Study On The Crustal Deformation Pattern In Continental Regions Using The Space Geodesy

Many factors,including the lithospheric structures,kinematic and geometry of the tectonic faults,can influence and even determine the crustal movement and deformation pattern.In this dissertation I combined space geodesy,including Global Navigation Satellite System(GNSS)and Interferometric Synthetic Aperture Radar(InSAR),with regional fault activities,topographic and geomorphologic data,lithospheric properties and focal mechanisms of the historical earthquakes to study the crustal movement and deformation pattern of three different types of tectonism:(?)strike shear in the Pamir;(?)extension in the Sulawesi;(?)convergence and mountain building in the Papuan fold and thrust belt.In this dissertation,the main points of the investigations can be summarized as follows:(1)Strike shear in the Pamir.Due to the continues collision between Indian and Eurasian plates,deformation in the Pamir is characterized by crustal shortening,most of which occurs along the arcuate tectonic belt in the northern Pamir.However,significant E-W shear deformation is also observed in the Pamir.I analyzed the characteristics of the crustal motion in the region using the InSAR and GNSS data,and the role of Muji-Kongur belt palyed in the regional crustal deformation was investigated;the dynamic mechanism that is responsible for the shear deformation within the Pamir was also discussed.The main conclusions are as follows:(?)the Pamir Plateau is featured with north-south shortening,and most of the convergence is accommodated by the frontal Pamir thrust;(?)the Muji-Kongur fault zone is dominated by shear movement,the west-east oriented Muji fault is characterized by dextral strike-slip,whereas the north-south oriented Kongur is by extesion;(?)the Muji-Kongur belt can be considered as a tectonic boundary to accomodate the relative motions between the Pamir and the Tarim Basin;(?)the shear deformation within the Pamir is proposed as a mechanical response to the ductile flow of the weak materials buried in the lower crust.(2)Extension in Sulawesi.Located in eastern Indonesia,the K-shaped Sulawesi is developed as a complex tectonic unit to accommodate the convergence between the Australian plate,Sunda plate and Philippine sea plate.Sulawesi has experienced numerous different types of earthquakes,which reflects a complex deformation process that undergoing collision and transtension.The large-scale Palu-Koro strike-slip fault cuts through the central Sulawesi from the northwest to southeast.The crust to the east of the Palu-Koro fault presents significant northeast-southwest oriented extension.To understand the tectonic movement and evolution of the central Sulawesi,a kinematic model is proposed based on multiple sources of data,including the regional seismicity,fault kinematics and topographic data.The main conclusions are as follows:(?)crustal motion in Sulawesi consists of two phases:mass accumulation and mass divergence.The first phase contributes to the mountain building,whereas the second phase results in a mass deficit;(?)extension in central Sulawesi is caused by gravitational collapse,in which mass lateral extrusion along the large scale Palu-Koro strike slip fault played an important role.(3)Basement reverse faulting and shallow extension in Papuan fold and thrust system,central Papua New Guinea.Tectonic motion and crustal deformation in the Papua New Guinea is controlled by the collision between Pacific plate and Australia plate.The Papuan fold and thrust belt consisting of a series of subparallel thrust sheets is commonly governed by contractional tectonism,here extensional faulting is generally unexpected.I used observations from spaceborne interferometric synthetic aperture radar to analyze the co-and postseismic deformation related to the 2018 Mw 7.5 earthquake,and further investigate the source parameters related to the main shock and two aftershocks.Combined with the lithospheric propeteries,topographic and geomorphologic data,some conclusions are derived as follows:(?)four fault segments are required to produce the highly complex coseismic deformation.The earthquake was dominated by the basement reverse slip;(?)shallow extension is firstly observed in fold and thrust system using the space geodesy,which is proposed to be controlled by the reactivation of pre-existing reverse faults or simply the failures on the ancient extensional structures in the region;(?)the topographic contrast along the strike could be tightly related to the lateral rheological heterogeneities and geometrical complexities,western PFTB is characterized by cold and strong Proterozoic lithosphere,whereas the eastern part is featured with hot and weak Late Paleozoic lithosphere;(?)the coexistence of basement reverse faulting and shallow extension imminently following the main shock poses challenges to earthquake rupture forecasts and feeds new snapshots into seismic hazard models.