USING EFFECTIVE MEDIUM THEORY TO EXPLORE THE ROLE OF PRE-EXISTING CRACKS IN FAULT FORMATION

Rocks are rarely elastically isotropic. They can have pre-existing cracks or platy minerals (e.g. phyllosilicates such as mica and illite) changing its elastic properties, therefore it would be beneficial to include these heterogeneities in certain fault models. The effective medium theory (EMT) is an anisotropic constitutive model describing effective elastic properties for cracked solids. EMT relates anisotropy due to crack contributions with rock stiffness in order to approximate stresses, and EMT is dependent on two key parameters: crack density (ρ) and crack orientation (θ ). We have implemented EMT in DynEarthSol3D (https://github.com/rclam/DynEarthSol_edits), an open-source long-term tectonic modeling code, and are now investigating whether and how EMT can influence the formation of normal faults by prescribing ρ from 0.0 to 0.3 and θ from 0 to 90 degrees to a 100 x 10 km two-dimensional model for a crustal cross-section extending at rate of 3 cm/year. We present benchmark results verifying the implementation and preliminary results for the sensitivity of initial dip angles of normal faults into these parameters.