Accession Number : AD0765500

Title :   Snow Pack Stability Indices Relative to the Climax Avalanche.

Descriptive Note : Final rept. 1 Jan 71-1 Jul 73,

Corporate Author : MONTANA STATE UNIV BOZEMAN

Personal Author(s) : Bradley,Charles C. ; St. Lawrence,William F. ; Lang,Theodore E. ; Brown,Robert L.

Report Date : 30 JUL 1973

Pagination or Media Count : 23

Abstract : The purpose of the research is to develop instruments, methods, theories, and indices which would permit rapid field evaluation of snow pack stability relative to climax avalanches. The results include the development of the light weight Snow Resistometer capable of measuring snow strengths between 2-5000 g/sq cm at depths up to 250 cm. Field and laboratory experiments revealed that snow under stress emits acoustical signals and that these signals relate to the nature of the snow and the deforming force. Of particular interest is the fact that snow retains 'memory' of the kind and degree of stress it has undergone many hours after relaxation. Also of interest is that under certain kinds of stress the pattern of acoustical emission allows anticipation of the failure of the snow as much as 40 minutes in advance. Both of these findings have implications in terms of field analysis and safety. Two theories are presented: (a) a non-linear theory for snow deformation (b) a theory of buckling as a potentially important mechanism for slab avalanche release. (Modified author abstract)

Descriptors :   (*SNOW, MECHANICAL PROPERTIES), (*AVALANCHES, SOURCES), STRESSES, LOADS(FORCES), FAILURE(MECHANICS), DEFORMATION, INSTRUMENTATION

Subject Categories : Snow, Ice and Permafrost

Distribution Statement : APPROVED FOR PUBLIC RELEASE