西北地震学报2013，Vol.35Issue(2)：289-295,7.DOI:10.3969/j.issn.1000-0844.2013.02.0289
利用多个震源机制解求祁连山西段平均应力场方向
Determination of the Direction of the Mean Stress Field in the Western Qilian Mountains through Focal Mechanism Solution Analysis
摘要
Abstract
The western segment of the Qilian Mountains,which is controlled by some tectonic blocks,has complicated geography and geology.This study looked at 14 strong-moderate earthquakes and 66 small-moderate earthquakes from 2001 to 2012,used the stress tensor averaging method to calculate the direction of the mean stress axis in the area,and then analyzed the characteristics of the stress field.Moreover,we compared the results with another inversion result by using the FMSI inversion process.Finally,we conducted a detailed study of the tectonic stress field characteristics of the western segment of the Qilian Mountains.With the stress tensor calculation method,we obtained the average direction of T,B,and P axes by calculating the average stress tensor of focal mechanism solutions from multiple earthquakes.If the earthquake has a relatively independent discrete distribution in the block,we can deduce the direction of the principal stress axes in the regional tectonic stress field on the basis of the average direction of T,B,and P axes.In our research,we selected two groups of data,strong-moderate earthquakes and smallmoderate earthquakes from 2001 to 2012.We obtained 14 focal mechanism solutions for strongmoderate earthquakes occurring since 1900,with 4 above Ms6.0 and 10 between Ms5.0 and Ms 5.9.Furthermore,another was the earthquake that occurred on December 25,1932,the large Changma Ms7.6 in the western Changma fault.In addition,we used the CAP method and the vertical P-wave and S-wave amplitude ratio method to calculate the focal mechanisms of smallmoderate earthquakes.The focal mechanisms show that the characteristics of focus are mainly strike-slip and thrust earthquakes.The quantification results for stress tensor in three regions show that the azimuth of maximum principal compressive stress,σ1,is NE,and the horizontally compressed acts show evidence of definite subarea characteristics.关键词
应力张量/祁连山西段/应力场/震源机制解Key words
Stress tensor/ Western segment of Qilian Mountain/ Stress field/ Focal mechanism solution分类
天文与地球科学引用本文复制引用
王熠熙,张辉..利用多个震源机制解求祁连山西段平均应力场方向[J].西北地震学报,2013,35(2):289-295,7.基金项目
国家自然科学基金(41174059) （41174059）
中国地震局兰州地震研究所地震科技发展基金(2012M01) （2012M01）
中国地震局定向跟踪任务(2012020101) （2012020101）
