SCEC Award Number 24115 View PDF
Proposal Category Collaborative Research Project (Multiple Investigators / Institutions)
Proposal Title GNSS and InSAR Integration for 3-D Deformation Field and Time Series in California
Investigator(s)
Name Organization
Zheng-Kang Shen University of California, Los Angeles Zhen Liu National Aeronautics and Space Administration
SCEC Milestones A1-1, A2-2, A3-5, A3-6, C1-1, D1-1 SCEC Groups Geodesy, CEM, PBS
Report Due Date 03/15/2025 Date Report Submitted 03/26/2025
Project Abstract
 We have developed a method to integrate GNSS and InSAR data to produce a 3-D velocity field at the Earth’s surface. We applied the method to integrate GNSS and InSAR data to probe 3-D crustal deformation of California and western Nevada. Up to 3 decades of GNSS and InSAR data are incorporated. Our results show that: (a) Horizontal crustal deformation at the plate boundary zone is dominated by tectonic deformation around the San Andreas and Walker Lane fault systems, with most of the deformation field interpreted as caused by slip underneath known tectonic faults in the region. However, the residual deformation field is also significant and broadly distributed, and the mismatch between the observed and fault model interpreted deformation is particularly significant across the Walker Lane fault system and western Basin and Range Province, possibly resulting in significant underestimation of accumulated seismic moment and earthquake potential in the region. (b) Subsidence is widely spread in the San Joaquin Valley and Sacramento Valley, with the rates reaching 150-250 mm/yr and 10-25 mm/yr at the two valleys, likely exacerbated by intensive groundwater extraction. Significant subsidence is also detected around the Imperial and Cerro Prieto faults, in the Santa Maria Basin and Oxnard Plain, and along California coastline. (c) Abrupt vertical offsets are revealed across tectonically active faults, such as the Northern Great Valley, Calaveras, Lost Hills Thrust, and San Andreas faults, suggesting that as hydraulic barriers, faults can modulate vertical deformation driven by groundwater circulation in the substrate aquafer system.
SCEC Community Models Used Community Geodetic Model (CGM)
Usage Description The GNSS velocity data from CGM were used during our model development.
Intellectual Merit Our project contributes to advance knowledge and understanding of tectonic deformation in California and western Nevada by integrating geodetic data to produce a 3-D velocity map of the region. It addresses the main research objective outlined in the SCEC2025RFP: “(A) Improve observations with a focus on closing critical data gaps and work on synthesizing results in Community Earth Models…”. The method we developed to integrate geodetic data to produce a 3-D velocity map is original and creative, and responds to the main research objective “(D) Develop improved techniques for forecasting seismicity, simulating strong ground motion, and estimating surface deformation…”.
Broader Impacts Product of this project, the 3-D surface velocity field of California and western Nevada, can be used to infer and mitigate seismic hazard potential of the region.
Project Participants Zheng-Kang Shen, UCLA
Zhen Liu, JPL, NASA
Exemplary Figure Figure 1.
Integrated 3-D velocity field of California and western Nevada, with respect to stable North America. (a) and (b) are amplitudes of the horizontal and vertical velocities, respectively.
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