Hans Israelson

Monitoring underground nuclear explosions

The first underground nuclear tests were carried out in 1957 by the United States and the Soviet Union. As discussed in Chapter 1, in 1963 the Soviet Union, United Kingdom, and United States signed the Partial Test Ban Treaty (PTBT), which prohibited testing in the atmosphere, outer space, and under water, and since 1980 all nuclear explosions have been conducted under ground. Of the 2,052 nuclear explosions that have been carried out, 1,501 have been conducted under ground, though as noted in Chapter 1, there are minor divergences in the number of reported explosions. Most of the explosions involved the development and testing of nuclear weapons, although about 150 were part of programs for socalled peaceful nuclear explosions (PNEs) (Nordyke 2000).