Mechanical behaviour of fluid-lubricated faults

Cornelio, Chiara; Spagnuolo, Elena; Di Toro, Giulio; Nielsen, Stefan; Violay, Marie

Abstract

Fluids are pervasive in fault zones cutting the Earth's crust; however, the effect of fluid viscosity on fault mechanics is mainly conjectured by theoretical models. We present friction experiments performed on both dry and fluid-permeated silicate and carbonate bearing-rocks, at normal effective stresses up to 20 MPa, with a slip-rate ranging between 10 μm/s and 1 m/s. Four different fluid viscosities were tested. We show that both static and dynamic friction coefficients decrease with viscosity and that dynamic friction depends on the dimensionless Sommerfeld number (S) as predicted by the elastohydrodynamic-lubrication theory (EHD).Under favourable conditions (depending on the fluid viscosity (η), co-seismic slip-rate (V), fault geometry (L/H02) and earthquake nucleation depth (∝σeff)), EHD might be an effective weakening mechanism during natural and induced earthquakes. However, at seismic slip-rate, the slip weakening distance (Dc) increases markedly for a range of fluid viscosities expected in the Earth, potentially favouring slow-slip rather than rupture propagation for small to moderate earthquakes.

Citation

Cornelio, C., Spagnuolo, E., Di Toro, G., Nielsen, S., & Violay, M. (2019). Mechanical behaviour of fluid-lubricated faults. Nature Communications, 10, Article 1274. https://doi.org/10.1038/s41467-019-09293-9

• Journal Article Type: Article
• Acceptance Date: Feb 26, 2019
• Online Publication Date: Mar 20, 2019
• Publication Date: Mar 20, 2019
• Deposit Date: Feb 28, 2019
• Publicly Available Date: Mar 22, 2019
• Journal: Nature Communications
• Electronic ISSN: 2041-1723
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Article Number: 1274
• DOI: https://doi.org/10.1038/s41467-019-09293-9
• Public URL: https://durham-repository.worktribe.com/output/1307184