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K., +332: Measurement of snow hardness distribution. Annals of Glaciology, ,0, ,1῎-*.
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469

Investigation of collapse accidents of snow patches in Japan :report on an accident at Mt. Arasawa on August +, ,**.,and casualty analysis for the past .* years
Katsuhisa KAWASHIMA+, Yasushi KURIHARA,)* and Kaoru IZUMI+
+) Research Center for Natural Hazards and Disaster Recovery, Niigata University,
Nishi-ku, Niigata 3/*ῌ,+2+,) Graduate School of Science and Technology, Niigata University,
Nishi-ku, Niigata 3/*ῌ,+2+* Present address : Disaster Prevention Technology Division,
Railway Technical Research Institute, Kokubunji, Tokyo +2/ῌ2/.*
Abstract: A collapse accident of a snow patch occurred at Mt. Arasawa, Niigata Prefecture, on
August +, ,**.. This accident claimed the lives of - amateur photographers who were taking
photographs within a large snow tunnel formed by the snow melting underneath the snow patch.
Since such accidents have not been studied thus far, we carried out ﬁrsthand observations at theaccident site on Mt. Arasawa on August -, ,**.. In addition, data and information related to collapse
accidents of snow patches in Japan were collected from national and local newspaper articles. We
then carried out a statistical analysis of data for the past .* years from +30/ to ,**. to reveal thecharacteristics of this type of accident. A survey of the snow patch on Mt. Arasawa indicated thatthe collapsed snow area was as large as ,,* m,, and the mass of the collapsed snow was estimated to
be +/*ῌ,-* ton. Since the roof of the snow tunnel may have become a cantilever structure
immediately before the accident, this type of large-scale collapse was presumed to be caused bytensile fracture at the ﬁxed end of the roof because of its weight. From the casualty analysis, data
for ./ accidents and 0, casualties of snow patch collapses were compiled for the past .* years. It wasclariﬁed that there were many accidents and casualties in the Gunma Prefecture (Mt. Tanigawa) andToyama Prefecture (Northern Japanese Alps). As compared to accidents over the last .* years, theaccident at Mt. Arasawa in ,**. is characterized by the largest number of fatalities.
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