Seismological evidence for a multifault network at the subduction interface

This is the data generated in the paper: "Seismological evidence for a multifault network at the subduction interface".

Paper abstract:
Subduction zones generate the largest earthquakes on Earth, yet their detailed structure, and its influence on seismic and aseismic slip, remains poorly understood. Geological studies of fossil subduction zones characterize the seismogenic interface as a 100m-1km thick zone1–3 within which deformation occurs mostly on meters-thick faults1,3–6. Conversely, seismological studies, with their larger spatial coverage and temporal resolution but lower spatial resolution, often image the seismogenic interface as a kilometers-wide band of seismicity7. Thus, how and when these meter-scale structures are active at the seismic-cycle timescale, and what influence they have on deformation is not known. Here, we detect these meters-thick faults with seismicity and show their influence on afterslip propagation. Using a local 3D velocity model and dense observations of over 1500 double-difference relocated earthquakes in Ecuador, we obtain an exceptionally detailed image of seismicity, showing that earthquakes occur sometimes on a single plane and sometimes on multiple meters-thick simultaneously active subparallel planes within the plate interface zone. This geometrical complexity impacts afterslip propagation, demonstrating the influence of fault continuity and structure on slip at the seismogenic interface. Our findings can therefore help create more realistic models of earthquake rupture, aseismic slip, and earthquake hazard in subduction zones.

本数据集来自论文《俯冲带界面多断层网络的地震学证据》（Seismological evidence for a multifault network at the subduction interface）。

论文摘要：
俯冲带（subduction zone）是地球上孕育特大地震的构造区域，但其精细结构及其对地震滑移（seismic slip）与非地震滑移（aseismic slip）的影响机制仍未得到充分认知。针对古俯冲带的地质研究将发震界面（seismogenic interface）刻画为厚度100米至1千米的变形带1–3，该带内的变形主要集中在厚度为数米的断层上1,3–6。与之相对，地震学研究凭借更大的空间覆盖范围与时间分辨率，但空间分辨率相对较低，通常将发震界面成像为宽度达数千米的地震活动带7。因此，这些米级尺度的构造如何、何时在地震周期（seismic-cycle）时间尺度上活动，以及它们对变形过程的具体影响，目前仍不明确。本研究通过地震活动识别出这些厚度为数米的断层，并阐明了其对余滑（afterslip）传播过程的影响。研究利用厄瓜多尔地区的局部三维速度模型，以及超过1500次经双差定位法（double-difference relocation）重定位的密集地震观测数据，获得了分辨率极高的地震活动成像结果，结果显示：地震有时发生在单一平面上，有时则同时发育于板块界面带内多个厚度为数米且近于平行的活动断层平面上。这种几何结构的复杂性会影响余滑的传播过程，证明了断层连续性与结构对发震界面滑移过程的调控作用。因此，本研究结果可为构建俯冲带内更符合实际的地震破裂、非地震滑移以及地震灾害模型提供理论支撑。