CAJ | 학술논문

研究了宁夏南部地区（35°20＇～37°40＇ N，104°30＇～106°30＇ E）小震综合机制解的变化特征．发现在中强地震前，该地区小震综合机制解的P轴方位偏离平均值，向E或SE偏转，其仰角有增大的趋势，同时小震纵波（Pn和Pg）初动符号一致．6次中强地震的震源机制解表明，该地区P轴方位与主压应力方向基本一致，因此该地区发生破坏性地震的可能性不大．近几年来的地震活动图像显示，该地区的地震活动有向中卫、中宁和同心地区集中的迹象．
연구료저하남부지구（35°20＇～37°40＇ N，104°30＇～106°30＇ E）소진종합궤제해적변화특정．발현재중강지진전，해지구소진종합궤제해적P축방위편리평균치，향E혹SE편전，기앙각유증대적추세，동시소진종파（Pn화Pg）초동부호일치．6차중강지진적진원궤제해표명，해지구P축방위여주압응력방향기본일치，인차해지구발생파배성지진적가능성불대．근궤년래적지진활동도상현시，해지구적지진활동유향중위、중저화동심지구집중적적상．
The variation features of synthetic focal mechanism solution of small earthquakes before mid-strong earthquakes in south Ningxia region are studied.It is found that direction of the P axes drifted off average values and turned to E or SE,being accompanied by identified first motion mark of Pn and Pg waves of small earthquakes.The focal mechanism solutions of 6 mid-strong earthquakes in south Ningxia region show that the earthquakes occurred under the affect of principal compressive stress of NE,with no somewhat change in comparison with direction of principal compressive stress of regional stress field.So the possibility of the destructive earthquakes to occur in the region is smaller .But patterns of seismicity in recent years show it is possible that seismicity is going to concentrate in Zhongwei,Zhongning and Tongxin region in the future.