A Mixed-Flux-Based Nodal Discontinuous Galerkin Method for 3D Dynamic
Rupture Modeling
Abstract
Numerical simulation of rupture dynamics provides critical insights for
understanding earthquake physics, while the complex geometry of natural
faults makes numerical method development challenging. The discontinuous
Galerkin (DG) method is suitable for handling complex fault geometries.
In the DG method, the fault boundary conditions can be conveniently
imposed through the upwind flux by solving a Riemann problem based on a
velocity-strain elastodynamic equation. However, the universal adoption
of upwind flux can cause spatial oscillations in cases where elements on
adjacent sides of the fault surface are not nearly symmetric. Here we
propose a nodal DG method with an upwind/central mixed-flux scheme to
solve the spatial oscillation problem, and thus to reduce the dependence
on mesh quality. We verify the new method by comparing our results with
those from other methods on a series of published benchmark problems
with complex fault geometries, heterogeneous materials, off-fault
plasticity, roughness, thermal pressurization, and various versions of
fault friction laws. Finally, we demonstrate that our method can be
applied to simulate the dynamic rupture process of the 2008 Mw 7.9
Wenchuan earthquake along/across multiple fault segments. Our method can
achieve high scalability in parallel computing under different orders of
accuracy, showing high potential for adaptation to earthquake rupture
simulation on natural tectonic faults.