Numerical modelling of high-frequency seismic wave fields in complex, 2-D and 3-D, laterally varying, layered structures by the summation of elastodynamic Gaussian beams is discussed. The main attention is devoted to the expansion of the wave field into Gaussian beams, to the choice of initial parameters of Gaussian beams in these expansions and to the construction of synthetic seismograms. The Gaussian beam synthetic seismograms are regular even in regions where the ray method fails, such as the caustic region, critical region, etc. Due to the smoothing effects involved in the Gaussian beam procedure, the method is not too sensitive to the approximation of the medium and to minor details of the model. Moreover, the method does not require two-point (source-to-receiver) ray tracing. The evaluation of Gaussian beam synthetic seismograms requires approximately the same amount of computer time as the evaluation of ray synthetic seismograms. The memory requirements are also approximately the same. Numerical examples of Gaussian beam synthetic seismograms for 2-D and 3-D structures are presented. Various possible applications of Gaussian beams to seismological problem of practical importance are outlined.
Seismic waves, synthetic seismograms, Gaussian beams.
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