9614698 Langston This research involves the use of existing teleseismic data sets from the GSN and WWSSN to investigate the effect of 3D heterogeneity and layered anisotropy on teleseismic waveforms. Earthquakes, as a rule, occur in geologically interesting areas with clear evidence of structural heterogeneity. There is evidence that near-source heterogeneity can have significant effects on radiated teleseismic waves form earthquakes and that these effects will map back into inverted source parameters such as the spatial/temporal distribution of fault slip and source orientation. The frequency dependence of the near-source effect will be investigated theoretically for proposed structure models constrained by detailed geological and geophysical studies in the literature. The teleseismic data from observed earthquakes will then be modeled using forward calculation and inversion techniques to determine source parameters and to determine the influence of heterogeneity and anisotropy. ***
