Heterogeneity, Anisotropy, and Seismic Attenuation in Earth's Inner Core and Lower Mantle

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The small-scale structural fabric of Earth's inner core and lower mantle is important to the understanding of mantle convection, slab cycling, plume formation, and solidification of the inner core, including the dynamic deformation of the inner core boundary and its relation to the differential rotation of the inner core and mantle and the earth's magnetic field. Seismic modeling will be performed to image the small-scale (1-1000 km) fabric of the inner core and lowermost mantle that are important to these processes. Waveforms of the PKIKP seismic phase will be modeled to determine the depth dependence, lateral variation, anisotropy, and frequency dependence of inner core visco-elasticity, and crystalline fabric to constrain models of inner core solidification. Seismic waveform modeling will also be performed to constrain the statistical and deterministic structure of the lowermost mantle, which can provide important signatures that can enable a discrimination among the proposed origins of the heterogeneous structure in this region: remnant slabs, solid-solid phase transitions, pools of primitive mantle, partial melt, and core-mantle chemical reactions.--