Triggered by severe local rainfall in September, 1983, a large number of landslides occurred on slopes in the southern foot of the somma of Kuttara Caldera, SW Hokkaido. On the basis of slope movement features, they were classified mainly into two types: slump and debris-slide. Almost all the slump type landslides took place on slopes within a rock alteration zone in the southwestern part of the foot; whereas, the debris-slide type landslides showed a scattered distribution in the study area. Tuff breccia, parent rock in the alteration zone, was intensely altered to clay hydrothermally.
The alteration increased with increasing depth and is characterized by considerable amounts of montmorillonite and sulfides. The slipping surfaces of landslides of this type were found in the depth of tuff breccia formation. On the other hand, the slipping surfaces of debris-slide type landslides were found in a clayey crust that was formed by weathering of the surface part of the tuff breccia formation. The clayey crust is of several tens of centimeters in thickness and is composed mainly of halloysite and/or metahalloysite. It is likely that the degree and process of rock alteration played a very important role in controlling the type and distribution of landslides in the study area.

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For the purpose of investigating the mechanics of folding process that is formed in relatively shallow underground, we have conducted buckling tests on single layer and threelayered rock beams of KIMACHI sandstone and TOHOKU marble under moderate confining pressures, namely 0, 100, 300 and 500 kg/cm².
From this study, it became clear that folding deformation of rock beam under moderate confining pressure initiates at the near point of buckling fracture stress, and failure strength of those conform to the buckling experimental formula suggested by Shanley. Also, by means of conducting buckling test using intact rock, we confirmed that folding degree of multilayered rock beam depends on thickness of unit beam rather than total thickness of beam, and that of multilayered beam constituted with various rocks depends on competent layer.

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Thick deposits of Upper Pleistocene clays are often found over wide areas of the north west of Osaka Bay, and the geotechnical properties of the clays become more important as a number of large reclamation works are in progress in this area. In this paper, we examine the environment in which the Uppermost Pleistocene clay (Ma-12) was deposited, and the micro-fossil analyses and the X-ray analysis were carried out on samples taken at the RokkoIsland in Kobe. We further examine the relationship between the geotechnical properties and the geological conditions of the clay.
The results of analyses of pollen-, nanno- and diatom-fossils indicate a distinct variation of the sedimentary environment in Ma-12. However, it is found that there is no major variation in components of the clay minerals with depth, despite of the environmental changes in the clay. On the other hand the geotechnical studies of Ma-12 shows that the sedimentary environment has a strong effect on the geotechnical properties of Ma-12 especially on the value of the liquid limit and the compressibility.

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