Study For Co-seismic And Post-seismic Deformation Of The 2008 Yutian Mw7.2 Earthquake

Interferometric Synthetic Aperture Radar(INSAR)is an effective way to obtain surface deformation and monitor fault displacements,with all-weather,all-day,wide coverage and high spatial resolution.The 2008 Yutian Mw7.2 earthquake is difficult to field research and lack of ground stations,GPS and leveling survey.Using In SAR to obtain the coseismic deformation fields of the 2008 Yutian Mw7.2 earthquake based on ascending and descending orbits of ENVISAT ASAR data;SDM is used to invert the fault slip distribution;Using PSCMP to modeling and obtain the simulated NS direction deformation field combined with the coseismic deformation fields of ascending and descending orbits to calculate the 3D coseismic deformation field.Using Interferometric Point Target Analysis(IPTA)and Small Baseline Subset In SAR(SBAS)to regression analysis of differential interferometric phases in high coherent point targets based on 18 scenes of ENVISAT ASAR data from 2008 to 2010.Phase component as height corrections,linear deformation rates,atmospheric delay,non-linear deformation and error terms were calculated step by step.The analysis of the coseismic deformation fields shows that the 2008 Yutian Mw7.2 earthquake is mainly rupturing along the NNE-trending normal fault with a slight strike-slip component.The inversion of the coseismic slip distribution shows that the fault is divided into four segments along strike;slip distribution is concentrated mainly in 0 to 14 km depth and fault plane of F2,F3;The largest slip is about 5.31 m which is located in depth of 2.76 km along the fault plane of F2;the ratio of left-lateral strike-slip deformation to vertical deformation along the rapture tends to increase;the inverted seismic moment is about = 5.58 × 10 N·m,equivalent to moment magnitude Mw7.10.The results of calculation of three-dimensional coseismic deformation field show that the hanging wall of fault is subsidence deformation,the footwall of fault is uplift deformation,and the subsidence is obviously larger than the uplift,which proves that the earthquake is mainly normal fault;except that the mid-upper part of the hanging wall near the fault zone moved southeast wards,the hanging wall majority moved southwest wards,and the footwall majority moved northeast wards,demonstrating that the rupture has left-lateral strike-slip.The results of inversion,forward modeling and three-dimensional deformation field show that the 2008 Yutian Mw7.2 earthquake is mainly normal fault with a significant left-lateral strike-slip.The results of IPTA show that the cumulative deformation between two sides of fault is approximately 0.0734 m,and fault with a slight strike-slip component.The results of SBAS show that the hanging wall of fault is uplift deformation,the footwall of fault is mainly subsidence deformation.Post-seismic deformation is similar to co-seismic deformation,but value of deformation is much smaller.The main mechanism for post-seismic deformation may be the afterslip of post-seismic fault.