Research On Pre-seismic And Coseismic Deformation Monitoring Based On InSAR Data

In recent years,Interferometric Synthetic Aperture Radar(InSAR)technology is widely studied in monitoring earthquake deformation,differential interferometry technology obtaining radar line of sight the surface deformation can reach millimeter level,small baseline subset can overcome the temporal and spatial decorrelation.Small Baeline Subset InSAR(SBAS-InSAR)can effectively overcome the temporal and spatial decoherence and monitor the surface deformation for a long time,which is of great significance for the study of deformation monitoring before or after the earthquake.This paper introduces the principles of differential interferometry technology and small baseline technology to measure surface deformation,data processing flow and some key technologies in data processing.It also analyzes the sources of error briefly and common data processing software of interference processing.Taking the YuTian Ms7.3 earthquake on March 21 st 2008 as the research object,the results of the coseismic deformation experiment were obtained by four scenes ALOS PALSAR data and several conclusions were obtained by analyzing the coseismic deformation maps:(1)the YuTian earthquake is mainly characterized by the rupture of the main fault and the rupture characteristics of the left-lateral strike-slip movement.(2)in the northwest settlement plate(hanging plate)and the southeast rising plate(down plate),the maximum uplift value of the terrain is 51 cm,and the maximum settlement value is 113 cm.The Wenchuan Ms8.0 earthquake with high influence was selected as the research object and a small baseline treatment was conducted by the data of one and a half years before the earthquake.The main research results are:(1)on the whole,the entire deformation field is characterized by "convex" deformation along the fault,uplift along the fault and the two faults tend to decline.(2)The settlement value is bigger than the uplift value.The area of uplift in Wenchuan-Yingxiu area is smaller than Beichuan-Anxian area,but the whole increase is much bigger than the latter.This characteristic is same as the result of Beichuan County where the initial position of the epicenter and coseismic dislocation were the largest,indicating that Longmenshan is a feature of thrust faults.The research of this paper is to establish the process of earthquake in the source area by measuring the surface deformations before and after the earthquake.Due to the lack of deep geophysical data as support and complex underground deformation is difficult to detect,the study in this paper has not yet been able to explain the mechanism of surface deformation,but it has provided a feasible method for studying crustal deformation and forecasting and earthquake prediction.