Uppermost inner core seismic structure - new insights from body waveform inversion

Abstract

Differential travel times and waveforms of PKIKP and PKiKP phases in the 129°-141° distance range, deconvolved for the effects of source time functions and average mantle attenuation operators, are inverted for velocity and attenuation in the uppermost 80 km of the inner core, and the velocity gradient and attenuation in the lowermost 200 km of the outer core (F region). Results confirm degree-one velocity structure in the inner core whose fast and slow regions appear to be separated by transitions with a velocity contrast of about 1%. Although attenuation in the inner core also exhibits degree-one pattern, a high attenuation region (. Qp-1=[0.002,0.0067]) extends to the central Pacific, whi..