A Study on High-Speed Avalanches in the Kurobe Canyon, Japan

Abstract

ABSTRACT. Observations and measurements were made of high-speed avalanches at Shiai-dani, (he Kurobe canyon, (0 reveal their real features and properties, using strain-gauge-type load cells in measuring impact force and speed. A maximum impact pressure of 140 X 10 4 N m -' was obtained, as well as data indicating the existence of a number of wave fronts, ranging in speed from 9 to 60 m S-I inside an avalanche.Violent changes in atmospheric pressure ranging from -2 1 to + 5 mbar were observed near its path when a high-speed avalanche passed by. RESUME.

Snow Avalanche Motion and Related Phenomena

“…More recently, sophisticated instruments have been used and fantastically high impact pressures have been reported. La Chapelle (1977) mentions measurements made in the Japanese Alps by Shimizu and his colleagues (see Shimizu et al 1980) which indicate values of (0.47-2) X 103 kN m-2 , depending on snow fall, and a maximum impulse of 3.9 X 103 kN s m-2. The instruments were located at Shiai-dani on the reinforced concrete understory of a three-story construction barracks where in 1938, quoting La Chapelle, "this barracks was struck by an avalanche which carried away the superstructure on a 600 m aerial trajectory across an intervening ridge, across the Kurobe gorge, and' smashed it against a rock cliff on Mt.…”

Investigation théorique et expérimentale des caractéristiques dynamiques des avalanches de neige dense

“…Les références en notre possession (Shimizu 1972(Shimizu , 1973(Shimizu , 1974(Shimizu , 1980 font état de mesures d'effort effectués au moyen de pénétromètres, puis de jauges de contrainte. Les supports ont évolué et des assemblages de profilés métalliques très semblables à ceux qui étaient en place au Col du Lautaret ont été remplacés par des massifs en béton, système d'ailleurs plus adapté car de fréquence propre beaucoup plus faible.…”

The Intermittency Regions of Powder Snow Avalanches

“…In the past, PSAs were commonly thought to consist of a low-density, turbulent suspension layer above, and sometimes in front of, a dense flow (Norem, 1991;Zwinger et al, 2003). However, observations from the 1980s or earlier from Canada (Schaerer & Salway, 1980), Russia (Bozhinskiy & Losev, 1998;Grigoryan et al, 1982;Sukhanov, 1982), and Japan (Nishimura et al, 1993;Shimizu et al, 1980) have shown the existence of a third region, sometimes called the light flow layer or the saltation layer. In recent years there has been increasing evidence of this third region, which has characteristics of both a dense region and a suspension region.…”

“…Frequency-modulated continuous-wave (FMCW) radars, installed along the avalanche path at the VdlS test site, have repeatedly demonstrated the presence of surges and highlight a frontal region characterized by large signal intensity well above the basal dense layer (Figure 1 Signal fluctuations are clearly visible in many earlier data sets. Measurements of impact pressure and air pressure performed in the 1980s in Japan indicated the presence of oscillatory behavior in the dilute avalanche regions (Shimizu et al, 1980). The presence of snow balls of different sizes at different heights in the avalanche frontal region was studied by Schaer and Issler (2001).…”