Slow slip events (SSEs) are transient slip episodes taking place along the plate interface of subduction zones. They usually occur synchronously to tectonic tremors and/or seismic swarms, but the relationship between slip and seismicity remains unclear. Here, we study a well-instrumented seismic swarm-SSE sequence near a highly coupled segment along the Ecuadorian subduction zone. GPS data reveal that a one-week long SSE developed along the subduction interface at shallow depth (5–15 km) with an equivalent moment magnitude (Mw) of 6.3. During that period, a local temporary seismic network recorded >700 earthquakes with magnitudes ranging between 1.0 and 4.6. The distribution of seismicity illuminates a steep intraslab fault downdip of an oceanic relief, striking almost parallel to the trench. This seismicity migrates along strike of this active structure at a velocity of 10–15 km/day. This velocity is commonly observed in the case of slow slip propagation. Our observation suggests that the interplate SSE might have triggered a slow slip along the the intraslab active structure, which in turn drove the intraslab seismicity. In addition, at the northern part of the intraslab faults, a cluster of seismicity shows a radial expansion compatible with a fluid diffusion process. Overall, our study highlights the dynamical interaction between an interplate slow slip and an intraslab seismic swarm with the interplay of an intraslab aseismic slip propagation and fluid diffusion, both controlling the migration of seismicity.

中文翻译：

---

板内地震活动偏移与沿厄瓜多尔俯冲带的界面慢滑移事件同时发生


慢滑移事件（SSE）是沿俯冲带板块界面发生的瞬态滑移事件。它们通常与构造震动和/或地震群同步发生，但滑动与地震活动之间的关系仍不清楚。在这里，我们研究了厄瓜多尔俯冲带高度耦合段附近仪器齐全的地震群-SSE序列。 GPS 数据显示，在浅层（5-15 公里）沿俯冲界面形成了一个为期一周的 SSE，等效矩震级 (Mw) 为 6.3。在此期间，当地临时地震台网记录了超过 700 次地震，震级在 1.0 到 4.6 级之间。地震活动的分布揭示了海洋起伏的陡峭板内断层下倾，几乎与海沟平行。这种地震活动沿着该活动结构的走向以 10-15 公里/天的速度迁移。该速度通常在缓慢滑移传播的情况下观察到。我们的观察表明，板间 SSE 可能引发了沿板内活动结构的缓慢滑动，从而驱动了板内地震活动。此外，在板内断层的北部，地震活动群表现出与流体扩散过程相一致的径向扩张。总的来说，我们的研究强调了板间慢滑移和板内地震群之间的动态相互作用，以及板内地震滑移传播和流体扩散的相互作用，两者都控制着地震活动的迁移。