太白维山山前断裂活动特征的初步研究

A PRELIMINARY STUDY OF THE ACTIVE CHARACTERISTICS OF THE PIEDMONT FAULT OF THE TAIBAIWEI MOUNTAIN

本文立足于大量的野外第一手资料，综合解剖了太白维山山前断裂的几何结构，并就其运动学特征进行了初步探讨。认为：太白维山山前断裂第四纪以来的活动表现为正断型，其几何结构和运动特征都有着相同的分段性。我们将其划分为三段，西段结构简单，晚更新世以来无明显活动；中段结构复杂，一直强烈活动；东段活动强度较低。晚更新世晚期以来断裂（中段）的平均滑动速率为０．４ｍｍ／ａ，全新世以来达到０．６７ｍｍ／ａ，而且这种速率分布在断裂上变动幅度很大。断裂的活动以突然发生的快速错动事件为特征，近两万年以来沿断裂带可能发生了５次７级左右的地震事件，其平均重复间隔为３０００年左右。

Based on a large number of field investigations, this paper comprehensively dissects the geometric structure of the piedmont fault of the Taibaiwei mountain and makes a preliminary discussion on its kinematic characteristics. It is considered that the activity of the piedmont fault of the Taibaiwei mountain has been a normal fault one since the Quaternary period I its geometric structure and kinematic characteristics showed a same sectional property. It is divided into 3 sections, the structure of the west section is simple, which has not shown remarkble activity since Epileistoeene I the structureof the middle one is complex, which has shown strong activity, the activity strength of the east is relatively low. The average slip rate of the fault (middle section) has beeno. 4mm/a since late Epileistocene, reachihg 0. 6mm/a since recent and this slip rate varied greatly on the fault. The fault activity is characterized by sudden quick displacement events, 5 seismic events of magnitude 7 or so probablly occurred along the fault in the past twenty thousand years, the average repeat interval being about three thousand years.