Detection of underside P reflections at mantle discontinuities by stacking broadband data

Abstract

Underside P‐reflections at mantle discontinuities are difficult to observe directly on seismograms mainly because of their low amplitude. It is shown that stacking seismograms obtained at several epicentral distances but having their PP bounce points in the same region, enables the identification of such phases. This method is applied to data from Japanese and Taïwan events recorded by the NARS array and other broadband European stations; discontinuities at about 670 and 300 km are revealed beneath Northern Eurasia.