collecting information from an underground nuclear tests required miles of cable; the cable transmitted vital test information from the down-hole devise to the surface above. The photo of the white tower above shows miles of cable used for just one underground test. The tower served as infrastructure for holding and inserting the nuclear test devise in the underground shaft. Shafts depths varied across the site but could exceed thousands of feet.

Sedan Crater:  Sedan Crater was formed with a 100 kiloton nuclear explosive devise -- the devise was buried 635 feet below the desert alluvium. Sedan was fired at the NTS on July 6, 1962; it displaced 12 million tons of earth. The crater is 320 feet deep and 1,280 feet in diameter. Sedan was the largest cratering shot in the Plowshare Program. The crater is on the National Register of Historic Places and is visible from space.