F-K spectra for regional P coda are presented for events recorded at the Scandinavian NORESS, FINESA, and ARCESS arrays and the New England NYNEX array. The spectra are dominated by on-azimuth energy with apparent velocities between Pn (or faster) and Lg. Following this analysis, reflection coefficients calculated with an efficient boundary integral scheme are used to study the role irregular interfaces play in the creation of regional P coda. We find that observed crustal scattering in these regions is strikingly consistent with P-P and P-SV scattering from the two-dimensional (2D) irregular Moho and even more consistent with scattering from a 2D irregular near-surface interface.

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