Sliding and healing of frictional interfaces that appear stationary

Creators: Sirorattanakul, Krittanon¹; Larochelle, Stacy^{1, 2}; Rubino, Vito^{1, 3}; Lapusta, Nadia¹; Rosakis, Ares J.¹

1. California Institute of Technology
2. Lamont-Doherty Earth Observatory
3. Institut de Recherche en Génie Civil et Mécanique

Abstract

Frictional interfaces are found in systems ranging from biological joints to earthquake faults. When and how these interfaces slide is a fundamental problem in geosciences and engineering. It is believed that there exists a threshold shear force, called static friction, below which the interface is stationary, despite many studies suggesting that this concept is outdated. By contrast, rate-and-state friction formulations predict that interfaces are always sliding, but this feature is often considered an artefact that calls for modifications. Here we show that nominally stationary interfaces subjected to constant shear and normal loads, with a driving force that is notably below the classically defined static friction for which creep is known to occur, are sliding, but with diminishingly small rates down to 10⁻¹² m s⁻¹. Our precise measurements directly at the interface are enabled by digital image correlation. This behaviour contradicts classical models of friction but confirms the prediction of rate-and-state friction. The diminishing slip rates of nominally stationary interfaces reflect interface healing, which would manifest itself in higher peak friction in subsequent slip events, such as earthquakes and landslides, substantially modifying their nucleation and propagation and hence their hazard.

Copyright and License

© 2025 Springer Nature Limited. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Acknowledgement

We thank J.-P. Avouac, M. Acosta, A. Lattanzi and P. Arakalian for their discussions about and help with the experiments; A. Kiani and GALCIT machine shop at Caltech for specimens manufacturing; M. Gori for his involvement with preliminary experiments; and D. Mojahedi for administrative work related to the project. This study is supported by the US National Science Foundation (NSF) (EAR-2045285 and EAR-1651235), the US Geological Survey (grant nos. G20AP00037 and G16AP00106) and the NSF-IUCRC Center for Geomechanics and Mitigation of Geohazards (GMG) at California Institute of Technology (NSF award no. 1822214). Matlab was used to analyse the results and prepare the figures.

Funding

This study is supported by the US National Science Foundation (NSF) (EAR-2045285 and EAR-1651235), the US Geological Survey (grant nos. G20AP00037 and G16AP00106) and the NSF-IUCRC Center for Geomechanics and Mitigation of Geohazards (GMG) at California Institute of Technology (NSF award no. 1822214).

Data Availability

All data used in the analysis are available online at the CaltechDATA repository at https://doi.org/10.22002/jrxvw-23c32. Source data are provided with this paper.

Code Availability

VIC-2D software for DIC analysis is commercially available from Correlated Solutions, Inc. Code used to analyse DIC results and to generate figures is available online at the CaltechDATA repository at https://doi.org/10.22002/jrxvw-23c32.

Supplemental Material

Supplementary Information:

Supplementary Figs. 1–3 and Supplementary Tables 1–4

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