Abstract
An underground nuclear explosion caused surface cracks that were oriented as estimated from the measurement of preexplosion fractures and in situ stress. The explosion was detonated in a tunnel mined in volcanic tuff at a depth of 1,400 ft (427 m) beneath the surface of Aqueduct Mesa, Nevada Test Site. Preexplosion fractures in the tunnel have a strongly preferred strike to the north-northeast. The stress measurements indicated that explosion-induced fractures would strike N. 28° E. The regional structural grain and the resulting topography in this part of Nevada also trend north-northeast. The explosion-induced fractures, which lie away from slight collapse features near surface ground zero and inward from the topographic edge of the mesa, trend north-northeast.
