Three-Dimensional Basin Depth Map of the Northern Los Angeles Basins From Gravity and Seismic Measurements
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1.
California Institute of Technology
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2.
Louisiana State University
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3.
University of Arizona
Abstract
The San Gabriel, Chino, and San Bernardino sedimentary basins in Southern California amplify earthquake ground motions and prolong the duration of shaking due to the basins' shape and low seismic velocities. In the event of a major earthquake rupture along the southern segment of the San Andreas fault, their connection and physical proximity to Los Angeles (LA) can produce a waveguide effect and amplify strong ground motions. Improved estimates of the shape and depth of the sediment‐basement interface are needed for more accurate ground‐shaking models. We obtain a three‐dimensional basement map of the basins by integrating gravity and seismic measurements. The travel time of the sediment‐basement P‐to‐S conversion, and the Bouguer gravity along 10 seismic lines, are combined to produce a linear relationship that is used to extend the 2D profiles to a 3D basin map. Basement depth is calculated using the predicted travel time constrained by gravity with an S‐wave velocity model of the area. The model is further constrained by the basement depths from 17 boreholes. The basement map shows the south‐central part of the San Gabriel basin is the deepest part and a significant gravity signature is associated with our interpretation of the Raymond fault. The Chino basin deepens toward the south and shallows northeastward. The San Bernardino basin deepens eastward along the edge of the San Jacinto Fault Zone. In addition, we demonstrate the benefit of using gravity data to aid in the interpretation of the sediment‐basement interface in receiver functions.
Copyright and License
© 2023. American Geophysical Union. All Rights Reserved.
Acknowledgement
We are grateful to the nodal deployment volunteers, Los Angeles residents, and business owners who hosted our instruments. We thank Liu et al. (2018), Wang et al. (2021), and Ghose et al. (2023) for providing their receiver function results, and Tom Brocher for sharing the borehole data. This research was supported by the National Science Foundation awards 2105358 and 2105320. The BASIN project was partly supported by U.S. Geological Survey awards GS17AP00002 and G19AP00015, and Southern California Earthquake Center awards 18029 and 19033. Data collection was supported by Louisiana State University and the California Institute of Technology. Nodal instruments were provided by Incorporated Research Institutions for Seismology (IRIS), Portable Array Seismic Studies of the Continental Lithosphere (PASSCAL), the University of Utah, Louisiana State University, and the University of Oklahoma.
Funding
This research was supported by the National Science Foundation awards 2105358 and 2105320. The BASIN project was partly supported by U.S. Geological Survey awards GS17AP00002 and G19AP00015, and Southern California Earthquake Center awards 18029 and 19033. Data collection was supported by Louisiana State University and the California Institute of Technology. Nodal instruments were provided by Incorporated Research Institutions for Seismology (IRIS), Portable Array Seismic Studies of the Continental Lithosphere (PASSCAL), the University of Utah, Louisiana State University, and the University of Oklahoma.
Contributions
Conceptualization: Valeria Villa, Robert W. Clayton.
Data curation: Valeria Villa, Yida Li, Robert W. Clayton, Patricia Persaud.
Formal analysis: Valeria Villa, Yida Li.
Funding acquisition: Robert W. Clayton, Patricia Persaud.
Investigation: Valeria Villa, Yida Li, Robert W. Clayton, Patricia Persaud.
Methodology: Valeria Villa, Yida Li, Robert W. Clayton.
Project Administration: Robert W. Clayton, Patricia Persaud.
Resources: Robert W. Clayton, Patricia Persaud.
Software: Valeria Villa.
Supervision: Robert W. Clayton.
Validation: Valeria Villa, Yida Li, Robert W. Clayton, Patricia Persaud.
Data Availability
The basement time was obtained from Liu et al. (2018), Wang et al. (2021), and Ghose et al. (2023). Li et al. (2023) provided the Vs model. The basement depths obtained from well borehole logs are publicly available through the Geologic Energy Management Division's (CalGEM) online mapping application Well Finder https://www.conservation.ca.gov/calgem/Pages/WellFinder.aspx, Chino Basin Optimum Basin Management Program (Wildermuth et al., 2005), and Buwalda (1940). The Bouguer gravity data was provided by the Pan American Center Earth and Environmental Science portal. Figures were plotted using the GMT software, PyGMT, and Cartopy (Met Office, 2010; Uieda et al., 2022; Wessel et al., 2019). The 3D basin depth model is publicly available at http://doi.org/10.22002/D1.20252.
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Additional details
- National Science Foundation
- EAR-2105358
- National Science Foundation
- EAR-2105320
- United States Geological Survey
- GS17AP00002
- United States Geological Survey
- G19AP00015
- Southern California Earthquake Center
- 18029
- Southern California Earthquake Center
- 19033
- Available
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2023-07-20Issue Online
- Accepted
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2023-07-11Manuscript Accepted
- Caltech groups
- Division of Geological and Planetary Sciences, Seismological Laboratory
- Publication Status
- Published