马边-永善地震带及邻区新构造应力场和现代构造应力场的探讨

A Study on the Neotectonic and Present Tectonic Stress Field in Mabian-Yongshan Earthquake Belt and Adjacent Areas

本文用数学统计方法对马边-永善地震带及邻近地区水系格局的优势方向进行了计算,结合断层滑动参数、原地应力测量、地震震源机制解和三角测量资料进行对比分析认为:构造应力分区与活动的深大断裂围限的褶断隆起区和凹陷区有关,如马边凹陷区构造应力方向为NW向,而雷波-永善褶断隆起区和五莲峰褶断隆起区构造应力方向为NWW-NEE向。该区构造应力场有右旋渐变的特点,自南而北主压应力轴右旋转动约30～40°,并且,全新世以来的现代构造应力场继承了新构造时期构造应力场的特点。

This paper presents a comparison analysis on the drainage pattern,fault slip data,focal mechanism and in-situ stress measurement in the Mabian-Yongshan earthquake belt and its adjacent areas.It is suggested that there are a south and a north area separated by active fault and active tectonics.The directions of principal compression stresses are different,due to the difference of geologic structures.The direction of principal compression stress turned from NEE to NWW then to NW in the southern part of Wulianfeng fault-fold upwarping region and Leibo-Yongshan fault-fold upwarping region to the northern part Mabian downwarping region.The results clearly show that the direction of principal compression stress produce 30°-40°right-turning since late Tertiary period in the areas.