### ASA 124th Meeting New Orleans 1992 October

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

**Geza Seriani
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*Osservatorio Geofisico Sperimentale, P.O. Box 2011 Opicina, 34016 Trieste,
Italy
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**Jose M. Carcione
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*Osservatorio Geofisico Sperimentale and Hamburg University
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**Enrico Priolo
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*Osservatorio Geofisico Sperimentale
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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.]