Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changes

Abstract Rocks exhibit astonishing time-dependent mechanical properties, like memory of experienced stress or slow dynamics, a transient recovery of stiffness after a softening induced by almost any type of loading. This softening and transient recovery is observed in the subsurface and in buildings...

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Main Authors: Manuel Asnar, Christoph Sens-Schönfelder, Audrey Bonnelye, Andrew Curtis, Georg Dresen, Marco Bohnhoff
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-62667-0
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author Manuel Asnar
Christoph Sens-Schönfelder
Audrey Bonnelye
Andrew Curtis
Georg Dresen
Marco Bohnhoff
author_facet Manuel Asnar
Christoph Sens-Schönfelder
Audrey Bonnelye
Andrew Curtis
Georg Dresen
Marco Bohnhoff
author_sort Manuel Asnar
collection DOAJ
description Abstract Rocks exhibit astonishing time-dependent mechanical properties, like memory of experienced stress or slow dynamics, a transient recovery of stiffness after a softening induced by almost any type of loading. This softening and transient recovery is observed in the subsurface and in buildings after earthquakes, or in laboratory samples. Here, we investigate the anisotropy of nonlinear elastic effects in a sandstone sample under uniaxial loading. We report that slow dynamics is observed independently of propagation direction, while the acoustoelastic effect shows the expected anisotropy originating from the opening and closing of cracks. From this, we argue that slow dynamics is caused by the sliding of oblique grain-to-grain contacts and the resulting changes in frictional properties, as empirically described by rate-and-state friction and observed in laboratory experiments across block contacts. We establish a connection between the nonclassical nonlinearity of heterogeneous materials and the framework of rate-and-state friction, providing an explanation for the elusive origin of slow dynamics, and adding a different perspective for monitoring very early stages of material failure when deformation is still distributed in the bulk and begins to coalesce towards a fracture.
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institution Kabale University
issn 2041-1723
language English
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record_format Article
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spelling doaj-art-62934033ca79463db748e757b167fdce2025-08-20T03:42:52ZengNature PortfolioNature Communications2041-17232025-08-011611910.1038/s41467-025-62667-0Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changesManuel Asnar0Christoph Sens-Schönfelder1Audrey Bonnelye2Andrew Curtis3Georg Dresen4Marco Bohnhoff5GFZ Helmholtz Centre for GeosciencesGFZ Helmholtz Centre for GeosciencesGeoRessources Laboratory, Université de LorraineSchool of GeoSciences, University of EdinburghGFZ Helmholtz Centre for GeosciencesGFZ Helmholtz Centre for GeosciencesAbstract Rocks exhibit astonishing time-dependent mechanical properties, like memory of experienced stress or slow dynamics, a transient recovery of stiffness after a softening induced by almost any type of loading. This softening and transient recovery is observed in the subsurface and in buildings after earthquakes, or in laboratory samples. Here, we investigate the anisotropy of nonlinear elastic effects in a sandstone sample under uniaxial loading. We report that slow dynamics is observed independently of propagation direction, while the acoustoelastic effect shows the expected anisotropy originating from the opening and closing of cracks. From this, we argue that slow dynamics is caused by the sliding of oblique grain-to-grain contacts and the resulting changes in frictional properties, as empirically described by rate-and-state friction and observed in laboratory experiments across block contacts. We establish a connection between the nonclassical nonlinearity of heterogeneous materials and the framework of rate-and-state friction, providing an explanation for the elusive origin of slow dynamics, and adding a different perspective for monitoring very early stages of material failure when deformation is still distributed in the bulk and begins to coalesce towards a fracture.https://doi.org/10.1038/s41467-025-62667-0
spellingShingle Manuel Asnar
Christoph Sens-Schönfelder
Audrey Bonnelye
Andrew Curtis
Georg Dresen
Marco Bohnhoff
Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changes
Nature Communications
title Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changes
title_full Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changes
title_fullStr Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changes
title_full_unstemmed Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changes
title_short Anisotropy reveals contact sliding and aging as a cause of post-seismic velocity changes
title_sort anisotropy reveals contact sliding and aging as a cause of post seismic velocity changes
url https://doi.org/10.1038/s41467-025-62667-0
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AT andrewcurtis anisotropyrevealscontactslidingandagingasacauseofpostseismicvelocitychanges
AT georgdresen anisotropyrevealscontactslidingandagingasacauseofpostseismicvelocitychanges
AT marcobohnhoff anisotropyrevealscontactslidingandagingasacauseofpostseismicvelocitychanges