川滇活动地块东边界强震危险性研究

Study on the potential strong-earthquake risk for the eastern boundary of the Sichuan-Yunnan active faulted-block,China

以川滇活动地块东边界为例,利用最近31年的地震资料,根据精细b值计算结果,研究该边界断裂带的应力空间分布及其强震危险性.研究结果显示:(1)沿川滇活动地块东边界,b值空间分布显示在不同断裂以及同一断裂不同断裂段存在较大差异,从而反映出应力积累水平的空间差异.(2)小江断裂带主干断裂上的嵩明凹凸体及存在于主干断裂附近巧家与东川间以及嵩明北西的2个凹凸体、存在于安宁河断裂冕宁附近和则木河断裂西昌附近的凹凸体以及位于鲜水河断裂中南段道孚—乾宁间大尺度的凹凸体将是川滇活动地块东边界未来大震或强震的震源区.

Taken the eastern boundary of the Sichuan-Yunnan active faulted-block in southwestern China as an example, spatial stress distribution and potential strong-earthquake risk have been studied based on detailed b value calculation from seismic data of the last 31 years. The main results show： （1） The spatial distribution of b values displays significant heterogeneity for various faults and fault-segments of the eastern boundary of the Sichuan-Yunnan active faultedblock, which reflects the spatial difference of cumulative stress level along the boundary fault zones. （2） There are several asperities, one located at Songming on Xiaojiang main fault, one between Qiaojia and Dongchuan, and one at northwestern Songming near the main fault, two near Mianning on Anninghe fault and near Xichang on Zemuhe fault, and a large-scale one from Daofu to Qianning on central-southern portion of the Xianshuihe fault. The asperities may be the potential seismogenic sources of large or strong earthquakes along the eastern-boundary in the near future.