Faults and intrafault processes

断层和断层内过程在地震预测、地球内部大规模物质循环和废物隔离等问题上具有重要的学术意义和社会意义。然而，它们还没有得到全面的研究。本项目的目的是总结主要未解决的问题，组织跨学科的团队进行系统的故障研究，并对当前的任务展开调查。日本地质学会刚刚成立了一个“地质与地震”研究委员会，以阐明地质学在未来地震预测研究中的作用。今后三年，本项目将继续作为本委员会的三项任务之一。这个为期两年的项目的主要成果如下。(1)本资助项目安装了一台离子抛光机（GATAN691），建立了TEM下变形微观结构的系统观测系统。许多关于断层的描述，更多的，尽管大多是零碎的，散落在地质文献中。本项目强调了“日本断裂与断岩目录”的必要性，并以鹤川断裂、赤石断裂、中构造线、日隆主逆冲4条断裂的目录为原型。(3)利用高温双轴机器，研究了在温度随断层正应力的增加线性增加（如在地热梯度的情况下）的情况下，岩盐剪切带在极端剪切下从脆性变形到中间变形到完全塑性变形的完全转变。这些实验首次揭示了岩石圈强度剖面、糜棱岩变形条件和孕震带下界流变学意义。提出了一个新的断层和板块边界模型，实验结果也表明，断层的流变特性受到较弱的组成矿物的控制，即使它们的含量只有5%，这表明系统硅酸盐在断层流变学中的重要性。(4)基于断层高速摩擦特性的结果，提出了地震发生的两相失稳模型，该模型可以解释第二类地震静息。对天然断层岩的研究揭示了高速断层运动的证据。高速大位移下的断层本构性质是一个未开发的领域，需要在实验室实验和对天然断层岩的分析中进一步研究。少

Faults and intrafault processes are very significant, both academically and socially, in such problems as earthquake prediction, large-scale material circulations within the earth, and waste isolation. Yet they have not been studied comprehensively. The purpose of this project is to summarize major unsolved problems, to organize an interdisciplinary team for systematic fault studies, and to start investigation on the immediate tasks. The Geological Society of Japan has just started a research committee on "Geology and Earthquake" to elucidate the role of geology in future studies towards the earhquake prediction. The present project will be continued as one of the three tasks of this committee for the next three years. The major outcome from this two-year project are as follows.(1) An ion polisher (GATAN691) was installed with the present grant-in-aid and this estabished a system for systematic observation of deformation microstructures under TEM.(2) Great many descriptions of faults, … More though mostly fragmentary, are scatterred over geological literature. The necessity of "Catalogs of faults and fault rocks of Japan" have been emphasized in this project, and catalogs of 4 faults (Tsurukawa fault, Akaishi fault, Median Tectonic Line, and Hidaka main thrust) have been made as a prototype.(3) Complete transition from brittle, through intermediate, to fully plastic deformation under extreme shear has been studied for halite shear zones at temperatures increasing linearly with an increase in the normal stress to the fault (as in the case of geothermal gradient) using a high-temperature biaxial machine.These experiments have revealed for the first time the strength profile of lithosphere, conditions for mylonitic deformation, and the rheological meaning of the lower bound of the seismogenic zone. A new fault and plate-boundary model was proposed and experimental results also revealed that rheological properties of a fault is controlled by weaker constituent minerals even their content is as small as 5%, implying the significance of phylosilicates in the fault rheology.(4) Two-phase instability model for the earthquake generation has been proposed based on the results of high-velocity frictional properties of faults, and the model may account for the seismic quiescence of the second kind. Studies of natural fault rocks have revealed evidence of high velocity fault motion. Fault constitutive properties at high velocities and under large displacements are an unexplored area that needs further studies both in laboratory experiments and in the analyzes of natural fault rocks. Less