EFFICIENT FDTD ALGORITHM FOR PLANE-WAVE SIMULATION FOR VERTICALLY HETEROGENEOUS ATTENUATIVE MEDIA

Abstract

We propose an efficient algorithm for modeling seismic plane-wave propagation in vertically heterogeneous vis-coelastic media using a finite-difference time-domain FDTD technique. In the algorithm, the wave equation is re-written for plane waves by applying a Radon transform to the 2D general wave equation. Arbitrary values of the quality factor for P-and S-waves Q P and Q S are incorporated into the wave equation via a generalized Zener body rheological model.An FDTD staggered-grid technique is used to numeri-cally solve the derived plane-wave equations. The scheme uses a 1D grid that reduces computation time and memory re-quirements significantly more than corresponding 2D or 3D computations. Comparing the finite-difference solutions to their corresponding analytical results, we find that the meth-ods are sufficiently accurate. The proposed algorithm is able to calculate synthetic waveforms efficiently and represent viscoelastic attenuation even in very attenuative media. The technique is then used to estimate the plane-wave responses of a sedimentary system to normal and inclined incident waves in the Kanto area of Japan via synthetic vertical seis-mic profiles.