抄録
Geological zonation of landslides in very small scales was proposed based on major engineering geological division of Japanese Islands. In this paper, the term “landslides” involves all kinds of ground movements appeared in Japan. In the course of zoning works, the following problems are piscussed, namely; geomorphological development related to landforms which are controlled by lithological characteristics and types of landslides, recent crustal movements affecting the cause of landsliding phenomena, distribution density of landslides in narrower sense, etc.
As results, fifteen map units are defined with explanatory table of topographic, lithological, tectonic geological features, principal types of movements, possibilities of prediction and foreknowledge, planning of controll works. Also, typical geological cross sections are illustrated for each map units.
Map units represented in the zonation map are as follows:
1) Acidic intrusive rocks and gneisses
2) Ultramafic and mafic intrusive rocks
3) Paleozoic-Early Mesozoic eugeosynclinal deposits, crystalline schist facies
4) Paleozoic-Early Mesozoic eugeosynclinal deposits, non-metamorphosed facies
5) Cretaceous marine deposits of turbidite facies
6) Late Mesozoic-Paleogene eugeosynclinal and flysh-type deposits
7) Late Mesozoic-Paleogene terrestrial volcanic rocks
8) Tertiary non-marine to neritic deposits
9) Miocene submarine volcanic rocks
10) Middle Miocene-Pliocene marine clastic sediments
11) Pliocene-Pleistocene terrestrial volcanic rocks
12) Quaternary terrestrial and neritic clastic sediments
13) Quaternary pyroclastic rocks and sediments
14) Quaternary volcanic rocks
15) Late pleistocene-Holocene clastic sediments
