NUMERICAL-SIMULATION OF THE BANEBERRY EVENT

On December 18, 1970, Baneberry, a 42-TJ (10-kt) nuclear device, was detonated at a depth of 278 m in hole U8d at the Nevada Test Site. A shock-induced fissure near ground zero opened and vented radioactive gases and debris into the atmosphere. Calculational results describe the sequence of dynamic phenomena that very likely produced the vent. The calculations predict the experimentally observed surface motion and long positive-velocity pulse. The surface fissure through which the material vented is approximately the same radial distance from ground zero as the maximum horizontal displacement is calculated to be. Also, the calculations indicate an explosive-induced extension of the Baneberry fault to the surface. This extension was observed in pictures of the surface motion and later confirmed by postshot on-site inspection. The final calculated cavity radius is very close to the measured Banberry cavity radius. Finally, the calculations indicate that an open fracture path was generated that runs from the cavity to the Baneberry fault, up the fault to the spall region, and then vertically to the surface. This vent path predicted by the calculations is roughly consistent with the vent path found from the radioactivity in postshot drill holes.