福建近岸海域滨海断裂的应力分析

Stress analysis on the Binhai fault in Fujian coastal sea area

福建东南沿海地区曾发生多次强震。本文利用该区1604～1989年的47次地震的震源机制资料,采用力轴张量计算法推算了该区应力主轴方向,结果与其他文献给出的主压应力方向相符,即北西西-南东东向。在此基础上,得到最大剪切应力平面的走向和倾角。讨论了最大剪切应力平面与福建沿海近岸海域中存在的滨海断裂(牛山岛兄弟屿断裂)的位置关系。从应力分析的角度初步探讨了滨海断裂带上地震活动由北向南增强的原因。

A number of strong earthquakes have taken place in Fujian southeast coastal region. With the focal mechanism data of 47 main earthquakes Occurred in this region from 1604 to 1989, we deduced the directions of 3 stress principal axes by using the calculating method of mechanical axis tensor. The direction of principal compressive stress axis is consistent with the description of stress status provided by other literature, and it is in NWW-SEE. On this basis, we obtained the strike directions and dip angles of the maximum shear stress planes. Orientation relationship between the maximum shear stress planes and the Binhai faults in South-east Fujian sea area were discussed in the paper. In summary, from the stress analysis point of view,we made a preliminary approach to the reason that the seismic activities in the coastal fault zone strengthen from north to south.