f Geometrical-Spreading and Ray-Caustic Decomposition of Elementary Seismic Waves

The computation of the geometrical-spreading factor and the number of caustics is in general considered to be the most fundamental step in order to compote zero-order ray solutions for elementary-wave Green's functions along a ray that originates at a point source and passes through a 3-D vertically and laterally inhomogeneous isotropic medium.