3-D Broadband Modeling of Near-Field Ground Motions and Deformation in Dynamic Rupture Simulations of the 2019 Ridgecrest Earthquake Including Fault Zone and Fault Roughness Effects
Description:
We present large-scale modeling of near-field broadband (>5 Hz) ground motion parameters and deformation in dynamic rupture simulations of the 2019 Mw 7.1 Ridgecrest earthquake. We include an observationally constrained shallow low-velocity fault zone and band-limited self-similar fractal fault roughness. Fault roughness induces geometric and small-scale stress perturbations, which are effective in generating deterministic high-frequency radiation. The model also incorporates a strong velocity weakening rate-and-state friction law, complex non-vertical fault geometry, 3D velocity structure, high-resolution topography, 3D initial stress distribution, off-fault plasticity, and viscoelastic attenuation (Taufiqurrahman et al., ResearchSquare, 2022).
We examine different ground motion parameters (PSA, PGA, PGV, PGD) and compare them with observed seismograms and GMPEs. We are especially interested in the near-field, closer than 10 km to the rupture, where real observations of strong ground motions are sparse and GMPEs are poorly constrained. The modeled ground motion parameters exceed the empirical predictions close to the rupture zone (< 2 km), which is only partly explained by effects of the low-velocity fault zone. We discuss which (if any) surface observations can constrain the dynamics of earthquakes, in particular for rapidly decaying near-field source effects. For each examined parameter, we show how the values inferred from the surface compare to their equivalents inferred within the volume. We also analyze the distributions of plastic vs. elastic off-fault deformation and their partitioning into volumetric and shear components.
Session: Multi-scale Models for Seismic Hazard Analysis
Type: Oral
Date: 4/20/2023
Presentation Time: 02:45 PM (local time)
Presenting Author: Nico Schliwa
Student Presenter: Yes
Invited Presentation:
Authors
Nico Schliwa Presenting Author Corresponding Author nico.schliwa@geophysik.uni-muenchen.de Ludwig Maximilian University |
Alice-Agnes Gabriel algabriel@ucsd.edu University of California, San Diego |
Yehuda Ben-Zion benzion@usc.edu University of Southern California |
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3-D Broadband Modeling of Near-Field Ground Motions and Deformation in Dynamic Rupture Simulations of the 2019 Ridgecrest Earthquake Including Fault Zone and Fault Roughness Effects
Category
Multi-scale Models for Seismic Hazard Analysis