Integrated Studies of Internal and Permeability Structures, and Rheological Properties of Fault Zones

尽管地质文献中对断层有大量的描述，但由于缺乏对断层的综合和跨学科研究的统一观点，断层和断裂带的性质尚未完全阐明。这项研究的目的是在对天然断裂带的分析和实验室形变和流体流动实验的基础上，提出一个综合断层研究的原型，试图重现自然界中的断层内过程，并确定断层的物理性质。目前的研究基金用于购买一台精密平面磨床和一台车床，这几乎完成了首席研究员(T.Shimamoto)两年前搬到京都大学后的样品制备实验室。利用加压空气和气泡作为冷却剂和润滑剂，尝试了一种穿过断裂带的新方法，而不是像普通钻井那样使用泥浆水，因为泥浆水可能会破坏脆弱的断裂岩并改变其…。更高的r渗透率。该钻探被证明在收集几乎完整的断层泥和角砾岩方面是有效的。主要研究成果如下：断裂带的内部结构和渗透率结构尽管断裂带渗透率结构在断裂带流体循环和地震断层运动时及之前的孔隙流体热增压中具有重要意义，但人们对它的认识并不清楚。为此，利用一种新的伺服控制气体装置研究了野岛断裂、诺达尼断裂、中构造线和柳牙斯断裂的渗透率结构。结果表明，断层带由渗透率变化较大的极不透水断层泥和断层角砾岩带组成。断裂带的内部结构和渗透率结构非常多变，热增压作用可能发生也可能不发生，这取决于断裂带。本工作将扩展到其他断层的检查和高温下的渗透率测量。断层的高速摩擦和地震孕育过程用高速旋转剪切仪对摩擦熔化过程中的滑移弱化过程进行的实验表明，软化是由熔层的生长引起的，而不是由熔体粘度的降低引起的。这表明，决定滑动弱化距离(断层失稳的关键参数)的最关键因素是熔融速度，而不是断层的表面地形。这项工作将扩展到孔压作用下的高速摩擦试验。较少

Despite enormous amount of descriptions on faults in geological literature, the nature of faults and fault zones are not yet fully elucidate-d owing to the lack of unified viewpoint for comprehensive and interdisciplinary studies of faults. The purpose of this study is to pose a prototype of integrated fault study based on the analyses of natural fault zones and on laboratory deformation and fluid-flow experiments trying to reproduce intrafault processes in nature and determine physical properties of faults. The present research fund was to used to purchase a precise surface grinder and a lathe, and this nearly completed the specimen preparation laboratory after the principal investigator (T. Shimamoto) moved to Kyoto University two years ago. A new method of drilling through a fault zone was attempted for Nojima fault using pressurized air and bubble as coolant and lubricator, without using mud water as in ordinary drilling which is likely to damage fragile fault rocks and change thei … More r permeability. The drilling was proven to be effective in collecting nearly intact fault gouge and breccia. The major outcomes of the present research are as follows :Internal and permeability structures of fault-zonesFault-zone permeability structure is not known well irrespective of its crucial significance in fluid circulation in fault zones and in thermal pressurization of pore fluid at and prior to seismic fault motion. Thus a new servo-controlled gas apparatus was used to study permeability structures of Nojima fault, Neodani fault, Median Tectonic line and Yanagase fault. The results have revealed that the fault zones consist of very impermeable fault gouge and fault breccia zones with quite variable permeability. Internal and permeability structures of fault zones are very variable, and thermal pressurization may or may not occur depending on fault zones. The present work will be extended to the examination of other faults and to permeability measurements at high temperatures.High-velocity friction of faults and earthquake-generating processesExperiments on the slip-weakening processes during frictional melting using a high-velocity rotary shear apparatus have revealed that the weakening is caused by the growth of molten layer, not by the reduction of melt viscosity. This suggests that the rate of melting, rather than the surface topography of faults, is the most critical factor in determining the slip weakening distance (a critical parameter for fault instability). This work will be extended to high-velocity friction experiments under pore-water pressure. Less