Abstract: In the paper,we relocate the small earthquakes occurring in Linfen region from 1981 to 2010 by using the double-difference earthquake location algorithm. Our result shows that the distribution of relocated earthquakes is characterized by cluster activities,and most of the them occurred at the depths of 5～11km and 15～27km,which suggests that the two main seismogenic layers in this region are located in the upper and mid-upper crust. Earthquake frequency is high along both sides of the Subu Fault zone in the northern Linfen Basin,and most of the earthquakes in the north of Subu Fault zone are deeper than that in the south of Subu Fault. To some extent,this result indicates that the regional tectonic setting plays a major control role in the distribution of earthquakes. Analysis on the distribution of earthquake focal depths reveals that there exist deep faults which cut through the crust into the mantle in the middle of the Linfen Basin and connect with the active faults around the basin in the upper crust. The dislocations along the active faults on both sides of the basin are a reflex on the surface of faulting of the deep faults beneath the central basin.

Key words: the double-difference earthquake location algorithm, seismotectonics, deep faults, Linfen region

摘要： 应用双差地震定位法对临汾地区1981—2010年发生的地震进行重新定位，重定位的地震表现为丛集性分布；临汾地区地震多发生在5～11km 和15～27km 2个范围内，表明这2层是研究区的主要发震层，即基本位于地壳的中上部和中地壳层。临汾盆地北部苏堡断裂两侧地震频度高，且断裂以北多数震源深于以南地区，表现出区域构造对地震的控制作用。地震震源分布的构造成因分析表明，在临汾盆地中部有切穿地壳至地幔的深大断裂存在，盆地周边的活动断裂在上地壳与其相连，盆地两侧的活动断裂的错断活动是盆地中部深大断裂活动在地表的反映。

关键词: 双差定位法, 地震构造, 深大断裂, 临汾地区