Fault Damage Zone Effects on Ground Motions During the 2019 Mw7.1 Ridgecrest, CA, Earthquake
Description:
We have simulated 0-3 Hz deterministic wave propagation in the Southern California Earthquake Center Community Velocity Model (CVM) version CVM-S4.26-M01 for the 2019 M7.1 Ridgecrest earthquake. A data-constrained high-resolution fault-zone model is incorporated into the CVM in order to investigate the effects of the near-fault low-velocity zone (LVZ) on the resulting ground motions, constrained by strong motion data recorded at 161 stations.
The finite-fault source used for the simulation of the Ridgecrest event was obtained from kinematic inversion, enriched by noise following a von Karman correlation function above about 1 Hz with an omega-squared high-frequency decay. Our results show that the near-fault LVZ inherent to the fault zone structure significantly perturbs the predicted wave field in the near-source region, in particular by more accurately generating Love waves at its boundaries. Furthermore, the presence of the fault zone structure imbedded in the CVM increases the peak ground velocities in the western Los Angeles Basin (about 200 km from the source). The fault zone structure generally improves modeling of the long-period features in the data and lengthens the coda wave trains, in better agreement with observations. The favorable fit to data was obtained with a model including high-resolution surface topography, a 700 m-thick geotechnical layer (GTL) and frequency-dependent anelastic attenuation in the model domain, with Qs=0.1Vs (Vs in m/s) and a powerlaw exponent of 0.5 for frequencies higher than 1 Hz. We recommend that surface topography, a calibrated GTL and a fault zone velocity structure, where available, be included in ground motion modeling to obtain the least biased fit to observed seismic data.
Session: Multi-scale Models for Seismic Hazard Analysis
Type: Oral
Date: 4/20/2023
Presentation Time: 02:30 PM (local time)
Presenting Author: Kim B. Olsen
Student Presenter: No
Invited Presentation:
Authors
Kim Olsen Presenting Author Corresponding Author kbolsen@mail.sdsu.edu San Diego State University |
Te-Yang Yeh tyeh@sdsu.edu San Diego State University |
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Fault Damage Zone Effects on Ground Motions During the 2019 Mw7.1 Ridgecrest, CA, Earthquake
Category
Multi-scale Models for Seismic Hazard Analysis