Theoretical amplitudes of diffracted PcP pulses near the geometric edge of the core shadow are important in the determination of earth structure near the core–mantle interface. Frequency domain wave solutions are difficult to apply to earth models with wave-trapping structure near the core. Time domain ray solutions have previously been applied in the illuminated region, and deep in the shadow. A new time domain procedure, including an earth flattening transformation and a ray expansion with the Cagniard–de Hoop ray method, has made it possible to construct numerical seismograms near the geometric shadow edge for a model with a wave-guide structure suggested by seismic array observations at VASA in Alberta.

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