Research On The Decoherence Classification And Recovery Method Of The Coseismic Deformation Field Obtained By InSAR Technology

InSAR,as a kind of space earth observation technology,plays an important role in the field of seismic research and application.DInSAR technique can obtain the co-seismic deformation field with an accuracy of the centimeter,which provides accurate basic research data for the study of earthquake mechanism and seismological application.However,DInSAR is affected by the errors of the SAR system and the time-space baseline,resulting in partial data missing of the co-seismic deformation field,namely de-coherence.The phenomenon of de-coherence is especially obvious in the near-field of earthquakes,which seriously affects the interpretation of seismic mechanism and the application of seismology.Therefore,to solve the phenomenon of decoherence is the key step to obtain the complete co-seismic deformation field,and it is also an important link in seismological research.This paper proposed a complete set of the coherent recovery processes of the co-seismic deformation field based on the detailed analysis of the manifestation of de-coherence on the SAR image for the problem of de-coherence recovery of the co-seismic deformation field and puts forward the corresponding appropriate de-coherence recovery method for different types and degrees of de-coherence.The main contents and achievements of this paper are summarized as follows(1)The mechanism and source of decoherence are studied;The coseismic deformation fields of 30 typical earthquakes at home and abroad are obtained based on the DInSAR.Based on this,three main forms and four main types of decoherence are summarized.Different degrees of decoherence are defined,and the main solutions to restore decoherence are proposed.(2)An interpolation method for restoration of incoherence is proposed According to the type of incomplete decoherence.The spatial relationship between the incoherent and the uncoherent points is established by the interpolation method,and the values of the incoherent points are predicted.Different interpolation methods are used to restore the incoherence of the Kumamoto earthquake and the Ezgeleh earthquake.The results show that the Kriging interpolation method performs better for earthquakes with less true deformation points in the incoherent region,and the recovery accuracy can reach 87%.The various interpolation methods can achieve a good recovery effect for the earthquakes with many real deformation points in the incoherent region(3)A joint multi-source data recovery method is proposed for complete decoherence recovery.Method 1,the fault slip model is derived from the co-seismic deformation field including incoherence and fault information,and the deformation value at the incoherence can be inferred.Method 2,combined offset-Tracking range deformation.The range deformation of offset-Tracking is directly proportional to the line of sight of DInS AR,and the deformation trend of the point in the incoherent region and the nearest real deformation point is the same in these two deformation fields.The changing trend of the incoherent point and the real point on the offset-Tracking is calculated,and the corresponding relationship between the deformation of the DInSAR incoherent deformation field and the offset-Tracking is established by the least square method,and the complete incoherence recovery is realized.The two methods are applied to seismic incoherence restoration,and the recovery accuracy is verified by GPS.The results show that the two methods can recover the total decoherence accurately,and the relative error of the method based on the simulated deformation field is less than 8%.The relative error is less than 9%for the California earthquake of the method based on the joint offset-Tracking,but the maximum relative error is 31%for the Kumamoto earthquake.The results show that this method is more suitable for seismic incoherence recovery with large surface deformation and good quality of offset-Tracking data.(4)One group of incoherent 3D deformation and three groups of incoherent recovery 3D deformation are obtained by using the multi-line of sight method based on the incoherence deformation field and the incoherence recovery deformation field,taking the Ezgeleh earthquake as an example,and the 3D deformation fields obtained in this paper are verified by the 3D deformation fields published by other institutions.The results show that the three-dimensional deformation results based on three kinds of incoherence restoration methods are better than those obtained by incoherent deformation.The three-dimensional deformation anomalies caused by incoherence can be removed by incoherence recovery,and the three-dimensional results based on offset-Tracking incoherence recovery are more accurate.Therefore,incoherence recovery is helpful to obtain 3D deformation.