Bletery Quentin, Nocquet Jean-Mathieu
Université Côte d'Azur, IRD, CNRS, Observatoire de la Côte d'Azur, Géoazur, 250 rue Albert Einstein, 06560, Valbonne, France.
Institut de Physique du Globe de Paris, Université de Paris, CNRS, 75238, Paris, France.
Nat Commun. 2020 May 1;11(1):2159. doi: 10.1038/s41467-020-15494-4.
Both laboratory experiments and dynamic simulations suggest that earthquakes can be preceded by a precursory phase of slow slip. Observing processes leading to an acceleration or spreading of slow slip along faults is therefore key to understand the dynamics potentially leading to seismic ruptures. Here, we use continuous GPS measurements of the ground displacement to image the daily slip along the fault beneath Vancouver Island during a slow slip event in 2013. We image the coalescence of three originally distinct slow slip fronts merging together. We show that during coalescence phases lasting for 2 to 5 days, the rate of energy (moment) release significantly increases. This observation supports the view proposed by theoretical and experimental studies that the coalescence of slow slip fronts is a possible mechanism for initiating earthquakes.
实验室实验和动态模拟均表明，地震之前可能会出现缓慢滑动的前兆阶段。因此，观察导致缓慢滑动沿断层加速或扩展的过程，是理解可能导致地震破裂的动力学的关键。在这里，我们利用对地面位移的连续GPS测量，来成像2013年一次缓慢滑动事件期间温哥华岛下方断层的每日滑动情况。我们成像了三个原本不同的缓慢滑动前沿合并在一起的过程。我们表明，在持续2至5天的合并阶段，能量（矩）释放速率显著增加。这一观察结果支持了理论和实验研究所提出的观点，即缓慢滑动前沿的合并是引发地震的一种可能机制。
