Quantifying the influence of fault geometry via mesh morphing with applications to earthquake dynamic rupture and thermal models of subduction

TL;DR

This paper introduces a mesh morphing technique that efficiently generates geometrically varied models for geophysical simulations, enabling sensitivity analysis and uncertainty quantification with reduced computational effort.

Contribution

The authors develop a mesh morphing approach that preserves mesh connectivity, allowing automated generation of diverse geometries and integration with reduced-order models for geophysical applications.

Findings

Mesh morphing produces high-quality, accurate geometries for simulations.

ROMs built on morphed meshes achieve speedups of up to 10^9 times.

Method effectively incorporates geometric uncertainty into modeling.

Abstract

Subsurface geometries are often poorly constrained, yet they exert first-order control on key geophysical processes, including subduction zone thermal structure and earthquake rupture dynamics. Quantifying model sensitivity to geometric variability remains challenging due to the manual effort of mesh generation and the computational cost of exploring high-dimensional parameter spaces in high-fidelity simulations. We present a mesh morphing approach that deforms a reference mesh into geometrically varying configurations while preserving mesh connectivity. This enables the automated generation of large ensembles of geometrically variable meshes with minimal user input. Importantly, the preserved connectivity allows for the application of data-driven, non-intrusive reduced-order models (ROMs) to perform robust sensitivity analysis and uncertainty quantification. We demonstrate mesh morphing in two geophysical applications: (i) 3D dynamic rupture simulations with fault dip angles varying across a 40{\deg} range, and (ii) 2D thermal models of subduction zones incorporating realistic slab interface curvature and depth uncertainties informed by the Slab2 geometry dataset. In both cases, morphed meshes retain high quality and lead to accurate simulation results that closely match those obtained using exactly generated meshes. For the dynamic rupture case, we further construct ROMs that efficiently predict surface displacement and velocity time series as functions of fault geometry, achieving speedups of up to $10^9 \times$ relative to full simulations. Our results show that mesh morphing can be a powerful and generalizable tool for incorporating geometric uncertainty into physics-based modeling. The method supports efficient ensemble modeling for rigorous sensitivity studies applicable across a range of problems in computational geophysics.