The Effects of Source on the Generation of Short Period Surface Waves

Abstract

Short-period surface waves can usually be observed on strong motion records. Theoretical seismograms provide a useful tool for the prediction and interpretation of differences in the surface wave excitation of various earthquakes. The influence of source parameters (source depth, source type and orientation) on the excitation of Rayleigh waves for the elastic half-space and a single layered half-space model is discussed in detail.
Results show that the epicentral distance beyond which the fundamental mode Rayleigh waves can be generated is around 3 to 5 times of the source depth for the point dislocation source in the half-space model. These critical distances are a little longer than those for the finite length sou es. The orientation parameter is not generally of significance. When a at low-velocity layer is overlying on the top of the half-space, the computations suggest that the complex waveforms are observed and about 10 km of the critical distance obtained is not changed r all kinds of sources used in this study. Moreover, the most important quantity for identifying the Rayleigh wave, namely the ellipticity, is estimated to be in the range of 0.6 to 0.7, except with a layer over half-space model.

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