Analysis Of Geometric Changes And Regional Crustal Deformation Characteristics Of GPS Monitoring Network Before And After The Earthquake In Japan

Since the nineties of the 20th century,the space survey technology represented by GPS technology has become the main technical means to monitor the geological tectonic movement and geodynamic phenomena.GPS technology,with its characteristics of high accuracy,automation,high efficiency,all-weather and low cost,has attracted the attention of many experts and scholars in the field of earthquake monitoring,Many researchers at home and abroad use GPS observation results to conduct in-depth research and Discussion on the change of tectonic stress field,and obtain good results,which makes great contribution to earthquake prediction and prediction.In the crustal movement observation network,the high-precision processing of GPS continuous observation data of each observation station greatly improves the ability of monitoring plate movement and crustal movement.In the GPS monitoring network,the distance between the adjacent base stations is relatively long,and the number of observation stations is relatively small,so it is difficult to study the change movement of the crustal details by using the GPS observation data recorded by each observation station in the monitoring network,but it is possible to analyze the large-scale change of the space by using the observation data of the monitoring network.This paper uses the GPS observation data recorded by some IGS base stations in and around Japan during the two years before and after the 2009-2012 earthquake.The baseline solution and adjustment process of GPS observation data are completed by using GAMIT / GLOBK software.With the help of GPS three-dimensional unconstrained free network adjustment,high-precision GPS baseline vector is obtained,Based on the time series of all baseline length changes and the time series of angle changes between baselines in GPS monitoring network,the change of geometry network structure of GPS monitoring network is comprehensively measured.By using the GPS baseline vector with high accuracy,the time series of the parameters related to the strain field in the local area can be calculated,including the change trend of the baseline strain,the maximum area expansion of each unit area,the maximum shear strain,the first shear strain and the second shear strain.According to the change of the geometry network of the whole GPS monitoring network and the change trend of the strain field in each unit area,the dynamic change process of regional crustal deformation before and after the 9.0 Earthquake in Japan is studied and analyzed.