Faure Yohann, Bayart Elsa
Laboratoire de Physique, Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS, 46 allée d'Italie, Lyon, 69007, France.
Nat Commun. 2024 Sep 19;15(1):8217. doi: 10.1038/s41467-024-52492-2.
Seismic faults release the stress accumulated during tectonic movement through rapid ruptures or slow-slip events. The role of slow-slip events is crucial as they impact earthquakes occurrence. However, the mechanisms by which slow-slip affects the failure of frictionally locked regions remain elusive. Here, building on laboratory experiments, we establish that a slow-slip region acts as a nucleation center for seismic rupture, enhancing earthquakes' frequency. We emulate slow-slip regions by introducing a granular material along part of a laboratory fault. Measuring the fault's response to shear reveals that the heterogeneity serves as an initial rupture, reducing the fault shear resistance. Additionally, the slow-slip region extends beyond the heterogeneity with increasing normal load, demonstrating that fault composition is not the only requirement for slow-slip. Our results show that slow-slip modifies rupture nucleation dynamics, highlighting the importance of accounting for the evolution of the slow-slip region under varying conditions for seismic hazard mitigation.
地震断层通过快速破裂或慢滑事件释放构造运动过程中积累的应力。慢滑事件的作用至关重要，因为它们会影响地震的发生。然而，慢滑影响摩擦锁定区域失稳的机制仍然难以捉摸。在此，基于实验室实验，我们确定慢滑区域作为地震破裂的成核中心，增加了地震的频率。我们通过在实验室断层的一部分引入颗粒材料来模拟慢滑区域。测量断层对剪切的响应表明，这种非均匀性作为初始破裂，降低了断层的抗剪强度。此外，随着法向载荷的增加，慢滑区域超出了非均匀性范围，这表明断层组成并非慢滑的唯一条件。我们的结果表明，慢滑改变了破裂成核动力学，突出了在不同条件下考虑慢滑区域演化以减轻地震灾害的重要性。
