DOI: 10.35097/1921
title: Seismological evidence for a multifault network at the subduction interface

description: 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.
description: When using this data, please cite the paper "Seismological evidence for a multifault network at the subduction interface" (10.1038/s41586-024-07245-y)

Contents of this directory:
1. Catalogue_NonLinLoc.csv: Catalogue of earthquakes located with NonLinLoc in a 1D model.
2. Catalogue_full_picks.txt: Arrival times picked with machine-learning. For each earthquake, the header (lines starting with #) lists the origin time, longitude, latitude, depth, number of phases, and average horizontal uncertainty from NonLinLoc. For each pick, the station, traveltime, time residual from NonLinLoc and phase are listed.
3. Catalogue_differential_arrivaltimes.txt: Cross-correlation differential times for all earthquake pairs with an interevent distance below 10 km. For each pair, the header (lines starting with #) lists the ID number of both events. For each pick, the station, differential time, correlation and phase are listed. To limit the file size, we only include cross-correlations above 0.6. 
4. Catalogue_tomoDD.csv: Catalogue of all earthquakes relocated with double-difference in tomoDD in a 3D model. The total relative location error, calculated using bootstrapping, refers to the location error of the event relative to the rest of its cluster in TomoDD. Since all events were relocated in a single cluster in TomoDD, this essentially corresponds to the average location error relative to all other events. For details on the calculation of errors, please refer to the online methods of Chalumeau et al. (2024).
5. Errors_TomoDD.csv: Relative location errors for each event pair in TomoDD.
6. Catalogue_families.csv: Families of similar earthquakes with cross-correlations above 0.75. For details on the creation of families, please refer to the online methods of Chalumeau et al. (2024).
7. Stations.csv: List of station locations.

If you have any questions, please email Caroline Chalumeau [caroline.chalumeau@kit.edu / carochalu06@gmail.com] or Andreas Rietbrock [andreas.rietbrock@kit.edu]