Elastic Free-Field Motion Due to Nuclear Air Blast

Near surface ground motions in a half-space induced by the overpressures of a decelerating, decaying air blast from a surface nuclear burst were made using a plane-strain linear-elastic model. A parametric study of superseismic and transseismic motions defined the peak velocities and peak stresses as functions of longitudinal seismic velocity, Poisson's ratio, weapon yield, range and depth. Typical time histories are presented which characterize the transseismic and superseismic motion patterns. The free-field parameters are calculated by evaluating double convolution integrals of the distributed, transient air-blast overpressure or its time derivative and the closed-form influence functions. Explicit calculations of the wave-front discontinuities and their derivatives augment the solution.