Coseismic Deformation Derivation And Slip Velocity Inversion Of The Dangxiong Earthquake Based On InSAR Data

There are a large number of near north-south oriented normal faults in the Tibetan plateau.Nowdays there has been considerable controvesy over genetic mechanism of these faults.Using the geodetic data to inverse the dynamic parameters-slip velocity of fault,to understanding the dynamic process of fault slip.The fault has been analyzed where the earthquake occurred in this paper. Two-pass InSAR approch is used to extract the coseismic deformation which uses the Envisat C-band image data before and after the dangxiong earthquake.After that,okada elastic half-space dislocation model is used to inverse the three-dimention slip velocity with the high precision deformation information.The main researches and acheivements are as follws:1、The basic principle of D-InSAR has been introduced in this paper, the coseismic deformation has been extracted successfully using the Envisat image data and SRTM 3-arcseconds data based on the theory with interferometry experiment. The coseismic deformation extracted provides a large number of high-precision data for Okada dislocation model.2、For the existense of orbitial resudual error in the SAR data,a far fieldquadratic surface polynomial fitting method has been used to remove the orbitial ramps,the result has improved that almost all the error can be removed,more higher coseismic deformation can be obtained.3、Due to the SAR result often contain thousands to millins of data points,if all of them be used as constrained conditions,the noise away from the epicenter of the quake will be dragged-in the caculation process,Which may effect the precision of inversion.The uniform location algorithm has been improved in this paper,and be used to for InSAR data reduction.3000 observed points be chosed using c++ program within the seismic region.Thehigh consistency between the reducted deformation field and original deformation field improved the feasibility of this method.4、Taking the earthquake hit fault of dangxiong earthquake for example, Using the coseismic deformation observed by InSAR,combined the pso and improved pso algorithm with dislocation model to inverse the three-dimention slip velocity of the faults where the earthquake happened.By comparing the two inversed results,Through the emperical formula,It can be obtained that the seismic moment of dangxiong earthquake is about:3.61×1018Nm,the magnitude is about:Mw6.37.