SCEC Award Number 24079 View PDF
Proposal Category Collaborative Research Project (Multiple Investigators / Institutions)
Proposal Title Earthquake cycle investigation of the triggering and delay effect for large earthquakes on Southern San Andreas fault by Lake Cahuilla inundation and desiccation
Investigator(s)
Name Organization
Zhen Liu National Aeronautics and Space Administration Yingdi Luo University of California, Los Angeles Qingjun Meng University of California, Los Angeles
SCEC Milestones C1-1, C2-1, C3-1, D1-1, D2-2 SCEC Groups Seismology, FARM, EFP
Report Due Date 03/15/2025 Date Report Submitted 03/14/2025
Project Abstract
 Large earthquakes (M>7) frequently occur along the southern San Andreas fault (SSAF) with a quasi-periodic recurrence interval between about 116 and 221 years over the last millennia, except for the most recent long quiescence (>300 yrs). The SSAF locates beside ancient Lake Cahuilla that experiences periodic inundations and desiccations in historical time. Previous studies suggest a temporal correlation between Lake Cahuilla flooding and SSAF earthquakes, although a direct causal relationship is still in debate. In this study, we developed observationally constrained 3-dimensional fully dynamic earthquake cycle models to explore the influence of hydrologic perturbations associated with Lake Cahuilla on the SSAF earthquakes. We find that the perturbations from water loading, pore-pressure changes and nearby stepover fault movement all contribute to modulating cycle behaviors on the SSAF and perturbations applied at late interseismic stage tend to promote temporal correspondence between earthquakes and Lake Cahuilla high-stands although the simulated events in this study are not able to match all Lake Cahuilla water high-stands history. We also tested the hypothesis whether the prolonged earthquake interval since the last major event can be solely explained by the drought effect approximated through pore-pressure reduction and find an unfeasibly large pore-pressure reduction rate is required to prolong the earthquake interval from less than 200 yrs to more than 300 yrs.
Intellectual Merit Our project directly advances two SCEC research thrusts in SCEC2024 RFP: C) Develop methods and computational frameworks to extend knowledge beyond the available data using simulations, and verify and validate their predictions about earthquake phenomena; D) Develop improved techniques for forecasting seismicity, simulating strong ground motion, and estimating surface deformation, and for testing results in the context of natural and induced seismicity across and along the plate boundary system in California. It contributes to SCEC6 milestone D1-1. By understanding the mechanism behind the interval variation of large earthquakes (quiescence), it also contributes to the milestone D2-2.
Broader Impacts The funding from the project was used to support one early-career scientist and one postdoctoral scholar for continuing career development and training. The results provide the first quantitative assessment of earthquake cycle effects by Lake Cahuilla inundation and desiccation for improved earthquake hazard estimation along the SSAF with broad implications globally. The advanced computation framework developed in the project to account for the influence from tectonic and non-tectonic sources such as pore-pressure perturbation, boundary loading perturbation, dynamic/static stress perturbation (caused by surrounding fault rupture) on earthquake cycle simulations has broad application towards the entire SAF and other fault systems.
Project Participants Qingjun Meng (postdoc, JIFRESSE), Zhen Liu (JIFRESSE/JPL), Yingdi Luo (JIFRESSE). The research involves collaboration between JPL and JIFRESSE/UCLA.
Exemplary Figure Figure 6. The max sliprate history of simulated events based on model (a)M1_T3 and
(b)M1_A3 compared with paleoseismic record on SSAF (yellow patches, Hill et al., 2023).
The time of simulated events has been converted from simulation time to chronological time
(CE), aligned through Cahuilla paleo-lake ages (blue dashed lines, Hill et al., 2023). Meng, Liu and Luo(in review).
Linked Publications

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