摘要
1998年1月10日在北京西北约180 km的河北省张北县和尚义县交界地区发生的ML=6.2地震是华北地区近年的重要地震事件.历史上这一地区的地震活动水平不高,迄今在地表未发现有明显活动的断裂.张北-尚义地震发生后,不同机构给出的主震定位结果不尽相同,他们所给出的余震分布也没有显示出优势的展布方向.因此,张北-尚义地震的发震构造亟待研究.本文应用相对定位方法,对张北-尚义地震序列的主震和ML≥3.0余震重新精确定位.得出:张北-尚义地震序列的主震震中位置为41.145N、114.462E,位于宏观震中的北东方向约4 km处,震源深度15 km;余震震源分布在与震源机制解给出的走向为180～200的节面一致的、接近于竖直的平面内及其附近.张北-尚义地震序列的重新精确定位的结果清楚地表明了张北-尚义地震的发震构造是一近南-北向～北北东向的断层.这次地震是在与华北地区构造应力场方向一致的﹑近水平的。
On January 10,1998,an earthquake of ML=6.2 occurred in Zhangbei-Shangyi area,Hebei Province.This earthquake is an important event in the northern China in recent years.Historically,the seismic activity was low in this area.No active fault has been found in the epicentral area.After the occurrence of the Zhangbei-Shangyi earthquake sequence,the hypocentral locations given by different agencies were diverse and the hypocentral distribution of the aftershocks showed no dominate orientation, and the seismogenic structure of the Zhangbei-Shangyi earthquake remained ambiguous and needed to be studied.The main shock of ML=6.2 and aftershocks with magnitude ML≥3.0 of the Zhangbei-Shangyi earthquake sequence were relocated using a relative relocation technique.The epicenter of the main shock was:41.145癗 and 114.462癊,which was located 4 km apart from the macro-epicenter of this event.The focal depth of the main shock was 15 km.The epicenters of the aftershocks distributed in a nearly vertical plane and its vicinity with orientation N180～200癊.The results of relocation for the Zhangbei-Shangyi earthquake sequence clearly indicate that the seismogenic structure of this event is a nearly N-S to NNE striking fault with right-lateral and reverse slip,and that its occurrence is tectonically driven by the nearly horizontal and oriented ENE compression stress,same as that of the stress field in northern China area.
出处
《地震学报》
CSCD
北大核心
2002年第4期366-377,共12页
Acta Seismologica Sinica
基金
国家重点基础研究发展规划(973)
<大陆强震机理与预测>项目(G1998040702)资助课题(95-13-02-04)
中国地震局地球物理研究所论著00AC1017.
