Water vaporization promotes coseismic fluid pressurization and buffers temperature rise
Water vaporization promotes coseismic fluid pressurization and buffers temperature rise
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水汽化促进同震流体加压并缓冲温升
DOI：
10.1002/2016gl071932
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发表时间：
2017-03-16
影响因子：
5.2
通讯作者：
Ma, Shengli
中科院分区：
文献类型：
--
作者：
Chen, Jianye;Niemeijer, Andre;Ma, Shengli
我们研究了富含碳酸盐的断层泥层在1.3m/s的滑动速率下，在干燥和水饱和条件下的摩擦特性，同时监测断层泥-寄主岩石界面上不同位置的温度。所有的实验都显示出0.4-0.7的峰值摩擦强度，随后是强烈的滑动减弱到0.1-0.3的稳态值。使用孔隙流体与恒定的排水路径到大气中的实验表明，超过100摄氏度的温度高原的发展，同时与动态滑动减弱和孔隙水的持续蒸发的热力学考虑一致。当孔隙流体蒸发时，孔隙压力增加，而温度吸热缓冲，使得孔隙水沿着压力-温度相图中的液体-蒸气转变曲线移动。这种孔隙流体相变预计将发生在地壳相对较浅的自然地震中，增强流体加压，同时阻碍高温的实现。因此，汽化作用可能有助于解释大地震后短期内获得的低井下温度异常。
We investigated the frictional properties of carbonate-rich gouge layers at a slip rate of 1.3m/s, under dry and water-saturated conditions, while monitoring temperature at different locations on one of the gouge-host rock interfaces. All experiments showed a peak frictional strength of 0.4-0.7, followed by strong slip weakening to steady state values of 0.1-0.3. Experiments which used a pore fluid with a constant drainage path to the atmosphere showed the development of a temperature plateau beyond 100 degrees C, contemporaneous with the dynamic slip weakening and consistent with thermodynamic considerations of ongoing vaporization of pore water. Upon pore fluid vaporization, the pore pressure increases, while the temperature is buffered endothermically, such that the pore water moves along the liquid-vapor transition curve in a pressure-temperature phase diagram. Pore fluid phase transitions of this kind are expected to occur in natural earthquakes at relatively shallow crustal levels, enhancing fluid pressurization while impeding the achievement of high temperatures. Therefore, the operation of vaporization may help explain the low downhole temperature anomalies obtained shortly after large earthquakes.