Seismic Risk Research Based On Crustal Deformation Data

China,located in the convergence position of the famous seismic belt i.e.circum-Pacific seismic belt and Eurasian seismic belt,in the grip of India plate,the Pacific plate and Philippines plate,is affected by the compression of India plate and subduction of the Pacific plate,where late Quaternary and modern tectonic activity is intense and earthquake disasters occurred frequently.Tectonic movement is closely related to earthquake preparation.In general,most of the strong earthquakes are caused by thrust faults and strike-slip faults and normal faults with small scale may cause earthquakes with lower magnitude.Results indicate that the late Cenozoic and modern tectonic deformation in China is mainly characterized by active block movement.Furthermore,boundaries of active block mainly include active fault zones,active fold and active basin,by which active blocks control the strong earthquakes and whose seismic activity is controlled by its own tectonic movement rate.It is appeared that seismic activity is higher in western China than that in eastern China.Crust deformation measurement is an important method to study the relation between it and earthquakes,which can provides direct evidences with clear physical significance.Baseline data and leveling data obtained from across-faults site monitoring directly reveal the fault's movement,which is usually called across-faults data.In this dissertation,the screw dislocation model proposed by Savage et al.in 1973 is the basis,Xianshuihe fault zone is taken as the study area.Characteristic in near fault field is analyzed using across-faults data,with which the consistency of fault spatial movement from InSAR is compared.Besides,seismic risk of fault is estimated on the principle of seismic moment balance and slip deficit.At last,crustal deformation monitoring scheme is put forward combined with analysis and recognition of solid tidal deformation anomaly.The main results in this dissertation are as followed:(1)As a method for crustal deformation monitoring,the relative displacement of points across a fault is measured to study the fault's movement.A new fault kinematics parameters calculation method is proposed based on plane right angle coordinate system.Fault kinematics parameters calculated using previous and new method are compared using across-fault data of Xianshuihe zone,which are consistent with each other.A better layout way for across-fault sites are proposed from the problems when calculating fault kinematic parameters.(2)Dislocation model in near fault field is derived from screw dislocation model,which can reveal the deep locking information on position of across-fault site using baseline data.The result indicates that the locking depth of Laoqianning across-fault site is about 18 km,the locking depth of other sites on Xianshuihe fault zone is shallow.According to baseline change rate,the locking time of fault is estimated.(3)Time series analysis of SBAS-InSAR is used to study interseismic tectonic deformation.Deformation field from InSAR reveals the left lateral slip property of Xianshuihe fault zone.15 profiles vertical to fault strike are selected,the movement around fault of that 15 profiles meets the dislocation model in near fault field proposed in this dissertation.Locking depth is shallow using InSAR data as well as across-fault data and left lateral slip rate of the northeast part of Xianshuihe fault zone is about 10mm/a derived from screw dislocation model.Furthermore,layered dislocation model is put forward to explain shallow locking depth of fault zone.Accumulative seismic moments caused by fault slip and the release amount of M?5.0 earthquakes are calculated to estimate seismic risk of study area using fault slip deficit.Qianning part is the future danger area with strong earthquakes,combining with multi-types of results.(4)Compared with across-fault measurement,InSAR and GPS,solid tidal deformation measurement with higher precision can observe tiny deformation.Its abnormal changes are taken as examples to introduce the anomaly verification,information extraction of deformation observation on fixed point.Concentrated load model is used to analyze the effect of reservoir capacity change to ground tilt observation,a new calculation method using groundwater level change to correct strain and some suggestions to deformation observation layout for fixed point are put forward.(5)At last,from the advantage of observation precision,spatial resolution and temporal resolution for each crustal deformation monitoring method,a crustal deformation monitoring scheme is proposed based on multi-types of method to provide basis for scientific and proper distribution of crustal deformation monitoring network.