Abstract: The focal stress field of the Xinfengjiang earthquakes shows that the T-axis constantly trends towards NNE and is nearly horizontal, but the P-axis rotates from 0? to 180癷n a vertical plane perpendicular to the T-axis. Under the N-S horizontal tectonic compression the focal stress field is induced by a left-lateral transform fault at Heyuan resulting from the relative sliding between the rock mass in the reservoir area and on its southern side at different rate.

摘要： 引言新丰江水库自蓄水后,发生了一系列地震。区内存在三件基本事实:一、河源断裂近期具左旋错动^[1];二、地震主要沿水库狭谷区呈北西西向分布,河源断裂本身很少地震活动^[1、2];三、震源机制解表明,主张应力轴(T)稳定于北北东向,近于水平,主压应力轴(P)则在垂直T轴面内呈0-180°的旋转。