123-6 Refining Quaternary Slip on the Santa Cruz Island Fault

Session: Quaternary Research to Characterize Environmental and Geological Hazards

Presenting Author:

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Abstract:

In Southern California, the Santa Cruz Island Fault is a nearly vertical, E–W trending left-lateral fault that is structurally connected to the Los Angeles basin, contributing to earthquake hazard models that impact ~20 million people. The documented modern recurrence interval and slip rate of the Santa Cruz Island Fault are 5 k.y. and 0.8 m/ka, respectively, based on a study conducted along the westernmost 3 km of the terrestrial portion of the fault. 

In this study, we use new field and LiDAR data focusing on Quaternary units that interact with fault strands along-strike for 6.5 km of the eastern central valley, and the westernmost 3.5 km of the terrestrial portion of the main fault. We place new constraints on kinematics, timing, rupture length, recurrence interval, and single-event displacements that are associated with surface-rupturing earthquakes, which are recorded in Quaternary deposits and stream channel offsets. We combine field measurements with high (1-m) resolution LiDAR bare-earth DEMS to estimate fault-related geomorphic offset amounts and their kinematics. Radiocarbon and luminescence samples will be used to constrain the depositional ages of Quaternary units that will bracket the timing of earthquake events.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10488

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