In many subduction zones, the plate interface hosts intermittent, low-frequency, low-magnitude seismic tremor and low-frequency earthquakes (LFEs). Seismic activity clusters in episodic bursts that migrate along the fault zone in complex ways. Geological structures in fossil tremor source regions testify to large and pervasive variations of fluid pressure and permeability. Here, we explore the potential of fluid pressure transients in a permeable subduction interface to trigger seismic sources and induce interactions between them. We show how variations of pore pressure and permeability can act in tandem to generate tremor-like patterns. The core feature of the model is that low-permeability plugs behave as elementary fault-valves. In a mechanism akin to erosive bursts and deposition events documented in porous media, valve permeability opens and closes in response to the local fluid pressure distribution. The rapid pressure release and/or mechanical fracturing associated with valve opening acts as the source of an LFE-like event. Valves interact constructively, leading to realistic, tremor-like patterns: cascades, synchronized bursts, and migrations of activity along the channel, on both short and long time and space scales. Our model predicts that the input fluid flux is a key control on activity occurrence and behavior. Depending on its value, the subduction interface can be seismically quiescent or active, and seismicity can be strongly time-clustered, quasi-periodic or almost random in time. This model allows new interpretations of low frequency seismic activity in terms of effective fluid flux and fault-zone permeability.

中文翻译：

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渗透性俯冲界面中使用快速流体压力瞬变模拟的低频地震的偶发性和迁移

在许多俯冲带中，板块界面会发生间歇性、低频、低震级地震和低频地震 (LFE)。以复杂方式沿断层带迁移的偶发性爆发中的地震活动集群。化石震源区的地质结构证明了流体压力和渗透率的巨大而普遍的变化。在这里，我们探索了渗透性俯冲界面中流体压力瞬变触发地震源并诱发它们之间相互作用的潜力。我们展示了孔隙压力和渗透率的变化如何协同作用以产生类似震颤的模式。该模型的核心特征是低渗透性塞子表现为基本的故障阀。在类似于多孔介质中记录的侵蚀性爆发和沉积事件的机制中，阀门渗透率根据局部流体压力分布而打开和关闭。与阀门打开相关的快速压力释放和/或机械压裂是类似 LFE 事件的来源。阀门建设性地相互作用，导致现实的、类似震颤的模式：在短期和长期的时间和空间尺度上，沿着通道的级联、同步爆发和活动迁移。我们的模型预测输入流体通量是对活动发生和行为的关键控制。根据其值，俯冲界面可以是地震静止的或活跃的，地震活动可以是强烈的时间聚类、准周期性或几乎随机的时间。该模型允许根据有效流体通量和断层带渗透率对低频地震活动进行新的解释。