傾斜する地下水面に起因する亀裂・噴砂・崩壊などの地震災害  [in Japanese] On the cracks, sand craters and falls by the earthquake depending on the inclined surface of the groundwater  [in Japanese]

On the occasion of the earthquake in the central area of the Japan Sea (1983), the author investigated the cracks and sand crater that occurred in Akita Prefecture, and as a result he built up a hypothesis about the cause of these phenomena as follows (FUJITA & SUZUKI, 1983): Where the ground is composed of liquefiable material, which indicates the existence of inclined groundwater level, the ground would be liquefied by the earthquake and the buildings on the ground would slide horizontally together with the ground; consequently, cracks would be developed there, and the liquefied material intruding into the cracks would gush out as a sand spurt (Figs. 2, 4). In the present paper, this hypothesis is introduced first, and the cracks and sand crater produced by the 1964 Niigata earth-quake are examined by referring to the charts of the resultant damages (Figs. 5-11) and to various reports, thus leading to a conclusion that the hypothesis holds to a satisfactory extent. Lastly, the author expresses his view that the land slip which took place in the slope of the Kiso Volcano during the 1984 western Nagano Prefecture earthquake was caused by liquefaction within the scoria bed (FUJITA & SUZUKI, 1984), and maintains that this view supports the above-mentioned hypothesis.