山西洪洞、临汾历史大震区现今地震的重新定位

利用临汾地区无线传输地震台网资料，对1303年洪洞（M＝8）、1695年临汾（M＝73／4）两次特大地震所在区域1987年－1999年发生的1670次中、小地震进行了重新定位。结果表明，重新定位后震源深度的测定情况比原有结果有很大改善，定位精度明显提高。两次历史大震所在区域中现今地震的密集区，与两次大震各自的高烈度区长轴方向、形状和大小相吻合，反映了历史大震震源断层对现今小震活动的约束作用。小震震源深度的分布情况表明，两次历史大震的震源断层可能都比较浅。重新定位结果为利用现今小震的群体特征研究历史大震的震源断层提供了良好的基础资料。

The redetermination of hypocentral location for present earthquakes in Hongdong and Linfen area,Shanxi province

the hypocentral locations of 1670 medium and small earthquakes in Hongdong( M =8,1303)and Linfen( M =734,1695)areas are redetermined with the data recorded by Linfen wireless seismic network.The result shows that re determined results of forcal depths are much better than the old ones.The precision of hypocentral locations is improved.The dense area of present earthquakes in the region where the two historical strong earthquakes occurred is consistent respectively with the high intensity region of the two historical strong earthquakes in long axis' direction,shape and size.It reflects that present small earthquakes are restricted by focal faults of historical strong earthquakes.The distribution of focal depths of small earthquakes shows that focal faults of the two historical strong earthquakes should be shallow.It provides fine foundational ata for the study of focal fault of historical strong earthquakes with the group feature of present small earthquakes.