| OCR Text |
Show 9 In this case it would be more realistic to use Table 2, with winter avalanche months as the time unit. Snow data from this area suggest that the four months of January through April are the time of principal avalanche danger. For the purpose of analysis, each year consists of these four months. To the nearest whole months, the return interval is 103 months and the estimated life 100 months. Entering Table 2 at the nearest round numbers for these values, the encounter probability is found to be 0.632. Chances are thus better than six out of ten that the ski area center will experience at least some avalanche damage during its life. Such chances are quite unacceptable for facilities intended to house and entertain large numbers of visitors and the use of such a site must be rejected. The real chance of damage is actually greater than that indicated by Table 2. Because part of the record is missing, the return interval may actually be shorter. Because two separate avalanche paths are involved, there is a chance that the same unusual snow and weather conditions which could create a damaging avalanche on one could also create a damaging avalanche on the other. Thus there is a possibility of two non- independent events, which violates one of the restrictions on Table 2. But the Table still gives at least the general magnitude of the risk. |
