Searching for Blind Faults Beneath Metropolitan Los Angeles: Preliminary Results From the 2023 San Fernando Valley Array
Description:
The San Fernando Valley (SFV) in Southern California is one of the most densely populated regions of the greater Los Angeles area. This region is prone to large damaging earthquakes such as the 1994 (Mw6.7) Northridge and the 1971 (Mw6.7) San Fernando events that both occurred on a blind-thrust faults. Many studies have investigated the structure of the SFV using seismic reflection data, borehole logs, gravity and magnetic data, and deep seismic refraction profiles. Despite these efforts, the resolution of existing Earth models for the region is relatively low. This limits the high-frequency content that can be achieved in wavefield simulations for accurate earthquake hazard modeling and our ability to interpret near-surface structures and identify concealed or blind faults.
To improve the structural characterization of the SFV basin, a group of 29 volunteers installed 140 three-component SmartSolo nodal seismic stations across the basin on 21 October 2023. The deployment was comprised of a 15-km long linear array of 49 nodes spaced ~300 m apart, across the Northridge Hills fault and near the epicenter of the Northridge earthquake and a grid of 91 nodes that covered the SFV with an interstation distance of ~2500 m. Our arrays recorded continuously for ~30 days and captured 21 magnitude>5.5 earthquakes with epicentral distances of 30-90 degrees. We will present preliminary results from ambient noise tomography and receiver function imaging to investigate the seismic structure of the basin and changes across faults. Our study aims to improve ground motion simulations for the SFV and contribute to more accurate estimations of earthquake hazards.
Session: Earth’s Structure from the Crust to the Core [Poster Session]
Type: Poster
Date: 5/2/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Robert
Student Presenter: No
Invited Presentation:
Authors
Patricia Persaud Corresponding Author ppersaud@arizona.edu University of Arizona |
Alan Juarez-Zuniga ajzu@arizona.edu University of Arizona |
Robert Clayton Presenting Author clay@gps.caltech.edu California Institute of Technology |
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Searching for Blind Faults Beneath Metropolitan Los Angeles: Preliminary Results From the 2023 San Fernando Valley Array
Category
Earth’s Structure from the Crust to the Core