Basin Structure for Earthquake Ground Motion Estimates in Urban Los Angeles Mapped with Nodal Receiver Functions
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1.
Louisiana State University
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2.
University of Arizona
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3.
California Institute of Technology
Abstract
We constrained sedimentary basin structure using a nodal seismic array consisting of ten dense lines that overlie multiple basins in the northern Los Angeles area. The dense array consists of 758 seismic nodes, spaced ~250–300 m apart along linear transects, that recorded ground motions for 30–35 days. We applied the receiver function (RF) technique to 16 teleseismic events to investigate basin structure. Primary basin-converted phases were identified in the RFs. A shear wave velocity model produced in a separate study using the same dataset was incorporated to convert the basin time arrivals to depth. The deepest part of the San Bernardino basin was identified near the Loma Linda fault at a depth of 2.4 km. Basin depths identified at pierce points for separate events reveal lateral changes in basin depth across distances of ~2–3 km near individual stations. A significant change in basin depth was identified within a small distance of ~4 km near the San Jacinto fault. The San Gabriel basin exhibited the largest basin depths of all three basins, with a maximum depth of 4.2 km. The high lateral resolution from the dense array helped to reveal more continuous structures and reduce uncertainties in the RFs interpretation. We discovered a more complex basin structure than previously identified. Our findings show that the basins' core areas are not the deepest, and significant changes in basin depth were observed near some faults, including the San Jacinto fault, Fontana fault, Red Hill fault and Indian Hill fault.
Copyright and License
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Acknowledgement
We are thankful to the Incorporated Research Institutions for Seismology’s (IRIS) Portable Array Seismic Studies of the Continental Lithosphere (PASSCAL), Louisiana State University, University of Oklahoma, and Utah State University for providing nodal seismometers, as well as to all the volunteers who assisted with the nodal deployments.
Funding
This research is funded by the National Science Foundation (Grant Nos. 2105320 and 2105358), the U.S. Geological Survey awards (GS17AP00002 and G19AP00015) and Southern California Earthquake Center awards (18029 and 19033).
Contributions
Conceptualization: R.G. and P.P.; formal analysis: R.G. and P.P.; funding acquisition: P.P. and R.W.C.; methodology: R.G. and P.P.; project administration: P.P. and R.W.C.; investigation: R.G., P.P. and R.W.C.; writing—original draft preparation: R.G.; writing, review and editing: R.G. and P.P.; visualization: R.G. and P.P.; supervision: P.P. All authors have read and agreed to the published version of the manuscript.
Data Availability
The nodal dataset will be available through the IRIS Data Management Center in 2023. The receiver function files produced from this study are available at https://doi.org/10.5281/zenodo.7795769 (accessed on 20 August 2023).
Supplemental Material
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Additional details
- National Science Foundation
- EAR-2105320
- National Science Foundation
- 2105358
- United States Geological Survey
- GS17AP00002
- United States Geological Survey
- G19AP00015
- Southern California Earthquake Center
- 18029
- Southern California Earthquake Center
- 19033
- Accepted
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2023-10-10Accepted
- Caltech groups
- Division of Geological and Planetary Sciences (GPS), Seismological Laboratory
- Publication Status
- Published