Crustal Deformation Monitoring Based On SAR In The Eastern Segment Of The Altyn Tagh Fault And Its Mechanism

Nowaday tectonic deformation in north-eastern Tibetan Plateau, especially the control of the Altyn Tagh Fault (ATF) on this region is a hot spot of current active tectonics study. In this paper, SAR (Synthetic Aperture Radar) technique is applied to study the tectonic deformation characteristics of the eastern segment of the ATF and the deformation mechanism is studied thoroughly based on the combination of field survey records, geophysical data and GPS (Global Positioning System) survey dataSpeckle noise is a typical characteristic of SAR images. The reduction of speckle is necessary for any application of SAR technique. In this paper, second-generation wavelet transformation is introduced to SAR image de-noising and a new method of SAR image de-noising based on second-generation wavelet transformation is proposed. Experimental results show that the new method has favorable performance in despeckling and preserving edge and textual details and appears preferable to conventional filters such as Median Filter, Lee Filer, hard-thresholding and soft-thresholding.In recent years, the differential Interferometric Synthetic Aperture Radar (D-InSAR) technique has been widely used in surface deformation monitoring. In this paper, D-InSAR technique is applied to study the tectonic deformation characteristics of the eastern segment of the ATF. The results demonstrate that the ATF is an important crustal deformation boundary on the northeastern margin of the Tibetan Plateau. To north of this boundary, the surface deformation is weak and uniform while to south is strong but not uniform. From the west part to the east part in this area, the deformation intensity gradually decreases. Between these two parts exists the western part of the North Qilian Shan Fault, where the minimum deformation from January 1996 to January 1998 is about 1.0 centimeter. Besides, there exist two linear intensive deformation belts in south area, one is in N65°W direction, which is in accordance with the direction of the secondary compression-shear plane of the Altyn Tagh strike-slip fault zone. The other is in a roughly NW direction, which is consistent with the trend of the western part of North Qilian Shan Fault.The curstal deformation difference between south area and north area is supported by GPS survey data and active fault data. The linear intensive deformation belts in N65°W direction is controlled by the Altyn Tagh strike-slip fault and those in roughly NW direction is controlled by the western part of the North Qilian Shan Fault. And the mechanism of weak deformation in the interior of the Changma Basin is discussed.