[H-DS07] 地すべりおよび関連現象

[HDS07-04] 昭和２８年有田川水害で発生した深層崩壊の地質地形学的素因について

*荒井 紀之¹ (1.京都大学防災研究所)

キーワード：深層崩壊、降雨、付加体

To reveal the geological and geomorphological causes of deep-seated catastrophic landslides (DCLs) by heavy rainfall in the 1953 Aridagawa disaster, the detailed geological mapping and geomorphological analysis using the 1-m DEMs were undertook in the upper reaches of the Arida River in the Kii Mountains. This area is underlain by the Cretaceous accretionary complex, consisting of sandstone dominated alternating beds of sandstone and shale and their broken formation. As a result, southward dipping low-angle faults, shear zones of broken formation with laumontite veins and the Yanase fault formed the failure surfaces and most of the DCLs were distributed along the convex breaks of slope angle, undercut slopes and the ridge lines with deep weathered rocks.