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Observationally Constrained Multi-Scale Dynamic Rupture Modeling of the 2019 Ridgecrest Earthquakes

Session: Exploring Rupture Dynamics and Seismic Wave Propagation Along Complex Fault Systems I

Type: Oral

Date: 4/19/2021

Presentation Time: 10:00 AM Pacific

Description: 

Advances in high-performance computing allow us to combine and cross-verify observational constraints with physics-based modeling to provide mechanically viable insight into earthquake dynamics across complex fault systems. We present observationally and Coulomb stress modeling constrained 3D dynamic rupture scenarios combining the 2019 Mw6.4 Searles Valley and Mw7.1 Ridgecrest earthquakes, complemented by aftershock calibrated back-projection (Li & Ghosh, 2016) and kinematic parametric source inversion (PSI, Hallo and Gallovič, 2020). A detailed 3D non-vertical fault model of the quasi orthogonal intersecting fault network is built from relocated aftershocks and surface ruptures constrained by space geodesy and field observations. All faults are embedded in modeled cumulative (coseismic plus postseismic) Coulomb stresses (∆CFS), heterogeneous 3D SCEC community models of tectonic stresses, and subsurface materials. The faults intersect high-resolution topography and may cause off-fault plastic deformation during frictional failure. We validate a unified multi-scale scenario of both events with key observations including fault surface offsets, GPS and InSAR surface deformation, moment rate release, slip distribution, teleseismic, and strong ground motion waveforms. The dynamic model ruptures two conjugate faults simultaneously in the Mw6.4 event whereas only the SW-segment breaks the surface. The Mw7.1 dynamic rupture scenario includes the full state of stress: 3D tectonic loading, ∆CFS, and the dynamic and static stresses transferred by the Searles Valley scenario. We model complex rupture evolution including re-activation of the conjugate Mw6.4 segment, mixed crack- and pulse-like propagation, and delayed tunneling beneath the fault intersection. We quantify the considerable dynamic and static stress changes the Mw6.4 dynamic rupture model induces in the Mw7.1 hypocentral region, which is not enough to trigger rupture across the stress-shadowed main fault. We additionally analyse low-velocity fault zone effects (Qiu et al., 2020) on rupture speed and waveforms.

Presenting Author: Alice-Agnes Gabriel

Student Presenter: No

Authors