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

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 similar to 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.). (C) 2015 Elsevier B.V. All rights reserved.


Published in:
Earth and Planetary Science Letters, 429, 1-10
Year:
2015
Publisher:
Amsterdam, Elsevier
ISSN:
0012-821X
Keywords:
Laboratories:


Note: The status of this file is: Involved Laboratories Only


 Record created 2015-09-15, last modified 2018-03-17

Publisher's version:
Download fulltext
PDF

Rate this document:

Rate this document:
1
2
3
 
(Not yet reviewed)