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Title:: Dynamic Adjustment of Re-measurement Leveling Network and Its Application in Vertical Crustal Deformation in Sichuan-Yunnan Region

Author(s):: LI Layue; YANG Guohua; ZHENG Zhijiang; YIN Haiquan; JIA Yue; (The First Monitoring and Application Center,China Earthquake Administration,Tianjin 300180,China)

Keywords:: precise level measurement; Sichuan-Yunnan region; dynamic adjustment; crustal deformation; fault movement

摘要:: 以1995—2016年川滇地区实测水准资料为例,分别采用动态经典平差、拟稳平差、伪逆平差和GPS速率约束平差4种平差方法进行平差计算,分析探讨4种平差方法在水准网平差处理时的适用条件及优缺点; 最后分析了1995—2016年川滇地区的地壳垂直形变特征。结果表明:①在条件具备的情况下,GPS速率约束平差优于动态经典平差、拟稳平差和伪逆平差,主要体现在GPS速率可知、平差后速率误差明显减小,且能有效地抑制误差的传播与积累; 而拟稳平差、伪逆平差虽优于动态经典平差,但同样存在着基准假定的问题; ②1995—2016年川滇地区整体处于差异隆升阶段,只有四川盆地、滇西北和滇南少部分区域下沉,跨断裂剖面结果显示几条断裂带以继承性运动为主。

Abstract:: The starting point problem of leveling has always been a key issue in leveling network adjustments.Based on dynamic classical adjustment,Quasi-stable adjustment,pseudo-inverse adjustment and GPS rate-constrained adjustment,this paper takes the measured data of 1995—2016 in Sichuan and Yunnan as an example,and carries out the adjustment calculation by the above adjustment methods,then explores the advantages and disadvantages of these kinds of adjustment methods in the leveling network adjustment.On this basis,we analyze the vertical crustal deformation characteristics of the Sichuan-Yunnan region from 1995 to 2016.The results show that the GPS rate constraint adjustment is better than the dynamic classical adjustment,quasi-stable adjustment and pseudo-inverse adjustment in case of conditions.It is mainly reflected that the GPS rate is known,rate error after adjustment is significantly reduced,and it can effectively restrain the propagation and accumulation of error; while the Quasi-stable adjustment and pseudo-inverse adjustment are better than dynamic classical adjustment,but there are also the problem of the benchmark assumption.During the period of 1995-2016,the Sichuan-Yunnan region was in a period of differential uplift.Only a few parts of the Sichuan Basin,Northwest Yunnan and SouthernYunnan were subsiding.The results of the cross-fault profile show that several main faults in the Sichuan-Yunnan region are dominated by inherited movements.