Regional Comparisons of Avalanche-Profile and Runout Data

Statistical comparison of avalanche-path-profile data from four widely separated mountain ranges (coastal Alaska, California Sierra Nevada, Colorado Rocky Mountains, and western Norway) are compared and presented in tabular form. Only unusual (approx. 100-yr return period) avalanches were compared. Inspection of the data leads to the following conclusions: (1) The avalanche paths in Norway and Alaska are larger and steeper than those sampled in Colorado and California; (2) The best regression equation for predicting the a angle developed from Norway data predicts a which is too large in Colorado, the Sierra Nevada, and coastal Alaska; (3) The extreme avalanche runout distances, as defined by the dimensionless Runout Ratio, a measure of runout distance with respect to path size, are significantly larger in California and Colorado; (4) Larger runout ratios are associated with shorter path lengths in the Colorado and Sierra Nevada data; (5) The observed differences between runout distances suggests that statistical runout equations developed in one mountain area should not be applied to other areas.