DI13C-06:
Constraining the Velocity Structure at the Top of the Earth's Outer Core by SKKS and S3KS Differential Traveltimes
Monday, 15 December 2014: 2:55 PM
Li Zhao, Academia Sinica, Taipei, Taiwan, Vivian Chu-Hsin Tang, NTU National Taiwan University, Taichung, Taiwan and Shu-Huei Hung, NTU National Taiwan University, Taipei, Taiwan
Abstract:
It has been surmised that light elements such as O, S and Si may cause stratification beneath the core-mantle boundary (CMB), and seismological evidence has been presented both for and against this scenario. In this study, we investigate the effect of velocity structure under the CMB on the differential traveltimes between SKKS and S3KS waves. Due to the long propagation distances and interference with neighboring phases, the arrival times of SKKS and S3KS waves are difficult to define accurately. Therefore, we measure the differential traveltimes by cross-correlating the waveform of the Hilbert-transformed S3KS with that of SKKS. Differential traveltimes derived from synthetics calculated by the direct-solution method for different velocity structures under the CMB are compared with those from records to examine the existence of a low-velocity zone at the top of the outer core. We also conduct a Bayesian inversion of the observed differential traveltimes for the velocity structure at the top of the outer core.
