Insight on the anisotropic nature of the D'' layer through the analysis of SKS-SKKS splitting obtained via 3D spectral element modeling
Abstract
Constraining the nature of the anisotropy in the core-mantle boundary region is a key factor for properly predicting the flow of the lowermost mantle. The lack of seismic waves sampling this region and their uneven azimuthal distribution hamper a correct representation of mantle dynamics. We present preliminary results for a series of SKS-SKKS splitting analysis based on numerical forward synthetic tests in a realistic 3-D Earth model using the software AXISEM3D, a newly developed efficient hybrid spectral element method solver for 3-D structures. The anisotropic property of the computational domain in the bottom 300km of the Earth's mantle is fully described with a fourth-order elastic tensor with 21 independent coefficients. We tested a single crystal mineralogy of postperovskite with different orientations that are consistent with realistic mantle flow models and accounted for a wide coverage of azimuthal seismic raypaths. We take advantage of the computational efficiency of the method to achieve resolutions for seismic periods as low as 8s. Our preliminary results, based on forward full waveform modeling, represent a step forward for validating hypotheses for the anisotropy in the D'' layer derived by direct splitting measurements and ray-theoretical mineral physics based modeling tests. Our study also highlights the capability of AXISEM3D to handle high degrees of model complexity in full anisotropy and its potentials for future endeavours.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMDI43B0364T
- Keywords:
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- 7208 Mantle;
- SEISMOLOGY;
- 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICS;
- 8147 Planetary interiors;
- TECTONOPHYSICS;
- 8170 Subduction zone processes;
- TECTONOPHYSICS