Seismological evidence for a multifault network at the subduction interface

• 成果类型: Article
• 署名作者: Chalumeau, Caroline; Agurto-Detzel, Hans; Rietbrock, Andreas; Frietsch, Michael; Oncken, Onno; Segovia, Monica; Galve, Audrey
• 署名单位: Helmholtz Association; Karlsruhe Institute of Technology; Helmholtz Association; Helmholtz-Center Potsdam GFZ German Research Center for Geosciences; Escuela Politecnica Nacional Ecuador; Institut de Recherche pour le Developpement (IRD); Centre National de la Recherche Scientifique (CNRS); Universite Cote d'Azur; Observatoire de la Cote d'Azur
• 刊物名称: Nature
• ISSN/ISSBN: 0028-4529
• DOI: 10.1038/s41586-024-07245-y
• 发表日期: 2024-04-17
• 页码: 558-+
• 关键词: early aftershocks; scaling relationships; zone; earthquake; FAULT; seismicity; migration; slip; permeability; thrust

摘要

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 100 m-1km thick zone(1, 2-3) in which deformation occurs mostly on metres-thick faults(1,3, 4, 5-6). Conversely, seismological studies, with their larger spatial coverage and temporal resolution but lower spatial resolution, often image the seismogenic interface as a kilometres-wide band of seismicity(7). Thus, how and when these metre-scale structures are active at the seismic-cycle timescale, and what influence they have on deformation is not known. Here we detect these metres-thick faults with seismicity and show their influence on afterslip propagation. Using a local three-dimensional velocity model and dense observations of more than 1,500 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 several metres-thick simultaneously active subparallel planes within the plate interface zone. This geometrical complexity affects afterslip propagation, demonstrating the influence of fault continuity and structure on slip at the seismogenic interface. Our findings can therefore help to create more realistic models of earthquake rupture, aseismic slip and earthquake hazard in subduction zones.