川滇地区应变率场分布及其变化特征研究

Distribution and Variation Characteristics of Strain Rate Field in the Sichuan—Yunnan Region

基于GPS多期复测资料,利用最小二乘配置方法计算川滇地区应变参数,分析该区域应变率场分布及其变化特征并探讨其分布与强震关系。研究结果表明:1各时段应变率场空间分布的明显变化应属于大于GPS资料误差的真实地壳构造形变信息;2最大剪应变率及第一、第二剪应变率的结果反映了走滑断裂对区域变形的显著控制;3主应变率,东西、南北向应变率场动态结果反映的汶川地震孕震的空间尺度较大;4在本区大致反映北东向与北西向剪切变形的第一剪应变率、东西向应变率、南北向应变率及最大剪应变率与6级以上地震对应较好。

Based on repeated GPS data, least square collocation method is used to calculate the strain parameters in the Sichuan--Yunnan region. We analyse regional strain rate field distribution and its variation characteristics and relationship between strain rate field dis- tribution and earthquake occurrences. The results show that： （1） spatial distribution of strain rate which has some obvious change is greater than the error of GPS data at each time may be real tectonic deformation information; （2） results of maximum shear strain, first shear strain and second shear strain reflect that strike slip faults have a significant control over deformation; （3） results of principal strain, north--south strain and east-- west strain reflect that influence range of the 2008 Wenchuan earthquake is larger; （4） the first shear strain rate reflect north--east and north--west shear deformation, the east west, north--south strain and maximum shear strain are corresponding to earthquake of magnitude 6 or over in this region.