Slip tendency analysis as a tool to constrain fault reactivation: A numerical approach applied to three‐dimensional fault models in the Roer Valley rift system (southeast Netherlands)
Slip tendency analysis as a tool to constrain fault reactivation: A numerical approach applied to three‐dimensional fault models in the Roer Valley rift system (southeast Netherlands)
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DOI：
10.1029/2003jb002586
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发表时间：
2004-02
影响因子：
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通讯作者：
G. Wórum;J. Wees;G. Bada;R. Balen;S. Cloetingh;H. Pagnier
中科院分区：
文献类型：
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作者：
G. Wórum;J. Wees;G. Bada;R. Balen;S. Cloetingh;H. Pagnier
我们描述了一种新的数值方法来约束断层再活化的三维（3-D）模式。利用构造应力场的知识，在三角形表面模拟的断层上的每个位置处计算分解的剪应力和正应力（滑动倾向）的比率以及剪应力的方向。虽然计算的接触应力仅代表真实的应力的一阶近似值，但将滑动趋势的3‐D模式与断层的摩擦阻力进行比较，可以对断层再活化的概率提供有用的约束。该方法被应用于鲁尔谷裂谷系（荷兰东南部）的三维几何断层模型，该模型目前具有明显的构造活动性。输入应力张量受公布的应力指标的约束。分析表明，所观察到的断层活动可以解释在一个合理的范围内的摩擦参数和输入应力大小。此外，预测的滑动方向与当地地震的震源机制解之间也有较好的相关性。这表明，在研究区，在地壳的最上部有效的断层模型是适合的，以限制断层复活，即使在更深的部分的孕震层。分析进一步表明，断裂系统的断裂等级和区域构造环境是断裂复活的重要因素。因此，在评估计算的滑动趋势和滑动方向模式时，应始终考虑这些因素。
We describe a new numerical approach to constrain the three‐dimensional (3‐D) pattern of fault reactivation. Taking advantage of the knowledge of the tectonic stress field, the ratio of the resolved shear and normal stresses (slip tendency) as well as the direction of the shear stress is calculated at every location on the faults modelled by triangulated surfaces. Although the calculated contact stresses represent only a first order approximation of the real stresses, comparison of the 3‐D pattern of slip tendency with the frictional resistance of the fault can provide useful constraints on the probability of fault reactivation. The method was applied to 3‐D geometrical fault models in the Roer Valley Rift System (southeast Netherlands) which is presently characterized by pronounced tectonic activity. The input stress tensors were constrained by published stress indicators. The analysis demonstrated that the observed fault activity could be explained within a reasonable range of frictional parameters and input stress magnitudes. In addition a fairly good correlation was found between the predicted slip directions and the focal mechanisms of local earthquakes. This suggests that in the study area, fault models being valid in the uppermost part of the crust are suitable to constrain fault reactivation even in the deeper part of the seismogenic layer. The analysis further demonstrated that fault hierarchy and the regional tectonic contexts of the fault system are important factors in fault reactivation. Therefore they always should be taken into account during evaluation of the calculated slip tendency and slip direction patterns.