AVALANCHE FREQUENCY AND TERRAIN CHARACTERISTICS AT ROGERS PASS, BRITISH-COLUMBIA, CANADA

The frequency of avalanches at a given location is the primary variabl e for calculating the risk as input to zoning applications and decisio ns about avalanche-control options. In this paper, we present an in-de pth study of avalanche frequency using an extensive data base of avala nche-occurrence records from Rogers' Pass, British Columbia (43 avalan che paths; 24 years of records). This study, the first of its kind for high-frequency avalanche paths, yields the result that the frequency of avalanches may be described by a Poisson distribution. Study of the relationship between terrain variables and precipitation estimates sh ows that avalanche frequency is significantly correlated with path rou ghness, 30 year maximum water equivalent, east-west location from Roge rs' Pass summit, wind exposure and run-out zone elevation and inclinat ion. With the length of avalanche-occurrence records and quality of th e data, we believe our study is the most comprehensive in existence ab out avalanche frequency and its relation to terrain variables.