Comprehensive InSAR deformation analysis using ARIA standard products captures interseismic and shallow aseismic slip processes across California

Abstract:

The advent of routine and regular wide-swath SAR acquisitions with the current generation of satellite missions has raised the possibility of similarly routine monitoring of fault behavior over wide continental regions, including interseismic strain accumulation on faults, and shallow fault creep. We present preliminary results from one such effort spanning the state of California, leveraging open and free access to an operational archive of standard Sentinel-1 Geocoded UNWrapped interferograms (GUNW) hosted by the Advanced Rapid Imaging and Analysis (ARIA) Center for Natural Hazards project. The existing archive includes GUNW products from 9 tracks of Sentinel-1 data in both ascending and descending viewing geometries, and which cover all of California and span a period from late 2014 through to the present day.

We perform a state-wide time-series analysis of these data using the open source packages ‘ARIA-tools’ and ‘MintPy’ to estimate long-term (2014-2020) line-of-sight surface velocities and their corresponding uncertainties. We reduce the impact of tropospheric noise on these rates by applying corrections from the GACOS project, which leverages the ECMWF HRES model. Using the UCERF3 statewide fault catalogue to define fault surfaces and locking depths, we invert these velocities for strain accumulation rates on the major faults of California; where sharp cross-fault increments in velocity are identified, we solve additionally for shallow creep rates. Residuals to our model fits indicate areas where additional fault structures may be required, as well as the locations of long-term postseismic deformation transients, and of significant nontectonic and anthropogenic motions.