The apparent dielectric constant and the resistivity of Toyoura sand, Kasama decomposed granite soil and Sakan sand were measured associated with a wide variety of the volumetric water content and the saturation degree from saturated state to dried state. The sand specimens were saturated by using the solutions with different NaCl concentrations. The apparent dielectric constant at the saturated state was nearly independent of the resistivity of pore water at the lower NaCl concentration range (≤2, 000ppm), on the contrary, the apparent dielectric constant notably increased at the higher NaCl concentration range (≥5, 000ppm). Consequently, in the case of determination of the volumetric water content of sand with the higher salinity by using measured value of apparent dielectric constant, it is essential to obtain the calibration curves at the same salinity condition. In addition, the apparent dielectric constant at the same NaCl concentration sensitively decreased with the decrease of volumetric water content, in the every sand. The determined relationships between the apparent dielectric constant and the volumetric water content of Kasama decomposed granite soil and Sakan sand were in agreement with the empirical equation presented by TOPP et al., however, that one of Toyoura sand differed from the empirical equation because an inhomogeneous distribution of the pore water occurred in the specimen. The resistivity of the sands at the same saturation degree sensitively decreased with the decrease of the resistivity of pore water. Further, the relationships between resistivity of Toyoura and Sakan sands at the saturated state and the resistivity of pore water were linear, but that one of Kasama composed granite soil was non-linear.

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An eruption of Unzen volcano on November, 1990, the Usu volcano eruption on March, 2000, and the past many volcanic activity, such as the phreatic explosion of Miyake-jima on July, 2000, are troubling the life of people. However, in the volcano area, a scene of a rich hot spring and rich nature is blessed with tourist attractions. And the agriculture consisting mainly of a dairying is performed here. Moreover, there are many resort institutions, such as a cottage ground, because plateau peculiar to volcanic topography are distributed.
People around a volcano area are important for getting to know the risk of these natural disasters. The engineers have to understand the feature of a natural disaster, and have to consider how the risk of a natural disaster is reduced. Therefore, in this paper, we investigate the geology of a volcano area, the natural disasters resulting from the geographi cal feature and the countermeasure for the disasters.
The investigation is carried by the geomorphologic analysis based on aerial photointerpretation, and the analysis of geology information and land use information at the Nasu volcano area and the Ashio mountains where is near by that volcano.
The conclusions are shown as follows.
1) Many steep slopes are located in the mountainous area of our country. However, it is clear quantitatively that there is large gentle slope which may become the place of people life at the foot of a volcano area.
2) However, the various natural disasters may occur on the gentle slopes of the volcano area as the origin of that slopes.
3) Furthermore, these natural disasters consist of sediment disaster and slope disaster by heavy rain and volcanic eruption disaster. We propose that the device of risk management and land use which put in the concept of time is required, in order to enjoy the rich nature at the time of peaceful, corresponding to each natural disaster.

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It is expected to develop the GIS tool for adapting construction and maintenance of expressway. This paper discussed the data set division and its application method to project geological map based on geographical and boring survey data, which obtained from construction stages of Tomei expressway and New-Tomei expressway. GIS tool is effective to handle the surface information not only height data but also secondary data.

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The relation between geological features of tunnel wall and groundwater discharge, that were observed during the excavation of the Seikan Under-Sea Tunnel was successfully analyzed by using the quantification and the artificial neural network (ANN) models. Data obtained from a part of 1.9km long of a pilot tunnel excavated from the Honshu side was used. This selected part was divided into small parts of 10m length, then the total amount of discharge, total width of fault zones, number of fractures, dominant geological features and so on observed in every small part were summarized. Then, 190 data sets presenting the combination of tunnel discharge and geological features for all small parts were prepared for the analysis. The analysis can be divided into two processes. One is the process determining best parameters in the quantification and the ANN models that can well reconstruct the discharge of the selected 30-95 small parts from geological data (Training phase). Another is the process estimating discharge expected in the other small parts that are not used in the training phase (Test phase).
It was found that the discharge can be well reconstructed by ANN model with the correlation coefficient of large than 0.9, when the discharge measured at the former small part was treated as a data as well as the geological features. The ANN model gave better result than the quantification model and seems to be more applicable. Although the general trend of discharge distribution was well predicated by using ANN model in the test phase, the correlation between the predicted and the observed discharges was not so high. Form this result, it can be concluded other geological data such as rock type, connectivity of fractures and so on, must be used for better prediction.

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