Drawing seismic rays in layers with velocity gradients using only ruler and compass

Abstract

Because of its widespread use in seismic ray tracing, the case of a linear increase of velocity with depth in a given layer has drawn seismologists’ attention for many years. The ray integrals, which give the horizontal distance and the corresponding traveltime, can be evaluated in a closed form; the radius of curvature of the ray, the distance above the surface where the center of the circular ray lies and the shape of the wavefront are given by well‐known analytical equations.