【摘要】 为了研究地壳结构特征与强震孕育的关系,运用三维有限单元法,计算了邢台地震区壳内应力场的扰动状态。结果表明:地壳内深、浅断裂的存在,造成沿直立断层带的应力相对集中和不同部位的变化。在其上部出现平均应力和水平剪应力的增加,中下部出现平均应力的减小和水平剪应力的增加。前者有利于弹性位能的高度集中和主破裂的发生,后者有利于主破裂前蠕滑的发生。地壳内高速体、低速体、深断裂、莫霍面隆起是孕育强震的主要构造因素,但影响程度,范围、形式不同,高速块体是应力增强的体;直立断层带上及其邻近应力集中程度最高,应力变化梯度最大,是产生震前预滑及主余震发生的有利部位;莫霍面隆起加剧高速体内的应力增强,加大断层带上的应力变化梯度而有利于地震的孕育和发生。更多还原

【Abstract】 Using 3-D finite element method the state of stress field disturbance in Xingtai earthquake area is simulated. The corresponding results indicate that the existence of deep and shallow faults causes a different stress concentration around them. In the upper section of the vertical fault the mean stress and the horizontal shear thress increase, while in the central and the low section the mean stress decreases and the horizontal shear stress increases’ respectively. The former should be beneficial to the accumulation of the elastic potential energy and to the creation of the main rupture. The latter should be beneficial to the creeping slip before the main rupture. The existence of the combined high-low velocity body, vertical fault beeply buried in the crust and the upward movement of upper mantle are the important structural factors for earthquake preparation. The high velocity body is the main part for stress concentration. The creeping slip before an earthquake and the occurrence of main shock should take place within or near the vertical fault, as the stress concentration and the graient of stress change are biggest around there. The upward movement of upper mantle augments the stress concentration level greatly. This should raise the risk of the preparation and occurrence of an earthquake.更多还原