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.