Study On The Characteristics Of Crust Deformation In Yadong-gulu Rift Constrained By InSAR

Tibet Plateau is one of the area with significant lithospheric deformation in the world.The collision and extrusion of the Cenozoic India plate and the Eurasian plate shortened the crust by about 1000 km in the north and south direction,with an average elevation up to 4500 m.Today,India plate is still pushing northward with a velocity about 5cm per year,resulting a strong variety of tectonic activity in the Tibet Plateau.Therefore,Tibet Plateau has also became a ideal place to evolve plate tectonics theory and theorize new earth dynamic theory.As one of the most significant structural features in the Tibet Plateau---the rift valley in the south,which formed in the process of the orogenic crumpling,can help us to understand the continental collision,the deformation mechanism and the evolution process.Yadong-Gulu rift zone is the largest rift zone(nearly north-south oriented)in Tibet Plateau,which can help us to have a deeper understanding of the tectonic evolution.In recent years,the domestic and foreign scientists had carried out many GPS observations in these zones and had achieved good results.These GPS observations can meet some large scale deformation,but produce less effect to analyze the fault activity.Using InSAR technology to obtain a wide range of the surface deformation has a lot of advantages,such as low-cost,high accuracy,high resolution,all-weather,etc.SBAS-InSAR method,which can overcome the limitations of temporal-spatial decorrelation and atmospheric effects and can obtain more continuous sequence of deformation,is one of the most potential technology in the deformation monitoring.In this paper,based on 26 ENVISAT synthetic aperture radar(SAR)scenes during the period from 2003 to 2008,we took SBAS-InSAR technology to calculate the time-dependent LOS deformation fleid of Yadong-Gulu rift and surrounding region.The results of LOS direction deformation field suggests that the deformation rate,which is about 1-2mm/yr,is very small in these region.The deformation characters is uping toward east and downing toward west in the southern section,while up-orientedin the rift zone and down-oriented on both sides of the rift in the northern section.The main deformation characters of the northern regions of Nam Co is subside.The results of the slip rate,which was inverted by the LOS direction deformation,show that the southern and the northern of the rift has similar dip slip rate about 1mm/yr.This rate is relatively small.The locking depth is relatively deep and is 31 km in the southern section while 22 km in the northern section.The inversion of fault dip angle in the southern section and in the northern section is 52� and 40� respectively.