Abstract: This paper deals with the indicator system of net deformation ratio (NDR) of crustal movement,such as the bending deformation ratio in horizontal direction on the land surface S,the differential movement ratio in the vertical direction on the land surface τ,and the total deformation strength of crustal movement M_t.NDR system is a suit of dynamic geological indicators for quantitating seismic risk.We have made compution on NDR system of crustal movement prior to 5 earthquakes(M>6)occurring in 1966～1996 in the North China,and have found a close relation between abnormal mark on NDR system and seismic event.This method is used in forecast of earthquakes,engineering seismology,evaluation of crustal activity and study of geodynamics.

Key words: Crustal movement, Seismic risk evaluation, Earthquake precursor

摘要： 地壳运动全变率指标(NDR)系由地表横向变形弯曲度S,垂向切变反差度τ和地壳运动总强度M_t组成,是一组定量表示地震危险性的动态地质标志。对华北地区1966～1996年5次地震(M>6)震前地壳运动进行NDR系计算,发现NDR系异常特征与地震事件间存在密切关系。该法对地震预报、工程地震、评估地壳活动性及地球动力学研究等方面,具有广泛的应用前景。

关键词: 地壳运动, 地震危险性评估, 地震前兆