长江三角洲地区地形变特征的GPS监测和分析

Land deformation monitoring by GPS in the Yangtze Delta and the measurements analysis

本文介绍上海地区GPS综合应用网SCGAN在长江三角洲地区地形变的监测和研究中所取得的成果．对监测到的长江三角洲地区振幅达5～6mm的垂向季节性运动的地球物理机制进行较深入的分析和研究．研究表明，通过对大气压、积雪和土壤湿度质量负载、非潮汐海洋质量负载、以及基岩的热胀冷缩等地球物理机制因素引起地壳垂向季节性变化的定量分析，可以较好地解释GPS的监测结果，对两者间存在的一些系统偏差做了定性分析．而对上海市区4个GPS基准站监测到的振幅近10mm的垂向季节性变化，在扣除地球物理因素后，剩余5mm垂向季节性变化与上海近几年每年定期采、灌地下水引起的地下水水位的周期变化有关．

Results from land deformation monitoring in the Yangtze Delta by Shanghai Comprehensive GPS Application Network （SCGAN） and the related research are involved in this paper. The geophysics of the seasonal vertical movement with an amplitude of 5 - 6 mm measured in this area is studied in depth and analyzed. It is showed that a quantitative analysis on those geophysical factors causing the seasonal vertical movement of the crust could be very helpful to explain what is obtained in GPS monitoring, such as the atmospheric pressure, the mass load of snow cover and soil humidity, the non-tidal oceanic mass load, rock＇s thermal expansion and shrink and so on. Also we do some qualitative analysis on the systematic errors between them. As for the seasonal vertical movement with amplitude nearly 10 mm observed in 4 GPS stations in downtown Shanghai, when the effects of geophysical factors were deducted, the residual 5mm can be explained from the periodical up-and-down of the groundwater level caused by annually fixed pumping and artificial recharging groundwater in recent years.