| OCR Text |
Show If the slab's resistance to penetration is less than 100 kg, its stability is doubtful. If its resistance is over 100 kg, the slab usually has sufficient inherent strength to maintain its position. The snow ranger's reaction in any borderline situation is to check the slab out with explosives. The shear frame technique approaches the problem from a different angle by attempting to determine the cohesion of the various snow layers in terms of their resistance to shearing. Excavation is required, making the process more time- consuming than the penetrometer profile method. After the field tests have been made, the relative stability of the snowpack is calculated by mathematical formulae. SUMMARY AND EXAMPLES Obviously the process of avalanche hazard forecasting is not simple. The hazard fluctuates from hour to hour and from one part of an area to another, so that forecasting must be on a continuous basis. Five principles can be stated: 1. The variety of conditions which can produce avalanche hazard is great. 2. A strong preponderance of favorable factors is necessary to produce avalanche hazard. 3. Combinations of factors are more important than any single item. 4. Wind is dominant as a contributory factor. 5. Hazard forecasting is not a mechanical process. The factors are guides, not yardsticks, and must always be confirmed by testing in the field. - 55 ~ |
