| OCR Text |
Show likened to the rumble of heavy trucks or a train. No airblast was noted although there is a difference of opinion on this point. With a faster moving dry snow or slab type avalanche on such a precipitous slope, airblast should be practically a certainty. The slide apparently splashed or bounced when its main front hit the easier grade of the talus slope. This probably accounts for the phenomenon of trees in the slide path sheared off twenty feet above the level of the slide at rest. Conclusions 1. Due to their destructive power, climax avalanches are a serious problem in alpine ski areas or on approach roads. 2. Since they man infrequently, information may be deficient as to their location and the conditions favorable to their occurrence. « 3. Climax avalanche paths are often difficult to recognize. Administrators of alpine ski areas must seek by every means to locate climax avalanche slide paths and to obtain background weather data. Good terrain analysis will recognize likely locations. Historical records however fragmentary are valuable. Observation of the destruction of old slides is important. Aerial photos should be of value in many cases. Consultation with old timers should also be helpful. The plan of any alpine ski area will be influenced by climax avalanche possibilities. Permanent improvements especially must be so located as to have positive protection. 5. Case histories of climax avalanches in the vicinity of Alta where complete weather data is available yield information of general value. Climax avalanche occurrence depends upon special combinations of weather and snow conditions operating over a period of time. 6. Active protection from climax avalanches in areas of particular importance is feasible through the use of explosives. In example, Hustler Pace, an annual avalanche path at Alta known also to be a climax avalanche site, was blasted three times during the March 19^8 storm sequence. On each occasion a large slide was released. Nevertheless, on March 3°. during the final major storm of the month, a natural slide from Hustler Pace reached the bottom of the canyon. If the older snow had also been involved, a climax avalanche would probably have occurred. The End -96- |
