In stability analysis of paleo-landslide area, it is indispensable to have fully understandings of the past main slip surface (paleo-slip surface). In this paper, some mineralogical and chemical features of shear zone clay distributed in the Myoukurasawa paleo-landslide area were studied in order to make clear the efficiency of mineralogical/chemical method for evaluating paleo-slip surface.
The shear zone of the Myoukurasawa landslide area is located at the boundary part between bed rock and weathered moving soil, and composed of layered clay which is divided into six sublayers on the basis of the color. The brown clay sublayer in the lower part of the shear zone is characterised by a slip surface with slickenside. This shear surface on the brown clay sublayer (slip surface clay) possibly resulted from the principal displacement shear in paleo-landslide.
Clays and rocks from the landslide area were examined by means of X-ray powder diffraction (XRD), quantitative analysis of amorphous matter, quantitative chemical analysis by EPMA, CEC measurement, and exchangeable cation analysis. As a result, some mineralogical/chemical characteristics of shear zone clay were shown as follows; (1) quartz index values obtained by XRD for minerals in the shear zone suggest that vermiculitic minerals increases at the upper part relative to the slip surface, while illite increases at the lower part relative to the slip surface, (2) the XRD quantitative analysis for quartz indicates the contents of quartz in the shear zone clay are lower than those of the gray mudstone and black mudstone, (3) the quantitative analysis of amorphous matter suggests that the slip surface clay have the maximum amount in shear zone clay, (4) EPMA analysis show that shear zone clay are poor in SiO2 but rich in Al2O3 as compared with the gray and black mudstones, (5) CEC value of the slip surface clay shows a maximum in shear zone clay.
As mentioned above, mineralogy and chemistry of the clays are closely related to the occurrence of clays in the shear zone of the Myoukurasawa landslide area. Thus the mineralogical/chemical examination can be an usable method of characterizing shear zone clay also in other paleo-landslide areas. In particular, the amorphous matter formed in the shear zone during sliding can be an indicator for shear zone and slip surface. In addition, the decrease of quartz quantity in shear zone may be due to the development of shear cracks during sliding, suggesting that decrease of quartz can be an indicator for shear zone in the landslide area where weathering has been dominant.

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Accurate determination of evapotranspiration or evaporation from ground surface is very important to analyze precisely groundwater flow in the unsaturated zone near the surface. Also this determination is important for detailed analysis of moisture movement and pollutant migration near the ground surface because evaporation give a boundary condition of flow. However, there are not so many knowledge on the evapotranspiration from the actual field. The present authors reported that the evaporation and evapotranspiration from ground surface can be measured using a box type technique with high accuracy and good applicability. In this study, seasonal evapotranspiration changes were successfully measured from an actual grass field. Two places were selected in these measurements, the first is vegetated place and the second is sparsely vegetated place. Evapotranspiration was measured in these places in the all seasons during a year. It was found that the maximum evapotranspiration from the vegetated place in the summer season is about four times of it in the same place in winter season in same year and evapotranspiration from the vegetated place is about three times of it from the sparsely vegetated place in the winter season. The effect of solar radiation or sunlight on evapotranspiration was clarified. It was found that, the radiation has large effect on the evapotranspiration rate. The evapotranspiration rate increases with the increase of solar radiation. Also, the effect of plant density on the evapotranspiration rate was studied. It was found that the evapotranspiration increases linearly in case of white clover plant and the transpiration for this type of plant could be estimated, separately, from the evapotranspiration. Evapotranspiration could be simply and easily determined in all seasons using the box type technique.

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Nojima fault in Awaji island emerged as an earthquake fault in Hyougoken-nambu earthquake with more than 8km in length. On the other hand an opinion prenominates that there is no earthquake fault in Kobe district. The author pointed out later that some failures took place along Yokooyama fault in the earthquake. Now it is revealed that a dislocation happened in a tunnel at a point just crossing the fault at 80 m covering depth. The earthquake fault is normal one with right strike slip and coresponding to various geodetic measurement data, but not connect directly to the source fault. It should be determined that Yokooyama fault is a so-called sub-earthquake fault, one of the various modes.

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The Part 1 paper shows that the volumes of slope failure products have a good positive correlation with those of sediment-loads in reservoirs in a relatively long term such as a decade. The present study examines the relationship between both parameters in a relatively short term such as a flood duration in order to clarify the contribution of slope failure volumes to reservoir sedimentation. A simulation method is applied to this study. The main results obtained are as follows.
(1) A physically based river-bed fluctuation simulation method was applied to the A dam drainage basin, which is characterized with high rainfall in Japan, in order to estimate volumes of sediment-loads in reservoirs during actual floods. Three flood cases of the four showed that such calculated values were in good accordance with the comparable actual ones. Therefore, this result proved that the simulation method could properly reappear the reservoir sedimentation.
(2) By using the simulation method proposed here as a methodology the volumes of sediment-loads in reservoirs of two cases, one case considering the volume of slope failure products and the other not, were compared with each other. This was done to examine a contribution ratio of slope failure volumes to those of sediment-loads in reservoirs. The result of this case study applied to the A dam drainage basin showed that the average contribution ratio was about 5-10% during a flood.

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