Global Seismic Tomography and Implications for the Composition and Evolution of Earth

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This project will continue investigation into the structure and evolution of the Earth's deep interior. The research will build on previous high-resolution global seismic models that have demonstrated the many slabs of subducted lithosphere have sunk into the lower mantle. The research will improve seismic wavespeed models by 1) enhancing data coverage with new data (e.g., waveform based PP, PKP, PcP, and Pdiff data) and by using realistic 3D sensitivity kernels to account for finite frequency effects, 2) make models compatible with observed frequency shifts of the Earth's free oscillations, 3) use data to constrain variations in bulk sound speed and wavespeed ratios (e.g., Poisson's ratio), and 4) after having optimized data coverage, use a flexible parameterization to resolve small scale structure in well sampled region. The proposed work would also obtain quantitative estimates of uncertainties. For selected regions, the PI will collaborate with colleagues to study mantle flow across the upper and lower mantle transition zones in detail by integrating high-resolution imaging, waveform modeling, detailed plate reconstructions, and numerical flow calculations.