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Multi-Scale Seismic Imaging of Fault-Zone Structures in Southern California With Full-Waveform Inversions of Regional and Dense Array Data

Description: 

We discuss several methodologies for constructing multi-scale seismic velocity models for crustal fault zones at seismogenic depths with full-waveform inversion of earthquake and ambient noise data recorded by regional and dense sensor configurations. We first discuss applications for the area around the rupture zone of the 2019 Ridgecrest earthquake sequence in California, leveraging data from the regional network and dense 2D and 1D deployments with station spacings of ~5 km and ~100 m, respectively. To build self-consistent multi-scale models, we begin with pre-existing regional velocity model earthquake locations, and refine these results through iterative inversions of waveforms recorded by regional and 2D array stations. The improved results provide a structural context of small-scale fault zone models with resolutions up to the tens of meters using high-quality aftershock waveforms captured by dense linear arrays with frequencies up to 10 Hz. As a second focus area, we develop multi-scale imaging for the southern San Andreas fault using data recorded by a dense deployment near the Thousand Palms Oasis in the Coachella Valley at a time with very few local earthquakes. To utilize regional and teleseismic earthquake waveforms, we use double-difference kernels with the FK-injection SPECFEM3D solver to image the fault-zone structures beneath the dense array. The multi-scale results on fault zone and crustal structures contribute significantly to improved understanding of earthquake processes and seismic hazard assessments. The developed methodologies are broadly applicable to research on fault zones worldwide.

Session: 3D Wavefield Simulations: From Seismic Imaging to Ground Motion Modelling - III

Type: Oral

Date: 5/2/2024

Presentation Time: 02:00 PM (local time)

Presenting Author: Guoliang

Student Presenter: No

Invited Presentation: 

Authors