Application Of Differential SAR Interferometry In Measurement Of Seismic Deformations

The natural disaster of earthquake usually causes great damage. It is paroxysmal, catastrophic and unavoidable. The disaster of earthquake is quite severe in CHINA. The earthquake prediction is a cosmopolitan science puzzle. The research of detecting the surface displacement caused by earthquake to study the earthquake mechanism will provide scientific knowledge to earthquake prediction.Differential SAR Interferometry (D-InSAR) could detect surface displacement in look-of-sight direction at mm level, which is now being used to measure seismic displacement. Since InSAR is quite complicated in data processing and has restrict requirements for combination of SAR data pair, there are very few useable InSAR data available and even fewer successful applications.This dissertation introduced the principle and method of D-InSAR for surface displacement measurement, analyzed the procedure and mathematic model of InSAR. The Mani M7.9 Earthquake (November, 8^th, 1997) and the Kokoxili M8.1 earthquake (November, 14th, 2001) are chosen for research. The SAR data are acquired by ERS-1/2 satellites of European Space Agency.Using three-pass differential InSAR method for Mani earthquake, we got the interferometric fringes of co-seismic displacement field and found that, the displacement field is anomalistic ellipse-shaped with the long axis in NWW direction and the rupture is left-lateral. The 14 November 2000, Mw=7.8 Kokoxili earthquake ruptured more than 400 km of the western end of the left-lateral Kunlun fault. ERS SAR data covering the epicenter area are selected for research, also selected are DEM data acquired by SRTM mission. The long temporal interval between pre-seismic and post-seismic ERS-2 acquisitions and the complex topography lead to low correlation. Furthermore, the surface displacement is complicated. All these factors limited the application of InSAR. Three-pass differential interferometry, ultrashort baseline and external DEM based repeat-pass SAR interferometry are employed to assess the seismic displacement.The final results show that the external DEM based repeat-pass InSAR is better than three-pass differential method in such area.More attentions are paid to the following two topics: the spatial relationship between look-of-sight measurement and actual surface displacement, the interpretation of wrapped interferogram and unwrapped change product.