[S-CG49] Innovation through the Integration of Solid Earth Science and Materials Science

[SCG49-P06] Waveform inversion for the 3-D S-wave velocity structure inside the LLSVPs in D″

*Kenji Kawai¹, Keisuke Otsuru¹ (1.Department of Earth and Planetary Science, School of Science, University of Tokyo)

Keywords:LLSVP, Waveform inversion, Array analysis

The D″ region is the thermal boundary layer at the lowermost several hundred kilometers of the mantle and plays an essential role in mantle dynamics. In D″, two large low-shear-velocity provinces (LLSVPs) exist beneath the Pacific and Africa. Since their discovery in the 1980s, there has been debate on whether they are gatherings of small thermal plumes called "plume clusters" caused solely by the effect of high temperature or large masses of chemical heterogeneity referred to as "thermochemical piles." A fine image of structure within the LLSVPs is essential to distinguish between the two, but a sufficient resolution has not yet been achieved. In this study, we utilize many broadband body-wave seismograms from arrays in Thailand (TSAR) and in and around Africa that have recently become available. We conduct waveform inversion of the transverse component for the 3D S-wave velocity structure of the western boundary region of both the Pacific and African LLSVPs. This presentation will show our inferred models in D″ and discuss their geophysical interpretation and research prospects.