Pseudospectral approximation of the elastic wave equation on a staggered grid

Author(s):  
Bengt Fornberg
2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Ke-Yang Chen

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.


Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. T113-T121 ◽  
Author(s):  
Chunlei Chu ◽  
Paul L. Stoffa

We extended the pseudo-Laplacian to staggered grids based on the concept of normalized pseudo-Laplacian and applied it to constructing the pseudoanalytical formulations for the variable-density acoustic wave equation and the elastic wave equation. Acoustic wavefields only contain P-waves and therefore only P-wave pseudo-Laplacians are required for acoustic wave propagation. In comparison, two sets of staggered grid pseudo-Laplacians are needed in the elastic case in order to properly compensate for time stepping errors for both P-waves and S-waves. We gave a thorough derivation of the pseudoanalytical method for the elastic wave equation, based on normalized pseudo-Laplacians implemented on staggered grids, and presented the resulting complete discretized formulas. We proved that the staggered grid pseudo-Laplacian reduces to the pseudo-Laplacian for the scalar wave equation on standard grids. When using zero compensation velocities for normalized pseudo-Laplacians, the pseudoanalytical formulas simply reduce to the pseudospectral equations. We demonstrated with numerical examples that staggered grid pseudo-Laplacians effectively compensate for second-order time stepping errors and help generate highly accurate acoustic and elastic wave solutions in variable-density media.


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