Japan Geoscience Union Meeting 2015

Presentation information


Symbol S (Solid Earth Sciences) » S-VC Volcanology

[S-VC48] Mitigation of Volcanic disaster - Basic and applied research

Sun. May 24, 2015 11:00 AM - 11:45 AM A05 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Kazutaka Mannen(Hot Springs Research Institute of Kanagawa Prefecture), Shinji Takarada(Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology), Eisuke Fujita(National research Instituite for Earth science and Disaster prevention, Volcanic research department), Hisashi Sasaki(Asia Air Survey Co., Ltd.), Chair:Kazutaka Mannen(Hot Springs Research Institute of Kanagawa Prefecture)

11:00 AM - 11:15 AM

[SVC48-08] The characteristics of rockfall and accident on Mount Fuji

*Jiro KOMORI1 (1.Teikyo Heisei University)

Keywords:mountaineering, mountain tourism, agglutinate, human-Induced rackfall, quiet interval, case study

Among the mass wasting on mountains, rockfall is general phenomena. These events in active volcanic area, including small slope failures are common, even if that is at quiet interval period. Nevertheless, in the case of Japan which disaster prevention measures around roads and settlements have been applied, rockfall phenomenon is recognized as affairs of other people. On the other hand, in the well developed country in terms of tourism and mountaineering business, actual risk of rockfall to the peoples will be high, if they enter to mountain areas without knowledge of landslide hazard.
In the Japanese mountain sightseeing route and trail, most accident-prone area by rockfall is Shirouma-daisekkei (Nagano Prefecture), then Mt. Fuji (Shizuoka and Yamanashi Prefecture). Besides, the most deadly accident occurred at Yoshida-osawa valley in Mt. Fuji in 1980. In spite of descending route was closed after the 1980 tragedy, fatal and injury rockfall accident almost every year. Furthermore, in the last seven years, more than 300,000 visitors passed through the 8th station (EL. 3500 m) of Mt. Fuji in every year. Hence, detail study for prior incidents of rockfall and possible danger area along the trail are required.
The past cases in rockfall accident were collected and studied based on newspaper, mountain journals and police reports. The following characteristics were revealed,
- major accidents have been occurring between the 8th station and the summit on all four mountain route (trail from Fujiyoshida/Subashiri, Fujinomiya and Gotenba)
- most of the accidents were recorded in the end of July to the middle of August
- temporal trend of occurrence time of the day is obscure
- human-induced rockfall is prone to occur from descending person or at descending route.
- the sources of regular rockfalls are cracky lava or weak agglutinated rock. A rock face with open crack near the summit of the Fujinomiya route seems to be ready to fall down. The location of present route should be shifted to elsewhere.