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Lateral Variations Across the Southern San Andreas Fault Zone Revealed from Analysis of Traffic Signals at a Dense Seismic Array
  • Hao Zhang,
  • Haoran Meng,
  • Yehuda Ben-Zion
Hao Zhang
University of Southern California
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Haoran Meng
Southern University of Science and Technology

Corresponding Author:menghr@sustech.edu.cn

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Yehuda Ben-Zion
University of Southern California
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We image the shallow seismic structure across the Southern San Andreas Fault (SSAF) using signals from freight trains and trucks recorded by a dense nodal array, with a linear component perpendicular to SSAF and two 2D subarrays centered on the Banning Fault (BF) and Mission Creek Fault (MCF). Particle motion analysis in the frequency band 2-5 Hz shows that the examined traffic sources can be approximated as moving point sources that primarily induce Rayleigh waves. Using several techniques, we resolve strong lateral variations of Rayleigh wave velocities across the SSAF, including 35% velocity reduction across MCF towards the northeast. Additionally, we derive Q-values and find strong attenuation around the BF and MCF. We further resolve 10% mass density reduction and 45% shear modulus decrease across the MCF. These findings suggest that the MCF is the main strand of the SSAF in the area with important implications for seismic hazard assessments.
22 Mar 2023Submitted to ESS Open Archive
26 Mar 2023Published in ESS Open Archive