关键词: 断裂, 地震, 地表断错, 危险性评价

Abstract: In this paper we introduce the concept of the risk of surface dislocation. The possibility of surface dislocation caused by earthquake is expressed here by probability. The risk of surface dislocation involves earthquake risk as well as the occurrence and distribution feature of surface dislocation. The risk of surface dislocation caused by earthquake can be expressed as(Jiang Pu et al., 1998): P=P₁?P₂?P₃ where P is the risk of surface dislocation caused by earthquake, P₁ represents earthquake risk; P₂ is the probability of the occurrence of surface dislocation at different earthquake magnitudes; P₃ is the distribution probability of the amount of surface dislocation. The earthquake risk can be determined through conventional analysis methods applied in engineering-seismology or through seismo-geological investigation and the analysis of seismic activity. Based on the worldwide data of surface dislocations produced by earthquakes, two parameters for evaluating the risk of surface dislocation are derived. They are the probability index of earthquake magnitude-surface dislocation(P₂)and the probability index of dislocation amplitude and its distribution(P₃), which involves the amplitude, distribution and width of dislocation, as well as the effect of overburden thickness. According to the principle, method and the related probability indexes given in this paper, the risk of surface dislocation in a certain urban area or an engineering site can be quantitatively evaluated.

Key words: fault, earthquake, surface dislocation, risk evaluation