Elastic wave equation simulation offers a way to study the wave propagation when creating seismic data. We implement an equivalent dual elastic wave separation equation to simulate the velocity, pressure, divergence, and curl fields in pure P- and S-modes, and apply it in full elastic wave numerical simulation. We give the complete derivations of explicit high-order staggered-grid finite-difference operators, stability condition, dispersion relation, and perfectly matched layer (PML) absorbing boundary condition, and present the resulting discretized formulas for the proposed elastic wave equation. The final numerical results of pure P- and S-modes are completely separated. Storage and computing time requirements are strongly reduced compared to the previous works. Numerical testing is used further to demonstrate the performance of the presented method. 1. Introduction Elastic wave numerical simulation has proven to be very efficient for modeling seismic wave propagation and seismic acquisition, and it can also guide seismic processing and seismic interpretation. The traditional numerical modeling method using first-order elastic wave equation can only generate the synthetic seismograms of each component in isotropic medium, in which the P- and S-waves are coupled. To obtain wave field of the pure P- and S-modes, the general method is wave field separation processing of the coupled wave field of each component, but it is difficult to get completely separated seismograms. If we use P- and S-wave equations, respectively, to generate P- and S-wave, the converted P- and S-wave will not appear in wave field; thus, it is not equal to full elastic wave field simulation. Carrying out full separation of wave field modeling of pure P- and S-wave (in its reconstructed wave field, each component comprises P- and S-waves that are fully separated) makes no need of wave field separation in the following multiwave processing [1], and it is suitable not only for the isotropic medium but also for the anisotropic medium [2]. What is more, it is of great practical importance for us to study seismic wave propagation mechanism and structure of geology as well as oil reservoir characterization. Ma and Zhu [3] presented an elastic wave numerical simulating method using second-order elastic wave equations to separate P- and S-waves with Fourier method. This leads to a new direction for elastic wave modeling study and inversion. But this method does not adapt to widely extended use because of its low efficiency and the difficulty to deal with the absorbing boundary condition.
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