Importance of mechanochemical effects on fault slip behavior during earthquakes
Importance of mechanochemical effects on fault slip behavior during earthquakes
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DOI：
10.1002/grl.50609
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发表时间：
2013-06
影响因子：
5.2
通讯作者：
T. Hirono;W. Tanikawa;G. Honda;J. Kameda;J. Fukuda;T. Ishikawa
中科院分区：
文献类型：
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作者：
T. Hirono;W. Tanikawa;G. Honda;J. Kameda;J. Fukuda;T. Ishikawa
最近对天然断层的分析和实验室岩石摩擦实验表明，在地震期间，断层中的矿物和流体发生了物理变化和化学反应。然而，这些物理化学过程究竟如何影响断层弱化和地震能量学还没有得到很好的理解。我们提出了定量的实验证据的机械化学变化的粘土矿物（伊利石）在摩擦滑动，并评估这些变化对滑动行为的影响。摩擦使伊利石的晶体结构发生畸变，脱羟基反应的活化能（Ea）显著降低。数值模拟表明，较低的Ea允许脱羟基作用在相对较低的温度（200-300°C）下发生，这反过来又通过矿物释放水的加压而大大降低了断层强度。因此，动态热化学力学过程可以强烈影响地震不稳定性，特别是沿着富含粘土的断层，例如俯冲带板块边界的浅部。
Recent analyses of natural faults and laboratory rock friction experiments have revealed that physical transformations and chemical reactions of minerals and fluids occur in faults during earthquakes. However, exactly how these physicochemical processes affect fault weakening and earthquake energetics is not well understood. We present quantitative experimental evidence of mechanochemical changes in a clay mineral (illite) during frictional slip and evaluate the effect of those changes on slip behavior. Friction distorts the crystal structure of illite and dramatically decreases the activation energy (Ea) of the dehydroxylation reaction. Numerical modeling shows that the lower Ea allows the dehydroxylation to occur at relatively low temperatures (200–300°C), which in turn drastically reduces fault strength by pressurization of released water from the mineral. Thus, dynamic thermo‐chemo‐mechanical processes can strongly affect earthquake instability, especially along clay‐rich faults such as those in the shallow part of subduction zone plate boundaries.