| Recently it has been recognized that electrical potential is generated before or during earthquakes and volcanic eruptions. The authors call these electrical potential changes、 generated through the failure process、 Micro Geo-Electric Signals (MGES). Using MGES、 an experimental study at the laboratory test and the field measurement has been carried in order to predict rock collapses and slope failures for these several years. The laboratory test results have shown that the MGES is generated prior to failure during the unconfined compression tests using various test pieces、 but it is not generated under the absolute dry condition. MGES has the correlation between the moisture weight percentages of test pieces、 but not has the correlation between the strength、 also types of rock、 and it is suggested that the generation principle is streaming potential method. The field measurements of an actual slope in a cold snowy region showed that it was difficult to recognize the changes of MGES generated by rock failure because the remarkable changes by the rainfall are included in the MGES. However、 there is a possibility to recognize the irregular changes of MGES generated prior to failure by application of the analysis methods such as Principal Component Analysis (PCA); that is a kind of multivariate analysis. It is suggested the first principal component indicate climatic changes of MGES、 and the second principal component indicates a MGES which is generated prior to failure. In addition、 it is suggested that MGES can be recognized the signs of failure by using the contribution rate of principal component. |
