Abstract
The “Green Tuff” region is defined as existence of abundant submarine volcanic rocks of Early Miocene and overlying oil-bearing pelitic clastic sediments of Late Miocene-Pliocene age. The region, which covers the western half of the Tohoku District in Northern Japan, is also characterized by predominant distribution of Tertiary landslides recognized by interpretation through aerophotographs.
In this entire region, reserches on the relations between geological and geomorphological conditions and the distribution of landslides are very few. In this paper, the features of Tertiary landslides distribution are especially discussed from geological and geomorphological point of view.
The areas of high distribution density of the landslides coincide with the areas where rapid upheaval movement occured during the Quaternary age. Geologically, a large number of the landslides occured in the areas dominated mainly by mudstone and tuff, and in the areas where has been intensively folded since Late Pliocene age.
It is a remarkable fact that the distribution pattern of the landslides is conformable with the characteristics of the late Cenozoic crustal movements. This suggests that the occurrence of the landslides is based on the tectonic history, specifically on its latest one of the region. Problems on prediction of landslides should be considered from such a point view.
