小江断裂带西支中南段断裂与地震活动性

The activity and seismicity in the middle-south segment of west-branch of the Xiaojiangfault

根据野外的实地调查与探槽开挖,对小江西支断裂中南段杨林—前所、乌纳—阳宗海、阳宗海—澄江等分支断裂的展布特征、活动性进行研究.结果表明:3条分支断裂作多重左阶斜列展布,第四纪活动以左旋走滑为主兼有倾向运动;其中杨林—前所、乌纳—阳宗海断裂全新世以来左旋走滑活动强烈,为公元1833年嵩明8级大震的发震断裂.阳宗海—澄江断裂全新世活动显著,为公元1750年澄江61/4级地震的发震构造.

Based on the field investigation and the trench excavation,we survey the distributional characteristics and activity of Yanglin-Qiansuo,Wuna-Yangzonghai and Yangzonghai-Chengjiang faultsinthe middle-south segment of west-branch of the Xiaojiang fault zone.The results showed that:These three branch faults are distrib-uted in multiple left-order oblique series,and the Quaternary activities are mainly sinistral strike-slip with in-clined movement;Yanglin-Qiansuo,Wuna-Yangzonghai faults faults have been active in left-lateral strike-slip since the Holocene,which is the seismogenesis fault of the Songming M_(S)8 earthquake in 1833 AD.The Yangzonghai-Chengjiang fault has significant activity in Holocene,which is the seismogenic structure of Chengjiang M_(S) 61/4 earthquake in 1750 AD.