发震构造的第三种型式

THIRD TYPE OF SEISMOGENETIC TECTONIC PATTERN

提出了一种新的发震构造型式－转换破裂型。其特征是地震不发生在主干断裂和共轭断裂面上，而是在其两侧一定距离的岩块中；发震断裂不与其平行而是成一定的交角；震源机制解的三个力轴与构造应力场相对应的三个力轴不一致，而是有规律地旋转了一定的角度。其成因是沿主干断裂或共轭断裂的两侧岩块，在滑动过程中对其前后邻接的岩块产生了一个转换应力场而引起的剪切破裂。

New type of seismogenetic tectonic pattern-transform fracture type is discussed in this paper. These earthquakes occured neither on major fault, nor on conjugate fault, but on rock mass at a distance from major fault and conjugate fault. A long axis of seismic intensity oftenintersect with them and the surface faults don't occur obviously. Two nodal in focal mechanism make a certain angle with them. Focal stress field differs from the tectonic stress field. If the axis of focal stress field is changing the tectonic stress field can be renewed. It is the basic characteristics of the transform fracture type for seismogenetic tectonic pattern.