Abstract: Along the valley of the Fubian river,which is located at Mucheng Lianghekou of the Maerkang region in Sichuan Province,there is a hidden fault of NW trending——the Fubian River fault. Occurrence of three major earthquakes during 1989～1991 is associated with this fault. Field investigations and analytical calculations demonstrate that it is one of the fractures in the arc shape structure of the inner Sichuan-Qinghai block. Since Quaternary the activity of this fault is characterized by variant distribution in space and time. Accordingly it has evident marks of segmentation. Under the recent regional stress field this fault has dominant movement of strike-slip. At the southeast end of it. where the trend of the fault changes,a local area of extension occurs.

Key words: Fault activity, Stress analysis, Arcuate zone

摘要： 在四川省马尔康地区木城—两河口一带,沿抚边河河谷有一条隐伏的NW向断裂——抚边河断裂,1989年至1991年该地区发生的3次中强地震与这条断裂有关。大量的野外调查和分析计算表明,这条断裂归属于川青块体内部弧形构造中的断裂,第四纪以来它的活动特征在时间和空间分布上具有不均一性,断裂分段标志明显;在主压应力为NWW向的现代区域构造应力场作用下,断裂活动以走滑为主,且在断裂走向发生变化的东南端形成了局部张性区。

关键词: 断层活动, 应力分析, 弧形带