利用区域地震台网的数字地震波记录资料,由垂直向记录Pg和Sg振幅比值,结合部分清晰的P波初动记录资料,计算得到了1985～2008年在豫北及邻区发生的145个中小地震的震源机制解.通过统计方法、系统聚类分析方法及采用格点尝试法,分析了震源机制解参数并求取了区域平均应力场.结果表明:研究区震源机制解以走滑型为主,应力轴比较接近水平,区域构造应力场以水平挤压为主要特征；震源机制解除走滑型外,还有一定数量的正断型和逆断型.整体显示中小地震震源机制解种类较多,分布散乱,表明小地震发生具有随机性,华北构造应力场整体的控制作用较弱.%Based on the data of digital seismic wave recorded by regional seismic network from 1985 to 2008, the focal mechanism solutions of 145 small and moderate earthquakes which occuired in North Henan and its adjacent region were determined by the amplitude ratio of Pg and Sg in vertical component records with clear initial motion of P-wave. Using the methods of statistic, systematic cluster analysis and grid point test, we analyze the parameters of focal mechanism solutions and calculate the regional mean stress field. The results show that the mainly focal mechanism solutions is strike-slip type, the main stress axis is close to horizon and the main characteristic of the regional tectonic stress field is characterized by horizontal compression in study area There are some normal and reverse fault types beside of strike-slip type for focal mechanism solutions. On the whole the focal mechanism solutions of small and moderate earthquakes have many types and scattering distribution, which indicates that small earthquakes occurred in random, and the whole controlling of tectonic stress field of North China is weak.
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