Integrated Sentinel-1 InSAR and GNSS Time-Series Along the San Andreas Fault System

International audienceMeasuring crustal strain and seismic moment accumulation, is crucial for understanding the growth and distribution of seismic hazards along major fault systems. Here, we develop a methodology to integrate 4.5 years (2015-2019.5) of Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) and continuous Global Navigation Satellite System (GNSS) time series to achieve 6 to 12-day sampling of surface displacements at ∼500 m spatial resolution over the entire San Andreas fault system. Numerous interesting deformation signals are identified with this product (video link: https://www.youtube.com/watch?v=SxNLQKmHWpY). We decompose the line-of-sight InSAR displacements into three dimensions by combining the deformation azimuth from a GNSS-derived interseismic fault model. We then construct strain rate maps using a smoothing interpolator with constraints from elasticity. The resulting deformation field reveals a wide array of crustal deformation processes including, on- and off-fault secular and transient tectonic deformation, creep rates on all the major faults, and vertical signals associated with hydrological processes. The strain rate maps show significant off-fault components that were not captured by GNSS-only models. These results are important in assessing the seismic hazard in the region