The geodetic measurements of accumulated strains along active faults
during their interseismic periods have a strong connection with faulting
dynamics and seismic hazards evaluation. InSAR has been widely applied
to study the interseismic deformation along active strike-slip faults
around the world. However, various limitations such as that from phase
unwrapping errors and tropospheric delays are often encountered,
hindering our interpretation and model inversion. Phase-gradient
stacking is a method that sums up wrapped phase differences of adjacent
pixels in multi-interferograms. It has been successfully conducted to
reveal local deformation signals across coseismic fractures, yet lacks
of application to relatively larger-scale deformation signals. Here we
apply the phase-gradient stacking method, for the first time, to study
the interseismic deformation along the North Anatolian Fault with
Sentinel-1 SAR images acquired from 2014 to 2021. We obtain the strain
rate field across the North Anatolian fault without the need of
unwrapping hundreds of large interferograms. Segments with surface creep
and strong coupling effects can be clearly distinguished in the phase
gradient maps, allowing us to directly invert for their long-term slip
rates and locking depths. Our preliminary, but promising results show
that the phase-gradient stacking method has advantages in studying
interseismic deformation along strike-slip faults by directly connecting
strain with fault parameters.