3D San Fernando Valley and Los Angeles Basin Depth Map from Receiver Functions Guided by Gravity Measurements

Valeria Villa, Robert W. Clayton, & Patricia Persaud

Submitted September 7, 2025, SCEC Contribution #14787, 2025 SCEC Annual Meeting Poster #TBD

The San Fernando Valley and Los Angeles basin are urban sedimentary basins known to increase the seismic hazard of the surrounding metropolis of approximately 14 million people. In 2022 and 2023, two surveys of hundreds of seismic nodes were deployed in the Los Angeles basin and San Fernando Valley. Each of these surveys had nodal geometries of two linear arrays with the rest of the stations deployed in a shotgun pattern. We developed a novel method to guide our receiver function results using gravity data. Receiver functions are a well-established method for estimating interface depths based on P-to-S converted phases at subsurface boundaries. However, single-station receiver functions can be difficult to interpret due to structural complexity, scattering, noise, etc., which leads to the majority of stations not in a linear array being unusable. By incorporating gravity, we can guide our receiver function phase picks by predicting the gravity anomaly and comparing it to observations at each given time unit. In areas where the density contrast may change, we further developed a Bayesian inference with a graph Laplacian. This method allows us to determine the density contrast per station according to its neighbors’ picks and densities. Our results highlight the success of this method; namely, the San Fernando Valley highlights the deep Sylmar basin, the San Fernando basin, and the Leadwell high found in other studies and boreholes (Juárez‐Zúñiga and Persaud, 2025). Our results also show good agreement with the industry profiles across the valley. For the Los Angeles basin, we demonstrate not only the detailed shape of the basin with its 10-km-wide central basin but also the utilization of the permanent broadband stations that were previously unfeasible to use (Ma and Clayton, 2016).

Key Words
basin, los angeles, San Fernando

Citation
Villa, V., Clayton, R. W., & Persaud, P. (2025, 09). 3D San Fernando Valley and Los Angeles Basin Depth Map from Receiver Functions Guided by Gravity Measurements. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology