We investigated the geomorphic transition and the existence of the reclaimed land by using the topographic map published in 1965 and 2002, and also chronologically comparing aerial photographs of the volcanic ash plateau in Kitami City, which is a major urban city in the Okhotsk region, East Hokkaido. Moreover, we also made a comparison between the ground conditions of the reclaimed land and the natural ground, based on the geotechnical information database created uniquely. In the plateau

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... ned, rapidly developed land, which was reclaimed from the 1970s, is included, and it became clear that such reclaimed areas are very vulnerable, judging from the N-values and the groundwater levels. It is presumable that such places are can be found in city areas all over the country, especially the newly developed residential areas. To prevent geotechnical disaster damage in each urban area, it is required to clarify how the landform was created and transformed afterwards. Thus, we must work out a master plan for disaster damage prevention, which can take care of not only the damages of underground lifeline networks, such as waterworks, sewers and gas pipes caused by the earthquakes but also daily failures caused by the vulnerability of the ground conditions.