Dynamics of fault gauge during seismic forcal process

本文研究了在Atotsugawa、Yanagase、Gosukebashi和Nojima等几个活动断层上采集的测具样品的物理性质，目的是了解测具在深部应力场作用下的行为。我们进行了一些基础实验，如粒度分析，晶格应变分析，地震波速度和抗剪强度的测量等。在电镜下发现，普通规范材料的晶粒尺寸分布范围在10 ~ 1mm之间。这意味着压力表在高围压下非常可压缩，在剪切变形下可能会膨胀。这种剪胀性可以帮助测震仪通过震源深度附近的应变来提高强度。通过x射线衍射分析确定了石英和伊利石矿物的晶格应变大小，发现与无应力环境下形成的同类矿物相比，石英和伊利石矿物的晶格应变明显大。另一方面，许多粘土材料表现出与剪切变形相关的电极化。这种现象无法解释。剪切诱导极化（SIP）的发生机理与吸附水层接触细颗粒表面的物理化学特性有关。

We have investigated the physical properties of gauges samples collected from the crops of several active faults such as the Atotsugawa F., Yanagase F., Gosukebashi F. and Nojima F. The purpose the study is to understand the behavior of gauge under stress field at deep zone. We have carried out some fundamental experiments such as grain-size analysis, lattice strain analysis of the included minerals, measurements of seismic wave velocities and shear strength etc. using gauge samples. Grain-size distribution of common gauge materials is found to a widely from 10 rnm to 1mm under electron microscope. This means that gauge is very compressible under high confining pressure and can be dilatant under shear deformation. The dilatancy will help gauge increase the strength by the strain near the depth of seismic source.The magnitude of lattice strain of quartz and illite minerals were determined using X-ray diffraction analysis and found to be significantly large compared with the same kind of minerals formed in stress-free environment.On the other hand, many clay materials showed electric polarization associated with shear deformation. This phenomenon could not be explained. The mechanism of this Shear-Induced Polarization (SIP) is considered to be related to the physicochemical characteristics of the absorbed water layer contacting the finer grain surface.