Analytical and numerical modeling of viscous anisotropy: A toolset to constrain the role of mechanical anisotropy for regional tectonics and fault loading

Dunyu Liu, Simone Puel, Thorsten W. Becker, & Louis Moresi

In Preparation June 29, 2022, SCEC Contribution #11877

Whether mechanical anisotropy is required to explain the dynamics of the lithosphere, in particular near fault zones where it may affect loading stresses, is an important yet open question. If anisotropy affects deformation, how could we quantify its role from observations? In this study, we derive analytical solutions and build a theoretical framework to show how a viscously anisotropic shear zone can lead to deviatoric stress heterogeneities as well as mismatched stress/strain principal axes. We also develop an open-source finite element approach to explore more complex scenarios in both 2-D and 3-D, and simulate three 3-D scenarios inspired by an anisotropic major strike-slip fault zone, the asthenospheric mantle, and the Leech River Schist above the Cascadia subduction zone. The findings from this study, and the method and tools may help geoscientists better understand, detect, and evaluate mechanical anisotropy in nature.

Citation
Liu, D., Puel, S., Becker, T. W., & Moresi, L. (2022). Analytical and numerical modeling of viscous anisotropy: A toolset to constrain the role of mechanical anisotropy for regional tectonics and fault loading. Geophysical Journal International, (in preparation).