Despite decades of observational, laboratory and theoretical studies, the processes leading to large earthquake generation remain enigmatic. However, recent observations provide new promising perspectives that advance knowledge. Here, we review data on the initiation processes of large earthquakes and show that they are multiscale and diverse, involving localization of deformation, fault heterogeneities and variable local loading rate effects. Analyses of seismic and geodetic data reveal evidence for regional weakening by earthquake-induced rock damage and progressive localization of deformation around the eventual rupture zones a few years before some large earthquakes. The final phase of deformation localization includes, depending on conditions, a mixture of slow slip transients and foreshocks at multiple spatial and temporal scales. The evolution of slip on large, localized faults shows a step-like increase that might reflect stress loading by previous failures, which can produce larger dynamic slip, in contrast to the smooth acceleration expected for a growing aseismic nucleation phase. We propose an integrated model to explain the diversity of large earthquake generation from progressive volumetric deformation to localized slip, which motivates future near-fault seismic and geodetic studies with dense sensor networks and improved analysis techniques that can resolve multiscale processes.

尽管进行了数十年的观察，实验室和理论研究，导致大地震发生的过程仍然是个谜。但是，最近的观察为提高知识提供了新的有希望的观点。在这里，我们回顾了有关大地震起震过程的数据，并表明它们是多尺度和多样的，涉及变形的局部性，断层非均质性和可变的局部加载率效应。地震和大地测量数据的分析表明，在大地震发生前的几年，地震诱发的岩石破坏和最终破裂带周围变形的逐步局域性使区域减弱。变形局限性的最后阶段取决于条件，包括多个时空尺度上的缓慢滑动瞬变和前震的混合。在大型局部断层上滑动的演化显示出阶梯状的增加，这可能反映了先前故障的应力负荷，与不断发展的抗震成核阶段所期望的平稳加速度相反，这可能产生较大的动态滑动。我们提出了一个综合模型来解释从渐进的体积变形到局部滑移所引起的大地震的多样性，这将通过密集的传感器网络和能够解决多尺度过程的改进分析技术来激发未来的近断层地震和大地测量研究。