Investigation of the Characteristic Behaviors of the Crustal Block Boundary Deduced from Leakage Current Vectors

本研究的目的是探讨地壳块体边界带的特征行为，通过分析泄漏电流矢量，这通常被认为是噪声的自电位分析。通过对池田站泄漏电流波形的比较，通过对北陆观测隧道（HKJ）和池田站（TIJ）两个观测点的地电特性的研究，得到了如下结果：（1）在北陆观测隧道（HKJ）和池田站（TIJ）两个观测点进行了观测。HKJ靠近铁路，TIJ位于Nukumi断裂带。2）分析了长期变化。在香港赛马场，自然电位的区域变化表现为湿润区相对较高，干燥区相对较低。在TIJ，Nukumi断层走向的垂直分量几乎稳定，并呈现出年变化。3）在HKJ和TIJ两个站点同时进行了1 Hz采样的泄漏电流观测。虽然TIJ处的漏电流幅值小于HKJ处的漏电流幅值，但两个部位的漏电流波形差异不大。通过对泄漏电流波形的FFT分析，发现两个地点的泄漏电流频率分量没有明显差异; 4）仅在TIJ处垂直于故障走向的分量上观察到了一些不同类型的泄漏电流，这一现象可能涉及到对故障结构的一些建议。

The object of this study is to investigate the characteristic behaviors of the crustal block boundary zone by analysing the leakage current vectors which are usually considered to be noises for self-potential analyzes. By comparing the waveformes of the leakage current observedat Ikeda station. apart from the street-car railway, with those at Hokuriku observation tunnel, near the railway, the geoelectric characteristics between those two stations can be estimated.Obtained results are as follows ;1)Observation have been carried out at two sites, Hokuriku observation tunnel (HKJ) and Ikeda station (TIJ). HKJ is closed to the railway and TIJ is on the Nukumi fault zone.2)Long-term variations were analyzed. At HKJ, areal variation of self-potential showed relatively high level in wet area and low in dry area. At TIJ, perpendicular components to the Nukumi fault strike have been almost stable and showed annual variations.3)Leakage current observation of 1 Hz sampling was carried out simultaneously at both HKJ and TIJ sites. Although the amplitudes of leakage current at TIJ were smaller than those of HKJ, those waveforms of both sites did not differ so much. By FFT analyzes of leakage current waveforms, remarkable differences in frequency components were not recognized in both sites.4)Some different types of leakage current were observed only by the components which are perpendicular to the fault strike at TIJ.This phenomenon might involve some suggestions about the fault structure.