Abstract: The deformation and gravity remeasurement data which are used to monitor the activity of the Nankou mountain frontal fault in Beijing is analysed systematically.It is suggested that each segment of the fault shows differential activities.The segment from Shangkou to Nankou has small amplitude of activity.The Nankou-Baiyangcheng segment has persistent activity at a larger rate.The Baiyangcheng-Mabaoquan segment is characterized by discontinuous wrench or tensional movement.The style of the fault may have been changed prior to and following major earthquakes.The development process of major earthqukae may be representative of the regional tectonic activity.The deep activities of each segment of the Nankou mountain frontal fault are in unity and there exists local strong tectonic motion.Much attention should be paid to this fault,in particular to the Nankou-Baiyangcheng segment.where major earthquakes may occur.

Key words: Fault activity, Crustal deformation survey, Gravity survey

摘要： 系统分析了监测南口山前断层活动性的形变及重力复测资料。研究认为：断层各段的活动性存在明显差异,上口～南口段活动幅度小,南口～白羊城段为持续张性活动,活动速率较大,白羊城～马刨泉段呈现间断性的扭动或张性活动；强震发生前后,断层活动方式发生转折,表明强烈地震的孕育发展进程,影响着区域构造活动的特性；南口山前断层各段深部活动具有统一性,并存在剧烈的局部构造活动；应重视南口山前断层发生强烈地震的可能性。特别是南口～白羊城段。

关键词: 断层活动性, 地壳形变测量, 重力测量