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

摘要： 引入地震断错危险性概念,用概率表示发生断错的可能性大小,断错危险性涉及到地震危险性和断错发生与分布特点.断错危险性的表达式为:P=P₁×P₂×P₃,式中,P表示断错危险性;P₁表示地震发生的危险性;P₂指不同震级条件下地表断错出现的概率;P₃为断错量值分布概率.以中国和世界地表地震断错资料为基础,建立震级-断错概率指数P₂和断错幅度及其分布概率指数,包括幅值及其分布、宽度和覆盖层厚度影响等指数P₃,为地表断错危险性量化评估奠定了基础.

关键词: 断裂, 地震, 地表断错, 危险性评价