Solution of problem on SIP (Shear-induced Polarization) in fault gouges and the development to the field observations.

对断层泥材料剪切变形时产生的电势进行了实验研究。在室内剪切变形试验中，常见的饱和细集料，如粘土，可以观察到一些电极化现象。这种现象被称为剪切激发极化(SIP)。这种现象可以用微粒与间隙水与电解液的物理化学相互作用来解释。然而，在一些非偶极子油处理的手工艺用粘土中没有检测到SIP，通过平面剪切应变试验来阐明感应电势的极性与变形和应变感的关系。在最大应变轴面(张力面)上产生的电荷符号为正号，在最小应变轴面上产生的电荷符号为负，在中间应变轴面上产生的电荷符号为中性。另一种变形试验也证实了这一特征。通过自然电位的测量，我们在滑坡现场观察到了泥浆。这些遗址位于日本东北部新泻县Jouetsu的布苏诺滑坡区和日本四国县高知县长冈市的Nuta Yone滑坡区。自然电位随滑坡位移量的增大而变化。滑坡块体边界处的电位分布存在较大的不连续性。在滑坡现场观测到的电位感与实验室模型实验获得的电位感相吻合。

An experimental study on the electrical potential induced in fault gouge materials accompanying with their shear deformation have been carried out. Some electrical polarizations could be observed in common saturated fine aggregates, such as clay during the shear deformation test in laboratory. This phenomenon is called SIP (Shear-induced Polarization). This phenomenon of SIP can be interpreted in terms of physicochemical interaction between fine particle and interstitial water with electrolyte. However, the SIP was not detected in the remolded clay for handicraft-use which treated with some non-dipole oil.The plane shear strain test was performed to clarify the relation of the polarity of induced potential with deformation and the sense of strain. Sign of electric charge generated on the plane of maximum strain axis (tensional) was plus, that on the plane of minimum strain axis was minus and that on the plane of intermediate strain axis was neutral. This characteristic property was confirmed in gouge sample by the other kind of deformation test.We observed SIP at sites of landslide by measurement of the spontaneous potential. The sites locate at large scale of landslide areas of Busuno landslide area in Jouetsu City, Niigata Prefecture, Northeast Japan and Nuta Yone landslide area in Nagaoka, Kochi Prefecture, Shikoku, Japan. The spontaneous potential changes with increasing the displacement of landslide. The large discontinuity of the electric potential distribution was observed at the boundary of landslide blocks. The senses of electric potential observed at landslide fields coincided with those senses obtained from the model experiments in the laboratory.