摘要
研究了宁夏南部地区 ( 35°2 0 '～ 37°40 'N ,1 0 4°30 '～ 1 0 6°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。
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 P n and P g 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.
出处
《西北地震学报》
CSCD
北大核心
2001年第2期142-148,共7页
Northwestern Seismological Journal
关键词
宁夏
应力场
震源机制解
P轴
地震活动趋势
Ningxia
Stress field
Focal mechanism solution
P axis
Trend of seismicity
