f The tip wave superposition method based on the refraction transform

In seismic modelling is widely used the diffraction Kirchhoffs integral with the spherical Green function obtained from the exact Kirchhoffs integral by means of replacement of the integral boundary values with their high-frequency asymptotics. This approach is only applicable in homogeneous medium because the Green function in the inhomogeneous medium is non-spherical. In [1] we introduced the tip wave superposition method (TWS) for seismic simulation in 3-D geological models with structurally complex target but with a homogeneous overburden. In this paper we generalize the TWS to account for an inhomogeneous overburden but restricted to the scalar case.