Quantifying the Sensitivity of Dynamic Rupture to Variable Fault Geometry Using Mesh Morphing

Gabrielle Hobson, Dave A. May, & Alice-Agnes Gabriel

Published September 10, 2023, SCEC Contribution #13204, 2023 SCEC Annual Meeting Poster #139 (PDF)

The dynamics of coseismic rupture has been shown to be sensitive to variability in fault geometry, for example: dip angle; roughness; and the existence and orientation of secondary fault segments. However, systematically quantifying the effect of variations in fault geometry within computational models of dynamic rupture is challenging for several reasons:
(i) Meshes required by DR simulation tools must conform to the fault geometry and the process of mesh generation is both time consuming and non-automated;
(ii) The spectrum of geometric variability one may consider is large;
(iii) A single dynamic rupture simulation may be computationally expensive.

To address points (i) and (ii), here we present an approach referred to as "mesh morphing" for dynamic rupture which was originally developed for CAD modelling in Engineering. The crux of mesh morphing is to mesh a geometry once, and then "warp" (or deform) the mesh vertices into a new geometric configuration, whilst retaining the original connectivity. The method allows for a non-intrusive and automated workflow to generate an ensemble of meshes which encapsulate variability in the fault geometry without repeating the meshing process. We have integrated the mesh morphing method with the dynamic rupture framework SeisSol (www.seissol.org). To verify that this process produces reasonable results, we apply it to the SCEC TPV 13-3D benchmark exercise. We assess the quality of deformed meshes to ensure they are suitable for use in dynamic rupture simulations. We then use this method to apply variations in fault dip and fault roughness to a megathrust reference geometry. This will permit future work aimed at quantifying the sensitivity of dynamic rupture simulations of a megathrust to variability in fault dip, fault roughness, and splay fault orientation.

Key Words
fault geometry, mesh generation, dynamic rupture

Citation
Hobson, G., May, D. A., & Gabriel, A. (2023, 09). Quantifying the Sensitivity of Dynamic Rupture to Variable Fault Geometry Using Mesh Morphing. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)