2001 Volume 54 Issue 1 Pages 147-158
Scattering of elastic waves including mode conversions between P- and S-waves is quite nonisotropic compared to that of acoustic waves. Thus, it is important to the analysis of coda waves of local earthquakes to use a fully realistic scattering model of seismic waves. In this paper, we summarize briefly a theory (Born approximation) on the scattering of elastic waves due to local spatial fluctuations of elastic parameters. The directional dependence of scattering amplitude for all scattering modes is evaluated for a random inhomogeneous medium characterized stochastically by using an autocorrelation function. We also review past seismological studies to confirm the usefulness and limitation of single scattering models (approximations), which have been used for the analysis of coda waves to investigate short-wavelength random heterogeneities of the lithosphere. It is shown that three-component seismogram envelope including both P- and S-coda waves is successfully modeled by using a single scattering model adopting the Born approximation for the evaluation of seismic scattering.
