用滑动方向拟合法反演富蕴地震断裂带应力场

STRESS FIELD IN THE FUYUN, XINJIANG EARTHQUAKE FRACTURE ZONE DETERMINED BY FITTING FAULT SLIP VECTOR DATA

  • 摘要: 本文根据野外考察测得的1931年新疆富蕴8级地震形成的地震断裂带内42组断层水平和垂直位移数据,求得42个断层面上的滑动方向.利用滑动方向拟合法(使计算的断层面上的剪切力方向与观测的滑动方向之间夹角最小)求出了断裂带上由北向南四个区段的驱动断层滑动的平均应力场.结果表明,四个区段的最大和最小主压应力轴皆水平,最大主压应力轴方位大致在 N15E 至 N30E 之间.整个断裂带的应力场相当均一,这说明富蕴大地震的发震原因不象是局部因素,而可能是大范围构造运动的结果.

     

    Abstract: Based on the horizontal and vertical offset data of 42 faults obtained from field survey in the epiceutral zone, caused by the great 1931 Fuyun earthquake of magnitude 8, the slip directions on the fault planes are deduced. The mean stress fields corresponding to 4 segments, from north to south, of the fracture zone have been estimated by minimizing the angle between the calculated shear stress and the observed slip vector on each fault.The result indicates that for the 4 segments the maximum and minimum compressive principal stress axes are all horizontal, while the maximum compressive principal stress axes take approximately the azimuths between N15E to N30 E. The overall stress field in the entire fracture zone is rather homogeneous, this implies that the underline cause for the great Fuyun earthquake could hardly be some local factors, but possibly tectonic movement on a large scale.

     

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