Degree

Doctor of Philosophy (PhD)

Department

Geology and Geophysics

Document Type

Dissertation

Abstract

Sedimentary basin structure in the northern Los Angeles area have been identified using a nodal seismic array along 10 lines across three basins. The dense array consists of 758 seismic nodes spaced ~250-300 m apart along the lines that recorded seismic responses for 30-35 days. We applied the receiver function (RF) technique to 16 teleseismic events to investigate the basin structure. Primary basin converted phases were identified in the receiver functions. 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 revealed 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 and Ps arrival times 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. This work has been previously published as “Basin Structure for Earthquake Ground Motion Estimates in Urban Los Angeles Mapped with Nodal Receiver Functions”, Geosciences 2023, 13, 320.

Date

1-11-2024

Committee Chair

Patricia Persaud

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