Abstract:

Stacks of global seismic network data reveal emergent high-frequency (1 Hz) energy extending back from the PKKP c caustic at 72 degrees to a distance of about 60 degrees. The arrival's emergent onset, long duration (150 s), apparent slowness, and proximity to the core phase PKKP indicate a deep scattering origin. However, the amplitude and timing of the observations are difficult to explain with simple models of PKKP scattering.