Manighetti Isabelle, Perrin Clément, Gaudemer Yves, Dominguez Stéphane, Stewart Nicholas, Malavieille Jacques, Garambois Stéphane
Université Côte d'Azur, OCA, IRD, CNRS, Géoazur, Valbonne Sophia Antipolis, France.
Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, CNRS, Paris, France.
Sci Rep. 2020 Feb 7;10(1):2124. doi: 10.1038/s41598-020-59229-3.
The Mw 7.8 2016 Kaikoura earthquake ruptured the Kekerengu-Needle fault resulting in the loading of its eastern continuation, the Wairarapa fault. Since the most recent earthquake on Wairarapa occurred in 1855 and is one of the strongest continental earthquakes ever observed, it is critical to assess the seismic potential of the Wairarapa fault, which might be prone to break. Using Lidar data, we examine its bare-earth morphology and reveal ~650 mostly undiscovered offset geomorphic markers. Using a code we developed in earlier work, we automatically measure the lateral and vertical offsets of these markers providing more than 7000 well constrained measurements. The data document the lateral and vertical slip profiles of the 1855 earthquake for the first time and show its total slip reached ~20 m at surface. Modeling the entire offset dataset reveals 7 prior earthquakes ruptured the entire fault, each similarly producing 16.9 ± 1.4 m dextral slip and ~0.6 m vertical slip at surface in the same central bend zone of the fault. Thus, the Wairarapa fault repeatedly produced giant earthquakes and is likely able to produce a similarly strong forthcoming event. The extreme large size of the Wairarapa earthquakes questions our understanding of earthquake physics.
2016年发生的里氏7.8级凯库拉地震致使凯克伦古-尼德尔断层破裂，从而对其东部延伸段怀拉拉帕断层产生了应力加载。鉴于怀拉拉帕断层上一次地震发生在1855年，且是有史以来观测到的最强大陆地震之一，评估可能易于断裂的怀拉拉帕断层的地震潜力至关重要。利用激光雷达数据，我们研究了其裸地地貌，并发现了约650个大多未被发现的错动地貌标志。使用我们在早期工作中开发的代码，我们自动测量了这些标志的横向和垂直错动，提供了7000多个约束良好的测量数据。这些数据首次记录了1855年地震的横向和垂直滑动剖面，并显示其地表总滑动量达到约20米。对整个错动数据集进行建模显示，之前有7次地震使整个断层破裂，每次在断层同一中央弯曲带地表均产生16.9±1.4米的右旋滑动和约0.6米的垂直滑动。因此，怀拉拉帕断层反复发生巨大地震，并且很可能能够产生一次同样强烈的未来地震。怀拉拉帕地震的极端巨大规模对我们对地震物理学的理解提出了质疑。
