Zoeppritz Equations and their Approximations
When an incident P-wave strikes the boundary (or interface) between two media obliquely, the wave is split into reflected and refracted P-wave components and reflected and refracted S-wave components. The reflection and transmission coefficients vary as a function of the angle of incidence (hence, of source-receiver offset) and of the media’s elastic properties, which comprise densities and bulk and shear moduli. The Zoeppritz equations (Chapter 1) give the reflection and transmission coefficients for plane waves, as a function of the angle of incidence and as a function of the three independent elastic parameters on each side of the reflecting interface. If the reflection amplitude is observed as a function of the angle of incidence, the variation of that parameter can be used to make inferences about the elastic parameters.