A region redefined by physics
Between 1964 and 1996, a remote section of the Lop Desert in northwestern China was the country's sole nuclear weapons testing area. Over 32 years, this site hosted 45 nuclear tests. The program began on October 16, 1964, with "Project 596," the atmospheric detonation of a uranium-235 implosion device. This first test had a yield of 22 kilotons, making China the world's fifth nuclear power. The early tests were atmospheric, but the program later shifted to underground detonations. In total, 23 tests were conducted above ground and 22 were performed underground.
The world's largest nuclear test site, Lop Nur covers about 100,000 square kilometers. The geology of the area is characterized by Paleozoic granitic and metasedimentary rocks. Underground tests were conducted in two primary ways: in horizontal tunnels bored into mountainsides and in deep vertical shafts drilled into areas of lower relief. These underground explosions, some with yields of several hundred kilotons, created immense cavities deep within the rock. The largest atmospheric test, on November 17, 1976, had a yield of 4 megatons.