抄録
The Tateyama volcano is located in the central part of the Japanese Islands and situated on the northern part of Norikura volcanic zone.
Volcanic activities of the Tateyama volcano in the late Quaternary, were classified into four stages. Andestic lava and pyroclastic materials were erupted during those activities. Eruption of the second stage produced so many pyroclastic materials as forming caldera. Afterwards this caldera was eroded and grew larger. A part of caldera wall was broken at Shiraiwa about twenty thousand years ago, and as the result, a lot of debris flowed over the caldera into Joganji River. The Tateyama Sabo Work is one of the largest Sabo work in Japan. Its most important work is the control of the Tombidoro which was produced by the deformation of the Tombiyama (Mt. Tombi) in the earthquake induced by the Atotsugawa fault in 1858. Deformation of the caldera wall by the earthquake may have occurred at any place in the caldera. But why did Tombi collapse occur at Tombiyama? From investigating topography of Kanayamadani and the Tombi collapse, I may conclude the cause of Tombi collapse is that Tombiyama was the terminal place of the right lateral Atotsugawa fault, and force of tension stress and depression concentrated here.
