Contribution of viscoelastic flow in earthquake cycles within the lithosphere‐asthenosphere system

Lambert, Valère; Barbot, Sylvain

doi:10.1002/2016gl070345

“…Meanwhile, fault dynamics is efficiently simulated with the boundary-integral method (Ando, 2018;Lapusta & Liu, 2009;Y. It is natural to augment the boundary-integral method with volume elements to represent distributed deformation (Barbot, 2018;Barbot et al, 2017;Goswami & Barbot, 2018;Lambert & Barbot, 2016). It is natural to augment the boundary-integral method with volume elements to represent distributed deformation (Barbot, 2018;Barbot et al, 2017;Goswami & Barbot, 2018;Lambert & Barbot, 2016).…”

Section: Subduction Dynamics With the Integral Methodsmentioning

confidence: 99%

“…This is accomplished using the integral method, combining boundary and volume elements to resolve all phases of the seismic cycle under rate-and-state friction-with the notable exception of the radiation of seismic waves-and the mechanical coupling between brittle and ductile deformation. The displacement and stress kernels for a volume element can be used to directly image the anelastic deformation in Earth's interior Qiu et al, 2018;Tsang et al, 2016) and to simulate forward models of deformation (Goswami & Barbot, 2018;Lambert & Barbot, 2016). It was extended to incorporating shear heating and heat diffusion by Goswami and Barbot (2018).…”

Section: Introductionmentioning

confidence: 99%

Asthenosphere Flow Modulated by Megathrust Earthquake Cycles

Barbot

¹

2018

Geophysical Research Letters

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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, that is, seaward, direction, the viscoelastic relaxation in the oceanic asthenosphere generates transient surface deformation in the opposite, that is, 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.

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“…In particular, a longstanding challenge has been to model earthquakes in a self-consistent way as a part of a seismic cycle (Wang et al, 2012). In addition, most of the recent seismic-cycle models with several exceptions (Freed & B€ urgmann, 2004;Freed et al, 2006Freed et al, , 2007Freed et al, , 2010Freed et al, , 2012Lambert & Barbot, 2016;Masuti et al, 2016;van Dinther et al, 2013b) use simplified linear rheological models, such as Burger's rheology (see review Wang et al, 2012, and references therein), that are not based on mineral-physics laboratory data.…”

Section: Introductionmentioning

confidence: 99%

“…Presently, modeling of the long-term (millions of years' time scale) deformation at plate boundaries (e.g., Baes et al, 2016;Burov et al, 2014;Gerya, 2011;Popov et al, 2012;Quinteros & Sobolev, 2013) and modeling of earthquakes and their seismic cycles (e.g., Barbot et al, 2012;Lambert & Barbot, 2016;Liu & Rice, 2007;Rice, 1993;Rice & Ben-Zion, 1996) are independent. A few models (Sobolev & Babeyko, 2004;van Dinther et al, 2013avan Dinther et al, , 2013bvan Dinther et al, , 2014 attempted to close the gap between these temporal scales, but these studies were limited to a minimum time resolution of several years.…”

Section: Introductionmentioning

confidence: 99%

Modeling Seismic Cycles of Great Megathrust Earthquakes Across the Scales With Focus at Postseismic Phase

Sobolev

¹

,

Muldashev

²

2017

Geochem Geophys Geosyst

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Subduction is substantially multiscale process where the stresses are built by long‐term tectonic motions, modified by sudden jerky deformations during earthquakes, and then restored by following multiple relaxation processes. Here we develop a cross‐scale thermomechanical model aimed to simulate the subduction process from 1 min to million years' time scale. The model employs elasticity, nonlinear transient viscous rheology, and rate‐and‐state friction. It generates spontaneous earthquake sequences and by using an adaptive time step algorithm, recreates the deformation process as observed naturally during the seismic cycle and multiple seismic cycles. The model predicts that viscosity in the mantle wedge drops by more than three orders of magnitude during the great earthquake with a magnitude above 9. As a result, the surface velocities just an hour or day after the earthquake are controlled by viscoelastic relaxation in the several hundred km of mantle landward of the trench and not by the afterslip localized at the fault as is currently believed. Our model replicates centuries‐long seismic cycles exhibited by the greatest earthquakes and is consistent with the postseismic surface displacements recorded after the Great Tohoku Earthquake. We demonstrate that there is no contradiction between extremely low mechanical coupling at the subduction megathrust in South Chile inferred from long‐term geodynamic models and appearance of the largest earthquakes, like the Great Chile 1960 Earthquake.

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“…This is accomplished using the integral method, combining boundary and volume elements to resolve all phases of the seismic cycle under rate-and-state friction-with the notable exception of the radiation of seismic waves-and the mechanical coupling between brittle and ductile deformation. The approach was introduced by Lambert and Barbot (2016) to model the seismic cycle in the lithosphere-asthenosphere system on long transform faults under the antiplane strain approximation. It was extended to incorporating shear heating and heat diffusion by Goswami and Barbot (2018).…”

Section: Introductionmentioning

confidence: 99%

Asthenosphere flow modulated by megathrust earthquake cycles

Barbot¹

2018

Preprint

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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, that is, seaward, direction, the viscoelastic relaxation in the oceanic asthenosphere generates transient surface deformation in the opposite, that is, 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.Plain Language Summary Mitigation and preparation for seismic hazards rely on numerical simulation of earthquakes grounded in laboratory experiments and field data. Surprisingly, bringing together theory and predictions is still remarkably challenging. In this study, I demonstrate how recent progress in numerical methods now affords an efficient way to simulate how earthquakes come about at subduction zones, including how other regions of the Earth deform during the seismic cycle. The model predicts unexpected results about the Earth's surface deformation following large earthquakes.

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Contribution of viscoelastic flow in earthquake cycles within the lithosphere‐asthenosphere system

Cited by 70 publications

References 45 publications

Asthenosphere Flow Modulated by Megathrust Earthquake Cycles

Asthenosphere Flow Modulated by Megathrust Earthquake Cycles

Modeling Seismic Cycles of Great Megathrust Earthquakes Across the Scales With Focus at Postseismic Phase

Asthenosphere flow modulated by megathrust earthquake cycles

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