Shock Spectra from Subsurface Nuclear Explosions

Equations are given for computing vertical and horizontal radial ground-stock spectra from an underground nuclear explosion. Parameters required are the yield of the explosion, the slant range from the explosion, and the seismic velocity and density of the geologic medium. The equations are based on shock spectra measured from 15 nuclear explosions in four media ranging from alluvium to granite. The reed gages used in the measurements and their field installation are described. A subsequent subsurface nuclear explosion provided an opportunity for evaluating the application of the equations. The computed shock spectra are compared with the measured values; good correlation is shown to exist.