1976年龙陵—潞西7.3、7.4级地震的共轭破裂及其极限主应力

1976 Longling Earthquakes Conjugate Ruptures and Its limitation of Principal Stresses Accompanying Variation of Depths in the Crust

一、引言共轭破裂构造由相互交叉的两组断裂组成,在地壳岩石中十分常见。李四光称其为“棋盘格式构造”;张文佑称其为“X”型构造系,并做出共轭破裂构造形成的实验;丁国瑜认为,我国广大区域普遍存在现今正在活动的北东和北西方向共轭的地壳破裂网络图像:张四昌对我国11次强震共轭破裂构造特征进行了总结。

Many examples show that earthquakes can form conjugate ruptures. The temperatures and pressures at the focus is different from the shallow of the crust and the ground. The higher temperatures and pressures, the larger conjugate rupture angles. Accompanying decrease of depths, temperatures and pressures become small and the conjugate rupture angles also become small. The conjugate angles of isoseismic lines on the ground also become small. The pure shear ruptures easy appear at the focus. The tension shear ruptures easy appear near shallow places of the crust from the focus upward. The paper discusses the conjugate ruptures of the Longling earthquakes and its limiting principal stresses accompanying variation of depths in the crust by mathematics mechanics methods and the result of rock mechanics experiments.