CRUSTAL REFLECTIONS AND THE NATURE OF REGIONAL P-CODA

F-K spectra for regional P coda are presented for events recorded at t he Scandinavian NORESS, FINESA, and ARCESS arrays and the New England NYNEX array. The spectra are dominated by on-azimuth energy with appar ent velocities between Pn (or faster) and Lg. Following this analysis, reflection coefficients calculated with an efficient boundary integra l scheme are used to study the role irregular interfaces play in the c reation of regional P coda. We find that observed crustal scattering i n 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.