Landers 1992 "reloaded": Integrative dynamic earthquake rupture modeling

Abstract

Key Points:• A new integrative physics-based simulation of the 1992 Landers earthquake reproduces a broad range of independent observation • Sustained dynamic rupture interconnecting the complex fault segments constraints pre-stress and fault strength • We discuss the interplay of rupture transfers, geometric fault complexity, initial stress, viscoelastic attenuation, and off-fault plasticity AbstractThe 1992 M w 7.3 Landers earthquake is perhaps one of the best studied seismic events. However, many aspects of the dynamics of the rupture process are still puzzling, e.g. how did rupture transfer between fault segments? We present 3D spontaneous dynamic rupture simulations of a new degree of realism, incorporating the interplay of fault geometry, topography, 3D rheology, off-fault plasticity and viscoelastic attenuation. The surprisingly unique scenario reproduces a broad range of observations, including final slip distribution, seismic moment-rate function, seismic waveform characteristics and peak ground velocities, as well as shallow slip deficits and mapped off-fault deformation patterns. Sustained dynamic rupture of all fault segments in general, and rupture transfers in particular, put strong constraints on amplitude and orientation of initial fault stresses and friction. Source dynamics include dynamic triggering over large distances and direct branching; rupture terminates spontaneously on most of the principal fault segments. We achieve good agreement between synthetic and observed waveform characteristics and associated peak ground velocities. Despite very complex rupture evolution, ground motion variability is close to what is commonly assumed in Ground Motion Prediction Equations. We examine the effects of variations in modeling parameterization, e.g. purely elastic setups or models neglecting viscoelastic attenuation, in comparison to our preferred model. Our integrative dynamic modeling approach demonstrates the potential of consistent in-scale earthquake rupture simulations for augmenting earthquake source observations and improving the understanding of earthquake source physics of complex, segmented fault systems.

Dynamic Wedge Failure and Along‐Arc Variations of Tsunamigenesis in the Japan Trench Margin

“…Significant inelastic off‐fault deformation has recently been documented for continental earthquakes (e.g., Dolan & Haravitch, ; Milliner et al, ; Rockwell et al, ; Zinke et al, , ). Dynamic rupture models (e.g., Kaneko & Fialko, ; Roten et al, ; Wollherr et al, ) showed that inelastic off‐fault deformation reduces fault slip at shallow depths, consistent with our subduction zone model results, which can explain the shallow slip deficit of earthquakes inferred from geodetic data (e.g., Fialko et al, ). We suggest that if shallow slip deficit is significant on continents, it is likely more significant in shallow subduction zones, due to low strength of marine sediments and possible high pore fluid pressure (e.g., Saffer & Tobin, ) in enhancing inelastic deformation.…”

Modeling Megathrust Earthquakes Across Scales: One‐way Coupling From Geodynamics and Seismic Cycles to Dynamic Rupture

“…Such models provide physically self‐consistent earthquake source descriptions by modeling spontaneous frictional failure across a predefined fault coupled to seismic wave propagation. By using modern numerical methods and hardware specific software optimization, dynamic rupture simulations can reach high spatial and temporal resolution of increasingly complex geometrical and physical modeling components (Wollherr, Gabriel, & Mai, ; Ulrich, Gabriel, et al, ). In comparison to the aforementioned approaches, such models fully incorporate inertia effects as well as the nonlinear interaction of seismic waves and fault mechanics governed by friction.…”

ExaHyPE: An engine for parallel dynamically adaptive simulations of wave problems

“…We would like to highlight that both of these methods omit manual mesh-generation, which is typically required as a pre-processing step in computational seismology applications and poses a major bottleneck. Hexahedral mesh generation can easily consume weeks to months and is limited for complex geometries of boundary and interface conditions, while form-fitted unstructured tetrahedral meshes allow for automatised meshing and complex geometries [56,57], however, pose numerical challenges, e.g. in form of misshaped sliver elements [58].…”