A new formulation for extrapolation of seismic wave field response and its derivatives

The aim of this study is to present a new symplectic integrator for the case of spatially varying velocity based on Leapfrog (L) and Rapid Expansion Methods (REM). First of all, approximation of the wave field at each time step has been considered using rapid expansion method. Then the wave equation is rewrite as Hamiltonian system. It can provide an accurate solution for the acoustic wave equation to simulate the wave field response at each time. After that, for much more accurate and stable solution to extrapolate the wave field and its derivative, a new formulation based on leapfrog and rapid expansion methods has been presented. The obtained results of simple model indicate that this new formulation provides a very high level of accuracy and stability for estimation of wave field response and its derivatives.