Modeling megathrust earthquakes across scales: one-way coupling from geodynamics and seismic cycles to dynamic rupture

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1029/2019JB017539. This is version 3 of this Preprint.

Downloads

Download Preprint

Authors

Iris van Zelst , Stephanie Wollherr, Alice-Agnes Gabriel , Elizabeth Madden , Ylona van Dinther 

Abstract

Taking the full complexity of subduction zones into account is important for realistic modelling and hazard assessment of subduction zone seismicity and associated tsunamis. Studying seismicity requires numerical methods that span a large range of spatial and temporal scales. We present the first coupled framework that resolves subduction dynamics over millions of years and earthquake dynamics down to fractions of a second. Using a two-dimensional geodynamic seismic cycle (SC) model, we model 4~million years of subduction followed by cycles of spontaneous megathrust events. At the initiation of one such SC event, we export the self-consistent fault and surface geometry, fault stress and strength, and heterogeneous material properties to a dynamic rupture (DR) model. Coupling leads to spontaneous dynamic rupture nucleation, propagation and arrest with the same spatial characteristics as in the SC model. It also results in a similar material-dependent stress drop, although dynamic slip is significantly larger. The DR event shows a high degree of complexity, featuring various rupture styles and speeds, precursory phases, and fault reactivation. Compared to a coupled model with homogeneous material properties, accounting for realistic lithological contrasts doubles the amount of maximum slip, introduces local pulse-like rupture episodes, and relocates the peak slip from near the downdip limit of the seismogenic zone to the updip limit. When an SC splay fault is included in the DR model, the rupture prefers the splay over the shallow megathrust, although wave reflections do activate the megathrust afterwards.

DOI

https://doi.org/10.31223/osf.io/f6ng5

Subjects

Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Keywords

numerical modelling, Seismotectonics, subduction zones, Geodynamics, Earthquake dynamics, dynamic rupture, seismic cycles

Dates

Published: 2019-02-15 20:33

Last Updated: 2019-11-08 17:37

Older Versions
License

GNU Lesser General Public License (LGPL) 2.1

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.