Generalized‐Screen Approximation and Algorithm for the Scattering of Elastic Waves

We describe the propagation and scattering of elastic waves in heterogeneous media. Decomposing the elastic wavefield into up‐ and down‐going constituents allows the introduction of the ‘one‐way’ wave equations and propagators. Such propagators account for transverse scattering and mode coupling. The generalized‐screen expansion of the symbol of the one‐way wave equation in medium contrast and medium smoothness induces an approximation of the propagator with an associated computational complexity of the one of the phase screen approximation. The generalized‐screen expansion extends the phase‐screen approach. It allows for larger medium fluctuations and wider‐angle propagation. We illustrate the accuracy of the generalized screen with numerical examples.