Abstract: Differential Synthetic Aperture Radar Interferometry (D-InSAR) is a newly developed technique for monitoring large-scale ground deformation with some prominent advantages such as high accuracy and pantoscopic view. The vertical crustal deformation accuracy can be measured by D-InSAR technology to the millimeter level, but due to restrictions of spatial, temporal decorrelation and atmospheric delay, the application to the monitoring of the crust long-term slow deformation is limited. The Permanent Scatterers approach, which is based on conventional InSAR technique, puts emphasis on processing time series of SAR interferograms by recognizing and analyzing single scatterers with a stable backscatter intensity or reliable phase behavior in time, to study the deformation histories of the earth's surface in a long time series. The PS approach can better conquer problems of temporal and spatial decorrelation, also the atmospheric delay effect, which will improve the efficiency of datum utilization when measuring large time scale deformation events. The PS-InSAR, as an innovation of D-InSAR technology, can overcome the loss of coherence time, and meanwhile, calculate and eliminate the atmospheric effects to ensure the normal operation of the interferometric processing. It acquires the accumulated deformation and its rates at the coherent points in the images.
In this paper, the basic principle, advantage and status of PS-InSAR are introduced. The slight deformation of Gangu area in the fault zone along the north fringe of west Qinling Mountains which is one of the major left-lateral strike-slip active faults in northeastern margin of Tibetan plateau is monitored by PS-InSAR technology using 14 scenes of ENVISAT ASAR data from May 2008 to September 2010. The result shows that the rate of the north wall of the fault zone is -1～-2mm/a, the rate of the south wall of the fault is 3～4mm/a, and relative slip rate between the two walls of the fault zone in Gangu area along the north fringe of west Qinling Mountains is approximately 5mm/a; the points target deformation rate and deformation direction both match with the left-lateral motion feature of the north fringe fault zone of west Qinling Mountains, and results have a good agreement with the study results by other scholars. This suggests that the PS-InSAR technology is capable of detecting crustal small deformation.

Key words: PS-InSAR, crustal deformation, fault zone, deformation rate

摘要： D-InSAR技术可以测得地壳垂直形变精度达到mm级，但由于其受空间、时间失相干和大气延迟的限制，导致其在监测地壳长期缓慢形变中的应用受到限制。而PS-InSAR作为D-InSAR技术的创新，在克服时间失相干的同时还可以计算并消除大气影响，使得干涉处理得到的结果更加精确。文中以西秦岭北缘断裂带甘谷地区为实验区，利用从2008年5月至2010年9月共14景ENVISAT ASAR数据，采用PS-InSAR技术对该实验区地壳微小形变进行探测。研究结果得到西秦岭北缘断裂带甘谷地区断裂带南北两盘的相对滑动速率约为5mm/a，点目标的形变速率和形变方向均与西秦岭北缘断裂的左旋运动特征相符，并与其他学者的研究结果有较好的一致性，表明PS-InSAR技术在监测地壳微小形变中具有广阔的应用前景和巨大的发展潜力。

关键词: PS-InSAR, 地壳形变, 断裂带, 形变速率