AN ACCURATE AND EFFICIENT SCHEME FOR WAVE-PROPAGATION IN LINEAR VISCOELASTIC MEDIA

The problem of wave propagation in a linear viscoelastic medium can be described mathematically as an exponential evolution operator of the form eMt acting on a vector representing the initial conditions, where M is a spatial operator matrix and t is the time variable. We propose an optimal polynomial approximation of eMt based on the powerful method of interpolation in the complex plane, in a domain which includes the eigenvalues of the matrix M. The new time-integration technique is implemented to solve the isotropic viscoacoustic equation of motion. The computational effort in forward modeling based on the new technique is half compared to that of temporal differencing when two-digit precision is required. We compute the seismic response to a single shot in a realistic geologic model which includes a gas-cap zone in an an anticlinal fold. -from Authors