Danré Philippe, De Barros Louis, Cappa Frédéric, Passarelli Luigi
Université Côte d'Azur, CNRS, Observatoire de la Côte d'Azur, IRD, Géoazur, Sophia Antipolis, Valbonne, France.
INGV - Istituto Nazionale di Geofisica e Vulcanologia, sezione di Bologna Viale Berti Pichat 6/2, Bologna, Italy.
Nat Commun. 2024 Oct 17;15(1):8943. doi: 10.1038/s41467-024-53285-3.
Earthquake swarms may be driven by fluids, through hydraulic injections or natural fluid circulation, but also by slow and aseismic slip transients. Understanding the driving factors for these prolific sequences and how they can potentially develop into larger ruptures remains a challenge. A notable and almost ubiquitous feature of swarms is their hypocenters migration, which occurrence is closely related to the processes driving the observed seismicity, in a similar way as seismicity accompanies slow-slip events at subduction zones. Here, we analyze global data on migrating sequences, and identify scaling laws for migration velocity, moment and duration measured on natural and injection-induced swarms, foreshock sequences, and slow slip events. We highlight two different behaviors among these sequences: one linked to slow slips, with elevated migration velocities and moments, and the other related to fluid-induced processes, featuring lower velocities and moments. These results provide metrics for distinguishing between the drivers of earthquake swarms, fluid or slow-slip related, and prompt a reevaluation of scaling laws of fault slip transients, especially for swarms.
地震群可能由流体驱动，通过水力注入或自然流体循环，但也可能由缓慢且无震的滑动瞬变驱动。了解这些多产序列的驱动因素以及它们如何可能发展成更大的破裂仍然是一项挑战。地震群一个显著且几乎普遍存在的特征是它们的震源迁移，其发生与驱动观测到的地震活动的过程密切相关，类似于俯冲带慢滑事件伴随地震活动的方式。在这里，我们分析了关于迁移序列的全球数据，并确定了在自然和注入诱发的地震群、前震序列以及慢滑事件中测量到的迁移速度、矩和持续时间的标度律。我们强调了这些序列中的两种不同行为：一种与慢滑有关，具有较高的迁移速度和矩，另一种与流体诱发过程有关，其特征是速度和矩较低。这些结果为区分地震群的驱动因素（与流体或慢滑相关）提供了度量标准，并促使重新评估断层滑动瞬变的标度律，特别是对于地震群。
