Abstract: Interpretation on landslide topography has been tried through air-photographs for granitic rock bodies of different ages of intrusion settlement in Tateyama area of the upper reaches of Kurobe-gawa, northern alpine region, central Japan. Many of those landslides are initial stage of slope deformation and small partial falls of those slopes. Those slope deformations are not related on the settlement ages of the granites but fracture systems formed in those granitic rocks. Occurrence of those slopes is the most frequent in Kurobe-gawa granite body of Pliocene or Pleistocene in settlement age. Up-facing low cliffs and linear depression areas are often observed along main and branch ridges. Convex partial slopes with somewhat round shaped are also found on the wide and long slopes. Those cliffs and the convex partial slopes are developed through the combination of the differential movement and deformation of segmented small pillar rock bodies separated by the fracture systems and the subsidence mainly due to rotational displacement of upper-slope rock bodies. The fracture systems show mainly six different strikes of NE-SW, NW-SE, NNE-SSW, WNW-ESE, NNW-SSE and ENE-WSW with high angle (nearly vertical) dips. It is proofed that the convex slope at the initial stage of slope deformation (ISSD) is finally a fall or slide at the catastrophic deformation stage through interpretation on the latest air-photographs.
Keywords: granitic rocks, landslide topography, initial stage of slope deformation, convex slope, fracture systems, site prediction
p.61-82

Abstract: Situations of occurrence of human damage caused by Typhoon Talas in 2011 in the Kii Peninsula, where is the main affected area of the typhoon disaster were summarized. 72 people were killed and 16 people were missing by the typhoon in the peninsula. 56 people (63%) were killed or missing by sediment disaster, 13 people (15%) were by flood disaster, 8 people (9%) were by other reasons. Main factors of death or missing of 11 people (15%) were unknown. In sediment disaster, human damages were from debris flows, landslides, and unexpected multiple disasters of landslides and flooding. For example, landslide debris rushed into swollen stream and caused high wave, and houses were washed away by the high wave. Such multiple disasters have not been assumed sufficiently, and they are one of future problems for preventing heavy rainfall disaster in the peninsula.
Keywords: Typhoon Talas in 2011, Kii Peninsula, human damage, landslide disaster, flood disaster
p.83-94

Abstract: In order to obtain some hints for the underlying mechanism of varieties in earthquake occurrence, a series of sandpile experiments have been performed. In the experiments even if made under the same condition, it is almost impossible to expect the perfect reproducibility, that is to say, the results vary from experiment to experiment, although they have, of course, common features in a statistical sense. In this report, we first describe the apparatus and the experimental methods in detail and then focus rather on the varieties of the experimental results, considering what brings the varieties into the experimental results. Then we found, for example, that the height of drop point of sand affects the maximum weight of a sandpile. As a new trial, we also made sandpiles on regular polygons (not on circular disks) and observed consecutions of avalanches at multi-parts of slopes, resulting in a large avalanche.
Keywords: earthquake, sandpile experiment, magnitude-frequency distribution, consecution
p.95-108

Abstract: The Kuster-Toksoz model as a rock physics model is applied to the seismic velocity data obtained in well loggings and laboratory tests to model cracked rocks. In this study, this model is applied to well logging velocity and density data obtained in a granitic rock to estimate the aspect ratio of the crack in the rock. It is also demonstrated that this model can be used for quantitative interpretation of seismic velocity reduction due probably to excavation damage of a tunnel, which has been recognized in many surveys in the past.
Keywords: rock physics, geophysics, cracked rock, Kuster-Toksoz model
p.109-116

Abstract: For the design of underground structures, a continuum analysis considering the nonlinearity of rock mass is usually used. On the other hand, discontinuities of hard rock, ranging from mm to m in scale, are governing the mechanical and the hydraulic properties. Therefore, the performance estimated by the continuum analysis might be different from that by discontinuity analysis. So, for the underground structures which are expected to have a hydraulic performance not only a mechanical performance, it is important to examine the stress-fluid coupled behavior considering discontinuities. Here previous studies about stress-fluid coupled analysis are surveyed and problems to be solved are discussed.
Keywords: hard rock, coupling behavior, tunnel, underground cavern, high level radioactive waste disposal
p.117-127