Extraction And Analysis Of Maddow Earthquake Co-seismic And Post-seismic Deformation Based On SAR And Optical Images

The extraction and analysis of co-seismic and post-seismic deformation characteristics are of great significance for the study of active fault movement,regional tectonic evolution and prevention of secondary disasters.In this paper,Sentinel-1 SAR and Sentinel-2,Landsat8 optical images before and after the Maddow earthquake were used as data sources,DInSAR and Pixel Offset Tracking technologies were used to extract the co-seismic deformation fields in multiple directions in this region.Moreover,multiple fusion solutions were used to extract the three-dimensional co-seismic deformation field,and then the characteristics of co-seismic deformation and surface rupture of the Maddow earthquake were analyzed.Finally,Sentinel-1images of nearly one year after the earthquake were used to extract the temporal deformation information of the post-earthquake by SBAS InSAR,and the characteristics of post-earthquake surface deformation were interpreted and analyzed.The research results are as follows:(1)Based on Sentinel-1 ascending and descending SAR images,DInSAR and Pixel Offset Tracking technologies were used to extract LOS(range)and azimuth co-seismic deformation fields of the Maddow earthquake.The deformation trend shows good consistency.Compared with DInSAR,the Pixel Offset Tracking technology has lower accuracy,especially in azimuth direction,but it can still capture reliable deformation information in the area of large gradient surface displacements and provide continuous deformation near the fault area.(2)Based on Sentinel-2 and Landsat8 optical images,2D co-seismic deformation fields in the East-West direction and North-South direction of the Maddow earthquake were obtained by using optical Pixel Offset Tracking technology.Sentinel-2 image with the higher resolution has higher precision than Landsat8 images,but compared with SAR Pixel Offset Tracking technology,optical Pixel Offset Tracking results have more high abnormal deformation values.(3)Based on the multi-direction co-seismic deformation of Maddow earthquake,the threedimensional co-seismic deformation field was calculated by using multiple fusion solutions.The results show that the co-seismic deformation is mainly East-West horizontal movement,and the earthquake is a left-lateral strike-slip type,with the deformation ranging from-2.00 m to 1.90 m.The North-South deformation is about-1.00 m ～ 0.60 m,which shows that the northern part of the earthquake area moves northward and the southern part moves southward.In the vertical direction,the deformation is between ±0.30 m along both sides of the fault zone.The surface rupture zone is about 176 km,and the strike is about N101.17°E to N101.43°E.The Seismic fracture is located as Jiang-fault.The rupture zone bifurcates at the southeast end and the northwest end.Branch fracture exists in the western section of the main fracture zone.(4)SBAS InSAR was used to extract the temporal deformation field after the Maddow earthquake,interpret and analyze the change characteristics of surface deformation after the earthquake.The post-earthquake deformation mainly occurred near the epicenter and southeast side,and the temporal deformation is gradually accumulated and then stabilized,which reflects the gradual release of energy on the fault after the earthquake.There is a settlement region in the post-seismic deformation field,which is basically consistent with the branch rupture location at the northwest end of the surface rupture interpreted by co-seismic deformation,indicating the reliability of the surface rupture interpretation results.