SKS Shear Wave Splitting Based on 3D Seismic Wave Simulations

Session: Advances in Seismic Imaging of Earth’s Mantle and Core and Implications for Convective Processes
Type: Oral
Date: 4/29/2020
Time: 11:30 AM
Room: 120 + 130
Description: 

Constraining the pattern and properties of seismic anisotropy in the Earth can help reveal relationships between mineral physics, mantle convection and seismology. Sources of anisotropy in the lithosphere as frozen-in anisotropy, transition zone and D" complicate shear wave splitting measurements, resulting in shear wave splitting that can differ from plate motion. If we better understand seismic anisotropy sourced in the lithosphere, we could also better constrain D" anisotropy, which requires correcting for the upper mantle to some extent. Ray theory is commonly used and is appropriate within certain limits, but not all implications have been explored. Ray theory’s validity depends on the period of waves, the scale of heterogeneities, the length of its propagation path and the superposition of multiple arrivals, making interpreting seismic anisotropy observations more difficult. In this work, we will explore the assumptions made in SKS shear wave splitting as well as tease out discrepancies between different models and observations of anisotropy within the Earth, by conducting numerical simulations via 3D global wave propagation solver SPECFEM3D_GLOBE. This work will help improve the understanding of how seismic anisotropy observations, like SKS shear wave splitting, are related to models of deformation in the Earth's mantle and the sources of anisotropy in the various regions of the crust and mantle, specifically the D" layer. The long-running goal is to use shear wave splitting in global full waveform inversion addressing appropriate parameterization to describe body-wave anisotropy in the mantle during the inversion process.

Presenting Author: Neala Creasy

Authors