We present a general optimization technique for the three-dimensional finite-difference (FD) modeling of seismic-wave propagation and earthquake ground motion. Our combined memory optimization (CDMO) naturally comprises core memory optimization and disk memory optimization. While core memory optimization is based on keeping only a limited number of model planes in core memory at a given time, disk memory optimization is based on data compression in the wavelet domain. CDMO enables significant reduction of both computer core and disk memory requirements. CDMO is general: It is applicable to any explicit finite-difference scheme on a conventional or staggered grid.
CDMO is presented on the example of the displacement finite-difference scheme. Accuracy of the scheme was tested through numerical comparisons with the discrete-wavenumber method. The scheme was shown to be capable to account for the position of the material discontinuity more accurately than other recent finite-difference schemes.
Extensive numerical experiments were carried out in order to find proper parameters of the wavelet compression and investigate effects of the compression on synthetics.