SCEC Award Number 25275 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 04/25/2026 Date Report Submitted 05/08/2026
Project Abstract
 We plan to continue our work on integrating geodetic data to produce 3-D velocity map and displacement time series for California and western Nevada. We have developed a 3-D velocity map of California and western Nevada by integrating GNSS and InSAR data. This solution has provided detailed mapping of the deformation field, except across a number of creep segments of the San Andreas fault system (SAFS), due to limited near-fault spatial resolution of the GNSS and InSAR data. NASA has conducted repeated surveys of the SAFS using UAVSAR since 2009. We plan to process these UAVSAR data, and combine the result with that of GNSS and InSAR to further enhance the 3-D deformation field, particularly across the creep faults.

We plan also to develop a robust method for GNSS/InSAR/UAVSR integration for a 4-D SCEC-wide integrated deformation field. This project aims at contributing to the synthesis work of the CGM’s group product, by continuing development of the integration method and applying that to obtain the time series solution for California and western Nevada. The result will provide the observational groundwork for the detection and understanding of temporal behavior of crustal deformation, such as coseismic and postseismic deformation, slow slip events on fault, and hydrologically modulated fault zone deformation, etc.
SCEC Community Models Used Community Geodetic Model (CGM)
Usage Description The GNSS-InSAR integration work has been published in JGR-Solid Earth November 2025, and according to Google Scholar, has been cited by colleagues already.
Intellectual Merit Assessment of three-dimensional (3-D) deformation field and its evolution with time is essential in studying physical processes of tectonic, hydrological, and anthropogenic activities and earthquake hazards. A unified and well-constrained 3-D displacement time series that combines the complementary strength of InSAR, GNSS, and UAVSAR datasets will be the key product of the Community Geodetic Model (CGM) to support the SCEC’s mission for Community Earth Models (CEMs) studies.
Broader Impacts Our results were presented at the SCEC Annual Meeting, where they were shared with the broader community and extensively discussed by colleagues from a wide range of disciplines.
Project Participants The work is mainly done by Zhengkang Shen at UCLA and Zhen Liu at JPL. Yuehua Zeng at USGS also participated the discussion.
Exemplary Figure Figure 2. Joint solution of 3-D crustal deformation using integrated datasets of GNSS, InSAR, and UAVSAR. Upper: (a) and (b) are the solution for the horizontal amplitude and vertical components respectively. The white frames mark the surface imprints of the UAVSAR lines. Lower left: (a), (b), and (c) are the UAVSAR de-ramped line-of-sight rate data, model predictions, and data postfit residuals. Lower right: Solution of fault surface creep along SAF in central California. The red and green symbols denote the modeled along-strike and vertical components, and the blue symbol denotes the observed fault-parallel component of creep from a composite dataset.
Linked Publications

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