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Long-wavelength topography and multi-scale velocity heterogeneites at the core-mantle boundary
  • Jack Broderick Muir,
  • Satoru Tanaka,
  • Hrvoje Tkalcic
Jack Broderick Muir
University of Oxford

Corresponding Author:jack.muir@earth.ox.ac.uk

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Satoru Tanaka
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Hrvoje Tkalcic
Australian National University
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The structure of the lowermost mantle and the core-mantle boundary (CMB) has profound implications for Earth’s evolution and current-day dynamics. Whilst tomographic studies of Vs show good agreement in the lowermost mantle, consensus as to Vp and especially CMB radius has not yet been reached. We perform a hierarchical Bayesian inversion for Vp in the lowermost 300 km of the mantle and the radius of the core-mantle boundary using differential travel time data. Concurrent with finding Vp perturbations of 0.56% RMS amplitude that spatially agree with previous studies in areas of low posterior variance, we find 4.5 km RMS amplitude core-mantle boundary radius perturbations with a broadly north-south hemispherical character, with spherical harmonic power evenly distributed between degrees 1-3. These results suggest that CMB radial processes are set by a longer scale process than the Vp perturbations.