Asthenosphere flow modulated by megathrust earthquake cycles

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1029/2018GL078197.

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Authors

Sylvain Barbot 

Abstract

Subduction megathrusts develop the largest earthquakes, often close to large population centers. Understanding the dynamics of deformation at subduction zones is therefore important to better assess seismic hazards. Here, I develop consistent earthquake cycle simulations that incorporate localized and distributed deformation based on laboratory-derived constitutive laws by combining boundary and volume elements to represent the mechanical coupling between megathrust slip and solid-state flow in the oceanic asthenosphere and in the mantle wedge. The model is simplified, in two dimensions, but may help the interpretation of geodetic data. Megathrust earthquakes and slow-slip events modulate the strain-rate in the upper mantle, leading to large variations of effective viscosity in space and time and a complex pattern of surface deformation. While fault slip and flow in the mantle wedge generate surface displacements in the same, i.e., seaward, direction, the viscoelastic relaxation in the oceanic asthenosphere generates transient surface deformation in the opposite, i.e., landward, direction above the rupture area of the mainshock. Aseismic deformation above the seismogenic zone may be challenging to record, but it may reveal important constraints about the rheology of the subducting plate.

DOI

https://doi.org/10.31223/osf.io/g8ahe

Subjects

Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Keywords

subduction, Seismic cycle, integral method

Dates

Published: 2018-04-03 17:54

Last Updated: 2018-05-31 11:18

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License

Academic Free License (AFL) 3.0

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