潮汐应力与大震关系研究

选用1976—2009年全球震源深度小于70 km, M_W≥7.0的地震为研究对象, 利用震源机制解资料, 对每个地震的发震断层面进行了判断, 得到233个地震的发震断层面解。 据此, 本文讨论了发震时断层面上的地球固体潮汐剪应力方向与滑动方向的关系以及潮汐正应力在发震时所处的相位, 发震时断层面的库仑应力值。 结果表明, 当潮汐剪应力方向与滑动方向一致时触发作用最为明显, 逆断层地震与潮汐的关系最为密切; 而当潮汐剪应力方向与滑动方向相反时, 地震较少发生。

Relationship of Tidal Stress and Large Earthquakes

In this paper, we focused on global earthquakes with M_W≥7.0 and hypocenter depths less than or equal to 70 km from the Harvard Centroid Moment Tensor (CMT) catalog during the period from 1976 to 2009. We obtained fault plane solutions of 233 earthquakes by choosing the real fault plane of each earthquake through the focal mechanism solution. Based on this, we discussed the relationship between the direction of tidal shear stress on the real fault plane and slip direction. At the same time, the phases of tidal normal stress and Coulomb failure stresses on the fault plane in the origin time are calculated. The results show that there are obvious triggering effects when the direction of tidal shear stress is the same with the slip direction, while earthquakes rarely occur when tidal shear stress goes in the opposite directions, and reverse fault earthquakes have the closest relationship with tide.