Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip

Violay, M.; Di Toro, G.; Nielsen, S.; Spagnuolo, E.; Burg, J.P.

Abstract

Earthquakes occur because fault friction weakens with increasing slip and slip rates. Since the slipping zones of faults are often fluid-saturated, thermo-mechanical pressurization of pore fluids has been invoked as a mechanism responsible for frictional dynamic weakening, but experimental evidence is lacking. We performed friction experiments (normal stress 25 MPa, maximal slip-rate ∼3 ms−1) on cohesive basalt and marble under (1) room-humidity and (2) immersed in liquid water (drained and undrained) conditions. In both rock types and independently of the presence of fluids, up to 80% of frictional weakening was measured in the first 5 cm of slip. Modest pressurization-related weakening appears only at later stages of slip. Thermo-mechanical pressurization weakening of cohesive rocks can be negligible during earthquakes due to the triggering of more efficient fault lubrication mechanisms (flash heating, frictional melting, etc.).

Citation

Violay, M., Di Toro, G., Nielsen, S., Spagnuolo, E., & Burg, J. (2015). Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip. Earth and Planetary Science Letters, 429, 1-10. https://doi.org/10.1016/j.epsl.2015.07.054

• Journal Article Type: Article
• Acceptance Date: Jul 24, 2015
• Online Publication Date: Aug 7, 2015
• Publication Date: Nov 1, 2015
• Deposit Date: Sep 23, 2015
• Publicly Available Date: Aug 7, 2016
• Journal: Earth and Planetary Science Letters
• Print ISSN: 0012-821X
• Electronic ISSN: 1385-013X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 429
• Pages: 1-10
• DOI: https://doi.org/10.1016/j.epsl.2015.07.054
• Keywords: Friction, Earthquakes, Fluids, Thermo-mechanical pressurization, Basalt, Marble.
• Public URL: https://durham-repository.worktribe.com/output/1431071