Abstract: Unstable events taking place alternately along two intersecting faults is proved by physical modeling. Two intersecting faults promote and restrain each other during deformation. One fault may make the other be locked for strain accumulation and may trigger slip along it. Slip rate, net slip and the numbers of unstable events depend on the orientation of the fault with respect to the principal stress axes. The slips along different fault segments show both translation and rotation of the fault block surrounded by them in the experiment. The affected area of unstable event is different for events occurred on different parts of the sample and it is wider for the event along the fault with high normal stress. Small precursory events usually occur before strong instability involving the intersecting faults. In fact, the movement of the fault block in the deformation field controls the alternate slips of intersecting faults.

Key words: Intersecting faults, Alternate slip, Block movement, Observation of physical field

摘要： 通过物理模拟证明交叉断层上会交替地发生失稳事件。两条交叉的断层在活动中既相互促进,又相互制约,即一条断层既可能使另一条断层发生闭锁而积累应变,又可能触发其错动。每条断层的位移速率、总位移量以及失稳事件数与断层方向和主压应力轴的夹角有关。各断层段的位移有时体现为断层围限块体的平移运动,而有时则体现为块体的旋转运动。发生在不同部位的失稳事件影响范围不同,在正应力较大的断层上失稳事件影响范围大。涉及交叉断层的较大失稳事件发生前常出现前兆性小事件。交叉断层的交替活动实际上由变形场中块体的运动所控制。

关键词: 交叉断层, 交替活动, 块体活动, 物理场观测