Sgambato Claudia, Faure Walker Joanna Phoebe, Mildon Zoë Keiki, Roberts Gerald Patrick
Institute for Risk and Disaster Reduction, University College London, Gower Street, London, WC1E 6BT, UK.
School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK.
Sci Rep. 2020 Jul 29;10(1):12724. doi: 10.1038/s41598-020-69681-w.
Whether the stress-loading of faults to failure in earthquakes appears to be random or to an extent explainable, given constraints on fault/shear-zone interaction and the build-up and release of stress over many earthquake cycles, is a key question for seismic hazard assessment. Here we investigate earthquake recurrence for a system of 25 active normal faults arranged predominantly along strike from each other, allowing us to isolate the effects of stress-loading due to regional strain versus across- and along-strike fault interaction. We calculate stress changes over 6 centuries due to interseismic loading and 25 > Mw 5.5 earthquakes. Where only one fault exists across strike, stress-loading is dominated by the regional tectonics through slip on underlying shear zones and fault planes have spatially smooth stress with predominantly time-dependent stress increase. Conversely, where faults are stress-loaded by across-strike fault interactions, fault planes have more irregular stress patterns and interaction-influenced stress loading histories. Stress-loading to failure in earthquakes is not the same for all faults and is dependent on the geometry of the fault/shear-zone system.
在地震中，断层因应力加载而导致破坏是看似随机的，还是在一定程度上可以解释的（考虑到断层/剪切带相互作用的限制以及多个地震周期内应力的积累和释放），这是地震危险性评估的一个关键问题。在此，我们研究了一个由25条活动正断层组成的系统的地震复发情况，这些断层主要沿走向彼此排列，这使我们能够分离出区域应变引起的应力加载效应与走向和沿走向断层相互作用的效应。我们计算了6个世纪以来由震间加载和25次震级大于5.5级的地震引起的应力变化。在走向方向上仅存在一条断层的地方，应力加载主要由区域构造作用控制，通过下伏剪切带的滑动实现，断层平面具有空间上平滑的应力，且应力增加主要与时间相关。相反，在断层因走向断层相互作用而受到应力加载的地方，断层平面具有更不规则的应力模式和受相互作用影响的应力加载历史。地震中断层因应力加载而导致破坏的情况并非对所有断层都相同，并且取决于断层/剪切带系统的几何形状。
