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本文是《强余震的时间分布特征及其理论解释》(地球物理学报,1979年1期)的继续。文中分析了我国11个强震的余震序列,结果表明,强余震的空间分布有以下特点: 1.强余震的平面分布。强余震主要分布在断层的两端附近及主震震中附近。 2.强余震的空间迁移具有以下特征: (1)强余震的迁移范围与主震破裂长度相当,且随着时间的推移,迁移的范围越来越大;(2)其总的迁移范围及迁移方向与主震破裂方式有关。对单侧破裂的较大主震,强余震相对其震中呈单侧迁移;对双侧破裂的主震,其强余震相对其主震震中会呈现松弛振荡式迁移;对于双震型地震,强余震往往对第一个“主震”表现为单侧迁移,对于第二个“主震”表现为两头跳现象。 3.强余震的垂向分布:位于主破裂的断层面内,且在其前缘上。 本文从断裂力学和流变学角度,对上述观测事实进行了初步理论解释。
This article is the continuation of the time distribution of strong aftershocks and its theoretical explanation (Journal of Geophysics, 1979, 1). The aftershock sequence of 11 strong earthquakes in China is analyzed in this paper. The results show that the spatial distribution of strong aftershocks has the following characteristics: 1. The plane distribution of strong aftershocks. Strong aftershocks are mainly distributed near the two ends of the fault and near the epicenter of the main shock. (2) The spatial distribution of strong aftershocks has the following characteristics: (1) the migration range of strong aftershocks is comparable with the length of main shock rupture, and the scope of migration increases with the passage of time; (2) the total migration range and Migration direction and the main earthquake rupture mode. In the case of larger mainshocks with unilateral rupture, the strong aftershocks migrate unidirectionally relative to their epicenters. For the main ruptures with bilateral ruptures, their strong aftershocks may exhibit loosely oscillating migration with respect to the epicenter of their mainshock; Aftershocks tend to exhibit a one-sided migration to the first “main shock,” and a “two-headed” phenomenon to the second “main shock.” 3. Vertical distribution of strong aftershocks: Located within the fault plane of the main fault and on its leading edge. In this paper, from the fracture mechanics and rheological point of view, the above observations made a preliminary theoretical explanation.