| The permanent scatterers approach (PS InSAR), which is based on conventional InSAR technique, put 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. Compared with the conventional InSAR technology, 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, to measure large time scale deformation affair. However, there are still some problems hamper the successful application of PS approach, which are identification of reliable point targets, three-dimensional analysis of PS interferometric phase. At present, the successful application of PS approach is mainly limited to ground surface sedimentation of urban area or diggings, where abundance of natural permanent scatterers can be identified. By contrary, fewer natural point targets will be recognized in Damxiong area, which is selected as the test area of the paper, for lack of human building and structure, only naked rocks are identified as permanent scatterer candidate. The paper will put emphasis on the study of some key aspects of PS technology, applying the PS approach on active fault, to detect the micro-movement of earth surface among seismic diapauses induced by active fault.The limited factors of conventional InSAR are analyzed in paper, which are temporal decorretaion, spatial decorrelation and atmospheric delay. The basic principle, advantage and status are introduced.Methods of point targets'identification are investigated, including coherence, spectral diversity, phase and backscatter intensity. Moreover, new criterions are compensatory for method of backscatter intensity. Identification of manual corner reflector is researched based on these methods. Selection of common master image is studies subsequently.The phase model of convention InSAR are computed and analyzed, especially the temporal and spatial behavior of it. Furthermore, relations of unwrapped interferometric phase with two dimensions which corresponding to the perpendicular baseline and time difference are analyzed, which indicates a linear dependence of phase on the two terms. The related slopes of them correspond to relative terrain height correction and relative linear deformation rates. On base of this theory, a model of two-dimensional linear regression analysis is established for PS interferometric phase. Residual phases are studies at last, which is composed of non-linear deformation phase, atmospheric delay phase and phase noise.Methods of spectral diversity and stable intensity are combined to identify point targets candidate. This is quite different form former studies, for which single method is used only. After analysis of geological structure and influencing terms of test area, the optimal parameters are selected and combined for PSC selection. Interferometric phase of PSC are analyzed using two-dimensional linear regression analysis model. Maps of deformation histories are obtained after differential processing. Characteristics of typical point targets are analyzed, including deformation histories, influencing terms. Characteristics and disciplines of test area deformation are discussed. Key points of PS InSAR technique are summarized again.Research indicates, Nyainqêntanglha Range in northwest of Damxiong basin raise at a relative rate of 3mm/a along the line of sight of satellite, at the same time, the Damxiong basin descends in a certain degree, but the descending rates is a few different from the south to the north. In southeast of basin, the permanent scatterers descend at a relative rate of about 3-4mm/a along the line of sight of satellite. Affected by term of frozen earth, the displacement of permanent scatterers in the north of Damxiong basin are not obvious, but behave a descendent trend as a whole.
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