Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip
Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip
复制标题
DOI：
10.1016/j.epsl.2015.07.054
复制
发表时间：
2015-11-01
影响因子：
5.3
通讯作者：
Burg, J. P.
中科院分区：
文献类型：
--
作者：
Violay, M.;Di Toro, G.;Burg, J. P.
地震的发生是因为断层摩擦力随着滑动和滑动速率的增加而减弱。由于断层的滑动带通常是流体饱和的，孔隙流体的热机械加压被援引为摩擦动力学弱化的机制，但缺乏实验证据。我们进行了摩擦实验（法向应力25 MPa，最大滑动速率类似于3 ms（-1））在粘性玄武岩和大理石（1）室内湿度和（2）浸泡在液态水（排水和不排水）条件。在这两种岩石类型和独立的流体的存在下，高达80%的摩擦弱化，在第一个5厘米的滑动测量。适度的增压相关的弱化只出现在滑移的后期阶段。在地震期间，由于触发了更有效的断层润滑机制（闪热、摩擦熔化等），粘性岩石的热机械加压弱化可以忽略不计。(C)2015 Elsevier B. V.版权所有。
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.