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Durham University

Department of Earth Sciences

Profile

Publication details for Prof Stefan Nielsen

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

Author(s) from Durham

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.).