震级—破裂长度关系与断层破裂模型

现代工程地震的进展之一是对所论地区作概率的地震危险性分析。1968年,Cornell首先对地震危险性分析作系统的研究,提出了著名的“点源模型”。70年代,洪华生(A.H-S)等提出断层破裂模型。该模型假设,断层破裂长度仅由震级决定,场地烈度由场地到断层破裂区的最短距离决定。由于断层破裂模型的广泛使用,震级-破裂长度关系的研究已成为危险性分析工作的一部分。

RUPTURE LENGTH MAGNITUDE RELATIONSHIP AND FAULT-RUPTURE MODEL

There have been many papers on rupture length magnitude relationship, most of which are based on single method. Owing to the frequent use of fault-rupture model introduced by Der Kiureghian and Ang, the relation between rupture length and magnitude has been an important part in the seismic risk analysis. There are many methods to calculate rupture lengths of earthquakes, which can be divided into three kinds. The first arc empirical method, such as directly taking measures of long axes of aftershock areas, fault and deformation belts on the earth surface, and the long axes of isoseismals of 8 degree. The second is a combination of theory and pratice, such as calculating rupture length based on isoseismals, seismic wave or deformation survey data. The third is a theoretical method. That is to introduce a function of rupture length and magnitude theoretically, and the determination of contants relies in the parameters of the model. In this paper, based on 103 earthquake examples in the main-land of China, various above methods are compared and rupture length-magnitude empirical formulae are obtained by regression and multivariate analysis.There are obvious inherent uncertainty in rupture-length magnitude relationship, which can be seen practically and theoretically. A recommendable method to eliminate the uncertainty in seismic risk analysis is to avoid the use of rupture length magnitude relation, that is to introduce a seismic risk analysis model without above relation, which will be given in another paper