Forward modeling and wave field analysis of seismic surface waves and guided P-waves
Surface waves and guided P-waves,as two boundary-related wave phenomena,are a crucial part of the near-surface seismic wave field.This study investigated their generation mechanism and propagation regularity using the high-order staggered-grid finite-difference algorithm.First,it solved the problems like numerical dispersion and boundary conditions in numerical simulation.Based on this,it designed medium models under different thicknesses and elastic parameters for forward modeling.Furthermore,it extracted dis-persion profiles and amplitude versus offset curves for analysis.In the case of a low-velocity thin layer on the surface,guided P-waves can be generated when the phase velocities of P and SV waves from the same source exceed the S-wave velocity but are less than the P-wave velocity of the underlying high-velocity layer.In media with high Poisson's ratios(＞0.4),the phase velocities of surface waves and guided P-waves are sensitive to the S-and P-wave velocities,respectively.Surface waves and guided P-waves usually contain near-sur-face information that is unavailable in refracted and reflected waves.The appropriate acquisition,analysis,and inversion of near-surface information enable the establishment of a high-resolution near-surface model.This study generalized the generation conditions and wave field characteristics of surface waves and guided P-waves under the same source and deepened the understanding of their propagation regularity,laying a foundation for inversion and denoising research.
surface waveguided P-wavenumerical simulationgeneration conditionwave field analysis
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