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Abe, O., Nakamura, T., Lang, E.T. and Ohnuma, T.,

: Comparison of simulated runout distances of

snow avalanches with those of actually observed

events in Japan. IAHS Publication, , .

Gubler, H., : Measurement and modeling of snow

avalanche speeds. IAHS Publication, , .

:

pp.

Issler, D., : Experimental information on the dy-

namics of dry-snow avalanches. Dynamic re-

sponse of granular and porous materials under

large and catastrophic deformations. Lecture

notes in applied and computational mechanics, ,

Berlin, Germany, Springer Verlag, .

Johnson, Jr., R.C., Ramey, G.E. and O’Hagan, D.S.,

: Wind induced forces on trees. Journal of Flu-

ids Engineering, , .

:

.

Kern, M., Bartelt, P., Sovilla B. and Buser O., :

Measured shear rates in large dry and wet snow

avalanches. Journal of Glaciology, , .

:

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125

AKEUCHI ORITA ISHIMURA AKAMOTO

AGINO OTO URAKAMI NDO

. :

: .

. Takeuchi, Y., Yamanoi, K., Endo, Y., Murakami, S.

pp. and Izumi, K., : Velocities for the dry and wet

: snow avalanches at Makunosawa valley in

. Myoko, Japan. Cold Region Science and Technol-

Nishimura, K. and Ito, Y., : Velocity distribution ogy, , .

in snow avalanches. Journal of Geophysical Re-

search, , No. B , . Evgeniy Podolskiy

: :

.

: .

.

Yukari T , Hiroyuki T , Koichi N , Tomoki S ,

Hiroaki H , Yoshiaki G , Shigeki M and Yasoichi E

: A large-scale dry slab avalanche occurred at the Makunosawa valley in Myoko on

February , , which damaged many trees in the valley. We investigated the extent of damage

to the artificial cedar forest. We also estimated the decrease in avalanche velocity in the forest. Our

aim is to verify the role of forests in reducing the avalanche velocity. We found that the cedar trees

were broken by the bending stress. The damage was most near the upper edge of the forest. The

number of damaged trees decreased gradually in the forest. On the basis of these observation

results, we estimated the avalanche velocity from the bending stress of the broken cedar trees. We

considered two cases in the calculations: ( ) only the suspension layer of avalanche flowing into the

cedar forest and ( ) two layers of avalanche, consisting of a suspension layer (density: kg m ) and

a dense-flow layer (density: kg m ), flowing into the forest. In result, the avalanche was

estimated to flow into the cedar forest at the velocity of m s with a m high suspension

layer and a dense-flow layer less than m in height. The calculation result showed that the

avalanche slowed down in the forest and stopped around m from the upper edge of the forest.

This result is consistent with the observations.

) Tohkamachi Experimental Station, Forestry and Forest Products Research Institute,

Tatsu-otsu , Tohkamachi

) Hokkaido Forestry Research Institute, Koshunai-cho, Biei

) Graduate School of Environmental Studies, Nagoya University,

Furo-cho, Chikusa-ku, Nagoya

) Forestry and Forest Products Research Institute,

Matsunosato, Tsukuba

) Kyushu Research Center, Forestry and Forest Products Research Institute,

Kurokami, Kumamoto

) Ken’s-house , Honcho , Tohkamachi

Abstract

Study of extent of damage to cedar forest by large-scale slab avalanche, and

estimation of the avalanche velocity at Makunosawa, Myoko, Japan

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