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図書 |
図書
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edited by Koji Suzuki, Yasuo Ikeda, Ikuro Maruyama
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| 2.
論文(リポジトリ) |
論文(リポジトリ)
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Tiwari, Binod ; Marui, Hideaki ; Sato, Osamu ; Yamagishi, Hiromitsu ; Watanabe, Naoki ; Furuya, Gen ; Suzuki, Koji ; Inaba, Kazunari ; Shimura, Kazuo ; Yamazaki, Fumiaki
概要:
Mount Usu is erupting frequently from 18th century. Comparing the recent eruptions, the property of the erupted materials have been found different in various eruption periods. The major eruption in 1978 had been concentrated in
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Mount Koushu and Mount Oushu. However, the eruption of 2000 had been localized around Nisiyama and Kompirayama area. The soil samples collected from Nishiyama and Kompirayama had shown slight difference in strength and other soil physical properties. The mineralogical properties also show the possibility of different rocks in the vicinity of Nishiyama and Kompirayama. The strength of the soil and the mineralogical property of the volcanic ash in 1978 and 2000 eruptions show considerable difference in the soil properties. Due to the difference in nature of eruption and high clay content in Nishiyama, it exhibited less shear strength than the soil from Ousu in 1978. The density of the soil near crater of Nishiyama is very low with high silt content. This clarifies the possibility of mass movement in various forms after the rainfall. Recalling the triggering of huge mass movement at mount Usu after 1978 eruption, the possible mass movement there in future can not be neglected, based on the low strength, existing land deformations and potential topography for slides.
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| 3.
論文(リポジトリ) |
論文(リポジトリ)
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Tiwari, Binod ; Marui, Hideaki ; Sato, Osamu ; Yamagishi, Hiromitsu ; Watanabe, Naoki ; Furuya, Gen ; Suzuki, Koji ; Inaba, Kazunari ; Shimura, Kazuo ; Yamazaki, Fumiaki
概要:
In the long history of volcanic eruption at mount Usu, there were periodic major eruptions in about 33 years interval. However, major eruption had evidenced there after 23 years in 2000. Due to the preparation of hazard map and
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development of good seismological network, there were no human casualties. However, the natural disaster due to that eruption had left panic to the people in the area. The eruption was still active after several months of first eruption. The major craters were formed at Nishiyama and Kompirayama. There is the possibility of huge mass movement in various forms after the rainfall. Recalling the triggering of huge mass movement at mount Usu after 1978 eruption, the possible mass movement there in future cannot be neglected, based on the in situ soil condition, existing land deformations and potential topography for slides.
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| 4.
論文(リポジトリ) |
論文(リポジトリ)
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Oki, Yasue ; Xu, Huilong ; Watanabe, Naoki ; Suzuki, Koji ; Sato, Osamu
概要:
A destructive earthquake of M6.0 on the Richter scale occurred at 18km east away from Niigata city in flat paddy field o
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f the Niigata plain. The epicenter was so shallow at 10km deep that 55 houses were completely collapsed and 165 houses were half collapsed, but no one died. The distribution of seismic intensity was analyzed by the rotatory moment calculated from overturned rectangular gravestones. The vertical acceleration at the epicenter was encountered as fairly larger than the acceleration of gravity. The seismic intensity 6 on the scale of the Japan Meteorological Agency (JMA) covered an area of 5.2×1 km trending NNE-SSW, which may indicate the distribution of the buried ruptured fault beneath the plain. This destructive earthquake actually came true at the eastern margin of the seismic gap, which might be a precursor of a strong destructive earthquake, soon, as predicted by Mogi (1988), Ishikawa (1990,1994) and Ohtake (1994). Special attention for the impending earthquake disaster should be required in the Niigata area, soon.
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