衛星画像データの解析による地すべり発生地の特徴

抄録

Landslide often generates during rainfall or snow-melting season on slope of Mt. Zinbadaira, where is located at a distance of about 10 km west from Nagano-city. Image data of MOS-1 are examined in order to clarify the characteristics of ground surface with distribution of landslide occurred in the past. In this analysis, CCT value ratio of the near-infrared band to the visible band is discussed, taking mean value of a group of pixels in meshes drawn in the investigated area. It is ascertained that a number of landslides occur in such regions as the band ratio abruptly varies. From it's distribution, surface conditions are divided into two categories by comparing with the topography. At first the ratio has comparatively smaller one in the slope area where turns into gentle from steep mountain side, and it seems that creep movement of slide deposit disturbs vegitation cover. On the other hand, the band ratio becomes larger in steep slope area where may be formulated by erosion along dales in the lower part of the area. Accordingly there is a possiblity that slope becomes unstable due to the increase of water content in such area as showing plant growth.