Abstract: By the use of the previous information of M_L 6.5 earthquake in the west of Beijing in 1730 together with the data of drills, electromagnetism and gravity, the Qinglongqiao-Qiliqu and Shahe active faults are identified for the first time. Although at present all aspects of the earthquake are not fully known, the authors consider that the two active faults are responsible for the earthquake and the first one plays the leading role. The establishment of seismogenic faults and epicenter of the earthquake will benefit for the disaster mitigation and city construction of Beijing.

Key words: active faults, earthquake, seismogenic faults, epicenter

摘要： 在前人研究1730年北京西郊6.5级地震的基础上，综合井孔、电磁和重力资料，经分析初步确定了青龙桥—七里渠活动断层和沙河断陷南缘活动断层的存在及其位置、规模和基本特征，认为这两条活动断层是此次地震的发震构造，其中青龙桥—七里渠断层在此次地震中起主导作用。对这两条活动断层的形成机制作了简单的力学分析，认为青龙桥—七里渠活动断层应该向南北继续延伸。这些活动断层和震中位置的确定，有利于首都地质灾害防治和城市建设。

关键词: 活动断层, 地震, 发震构造, 震中