Research On Characteristics Of Inversion For Earthquake Fault Slip Constrained By InSAR And GPS Geodetic Deformation Data

Earthquake,as a direct form of active faulting,can cause a strong and widespread damage and destruction,which makes exploring earthquake mechanism as an important scientific goal for the Earth science.InSAR and GPS spatial geodetic techniques nowadays are becoming a stable and efficient way to monitor crustal displacement that can provide plenty of geodetic deformation data with high precision and spatiotemporal resolution.With the deep combination of geodetic techniques and the fault dislocation theory,and subsequent successful application,make the inversion for source mechanism constrained by geodetic deformation data ultimately as a reliable method.However,there are still some questions about inversion for earthquake fault slip distribution constrained by geodetic deformation data,for example,the reliability of inversed slip distribution relying on single InSAR LOS deformation,the characteristics of slip distribution inversion based on InSAR deformation field consisting of interferometric decorrelation near fault field,the accurancy of slip distribution inversed by GPS deformation with the different dimensionality and density,and the sensitivity of deep slip inversion constrained by geodetic deformation.This thesis takes the typical strike-slip fault,normal fault,thrust fault as the experimental objects to analyze and discuss the above questions.In order to validate the reliability of inversed slip distribution relying on single InSAR LOS deformation,this thesis makes the experiments with slip distribution inversion based on LOS deformation field added different random noise.The result shows that the slip inversion residual is 30%to 90%of accepted maxium residual and the explaination of deformation field along north,east,and up direction are more than 95%,which illustrates that single LOS deformation with the normal observation accuracy can be utilized for the reliable fault slip distribution inversion where the magnitude is more than 7.0.To analyze the characteristics of slip distribution inversion based on InSAR deformation field consisting of interferometric decorrelation near fault field,this thesis makes the experiments with slip distribution inversion constrained by LOS deformation field with different absoluted deformation remained.The result shows that the interferometric decorrelation has little effect on slip distribution inversrion where the decorrelation deformation is located in acceptable deformation interval.In the experiment,if more than 20%of LOS maximum absoluted deformation is used for inversion,the reliable fault slip distribution can be obtained completely.In order to access the inversion accurancy of slip distribution from the different dimensional GPS deformation,this thesis designs five experiments about slip distribution inversion based on three-dimensional GPS deformation,two-dimensional along north and east direction deformation,and single north,single east,single up deformation,respectively.The result shows that the inversion accurancy from two-dimensional deformation is slightly higher than that from three-dimensional GPS deformation and more better than that from single dimensional deformation.If the horizontal and vertical accurancy of GPS data are 3mm and 10mm respectively,the enough and any dimensional GPS observation can be used for acquiring fault slip distribution with high-precision.To analyze the characteristics of inversed slip distribution from the GPS deformation with different density,this thesis makes the experiments with slip distribution inversion constrained by different grid density of GPS sites.The result shows that,considering the Laplacian smoothing,a reliable fault slip can be obtained if the number of uniform distributed GPS sites is more than 1/7 of the number of discreted sub-faults.And then,take the Japan 2011 earthquake as an example to confirm the characteristics of slip distribution inversion from GPS deformation with different density,which illustrates that the result of example experiment agrees well with that of simulation experiment.In order to analyze the sensitivity of deep slip inversion constrained by InSAR and GPS geodetic data,this thesis makes the experiments with slip distribution inversion where the deep slip area varies along depth direction.The result shows that the detection capability of deep slip inversion based on InSAR geodetic deformation with high accuracy(3mm)is higher than based on InSAR geodetic deformation with normal accuracy(30mm),and is slightly lower than based on sufficient and high accurate three-dimensional GPS deformation(3mm),which illustrates that the accuracy of geodetic deformation data has more effect on detection capability of deep slip than the dimensionality of data.