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Podolskiy,E.A.,K.Nishimura,O.AbeandP.A.Chernous
,*+*a: Earthquake-induced snow avalanches: I. Historical case studies. Journal of Glaciology, /0 (+31),
.-+῍..0.
Podolskiy,E.A.,K.Nishimura,O.AbeandP.A.Chernous,
,*+*b: Earthquake-induced snow avalanches: II. Experimental study. Journal of Glaciology, /0 (+31),
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DISPLAY_IDU*****.&CONTENTS_ID+/3..
Avalanches induced by North Nagano Prefecture earthquake
on +, March ,*++
Isao KAMIISI+, Hiroki MOTOYOSHI+, Masaaki ISHIZAKA+ and Takeshi SATO+
+ Snow and Ice Research Center,
National Research Institute for Earth Science and Disaster Prevention, Japan
Abstract: The North Nagano prefecture Earthquake Mg0.1 on +, March ,*++ induced surfacesnow avalanches, full-depth avalanches, collapse of the block-like snowpack and cracks on the
surface of the snowpack over wide areas, where the seismic intensity was 0 or more. Especially,
within the area, failure surfaces of the snow avalanche were stepped and irregular. The avalanches
filled roads at many locations, some of which occurred at slopes even though avalanche supporting
structures had been deployed. Earthquake-induced avalanches of snow mixed with rock and sand
flew long distances due to high fluidity. According to the snowpack and weather conditions, the
likelihood of avalanche at the time of the earthquake was estimated to be low. We calculated the
stability index of the snowpack by using an equation that incorporates the earthquake acceleration.
The result shows that the index of the sliding surface for a surface-snow avalanche, consisting of wet
melt forms snow, was estimated to be +./ or less which supports the possibility of earthquakeinduced avalanche. Further research is needed to understand the snowpack collapse mechanism
caused by an earthquake.
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