Experimental studies on coupled deformation and chemical reactions

本研究的主要目的是探讨孔隙流体在岩石流变学和地震起爆过程中的作用。选取中构造线、野岛断裂、新谷断裂、kanawa断裂、Yanagase断裂和Hanaore断裂为代表断裂，采用振荡法和恒流法，结合变形流体流动测定仪测量了深地壳条件下的渗透率和库容。在本研究开始时，只有几篇论文报道了内部和渗透率结构，但我们从这些断层中收集了大约500个样本，收集了5000多个渗透率数据。近三十年来，热加压（即由于摩擦加热引起的孔隙压力上升）被认为是地震发生时断层减弱的一种机制，但由于缺乏足够的断层带渗透率数据，其意义仍有待评估。我们的数据清楚地表明，断裂带的渗透率结构是可变的，有些断层会发生TP，而另一些则不会。对TP过程的分析也表明，断层的滑动弱化距离D_c约为1米的几个数量级。近20年来，地震测定的D_c和实验室测量的D_c之间存在几个数量级的差异（D_c悖论）。TP过程产生的D_c值与地震确定的D_c值在同一数量级上，高速摩擦研究可以解决D_c悖论。

The main purpose of the present studies has been to investigate the role of pore fluids on rock rheology and earthquake initiation processes. We selected Median Tectonic Line, Nojima fault, Neodani fault, Kannawa fault, Yanagase fault and Hanaore fault as representative faults and have measured permeability and storage capacity under deep crustal conditions using an oscillation method and a constant flow method with a deformation and fluid flow gas apparatus. There were only several papers reporting internal and permeability structures when the present studies started, but we have collected over 5,000 permeability data for about 500 specimens collected from those faults. Thermal pressurization (TP), i.e., pore pressure rise due to frictional heating, has been proposed as a mechanism for the weakening of faults at the initiation of earthquakes for over the last three decades, but its significance has remained to be evaluated due to the lack sufficient data on fault-zone permeability. Our data clearly shows that fault zones are variable in permeability structures and that TP will occur for some faults, but not for others. Analyses of TP processes have also shown that the slip weakening distance, D_c, of fault is on the order of several fractions of 1 meter. There has been several orders of magnitude difference in D_c between seismically-determined and laboratory measured D_c for nearly 20 years (D_c paradox). TP processes yield D_c values on the same order of magnitude as determined seismically and high-velocity frictional studies may solve D_c paradox.