ABSTRACT: We investigate the capabilities and limitations of the Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques,
in particular of the Small BAseline Subset (SBAS) approach, to measure surface deformation in active seismogenetic areas.
The DInSAR analysis of low-amplitude, long-wavelength deformation, such as that due to interseismic strain accumulation, is
limited by intrinsic trade-offs between deformation signals and orbital uncertainties of SAR platforms in their contributions
to the interferometric phases, the latter being typically well approximated by phase ramps. Such trade-offs can be substantially
reduced by employing auxiliary measurements of the long-wavelength velocity field. We use continuous Global Positioning System
(GPS) measurements from a properly distributed set of stations to perform a pre-filtering operation of the available DInSAR
interferograms. In particular, the GPS measurements are used to estimate the secular velocity signal, approximated by a spatial
ramp within the azimuth-range radar imaging plane; the phase ramps derived from the GPS data are then subtracted from the
available set of DInSAR interferograms. This pre-filtering step allows us to compensate for the major component of the long-wavelength
range change that, within the SBAS procedure, might be wrongly interpreted and filtered out as orbital phase ramps. With this
correction, the final results are obtained by simply adding the pre-filtered long-wavelength deformation signal to the SBAS
retrieved time series. The proposed approach has been applied to a set of ERS-1/2 SAR data acquired during the 1992–2006 time
interval over a 200×200km area around the Coachella Valley section of the San Andreas Fault in Southern California, USA.
We present results of the comparison between the SBAS and the Line Of Sight (LOS)—projected GPS time series of the USGC/PBO
network, as well as the mean LOS velocity fields derived using SBAS, GPS and stacking techniques. Our analysis demonstrates
the effectiveness of the presented approach and provides a quantitative assessment of the accuracy of DInSAR measurements
of interseismic deformation in a tectonically active area.
KeywordsDeformation time series–differential SAR interferometry–Small BAseline Subset (SBAS)–interseismic deformation–San Andreas Fault
Pure and Applied Geophysics 04/2012; · 1.79 Impact Factor