抄録
Over 6, 000 spots of landslide were made clear by the Hokkaido Branch of the Japan Laadslide Society. The writer draws their digital map on 150''×225'' mesh.
Geomorphology is in low relief or was periglacial in an ice age. Heavy stormy rain is rare unlike any region else in Japan. Mass 'movement is inactive, but a great number of ancient marks remain uneroded because of low relief and light precipitation.
Mass movement groups may be divided into 19 zones according to geological classification.
Quaternary pyroclastic sediment, 13…1
Miocene-Pliocene marine sediment (Green tuff area), 10a…4
Miocene-pliocene marine sediment (non-Green tuff area), 10b…6
Miocene submarine volcanic rock, 9…2
Non-marine or neritic tertiary sediment, 8…2
Late mesozoic-paleogene tertiary orthogeosyncline sediment and flysh alternation, 6…1
Paleozoic-early mesozoic orthogeosyncline sediment (non-metamorphic), 4…1
Paleozoic-early mesozoic orthogeosyncline sediment (metamorphic) & pre-tertiary mafic rock, 3&2…2
For naturnl mass movement during the past 22 years, it is only 78 conservation areas in which stimulative deeds are prohibited and preventive and/or control works are administratively constructed.
