Model output for the paper "On the cause of enhanced landward motion of the overriding plate after a major subduction earthquake"

This repository contains the relevant data (part of numerical model output) used to plot the figures in the main body of the manuscript entitled "On the cause of enhanced landward motion of the overriding plate after a major subduction earthquake", by Mario D'Acquisto, Matthew Herman, Riccardo Riva, and Rob Govers, submitted for publication in Journal of Geophysical Research: Solid Earth.

Paper abstract: "Greater landward velocities were recorded after 6 megathrust earthquakes in subduction zone regions adjacent to the ruptured portion. Previous explanations invoked either increased slip deficit accumulation or plate bending during postseismic relaxation, with different implications for seismic hazard. We investigate whether bending can be expected to reproduce this observed enhanced landward motion (ELM). We use 3D quasi-dynamic finite element models with periodic earthquakes. We find that afterslip downdip of the brittle megathrust exclusively produces enhanced trenchward surface motion in the overriding plate. Viscous relaxation produces ELM when a depth limit is imposed on afterslip. This landward motion results primarily from in-plane elastic bending of the overriding plate due to trenchward viscous flow in the mantle wedge near the rupture. Modeled ELM is, however, incompatible with the observations, which are an order of magnitude greater and last longer after the earthquake. Varying mantle viscosity, plate elasticity, maximum afterslip depth, earthquake size, and megathrust locking outside of the rupture does not significantly change this conclusion. The observed ELM consequently appears to reflect faster slip deficit accumulation, implying a greater seismic hazard in lateral segments of the subduction zone."

The model consists of a three-dimensional (3D) finite element method (FEM) simulation of the megathrust earthquake cycle with two fully elastic plates and Maxwell viscoelastic mantle.

The software used to perform the simulations and extract the model output in the files stored here was GTECTON (Govers & Wortel, 1993, 2005; Govers et al., 2018), version 2021.0. The software used to generate the relevant figures in the paper from the data was Generic Mapping Tools (GMT) (Wessel et al., 2019) version 6.3.0.

Each directory corresponds to a different model. The meaning of each model name, as well as the meaning of the file name and the internal data format of the files, are specified in the readme file (readme.txt). All files are plain text files.

For more information regarding the goals, model features, and output, please refer to the paper.

Contact person: Mario D'Acquisto - m.dacquisto@uu.nl