曲江断裂及其周边地区现今地壳垂直形变特征

CHARACTERISTICS OF RECENT VERTICAL CRUSTAL DEFORMATION IN QUJIANG FAULT AND ITS NEIGHBOURING REGION

曲江断裂及其周边地区 195 5～ 1973年的水准测量资料的处理分析结果显示 :1970年 1月 5日通海 7.7级大地震 (震中 :2 4°0 1′N ,10 2°4 3′E)前 ,沿曲江断裂形成半径达 4 5km的大面积下沉区 ,下沉中心的下降速率每年近 2 0mm。与檀原毅 196 6年提出震级与地壳形变半径的经验关系式M =1.96lgr+ 4 .4 5有较好的符合关系 ,表明这种大面积下沉是通海大地震的一种典型的垂直形变异常现象。 1986年以来昆明市的水准观测资料显示 :官渡 呈贡一带存在一个半径约 5km的下沉区 ,近几年来下沉中心下降有加速现象 (下降速率每年达 30mm) ,该下沉区也正好位于黑龙潭 官渡断裂与富民 呈贡断裂隐伏段的交汇部位 ,按震级与地壳形变半径经验关系式推算 ,该下沉区附近未来最大地震震级应为

The analytical result of the leveling data during 1955 to 1973 in Qujiang fault and its neighbouring region shows that a large area subsidence region with the radius of 45 km was formed along Qujiang fault before the Tonghai earthquake \%M\%=7.7 ( the epicenter: 24°01′N, 102°43′E), and the subsiding rate at the center is approximately 20mm/a. This is well consistent with the empirical equation between the earthquake magnitude and the radius of crustal deformation \%M\%=1.96lg\%r\%+4.45 proposed by Darnbara T.in 1966, and seems to be a typical abnormal vertical deformation related to the Tonghai earthquake. The leveling data of Kunming city since 1986 show that a subsidence region with the radius of approximately 5 km exists in Guandu Chenggong region, and the subsidence at the subsidence center (30mm/a) accelerates in the late years. This subsidence region is just located in the intersecting zone between the concealed sections of Heilongtan Guandu and Fumin Chenggong faults. According to the empirical equation between the earthquake magnitude and the radius of crustal deformation the potential maximum earthquakes with the magnitude of about 6 may occur around the subsidence region.