Seasonal Hydrological Load Displacement And Stress-strain Analysis In Sichuan Province

GNSS technology has become an important means to monitor crustal deformation and analyze plate movement.In this study,52 stations with uniform distribution in Sichuan and surrounding areas were selected,and the time series data were processed and analyzed to obtain the hydrological load deformation field model in Sichuan.On this basis,based on the horizontal seasonal load displacement,the stress-strain field model of the load in this region was calculated.The spatial and temporal correlation between precipitation and load displacement and the disturbance mode of hydrological load on the stress-strain field of active faults are analyzed based on the precipitation data in this area.In addition,the Coulomb stress in three fault zones is calculated and the regulating mechanism of hydrological load on the Coulomb stress is comprehensively analyzed.The main achievements of this paper are as follows:(1)According to the position time series data of 52 GNSS stations in Sichuan and surrounding areas selected in this work,a high-precision GNSS position time series processing strategy was designed,which could extract the high signal-to-noise ratio surface displacement caused by hydrological load.Results show that the maximum amplitude of horizontal and vertical load displacements reach up to 2.3mm and 9.4mm respectively,presenting periodic changes throughout the year.(2)There is very strong correlation between the regional vertical load displacement and hydrological load of the Bayan Kara Block and the Sichuan-Yunnan Rhombic Block,vertical load displacement of Sichuan basin is characterized by a cyclical change;compared with vertical load displacement of the largest of the Bayan Kara Block and Sichuan-Yunnan Rhombic Block in the presence,the vertical displacement of the maximum load of Sichuan basin has the lag of 2-3 months.Combined with precipitation and topography,the hydrological load is the main factor affecting the vertical seasonal deformation in this region.(3)The disturbance mode of hydrological load on the stress and strain field of active fault is investigated.The results show that there is a strong negative correlation between horizontal strain and precipitation,and the correlation coefficient is-0.898.The phase of the Coulomb stress and the area change is also very close.In this paper,it is analyzed that hydrological load causes periodic crustal deformation and adjusts the distribution of stress and strain field in the crust.