  In the solid/liquid and liquid/solid scenarios, for the cases in which the P
and S reflected waves are represented by complex amplitudes, we give the closed
formulas for the Goos-Haenchen phase from which we can then determine the
lateral displacements. We compare the results of the analysis done by using the
Zoeppritz equations with the calculations which appear in Optics. We also
discuss under which circumstances the plane wave analysis is valid and what
happens for critical incidence where divergences appear. For the liquid/solid
interface, the incidence angles maximizing the lateral displacement are given
as solutions of a polynomial equation.
