Ser m1 "21d, National Research Conseil national no, 1468 cO . ~1 uncil Canada de recherches Canada C 2 n 7 B LDG Institute for lnstitut de -- -4 Research in recherche en Construction construction Avalanche Accidents in Canada 111. A Selection of Case Histories 1978 - 1984 by P.A. Schaerer NRCC 27950 Price $10 AVALANCHE ACCIDENTS IN CANADA 111. A SELECTION OF CASE HISTORIES 1978-1984 ANALYZED by P.A. Sehaerer 3. C. Avalanche Centre Institute for Research in Construction IRC Paper No. 1468 ISSN 0381-4319 Ottawa, July 1987 @ National Research Council of Canada 1987 AVALANCHE ACCIDENTS IN CANADA fIL. A SELECTION OF CASE HISTORIES 1978-1984 by P.A. Schaerer ABSTRACT The circumstances, rescue operations, snow and weather conditions, and avalanche data of 49 avalanche accidents in Canada are described. Skiers, mountain climbers, snowmobile operators, workers, and various structures were involved. Statistics of avalanche accidents in Canada from 1978 to 1985 are included. ACCIDENTS CAUSBS PAR LES AVALANCHES AU CANADA 111. CHOIX DE CAS DOCUMENTES DIACCIDENTS DE 1978 A 1984 par P.A. Schaerer L'auteur dgcrit les circonstances de 49 accidents causgs par des avalanches au Canada, les opgrations de sauvetage, les conditions m~t&orologiqueset d'enneigement de m6me que les donnges ayant trait aux avalanches ellesmi5mes. Ces accidents ont impliqug des skieurs, des alpinistes, des motoneigistes, des ouvriers ainsi que diverses constructions. Ce document renferme aussi les statistiques concernant les accidents causes par des avalanches au Canada de 1978 a 1985. FOREWORD Winter travellers in mountains are frequently exposed to avalanche hazards for considerable periods of time but seldom observe avalanches in motion or the destruction they cause. Descriptions of accidents and the circumstances leading to them, however, can be useful in alerting people to potential dangers and stimulate concern for safety measures. To promote such awareness the Avalanche Centre of the Institute for Research in Construction, National Research Council of Canada (NRCC), collects and publishes statistics and case histories of avalanche accidents. The present publication, Volume 111 of a series, describes 47 avalanches that resulted in death, injury, or property damage between 1978 and 1984, plus two major disasters of previous years, 1910 and 1950. Volumes I and I1 (Stethan and Schaerer 1979; 1980) describe avalanche accidents before 1978. The information now presented was compiled by staff members Peter Schaerer and Paul Anhorn and snow safety consultant Chris Stethem, who worked under NRCC contract No. OSX83-00171. The accident data were collected through interviews with eye witnesses and people involved in rescue operations, as well as from newspaper articles and reports compiled by the Alpine Club of Canada. It is hoped that the experiences of the unfortunate victims and the lucky survivors will promote interest in safety measures. It is recommended that people who traverse avalanche terrain develop the skills to evaluate weather conditions and snow profiles. ACKNOWLEDGEMENT This publication would not have been possible without the cooperation of the numerous individuals and agencies who shared their knowledge and experience. The National Research Council of Canada wishes to thank the following: The superintendents and warden services of Banff, Jasper, Yoho, Kootenay, Glacier and Mount Revelstoke National Parks, Parks Canada The Alpine Club of Canada Apex Alpine Recreations Ltd. Rrinco Mining Limited, British Columbia Ministry of Transportation and Highways CMH Heliskiing CN Rail CP Rail Fernie Snow Valley Ski Ltd., Kananaskis Country, Alberta Royal Canadian Mounted Police Whistler Ski Corporation Terry Barter Frank Baumann Jim Ray Jim Brewin Gordon Burns David Cronmiller Michael Demuth Geoff Freer Pat Harrison Robin Mounsey Kris Newman Sepp Renner John Tweedy Michael Zylicz INTRODUCTION Avalanche researchers at the National Research Council of Canada have collected information about avalanche accidents in Canada since 1969 that resulted in death or significant property damage. Table I is a summary arranged according to the type of accident. Fatalities have averaged seven per year, but there has been a shift lately to a greater number among those engaged in recreational ac.tivities as opposed to those at work. Comparison of Tables I and I1 makes this particularly clear. Table I1 reflects the recorded-accident distribution for the years between 1953 and 1969, but probably does not contain the correct total number since not all accidents were recorded in that period. A decrease in the number of accidents on roads and in residences and the workplace reflects greater concern for safety. For example, mines used to be developed with little consideration for avalanche paths, but management is now more aware of the danger and provincial mine inspectors are trained to recognize hazardous terrain that requires the introduction of safety measures. It has become common practice to consider avalanche hazards when permits for land development and building are issued. The hazards on roads are monitored by trained maintenance personnel who close them during critical periods and use explosives to control avalanches in some areas. The tendency for a greater number of accidents to be associated with recreational activities has also been noted in the United States where climbers represent the greatest number of victims (Williams and Armstrong, 1984). These statistics lead to the conclusion that education about avalanche safety should now be aimed mainly at skiers, climbers and snowmobile operators. Property damage includes destroyed or damaged buildings, bridges, tramways, chairlifts, hydro transmission lines, machinery, railway equipment, and road vehicles. The true value of damage is suspected to be greater than that shown in Table I since minor damage may go unreported and the additional monetary loss due to disrupted service on roads, railways, powerlines and mines is not calculated. The value of lost or interrupted service is often greater than the cost of replacing destroyed structures and equipment, hut it is difficult to estimate. A reasonable figure would be about $1 million per year if all unreported avalanche events and losses from interrupted services were included. The statistics on fatalities and property damage in Table I do not reflect the full extent of the avalanche hazard. Every year many people are caught in avalanches but escape unharmed or with minor injury. In order to obtain a more accurate picture, industry and government agencies were requested in 1979 to report all incidents involving persons, vehicles or property. The forms used for reporting are contained in the Guidelines for Weather, Snowpack and Avalanche Observations (Avalanche Research Centre, 1986). The names of persons involved need not be reported and information from individual reports is confidential, made public only in summarized form. Table 111, a summary of reports between 1979 and 1985, shows that an average of 42 people per year have encounters with avalanches. It is suspected that the true number may be about double this since many people are not aware of the reporting system, forget to file a report, or wish to avoid publicity. Noteworthy from Table 111 is the number of people (an average of four per year) completely buried but rescued alive. These rescues are effected by witnesses who find the buried person either by transceiver signals or by probing and shovelling immediately at the most likely spot. The number of incidents reported in Table I11 are distributed about equally among the three mountain systems of Western Canada: Rocky Mountains, Columbia Mountains, and Coast Mountains. Most Frequent Mistakes The principal objective of this and the earlier publications on avalanche accidents (Stethem and Schaerer, 1979, 1980) is to draw attention to mistakes and to learn from them. Accidents involving people have occurred when either terrain or snow stability was judged to be safe but was not, or people made errors after recognizing unsafe conditions. Analysis of the accident case histories shows that mistakes were made repeatedly through failure to recognize the following: - deposition of wind-transported snow, - possibility of avalanches releasing above a travel route, - terrain traps in narrow valleys, - steep slopes, trees, rocks, crevasses below a travel route, - weak layers and bonding deep in the snowpack, - influence of high air temperatures and solar radiation, - possibility of a second avalanche in the same path, - concentration of people in an avalanche path, - need to wear transceivers and carry shovels. Errors in Terrain Analysis Many back-country travellers seem to lack the knowledge and skill to recognize the subtle variations in terrain that cause depositions of drifting snow. Accidents have occurred when snow slabs fractured on the lee side of small ridges running in the fall line of long slopes, in shallow cirques where one side is more subject to deposition of wind-transported snow than the other, and below rolls of terrain. Avalanches that started on the slopes above skiers and snowmobilers were the cause of numerous accidents. Travellers often crossed a slope not steep enough to slide until their weight and motion produced a local failure that propagated to steeper slopes above. Usually the avalanche starting high above was large and moving fast when it reached the victims, making escape impossible. Skiers travelling through narrow valleys have been trapped and