Self-consistent models of Earth’s mantle and core from long-period seismic and tidal constraints

Summary In this study we inverted a large set of normal-mode centre frequencies and quality (attenuation) factors, including geodetic data (mass, moment inertia tidal response), using self-consistently-built models the radial elastic anelastic seismic structure Earth. The mantle are constructed petrologic phase equilibria in combination with laboratory-based visco-elastic model that connects dissipation from to periods, whereas properties for well-mixed homogeneous core computed equations-of-state. Relative preliminary reference (PREM), find fit observations, P- S-wave velocities have be slightly faster slower, respectively, while outer-core P-wave velocity is slower on account different gradient, inner-core similar, within uncertainties inferred parameters. terms density, less dense outer more than PREM, inner similar PREM. These changes driven part by astronomic-geodetic data. considered here resolves response Earth’s long-period (∼100 s) (18.6 yrs) accounting both measurements. To impact structure, travel times compared these observations globally-averaged reprocessed ISC catalog resulted an excellent match. attempt further refine core, also multiple core-mantle-boundary underside-reflected body wave time While match underside reflections clearly improves as result steeper gradient relative normal-modes- astronomic-geodetic-data-only case, subtle differences nevertheless persist appear support change outermost evocative stably stratified layer. Finally, potential means refining composition, density contrast across boundary (ICB) based our models. most probable ICB difference found 0.3–0.45 g/cm3, which lower range earlier body-wave- normal-mode-based predictions. This suggests compositional heterogeneity associated light-element partitioning, principal driving mechanism convection powers geodynamo, may effective previously thought, calling exsolution solids liquid possible additional source energy. would help address problem young core.