Abstract
The speeds of propagation of seismic waves are computed by detecting the effect of the waves that propagate when a pulse of energy, in the form of a small explosion, is released near the surface of the ground. The pulse is detected and recorded by underground sensors. The times between the initiation of the pulse and the point when it reaches the various sensors are denoted the travel times. In this paper we consider two questions. Is it possible to compute the wave speed profile from accurately measured travel times? If so, how can this be done?