Post-seismic Crustal Deformation Detection on Coherent Targets: a Case Study in Kunlun Fault after 2001 Kokoxili Earthquake

The 14 November 2000, Ms8.1 Kokoxili earthquake is of huge influence in the world, which ruptured more than 400 km of the western end of the left-lateral Kunlun fault. The Kunlun fault is active and also after the heavy earthquake, it will definitely undergo an adjusting and balancing process. SAR Intereferometry (INSAR) is an effective measure for crustal deformation measurement even for minor displacement on the look-of-sight direction. INSAR has been widely used for co-seismic deformation application, however for preand proseismic deformation, very less successful case has been reported. The complexity and out-breaking of seismic deformation makes the detection often difficult. Also, long time difference and totally different seasons make the correlation between INSAR pairs decrease greatly. The Coherent Targets Monitoring technique is providing superior ground deformation mapping compared with standard interferometry based on one pair of Master/Slave scenes. This is because using a larger data set it is possible to estimate and correct for additional phase error sources. Also the point targets detected as coherent targets are generally characterized by stronger signal that provides more accurate phase information than the clutter present in the rest of the scene. This paper concentrates on the coherent point target analysis of long-term ENVISAT data set of east Kunlun fault, where the Ms 8.1 Kokoxili earthquake bursted in 2001. The data starts from 2003-4-3 and ends at 2007-8-30, which is more than 5 years. Altogether 16 scenes of ENVISAT ASAR images are chosen. The related information of the ASAR data is given in Tab.1. Tab.1 Information of chosen ENVISAT ASAR data No Orbit Track Acq. Date Swath 1 5698 133 2003-4-3 I2 2 6199 133 2003-5-8 I2 3 7201 133 2003-7-17 I2 4 9706 133 2004-1-8 I2 5 14215 133 2004-11-18 I2 6 15718 133 2005-3-3 I2 7 17722 133 2005-7-21 I2 8 18724 133 2005-9-29 I2 9 20728 133 2006-2-16 I2 1