祁连山强震构造带分段及其地震危险性评估

SEGMENTATION AND RISK ESTIMATION AND RISK EQRTHQUAKES ON QILANSHAN ACTIVE FAUL ZONE

祁连山强震构造带由祁连山北缘断裂和海原断裂组成。断裂带主要表现为压扭性左旋滑动，最大滑动速率达９ｍｍ／ａ。沿带有一系列的古地震事件，且有多次历史地震发生。海原８．６级地震就发生在该带上。根据该带的断裂活动习性，按照一定的原则和依据划分成３个一级断层段和１７个二级断层段。建立了古地震、历史大震图像识别和地震重现间隔二元分析的数学模型。在此基础之上对该带作了地震危险性别定，划分出３个Ａ类危险段和４个Ｂ类危险段。

Qilianshan active fault zone is situated in the northeastern border of Tibet Plateau.It con-sists of North Qilianshan fault and Haiyuan fault. It is mainly a compressive-sheared and sinis-tral-slipping fault zone，its slip rate at most up to 9mm／a。Many ancient earthquakes and histori-cal earthquakes occurred in the zone.On the basis of the active behavior of the fault zone，threesections and seventeen segments were divided．According to the relation of ancient earthquakes，slip rate and length of segrnents，a bivariate regreession model was set up． The evalution of riskwas made. Finally，we can disfinguish between three risk segments of type A and four risk seg-ments of type B.