Sensitivity Study of Local Shear-Wave Splitting to 3D Anisotropic Structures

Session: Full-Waveform Inversion: Recent Advances and Applications [Poster]
Type: Poster
Date: 4/29/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Shear waves from intraslab earthquakes will split into two separate waves as they pass through certain anisotropic structures on their way to being recorded by seismometers at the Earth’s surface. The presence of split shear waves from intraslab earthquakes provides compelling evidence for subsurface anisotropy, either within the subducting plate, the mantle wedge or the crust. It is challenging to link a surface observation of local shear-wave splitting with a subsurface structure, because several characteristics are desired: the location of the structure, the strength of the perturbation and the type of anisotropy (e.g., tilted transverse isotropy). Here we establish a set of shear-wave splitting observations in the Alaska subduction zone, and we use them to motivate a numerical study using three-dimensional wavefield simulations. We examine the frequency-dependent influence of different types of anisotropy within the mantle wedge on synthetic seismic waveforms. Our objective is to identify the types of anisotropic parameters that will provide the strongest influence on local shear-wave splitting. We also hope to explore the misfit measures that are amenable to 3D anisotropic tomographic inversions. Our long-term goal is to perform an adjoint-based anisotropic tomographic inversion in the Alaska subduction zone.

Presenting Author: Aakash Gupta

Authors