ASA 124th Meeting New Orleans 1992 October

5aPAb5. Numerical simulation of interface waves by high-order spectral modeling techniques.

Geza Seriani

Osservatorio Geofisico Sperimentale, P.O. Box 2011 Opicina, 34016 Trieste, Italy

Jose M. Carcione

Osservatorio Geofisico Sperimentale and Hamburg University

Enrico Priolo

Osservatorio Geofisico Sperimentale

This work presents two different approaches for simulating interface waves in elastic media. The techniques are both based on a Chebychev expansion of the wave field. The first algorithm solves the elastodynamic equations in differential form by computing the spatial derivatives with the Chebychev pseudospectral method. The second algorithm uses the Chebychev polynomials as an interpolant base in a variational formulation, and is called the spectral element method. Both techniques, in particular the second, posses spectral accuracy and are suitable for treating interface problems for which boundary conditions and arbitrary interface geometries are naturally taken into account. The reason for using two different approaches is the crossvalidation of the results. Most wave propagation problems have no analytical solution, and if two different techniques give the same solution, one is sure that this solution is free of numerical artifacts. The first example compares numerical and analytical solutions of Rayleigh waves propagating along the surface of an homogeneous half-space. This test confirms the accuracy of the numerical algorithms. The second example has no analytical solution and compares the numerical results of a Stoneley wave generated by a Rayleigh wave at a vertical interface touching the surface. [Work supported by EEC.]