Abstract:The interferometric SAR (Synthetic Aperture Radar)technique has the capability to measure ground deformation in a wide range of applications.It is possible to exploit (Differential-) SAR interferometry to measure small terrain displacements, but single measurements can be considered reliable only in cases of larger displacements, and several types of incoherent temporal change reduce the accuracy of the interferometric phase.The exploitation of several measures (i.e., interferometric stacking and analysis of SAR phase time series) is of great interest with regard to the improvement of single measurements.The exploitation of a series of N SAR images (interferometric stacking) allows the identification of areas (pixels) that show a coherent and consistent signal (displacement) over time. The persistent scatterer (PS)-InSAR technique, which is more applicable to point targets and man-made features than InSAR, can effectively reduce the losses of temporal and spatial coherence, and reduce the influence of atmospheric effects. In cases where interference fringes of conventional D-InSAR cannot be formed, radar image time series and the phase stability of permanent point targets can be used to obtain deformation rates of discrete PS pixels.The Stanford method for persistent scatterers (StaMPS) software package that implements an InSAR persistent scatterer (PS) method is used in the study.There are two preprocessing steps necessary before beginning the PS/MTI processing method:focusing of the raw data and forming interferograms from single-look complex images.ROI PAC was used for the focusing and Doris for the interferogram formation.The fault zones located in Quanzhou in Fujian Province are the research object, and 22 ERS SAR datasets from 1996 to 1999 were used for processing by the PS-InSAR method. After the steps of SLC image generation, interferogram formation, phase noise estimation, PS selection, PS weeding, phase correction, and phase unwrapping, the time series of each pixel was processed separately and a set of height residuals and average displacement rates was extensively tested;the pair "flattening at best" the measured phases was selected as the solution. We obtained the crustal deformation that corresponded to the maximization of the temporal coherence of the pixel time series for a linear displacement of the active fault in the Quanzhou area. The results show that the displacement rate of the main faults is 3~5 mm/a, indicating that the fault zones remain active with the potential for seismic hazard.
