A flexible wavefield simulation method for layered viscoelastic media with dipping interfaces

Partial wavefield simulation is very useful in seismic interpretation and inversion. In this work, we propose a flexible and fast method for simulating seismic wave propagation in dipping layered viscoelastic media. This method can effectively calculate various partial wavefields, e.g., primary reflected P-waves or primary reflected S-waves, P-S or S-P converted waves, and the multiples which we are interested in. Since the vector wave equations are independent of the coordinate system, we alternately study wave propagation in global and local coordinate systems. Firstly, for a single dipping interface, the reflection and transmission coefficients of plane waves and the expressions of secondary waves are obtained by coordinate transformation. Then, the reflection and transmission coefficients of multi-layered media with dipping interfaces are obtained by a recursive approach. Lastly, a fast integral method is used to synthesize the wavefield for a point source, and a novel integral path is chosen through comparison. Analysis shows that this method is stable for all frequencies and slownesses. Numerical examples and a comparison with a finite difference solution demonstrate that our method is effective.