[S17-1] Outer core structure and dynamics (Oral contributions)

[S17-1-01] Seismic structure of the Earth's outermost core

^○Satoshi Kaneshima (Kyushu University)

invited

In this talk we review seismological studies that investigate the Vp structure of the Earth's outermost core. The models obtained so far are reviewed. The types of data that can be used are presented. It is shown that differential travel times of SmKS waves are the most powerful data for this purpose. High-quality SmKS differential times are well fit by a Vp model of the Earth's outermost core, KHOMC (Kaneshima and Helffrich, 2013). The observations obtained so far provide the evidence for the presence at the top of the outer core of a layer that has a distinctively steeper Vp gradient than the bulk of the outer core. The most recent estimate of the layer thickness is nearly 400 km. The Vp anomalies relative to PREM for the depths 400 to 800 km below the CMB appear to be insignificant. The Vp structure of the deeper outer core is also discussed. Finally we compare the seismological models with geomagnetic models and mineral physics studies.