Impressions from applying ISO31000 to avalanche mitigation projects

31 Jamieson, B. Jones, A.S.T. 9999 Impressions from applying ISO31000 to avalanche mitigation projects International Snow Science Workshop Grenoble, France 7/10/2013 ISO 31000, enterprise risk management, uncertainty, organizational objectives ISO 31000 is an international standard for risk management. It offers standard risk concepts, terminology and processes for diverse organizations and their component departments. Few applications to avalanche mitigation projects are publicly available. While not authorities on ISO 31000, we share our impressions from applying it to examples of avalanche mitigation for infrastructure. ISO 31000 defines risk as the effect of uncertainty on (organizational) objectives. These effects can be positive or negative. For organizations ultimately responsible for managing avalanche risk (the risk owner), their objectives often include profit, positive relations with the workforce and environmental stewardship. These objectives are subject to diverse influences including uncertain negative events such as loss of life, employee injuries, property damage or transportation delays, all of which can be caused by snow avalanches. To illustrate ISO 31000 concepts and terminology, we use a simple example of a proposed mining road threatened by snow avalanches. Avalanches can threaten worker safety and cause delays of ore as well as of crew changes. The mining company (MC) contracts an avalanche consultant to assess the avalanche hazards and recommend mitigation options. The consultant recommends a mitigation option involving a deflection dike combined with an avalanche forecasting and control program. MC rejects the recommended mitigation option because the proposed dike would affect a stream, i.e. affect MCâ��s environmental objectives, which were not part of the terms of reference of the contract. To ensure ISO 31000 is implemented in the contract, MC issues a second avalanche mitigation contract that includes assessing the environmental risk. Following completion of the second contract, MC selects risk treatments including a forecasting and control program without static defences, a worker safety program specific to the avalanche prone road, increased insurance for the cost of potential delays in shipping ore, and expanded liability coverage. ISO 31000 offers a framework for an enterprise-wide management of risk i.e. the effects of uncertainty on the organizationâ��s objectives. We illustrate how ISO 31000 can be applied to an organization responsible for managing avalanche risk and the benefit of it being applied at all levels. Abstract submitted. 31 Schirmer, M. Jamieson, B. 9999 Limitations of an infrared camera to measure snow pit -wall temperatures International Snow Science Workshop Grenoble, France 7/10/2013 Snow profile, infrared image, thermal structure Kinetic snow metamorphism is known to be crucial for avalanche formation and is driven by temperature gradients. Faceting close to a crust can be observed even in the absence of gradients needed for kinetic metamorphism when measured with thermometers 10 cm apart. Interesting results were found with recent studies that visualized small scale thermal structures with an infrared(IR) camera. The studies found melt-freeze crusts as being warmer or cooler than the surrounding snow depending on the large scale gradient direction. However, an important assumption within the studies was that a thermal photo of a freshly exposed snow pit is similar enough to the snow internal thermal structure. In this study, we tested this assumption by recording thermal videos during the exposure of the snow pit wall. The results show increasing gradients with time in the first minute both at melt-freeze crusts and at artificial surface structures such as shovel scours. Cutting through a crust with a cutting blade or a shovel produced small concavities even when the aim was for a planar surface. Our findings suggest a surface structure dependency of the thermal signal, which is only observed at times with large temperature differences between air and snow. We were able to reproduce the hot-crust/cold-crust-phenomenon and relate it entirely to surface structure in a temperature-controlled cold laboratory. Concave areas cooled/warmed slower compared to convex areas when applying temperature differences between snow and air. This can be explained with increased emission or increased turbulent heat exchange between air and snow at convex areas. Thermal videos suggest that such processes influence the snow temperature within seconds. Our findings show the limitations of the use of a thermal camera for pit-wall temperatures; at interesting times, i.e. large gradient between air and snow, the interaction of snow pit and atmospheric temperatures will be enhanced. At interesting areas, i.e. crusts or other heterogeneities, we were not able to produce a homogenous snow pit surface and non-internal gradients will appear at the exposed surface. The immediate reaction speed of the snow pit temperature with the atmosphere complicates the capture of the internal thermal structure of a snowpack even with thermal videos. Instead, the shown structural dependency of the IR signal may be used to detect structural changes of snow, e.g. caused by kinetic metamorphism. The IR signal can also be used to measure near surface temperatures in a homogenous new snow layer. Abstract submitted. 31 Thumlert, S. Jamieson, B. 9999 Measurements of triggering stress transmitted through the upper snowpack International Snow Science Workshop Grenoble, France 7/10/2013 Stress, localized dynamic loading, snow properties, snow stability evaluation, bridging In the majority of fatal avalanches, skiers and snowmobilers apply load to the snow cover that triggers the initial failure in a weak layer. Understanding how the stress due to the dynamic surface load transmits through the snow cover can help people avoid situations where they can trigger avalanches. Capacitive sensors were used to measure this dynamic stress within the mountain snow cover. The sensors were used on 33 separate field days to collect over 6,500 measurements with loading by skiers, snowmobiles, falling skiers, people walking, drop hammer experiments and hand tapping on shovel blades as in some stability tests. The change in shape and magnitude of the induced stress was observed for three â��typicalâ�� snow cover structures. Relatively soft snow allowed the specific levels of dynamic stress to penetrate deeper into the snow cover, thus increasing the probability of initiating a failure in a weak layer. Whereas, supportive surface layers spread the stress out laterally and decreased the depth to which specific levels of stress penetrated. We described the snow cover for the experiments according to a bridging index which allowed us to analyze the snow cover necessary to effectively spread the induced stress from a â��typicalâ�� skiing turn and the uphill passage of a snowmobile. Using consistent and repetitive dynamic loading with a â��drop hammerâ�� device, more stress was observed in a fully isolated column of snow compared to unisolated snow. This yielded information about the bridging ability of varying snow stratigraphies. In summary, we present data describing how stress from human triggers penetrates the snow cover. Abstract submitted. 31 Bellaire, S. Jamieson, B. 9999 On estimating avalanche danger from simulated snow profiles International Snow Science Workshop Grenoble, France 7/10/2013 avalanche warning, avalanche danger, SNOWPACK, snow cover simulations, data sparse areas. Estimating avalanche danger is the primary goal of avalanche warning services. Typically avalanche danger is estimated based on a variety of information such as manual snow profiles, avalanche observations as well as weather data. However, this required information is often not available especially in data sparse areas. It has been shown that coupled snow cover and numerical weather prediction models can provide such information on the snow cover. For this study we simulated the snow cover for three elevation bands â�� alpine, treeline, below tree-line â�� at Glacier National Park, B.C., Canada for the winter season 2012-2013 between December and March. Snow cover simulations were performed using the Swiss snow cover model SNOWPACK forced by weather data from the Canadian high-resolution numeric weather prediction model GEMLAM. Experienced forecasters estimated the regional avalanche danger (Low to Extreme) daily during the same period for the three elevation bands. Multivariate classification trees were used to estimate the avalanche danger from the simulated profiles. Classification trees were built using four parameters derived from the simulated profiles. These four parameters were the new snow amounts â�� 24-hours and 3-days â�� as well as measures for the likelihood of triggering and the expected avalanche size â�� based on Sk38 and the depth of a critical layer. A comparison of the avalanche danger estimated from the simulated profiles with the forecasted avalanche danger showed that the avalanche danger was estimated correctly with an accuracy of 76% for the alpine, 66% for tree-line and 72% below tree-line â�� overall accuracy 71%. Although the simulated avalanche danger tends to be slightly underestimated, especially for tree-line and below tree-line such a model chain can be a valuable tool for avalanche warning services especially for data sparse areas. Abstract submitted. 31 Horton, S. Schirmer, M. Jamieson, B. 9999 Spatial predictions of surface hoar and crust formation International Snow Science Workshop Grenoble, France 7/10/2013 surface hoar, melit-freeze crusts, formation, evolution, avalanche forecasting, snowpack stratigraphy, snowpack properties Understanding the distribution of critical snowpack layers over terrain is important to assess the avalanche hazard. Two common critical layers, surface hoar and melt-freeze crusts, form near the snow surface under specific weather conditions. In this study we modelled the distribution of such layers on a regional scale using forecasted weather data. To calibrate the models we measured the crystal size of surface hoar and the thickness and hardness of melt-freeze crusts at six study sites in the Columbia Mountains of British Columbia. We also tracked buried layers at these sites with weekly snow profiles. Surface hoar formation was modelled with the latent heat flux and melt-freeze crusts with a semi-physical model using radiation, temperature and precipitation data. Layers were also modelled with the snow cover model SNOWPACK. Forecasted weather data were used to map the formation of surface hoar and crusts on 2.5 and 15 km grids across the Coast, Columbia and Rocky Mountains. These predictions were compared to observations made by avalanche professionals at over 100 study plots. The model identified regions where surface hoar and melt-freeze crusts formed (presence or absence of a layer) and areas where the formation was more developed (indicated by surface hoar size and crust hardness and thickness). By coupling weather and snowpack models, spatial predictions of these critical layers could help forecasters assess avalanche hazard in data sparse areas. Abstract submitted. 31 Sinickas, A. Jamieson, B. 9999 Validating a relationship between avalanche runout distance and frequency International Snow Science Workshop Grenoble, France 7/10/2013 Statistical models, Runout Ratio, frequency, magnitude, Poisson, Gumbel, vegetation trim lines, avalanche runout, snow avalanches, runout zone, avalanche path Statistical runout models such as the alpha-beta or Runout Ratio can provide good estimates of extreme avalanche runout, but do not describe more frequent runout distances, such as ten or thirty-year events. These boundaries are critical in many hazard mapping and analysis projects. This paper presents an assessment of a model which expresses return period as a function of runout distance. We created runout-return profiles from field trim line observations (38 paths) and occurrence records from transportation corridors (28 paths) in Canada. Over 250 points along these profiles were compared to model estimates. Model generated return periods fell mostly within the field observed range for 24 cases out of 143. Model generated return periods fell within 5 years of the 10, 15 and 30 year runout levels determined using occurrence records for 4 out of 31 cases. The model tended to overestimate return periods. Abstract submitted. 31 Conlan, M. Jamieson, B. 9999 Weather preceding deep slab avalanches International Snow Science Workshop Grenoble, France 7/10/2013 avalanche forecasting, deep slab avalanche, preceding weather, natural, spontaneous, localized dynamic loading, persistent weak layers Deep slab avalanches release on persistent weak layers of facets, surface hoar, depth hoar, or poorly bonded crusts and are generally hard to forecast. They are triggered either naturally from weather or from localized dynamic loads (LDLs) such as skiers or snowmobilers. For natural deep slab avalanches, weather preceding the release plays a key role in formation; load from precipitation or wind transported snow applies higher stress on underlying persistent weak layers. Alternatively, warm temperatures or solar radiation can reduce slab stiffness allowing for an increased strain rate on buried weak layers. Deep slab avalanches that release from LDLs are caused by the increased stress applied to buried persistent weak layers. For some deep slab avalanches that release from stress induced by LDLs, preceding weather likely also plays a strong role. For this research, 48 deep slab avalanches were accessed in Western Canada between 1993 and 2013 to obtain information on the persistent weak layer and overlying slab. Weather parameters such as precipitation amount, daily minimum and maximum temperature, and wind speed and direction were obtained from the nearest weather station for the two weeks prior to release of the accessed avalanches. Results indicate that the accessed natural deep slab avalanches typically occurred from either rapid mass loading via precipitation and/or wind transported snow or from snowpack warming by solar radiation. For some of the releases triggered by LDLs, we speculate that rapid loading from precipitation or wind transported snow increased the stress on the persistent weak layers to the point where the LDLs were critical. We also speculate that warming reduced slab stiffness for some deep slab avalanches, allowing the stress from the LDLs to reach deeper in the snowpack and subsequently initiate a fracture in the buried persistent weak layers. Examples of such releases are discussed. Case studies of natural releases that likely occurred from precipitation loading, wind loading, and solar warming are described. A natural deep slab avalanche that likely released from precipitation loading received approximately 22 cm of snow during the day of release, along with further loading from wind transported snow. The natural release that likely occurred from wind loading received only 15 cm of snow over the preceding four days but up to another 90 cm from wind transported snow. The natural release from solar warming received only 9 cm of snow in the preceding five days from release but was on a south-facing slope and exposed to direct short-wave radiation during the day of release. Abstract submitted. 31 Bellaire, S. Thumlert, S. Jamieson, B. Statham, G. 9999 Does climate change affect avalanche activity? - a study at Rogers Pass, Canada International Snow Science Workshop Grenoble, France 07/10/2013 climate change, avalanche activity Long-term changes of the climate system have been observed. It has been shown in recent years that short term changing atmospheric conditions influence the formation and evolution of the seasonal mountain snow cover and therefore can influence the avalanche hazard. To investigate the effect of longterm changes of the climate system on avalanche formation we analyzed homogenized weather data, i.e. air temperature and precipitation, from Rogers Pass (1340 m a.s.l.) as well as non-homogenized weather data from Mt. Fidelity (1905 m a.s.l.). Both weather stations are located in Glacier National Park, British Columbia, Canada. Avalanche data from the same region were recorded between 1965 and 2012 along the section of the Trans Canada Highway located within the park. Although not significant, the mean annual air temperature showed similar trends for the last decades as already found for the Northern Hemisphere (+0.5 Â°C Mt. Fidelity, +0.7 Â°C Rogers Pass). The largest increase of the monthly mean air temperature was found for the early winter months from November to January. A general decreasing trend of the solid precipitation ratio, i.e. more rain, was found during recent decades, especially for the early winter season from October to December. The increase in early season rain might have favoured the formation of early season rain crusts. The frequency of natural avalanches within Glacier National Park did not increase during the last decades â�� perhaps confounded by variations in explosive use â�� but a trend towards more avalanches in January and March was found which might be related to the formation of early season rain crusts and would therefore suggest a potential shift towards deeper instabilities. Abstract submitted. 31 Haladuick, S. Jamieson, B. 9999 Snowpack tests and their association with local avalanche danger International Snow Science Workshop Grenoble, France 07/10/2013 avalanche danger, snowpack tests, regional bulletin, compression test, rutschblock test The regional avalanche bulletin is an expert assessment of the avalanche danger for a specific region. This rating can differ from the local avalanche danger for several reasons, including the size of the forecast region, which in Canada ranges from 100 to 30,000 km2 compared to the 10 km2 covered in a typical backcountry day. This study assesses the correlation between snowpack tests (rutschblock and compression tests including fracture character and release type) and the local and regional avalanche danger. The results were grouped for analysis by the dominant avalanche problem / situation of the day, e.g. loose dry, wet (loose and slab), wind slab, storm slab, persistent slab and deep slab. This paper presents observations of snowpack tests, local avalanche ratings and key avalanche problems, collected over 374 field days since the winter of 2009. These field days yielded 627 individual ratings for comparison with 621 compression tests and 44 rutschblocks. The snowpack tests were performed in a representative location and accompanied by a profile to identify the failure plane and slab properties. An earlier study with a much smaller dataset showed weak but significant correlations between snowpack test results and local danger. We expect that rutschblock tests, being larger and more representative of human-triggering, will correlate better with the local avalanche danger than compression tests. We also expect that snowpack test results will correlate better with the local avalanche danger rating than with the regional bulletin. The results of this study could be useful in the preparation of public avalanche bulletins. Abstract submitted 0 Conlam, M. Tracz, D. Jamieson, B. 9999 Measurements and weather observations at persistent deep slab avalanches Cold Regions Science and Technology slab avalanche, persistent weak layer, cohesive slab, avalanche forecasting, snow stability, snow strength, preceding weather 3 Bellaire, S. Jamieson, B. Statham, G. 2013 Relating avalanche activity to climate change and coupled ocean-atmospheric phenomena Davos Atmosphere and Cryosphere Assembly DACA-13 Davos, Switzerland 12/07/2013 climate change, avalanche activity, La Niña, PDO Climate change is evident and long-term changes of the climate system have been observed. It has been shown that changing atmospheric conditions influence the formation and evolution of the seasonal mountain snow cover and therefore determine the avalanche hazard. For this study we analyzed weather data measured at two weather stations between 1965 and 2012 located in Glacier National Park, British Columbia, Canada as well as avalanche data from the same region, i.e. along the section of the Trans Canada Highway located within Glacier National Park. The mean annual air temperature showed similar trends for the last decades as already found for the Northern Hemisphere (+0.5 Â°C Mt. Fidelity, +0.7 Â°C Rogers Pass). The largest increase of the monthly mean air temperature was found for the early winter month from November to January. A decreasing trend of the solid precipitation rate, i.e. more rain events, was found for the early winter season (October to December) favouring the formation of early season rain crusts. This might be related to climate change induced warming during the last decade favouring more weaknesses deep in the snowpack and potentially more deep slab avalanches. The frequency of natural avalanches within Glacier National Park did not increase during the last decades, but a trend towards more avalanches in January and March was found which might be related to the formation of early season rain crusts and therefore a shift towards deeper instabilities. An increasing frequency of avalanche activity could be expected during winters associated with La NiÃ±a or the cold phase of the Pacific Decadal Oscillation (PDO). Winters where La NiÃ±a and the cold phase of the PDO are in phase showed higher avalanche activity. Abstract only. 31 Schweizer, J. Jamieson, B. Reuter, B. 2013 How surface warming affects dry-snow instability 31 25,31 warming, dry snow, solar radiation, slab avalanche Warming is believed to be one of the most prominent causes of snow instability â�� although experimental evidence is rare. We know that â�� due to the low thermal conductivity of snow â�� warming at the snow surface rarely affects the weak layer temperature. In the case of dry-snow slab avalanches, instability is not due to weakening of the weak layer, but is believed to be due to increased deformation within the near-surface layers of the slab. Solar radiation can penetrate the surface and effectively reduce the stiffness of the upper layers. Changing slab properties directly affect snow instability in many ways. Recent field measurements provide insight into the processes believed to promote dry-snow instability. But still, field evidence is rare, which is also because the effects of surface warming are subtle and likely only promote instability during certain slab/weak layer conditions. 0 Thumlert, S. Exner, T. Jamieson, B. Bellaire, S. 2013 Measurements of localized dynamic loading in a mountain snowpack Cold Regions Science and Technology Elsevier 85 2013 94-101 avalanche forecasting, snowpack stratigraphy, snowpack properties, snowmobile, skier, capacitive sensors In the majority of fatal avalanches, skiers and snowmobilers apply load to the snow cover which triggers the initial failure in a weak layer. Understanding how the stress due to the dynamic surface load transmits through the snow cover can help people avoid situations where they can trigger avalanches. Capacitive sensors were used to measure this stress within the mountain snow cover. The three main variables affecting stress transmission through the snow cover investigated in this paper are the type of loading, depth and snow cover stratigraphy. At specific depths, snowmobiles added more stress than skiers did, thus increasing the probability of initiating a fracture in a weak layer and releasing a slab avalanche. The increased penetration depth of snowmobiles into the snow cover compared to skiers was the primary reason for this increase in stress. A decrease in stress was observed with increasing depth. A decrease in stress was observed with increased snow cover hardness. Supportive surface layers created a â��bridging effectâ�� that spread stress out laterally and decreased the depth to which it penetrated. http://dx.doi.org/10.1016/j.coldregions.2012.08.005 3 Thumlert, S. Jamieson, B. Exner, T. 2012 How do you stress the snowpack? International Snow Science Workshop Anchorage, Alaska 1 506-512 16/09/2012 snowpack stratigraphy, stress, snowmobiler, skier, avalanche release In the majority of fatal avalanches, skiers and snowmobilers apply load to the snowpack which triggers the initial failure in a weak layer. Understanding how the stress from a dynamic surface load transmits through the snowpack can help people avoid situations where they can trigger slab avalanches. Capacitive sensors were used to measure this stress within the mountain snowpack. The three main variables affecting stress transmission through the snowpack investigated in this paper are the type of loading, depth and properties of the snowpack. A decrease in stress was observed with increasing depth. At specific depths, snowmobiles added more stress than skiers did, thus increasing the probability of initiating a fracture in a weak layer and releasing a slab avalanche. The increased penetration depth of snowmobiles into the snowpack compared to skiers is the primary reason for this increase in stress. Falling skiers added about 3 times more stress than typical skiing. Skiers added about 1.5 times more stress than snowboarders. A decrease in stress was observed with increasing depth. Supportive surface layers created a â��bridging effectâ�� that spread stress out laterally and decreased the depth to which it penetrated. 3 Horton, S. Bellaire, S. Jamieson, B. 2012 Modelling surface hoar formation and evolution on mountain slopes International Snow Science Workshop Anchorage, Alaska 1 194-200 16/09/2012 surface hoar, avalanche forecasting, snowpack stratigraphy, persistence, weak snowpack layer Predicting the spatial distribution and persistence of surface hoar layers is a challenge to avalanche forecasters and backcountry recreationists. This study evaluates surface hoar size predictions made with empirical weather based models and discusses how buried layers change over time. Surface hoar layers were observed during the 2011-2012 winter at flat, north and south facing slopes in the Columbia Mountains. Two models were developed to predict crystal size, one using a constant growth rate and the other estimating vapour deposit from the surface energy balance. Weather station data and forecasted data from the GEM15 numerical weather prediction model were used to simulate the growth of layers over seven winters. Reasonable size predictions were made with growth rates of 2.1 and 2.6 mm per day (r2 = 0.44), although specific rates appeared to change with season. The surface energy balance model made good predictions of crystal size with real station data (r2 = 0.74) and reasonable predictions with the output of GEM15 (r2 = 0.49). Time series of shear frame and propagation saw test results were made from observations on a buried surface hoar layer that formed in February 2012. The large crystals in this layer showed a steady increase in shear strength while the potential for fracture propagation remained high. The results of this study show promise for modelling surface hoar formation and evolution in snow cover models. 3 Conlan, M. Tracz, D. Jamieson, B. 2012 Measurements at recent deep slab avalanches International Snow Science Workshop Anchorage, Alaska 1 55-61 16/09/2012 deep slab avalanches, avalanche forecasting, snowpack tests Hard-to-forecast deep slab avalanches can release unpredictably under diverse conditions ranging from storms to clear days to locally induced stress to the snowpack. For the formation of many natural avalanches, a point is reached where the mass loading of overlying snow overpowers the mechanical properties of the weak layer. This can occur from additional loading above the weak layer, such as from precipitation or wind loading. Furthermore, natural failure can occur from solar warming and temperature variations. External stresses applied to the snowpack from skiers, snowmobilers, and other forces can also trigger deep slab avalanches. We collected field measurements of the properties of the failure layers and slab load to determine trends and correlations between such variables. The failure planes were analyzed using the deep tap test, propagation saw test, shear frame tests, and hand hardness and the overlying loads were calculated using density measurements. Spatial variability across the crowns was also assessed by use of multiple profiles and tests. Deep tap tests consistently yielded sudden (Q1) fractures and the cut length in the PST was usually less than 60% of the column length when the fracture propagated to the end. Preliminary results on spatial variability indicate that DT and shear frame results tended to increase with slab depth at some deep slab locations and crown thickness typically varied substantially. Locations with a thin snowpack, such as near rocky cliffs, were likely trigger points for some of the deep slab avalanches. 3 Bellaire, S. Jamieson, B. 2012 Nowcast with a forecast – Snow cover simulations on slopes International Snow Science Workshop Anchorage, Alaska 1 172-178 16/09/2012 SNOWPACK, snow cover modeling, avalanche warning, numerical weather prediction models, snow cover stratigraphy The snow cover model SNOWPACK simulates the snow cover formation and evolution based on meteorological parameters. In the past, these parameters were measured by automatic weather stations. Recently, SNOWPACK was also forced with data from numerical weather prediction models (NWP). In this case study we assess the capability of such a model chain to simulate critical layers, i.e. surface hoar and melt-freeze crusts for a virtual north and south-facing slope as well as a level study plot. Meteorological key parameters for the snow cover formation and evolution, e.g. precipitation, radiation, air temperature and relative humidity were measured and compared to the forecasted data to evaluate the performance of the NWP model. Systematic errors of the NWP model were corrected and SNOWPACK finally forced with the adjusted data. Monthly manual profiles observed between January and March â�� north, south, flat â�� during the winter of 2010-2011, were compared to the corresponding snow cover simulations. The simulated stratigraphy was found to be in good agreement with the observations. Presence and absence of critical layers â�� surface hoar and melt-freeze crusts â�� were modeled with an accuracy of 81%. The simulated snow height tended to be over-estimated for all aspects and the leveled site, especially in March on the south-facing aspect. Nevertheless, the model chain showed a good performance considering the source of the input data. This study showed that such a model chain could become a useful tool for avalanche warning services in the future, especially for data sparse areas. 3 Sinickas, A. Jamieson, B. 2012 Statistical avalanche runout models: How well can computers predict beta? International Snow Science Workshop Anchorage, Alaska 2 716-722 16/09/2012 snow avalanches, avalanche runout, DEM, field survey, beta point, alpha point, We reviewed the performance of a 23 m and 30 m Digital Elevation Model (DEM) and Google Earth in predicting beta (Î²) points for statistical runout modeling. Our objective was to find the resolution of DEM that was comparable to field survey error. We compared predicted Î² against field-determined Î² for 30 paths, using a field survey error range approximated from several error and repeatability measures. We found that none of the digital methods predicted Î² entirely within the range; however the 23 m DEM and Google Earth performed best. The 23 m DEM was biased to more conservative (downslope) estimates. The data suggested that a resolution of less than 23 m was required to match the error of a field survey; however, higher accuracy data may justify using a coarser resolution digital model. Judgment involved with Î² placement was a major contributor to uncertainty in this study. 3 Gauthier, D. Jamieson, B. 2012 The Propagation Saw Test (PST): A review of its development, applications, and recent research International Snow Science Workshop Anchorage, Alaska 2 1047-1053 16/09/2012 PST, propagation saw test, fracture propagation, snowpack stratigraphy, avalanche forecasting The Propagation Saw Test (PST) method was developed independently in Switzerland and in Canada in 2005 and 2006. It was inspired partly by observations of fracture propagation in earlier cantilever beam tests, and was partly based on notched-specimen tests that are common in fracture mechanics research. The PST has been used - in various modified forms - for investigation and verification of both shear-fracture and weak layer collapse failure models, for spatial variability studies, and for real-world avalanche forecasting and instability assessment. Many PST research and development studies have been conducted over the last several years, and recently there has been some debate regarding the best methodology and interpretation or application of test results. For these reasons, and given the recent or forthcoming adoption and standardization of the PST method by a number of international avalanche associations, we feel that researchers and practitioners could benefit from a comprehensive review of the development of the PST, its applications, and recent research which makes use of it. In this paper, we briefly review peer-reviewed articles, conference papers and presentations, and academic theses related to: the general test configuration and its relationship to fracture mechanics; the results of field experiments designed to test the influence of column size, cut direction, and slope angle on the test method; observations of â��criticalâ�� cut lengths, independent of column size in standard and non-standard test geometries; the empirical relationship between snowpack parameters and PST results; the basis for the original and modified test dimensions and methods; the verification of the method and validation of its application to the initiation and propagation of fracture; its applications to other research problems, such as fracture mechanics and spatial variability. 3 Buhler, R., Jamieson, B. 2012 Tracking melt-freeze crust evolution International Snow Science Workshop Anchorage, Alaska 1 84-91 16/09/2012 melt-freeze crust, snowpack evolution, persistent weak layer, Columbia Mountains, thermal imaging, crust index Melt-freeze crusts are one of the most critical layers for slab avalanche formation. These layers usually undergo complex metamorphism and associated snow cover stability may increase or decrease over time. Typical field observations are of a subjective nature and hence tracking changes to these layers can be inconsistent amongst multiple observers. In order to improve the way melt-freeze crusts are observed we present three tracking systems used over the 2011-12 winter season: a set of quantitative measurements, a simple new crust index (CI), and the use of a thermal imager. During the winter season 2011-12, six melt-freeze crusts were tracked over time with these methods in the Columbia Mountains, British Columbia, Canada. The physical properties of a melt-freeze crust can be best described using a set of quantitative measurements - shear frame, push gauge and density â�� but these may be operationally impractical. The crust index consists of two parts: the first part describes the bonding at the upper and lower interface of a melt-freeze crust; the second part describes the internal lamination or bonding within the crust. In addition, a thermal camera was used to measure small scale temperature gradients. This allowed us to monitor changes in the temperature gradient over time above and below melt-freeze crusts. 3 Shea, C. Jamieson, B. Birkeland, K. 2012 Using a thermal imager to quantify buried thermal structure in natural snow International Snow Science Workshop Anchorage, Alaska 1 269-276 16/09/2012 thermal imaging, infrared imaging, avalanche forecasting, temperature gradient, snowpack stratigraphy Avalanche researchers and practitioners have long measured snowpack temperaÂ¬tures in snow pits with thermometers about 10 cm apart. This led to the assumptions that temperature gradients are smooth and that temperature changes are regular. For this study, we used a thermal imager in standard snow pits in the Canadian Rocky Mountains during two seasons between 2010 and 2012. We collected the ï¬�rst season of data in a very shallow, below treeline snowpack study plot, and the second season of data in a deeper, treeline study plot. Data included thousands of thermal images, as well as visual macro images of the snow crystals in each pit layer to monitor changes. We observed strong temperature gradients on the scale of individual snow crystals. We found that these small scale gradients correlated with future snow crystal changes. We also found that these gradients changed quickly with the weather, even at depth. This paper focuses on our most recent ï¬�ndings from the 2011-12 season, and describes our overall progress in extracting data from thermal images to use for research and forecasting. We use correlations to present very general relationships between thermal data, crystal size, and layer stability tests. We also present temperature and gradient changes at depth during a period of clearing. 3 Jamieson, B. Jones, A.S.T. 2012 Vulnerability: Caught in an avalanche – then what are the odds? International Snow Science Workshop Anchorage, Alaska 1 1-8 16/09/2012 avalanche, vulnerability, risk, roads, buildings, recreation, probability of death, balloon packs, worksite Vulnerability is an essential component in qualitative and quantitative avalanche risk analyses. It is the probable consequences given that the element-at-risk is hit by or caught in an avalanche. Since consequences vary with avalanche characteristics, there is a level of vulnerability associated with each type or size of avalanche. The avalanche size classification based on destructive potential is well suited to classifying vulnerability into different levels. We review vulnerability for vehicles on roads, buildings as well as backcountry recreationists and workers. Quantitative vulnerability typically requires some data, although expert estimation can be used with or without data. Quantitative vulnerability has the advantage that it can be used in comparisons with other risks to determine if a risk is acceptable. For backcountry recreation, data from non-fatal injuries are limited, so most calculations of vulnerability for people use only the expected probability of death. Using Canadian accident data, we estimate the vulnerability (probability of death) to roughly 0.004 to 0.007 for a Size D2 avalanche (destructive scale) and ten times higher for a Size D3 avalanche. We show how balloon packs can change the vulnerability of recreationists, and include an example of how vulnerability can be used in an avalanche risk assessment for a worksite. 31 Bellaire, S. 2012 What if you know what is next? Asarc working on snow cover simulation in data sparse areas The Journal of Canada's Avalanche Community Canadian Avalanche Association, Revelstoke, BC, Canada 99 50-51 01/2012 SNOWPACK, snowpack simulation, data sparse areas, GEM15 2 Tracz, D. 2012 Deep Snow Slab Avalanches Civil Engineering Calgary University of Calgary 215 avalanche forecasting, slab avalanches, antecedent weather, snowpack tests, regional characterization Deep slab avalanches are a unique and difficult-to-forecast natural hazard. This thesis analyzed a variety of data sources from southwestern Canada including two large databases and data collected at 27 recent deep slab avalanches. A statistical method based on non-exceedance probability of average slab thickness and weak layer age was developed to regionally define deep slab avalanches. Local weather preceding deep slab events was investigated to discriminate days with deep slab avalanches from those without. Snowpack characteristics and tests were analyzed to find similarities among deep slab avalanche events. Precipitation during days with deep slab avalanches was found to be significantly more than days without deep slab avalanches. The Propagation Saw Test (PST) and Deep Tap Test (DT) were found to be useful snowpack tests for identifying deep slab hazard. The failure layer of deep slab avalanches typically was softer, contained larger snow grains, and was less dense the either of its adjacent layers. 0 Johnston, Katherine. Jamieson, Bruce. Jones, Alan 2012 Estimating Extreme Avalanche Runout for the Columbia Mountains and Fernie Area of British Columbia, Canada Canadian Geotechnical Journal 49 11 1309-1318 statistical runout estimation, snow avalanches, alpha-beta, runout ratio, runout zone, beta point Extreme snow avalanche runout is typically estimated using a combination of historical and vegetation records as well as statistical and dynamic models. The two classes of statistical models (Î± â�� Î² and runout ratio) are based on estimating runout distance past the Î²-point, which is typically defined as the point where the avalanche slope incline first decreases to 10Â°. The parameters for these models vary from mountain range to mountain range. In Canada, Î± â�� Î² and runout ratio parameters have been published for the combined Rocky and Purcell Mountains and for the British Columbia Coast Mountains. Despite active development, no suitable tall avalanche path model parameters have been published for the Columbia Mountains or for the Lizard Range area around Fernie, BC. Using a dataset of 65 avalanche paths, statistical model parameters have been derived for these regions. http://www.nrcresearchpress.com/doi/abs/10.1139/t2012-079#.UI3EaWef0R8 2 Exner, T. 2012 Field studies of snowpack stress and deformation due to surface loads and temperature effects Geoscience Calgary, Alberta, Canada University of Calgary 211 avalanche forecasting, snowpack stratigraphy, daytime warming, stress, snowpack properties, localized dynamic load, skier stress Snow surface loads such as skiers and snowmobiles are the triggers of the slab avalanche in many avalanche accidents. In most cases a cohesive slab overlies a weaker layer. Slab avalanche release strongly depends on stresses reaching the weak layer. Daytime snow temperature changes also can have a substantial impact on the release process of natural and human-triggered slab avalanches. Daytime variations of the near-surface layers affect the stiffness and the creep of the upper snowpack on a slope. For this study, a method was developed to measure normal stresses in the snowpack due to surface loads. These surface loads were skiers and snowmobiles in field experiments and metal weights in cold lab experiments. During the outdoor skier stress experiments and the cold lab studies the effect of warming and cooling of the near-surface layers and the effect on normal stress distribution was investigated. The impact of daytime heating of the near-surface layers on snowpack creep was monitored in field experiments. Overall, normal stresses due to surface loads penetrated deeper into the snowpack with warming of the near-surface layers or decreasing layer stiffness. Snowmobiles affected the snowpack over a larger area and stresses penetrated the snowpack deeper than for skier loads. In the case of the skier loads the bending of the skis appeared to have a considerable effect on the normal stress distribution. Creep of the near-surface layers accelerated with solar daytime warming and also affected layers below the warming front. 31 Shea, C. Jamieson, B. Birkeland, K. 2012 Hot crust, cold crust The Avalanche Review 30 3 28 infrared image, melt-freeze crust 31 Conlan, M. Jamieson, B. 2012 Research to improve forecasting for deep slab avalanches The Avalanche Journal - The voice of Canada's avalanche community 100 70-72 avalanche forecasting, deep slab, deep tap test, propagation saw test, PST 0 Ross, C.K.H. Jamieson, B. 2012 The Propagation Saw Test: slope scale validation and alternative test methods Journal of Glaciology 58 208 407-416 avalanches, avalanche forecasting, snowpack test, fracture propagation, propagation saw test, snowpack stratigraphy The propagation saw test (PST) is a recently developed snowpack test that enables assessment of the fracture propagation propensity of selected persistent weak-layer and slab combinations, which are known to release dry-slab avalanches. In this paper, we assess the slopescale accuracy of the standard PST method at validated sites of observed weak-layer fracture initiation, with or without propagation. We also report on experiments with alternative test methods and varying saw thicknesses. Results show the standard PST method is comparably accurate to other common snowpack tests in predictive skill when predicting propagation propensity on the slope scale. Although a slight but significant dependence on saw thickness was found, it did not affect the interpretation in our validation study. Alternative methods such as scaling the test column length with weak-layer depth or leaving the upslope end of the column attached to the surrounding snowpack did not improve slopescale accuracy and these tests were often more difficult to interpret. http://www.igsoc.org/journal/58/208/j11J192.html 31 Shea, C. Jamieson, B. Birkeland, K. 2012 The Life of a Shallow Snowpack (poster) http://webapps2.ucalgary.ca/~asarc/files/ShallowSnowPoster_Shea_Jan2012.png 0 Shea, C. Jamieson, B. Birkeland, K. 2012 Use of a thermal imager for snow pit temperatures The Cryosphere 6 287-299 thermal image, infrared, snow stratigraphy, temperature gradient http://www.the-cryosphere.net/6/287/2012/ 3 Johnston, Katherine Jones, Alan Jamieson, Bruce 2011 Estimating extreme avalanche runout for the Columbia Mountains, British Columbia, Canada 5th Canadian Conference on Geotechnique and Natural Hazards Kelowna, BC 15/05/2011 extreme avalanche runout, statistical model, alpha-beta, runout ratio 3 Tracz, Dave Bellaire, Sascha Jamieson, Bruce 2011 Regional comparison of old-deep slab avalanches 5th Canadian Conference on Geotechnique and Natural Hazards Kelowna, BC 15/05/2011 deep slab avalanches, avalanche forecasting, snowpack statigraphy 31 Shea, C. J. Floyer 2011 Arfi: Avalanche Research Forecasting Interface The Journal of Canada's Avalanche Community 95 54-55 avalanche forecasting, geospatial interface, GEM15, GSWarm, weather stations, avalanche bulletins, webcams http://www.ucalgary.ca/asarc/arfi 31 Shea, C. Jamieson, B. 2011 A new thermal view Avalanche.ca - The Journal of Canada's Avalanche Community Canadian Avalanche Association, Revelstoke, BC, Canada 98 36-39 thermal photography, infra-red, temperature gradient, snowpack stratigraphy, heat flow 2 Johnston, K.S. 2011 Estimating Extreme Snow Avalanche Runout for the Columbia Mountains and Fernie Area of British Columbia, Canada Civil Engineering Calgary University of Calgary 139 snow avalanche, extreme runout, alpha-beta, runout ratio, Fernie, Columbia Mountains, extreme value statistics Extreme snow avalanche runout is typically estimated using a combination of historical and vegetation records as well as statistical and dynamic models. The two classes of statistical models (Î± â�� Î² and runout ratio) are based on estimating runout distance past the Î²-point, which is generally defined as the point where the avalanche slope incline first decreases to 10Â°. The parameters for these models vary from mountain range to mountain range. In Canada, Î± â�� Î² and runout ratio parameters have been published for the Rocky and Purcell Mountains and for the British Columbia Coastal mountains. Despite active development, no suitable tall avalanche path model parameters have been published for the Columbia Mountains or for the Lizard Range area around Fernie, BC. Using a dataset of 70 avalanche paths, statistical model parameters have been derived for these regions. In addition, the correlation between extreme and average snowfall values and avalanche runout is explored. 0 Bellaire, S. Jamieson, B. Fierz, C. 2011 Forcing the snow-cover model SNOWPACK with forecasted weather data The Cryosphere 5 1115-1125 avalanche forecasting, snowpack stratigraphy http://www.the-cryosphere.net/5/1115/2011/tc-5-1115-2011.html 2 Shea, Cora 2011 Four Applied Methods for Spatial Visualization in Snow Avalanche Forecasting Geoscience Calgary University of Calgary 153 This thesis presents four applied methods for seasonal snow observation with respect to avalanches. Previous avalanche-related spatial variation and scale studies have shown a clear need for observation and methods to focus on the scale of interest to human triggering. These methods have the common goal to reveal spatial variation of interest to avalanche formation and human triggering in an efficient, accessible manner. The four methods are: (1) A minimally destructive slope-scale sampling method, (2) A method to relate Google Earth terrain images to surface hoar formation in sparse trees, (3) A method of accessibly presenting complex GIS warming model data over real terrain, and (4) A method of measuring heat in the snowpack using a thermal imager. Despite their common goal of spatial visualization, each new method draws on a different subset of background literature and employs very different methods in development and use. Thus, each method is presented as a self-contained paper with independent results. Of note, these methods have all subsequently received active use, and conclusions from such use are discussed at the end of the thesis. 0 Shea, C. Jamieson, B. 2011 Some fundamentals of handheld snow surface thermography The Cryosphere 5 55-66 thermography, snow emissivity, photographic angle, solid state greenhouse effect http://www.the-cryosphere.net/5/55/2011/ 0 Shea, C. Jamieson, B. 2011 Sun effect on surface hoar illustrated by three case studies Cold Regions Science and Technology 68 3 95-105 shorwave radiation, surface hoar Three case studies demonstrate solar effects on surface hoar crystal size. These effects are presented via: (a) a comparison of night and day time crystal sizes and surface temperatures, (b) a comparison of crystal sizes over different times in one day, and (c) a spatial comparison of tree shadows and surface hoar presence. The three case studies include surface hoar size with overall area sample means from 0.2 mm to 10.3 mm and across the treeline and alpine elevation bands. Although sample locations include various aspects, most of the data are from east aspects. As previous studies have found difficulty explicitly linking physical shortwave and latent heat measurements with surface hoar growth and destruction, this paper takes an empirical approach. Through correlations between temperature and surface hoar size, we find that different processes dominate in alpine versus treeline areas. Also, previous work presents different opinions as to whether summed shortwave or maximum shortwave plays a more important role in surface hoar size change; here, we present data which show the maximum change in incoming direct shortwave affects surface hoar crystal size. http://dx.doi.org/10.1016/j.coldregions.2011.06.010 3 Gauthier, Dave Jamieson, Bruce 2011 Scenario-specific observations for regional snow avalanche warnings 5th Canadian Conference on Geotechnique and Natural Hazards Kelowna, BC snow avalanche warnings, risk scenarios, field observations, snow avalanche forecasting  <div class="WordSection1">  Avalanche forecasters are increasingly formalizing a risk-based approach to analyze different avalanche problems or scenarios. Since public danger warnings in Canada apply to large regions, users must down-scale the danger using local field observations. We conducted a field study in the mountains of western Canada on over 175 days. On each field day, an experienced team rated the local avalanche danger, identified the avalanche scenario of most concern locally, and observed a standard set of over 20 field observations. New snowfall over a two-day period correlated with local danger in all scenarios, but otherwise a unique set of observations correlated best with local danger for each scenario. The results provide an evidence-based selection of specific local observations for potential use in regional snow avalanche warnings. The identified observations may help recreationists make better informed decisions. </div> *Presenting author: <a href="mailto:bruce.jamieson@ucalgary.ca">bruce.jamieson@ucalgary.ca</a> 1-403-220-7479 31 Tracz, D. Jamieson, B. 2010 Characteristics of old-deep-slab avalanches Osterhuber, R. and Ferrari, M. International Snow Science Workshop Squaw Valley, California 148-154 17/10/2010 deep slab avalanche, avalanche forecasting, snow cover stability, snowpack properties, snowpack instability tests <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="ProgId" content="Word.Document" /> <meta name="Generator" content="Microsoft Word 12" /> <meta name="Originator" content="Microsoft Word 12" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping" /> <style id="dynCom" type="text/css"></style> <script language="JavaScript"> </script><style>  </style> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="ProgId" content="Word.Document" /> <meta name="Generator" content="Microsoft Word 12" /> <meta name="Originator" content="Microsoft Word 12" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping" /> <style>  </style>Deep and old slab avalanches (ODS) are often hard-to-forecast. The size and destructive potential of ODS avalanches can be disturbing. As a starting point for a study of hard-to-forecast avalanches we define ODS avalanches based on a large dataset spanning the three main mountain ranges of western Canada: Coast, Columbia and Rocky Mountains. The definition is based on extreme slab depth and extreme age of the snowpack weakness that failed causing the avalanche. Our data did not reveal a difference in slope angle or aspect between the deep-old-slab avalanches (ODS) and â��Otherâ�� avalanches. However, compared to Other avalanches, ODS avalanches were typically of greater size, involved less human triggering, released more often on crusts and weak layers of facets and tended to occur more often in early winter. <div>  <hr class="msocomoff" align="left" width="33%" size="1" />  <div>  <div id="_com_1" class="msocomtxt" language="JavaScript" onmouseover="msoCommentShow('_anchor_1','_com_1')" onmouseout="msoCommentHide('_com_1')"> <a title="_msocom_1" name="_msocom_1"></a> </div> </div> <div> <div id="_com_2" class="msocomtxt" language="JavaScript" onmouseover="msoCommentShow('_anchor_2','_com_2')" onmouseout="msoCommentHide('_com_2')"> <o:p></o:p>  </div>  </div> </div> 31 Johnston, K.S. Jamieson, B. 2010 Estimating extreme avalanche runout for the Lizard Range, Fernie, British Columbia, Canada Osterhuber, R. and Ferrari, M. International Snow Science Workshop Squaw Valley, California 252-257 17/10/2010 extreme avalanche runout, runout ratio, alpha-beta, runout estimation, snow avalanche <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="ProgId" content="Word.Document" /> <meta name="Generator" content="Microsoft Word 12" /> <meta name="Originator" content="Microsoft Word 12" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping" /> <style>  </style>Identifying the extreme avalanche runout is an important part of public safety for development in mountainous areas. Extreme avalanche runout is typically estimated using a combination of historical and vegetation records as well as statistical and dynamic models. The two main types of statistical models (Î± â�� Î² and Runout Ratio) are based on predicting runout past the Î²-point, which is generally defined as the point where the slope angle first decreases to 10Â° while descending the slope. Statistical models are commonly used for avalanche hazard mapping in Canada; however, the existing models cover broad geographical areas and may not accurately predict runout in some development areas. Located in southeastern British Columbia, the Lizard Range is a sub-range of the Canadian Rocky Mountains. Numerous recreational and residential developments are located in this area including the City of Fernie. Likely because of the heavy snowfall in this area, residential development in mountainous terrain in this area is intense. Possibly due to the heavy snowfall in this area, the existing statistical models for the Canadian Rocky Mountains tend to underestimate extreme avalanche runout for this area when compared to field evidence of extreme runout. Using a data set of 28 avalanche paths with vertical drops greater than 350 m, we use the existing Canadian statistical models to show how these models underestimate extreme avalanche runout for the Lizard Range. 31 Shea, C. Jamieson, B. 2010 GSWarm: An example of making a GIS model for everyday use Osterhuber, R. and Ferrari, M. International Snow Science Workshop Squaw Valley, California 523-529 17/10/2010 computer assisted forecasting, Geographic Information Systems (GIS), modelling Modeling snow processes over terrain with a Geographic Information System (GIS) takes a specific set of skills and a lot of computer processing power and time. These factors are often at odds with how such a model would be used for, say, daily avalanche forecasting. We used the near-surface snow warming statistical and empirical model SWarm as a basis for designing a simple and fast GIS tool. This simple GIS-based warming model, called GSWarm, resulted from (a) published user comments on existing snow and avalanche computer tools, (b) published graphic design principles, and (c) direct forecaster feedback. Using GSWarm as an example, we present key ideas used to provide a simple interface to a complex GIS model, including: (1) Calculating many possible scenarios ahead of time, so hypothesis testing of different weather and snow conditions can be done quickly. (2) Allowing small previews of many results to be seen on one screen, for selection of specific conditions without using input boxes. (3) Providing scaling and visualization help to the user rather than giving a single final result. These ideas represent a unique perspective on snow and avalanche computer model design. 31 Smith, M. Jamieson, B. 2010 Near-infrared photography to quantify temporal changes in melt-freeze crusts International Snow Science Workshop Squaw Valley, California 409-414 17/10/2010 specific surface area, crust evolution, near-infrared photography, snowpack stratigraphy Objective quantification of snowpack stratigraphy is a difficult task, especially when multiple observers may be tracking changes over time. Properties such as grain type and size, though well defined by various snow observation guidelines, are often interpreted differently. One potential solution is the use of near infrared (NIR) photography to track the specific surface area (SSA) of a given layer. Processed images provide a quantitative measure of in-situ grain morphology free of any requirements for interpretation in the field. For the past two winters the Applied Snow and Avalanche Research Group at the University of Calgary has used NIR photography to track changes in and around buried melt-freeze crusts in the Columbia Mountains of western Canada. Eight crusts were tracked using both NIR and manual observations for periods ranging from 5 to 12 weeks. This paper describes the methods used and presents results from this study. Advantages of the method over traditional observations are also discussed, as are challenges encountered over the past two seasons. 31 Gauthier, D. Jamieson, B. 2010 On the sustainability and arrest of weak layer fracture in whumpfs and avalanches Osterhuber, R. Ferrari, M. International Snow Science Workshop Squaw Valley, California 224-231 17/10/2010 fracture propagtion, fracture arrest, weak snowpack layer <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="ProgId" content="Word.Document" /> <meta name="Generator" content="Microsoft Word 12" /> <meta name="Originator" content="Microsoft Word 12" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping" /> <style>  </style>Recent theoretical and practical descriptions of weak layer fracture have focused on the echanics of achieving a state of propagation, which is assumed to be self-sustaining. Arrest of weak layer fracture has been addressed for shear-based models, but has often been overlooked for collapsing weak layers. Regardless of the failure mode, discrete weak layer crystals must fail in sequence during propagation. This means that the slab is responsible to â��communicateâ�� the fracture laterally as part of the propagation process. This communication ability is lost, and weak layer fracture propagation should arrest, if the continuity of the slab is destroyed by a fracture through its thickness. Often this is the case, for example in perimeter slab fractures in whumpfs; however, these perimeter fractures are difficult to explain without considering weak layer collapse, slab bending, and the spatial variability of the slab. In addition, it is unclear how weak layer fracture continues to propagate despite the en-echelon slab fractures sometimes observed during avalanche release. We propose several simple mechanisms by which perimeter fractures in whumpfs may occur, how weak layer fracture may repeatedly advance beyond the en-echelon slab fractures, and how these processes could be linked. We argue that fractures should propagate downward through the slab, and investigate the interaction or competition between the weak layer and slab fractures that may determine the arrest condition. In addition, we propose that a sustainability term is required to properly describe propagation propensity. 31 Schweizer, J. Jamieson, B. 2010 On surface warming and snow instability Osterhuber, R. and Ferrari, M. International Snow Science Workshop Squaw Valley, California 619-622 17/10/2010 Warming is believed to be one of the most prominent causes of snow instability â�� although experimental evidence is rare. We know that â�� due to the low thermal conductivity of snow â�� warming at the snow surface rarely affects the weak layer temperature. In the case of dry-snow slab avalanches, instability is not due to weakening of the weak layer, but is believed to be due to increased deformation within the near-surface layers of the slab. Solar radiation can penetrate the surface and effectively reduce the stiffness of the upper layers. Changing slab properties directly affect snow instability in many ways. Whereas measurements have shown that the surface layers in fact creep more rapidly due to warming, field evidence is mostly lacking on how these changes affect snow instability. This might be because the effects of surface warming are subtle and/or only observable under certain slab/weak layer conditions. 31 Shea, C. Jamieson, B. 2010 Use of thermal photography to measure snowpack properties Osterhuber, R. and Ferrari, M. International Snow Science Workshop Squaw Valley, California 24-30 17/10/2010 heat conduction, surface hoar, thermal photography, thermal profile, infrared, emissivity Many snow processes are linked to snow temperature. A thermal photograph captures tens of thousands of surface temperature measurements in a single, powerfully visual image. Surface temperature directly drives surface hoar growth and near surface faceting, and it indirectly affects albedo and crust formation. We introduce this new application of thermography by presenting images (thermographs) and thermographic videos from winter 2010. Three different aspects are presented: (1) the link between surface temperature and surface hoar formation, (2) the spatial variation of temperatures on a pit wall, and (3) the effect of crystal type on conduction. Currently, due to cost and technical demands, thermography may remain primarily a research tool. However, thermography is a promising new technique that produces both quantitative and intuitively visual results. 31 Bellaire, S. Jamieson, B. Schweizer, J. 2010 When to dig? Thoughts on estimating slope stability Osterhuber, R. and Ferrari, M. International Snow Science Workshop Squaw Valley, California 424-430 17/10/2010 stability tests, sampling strategy, avalanche formation, snow cover stability, avalanche education, stability evaluation, field observations <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="ProgId" content="Word.Document" /> <meta name="Generator" content="Microsoft Word 12" /> <meta name="Originator" content="Microsoft Word 12" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping" /> <style>  </style> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="ProgId" content="Word.Document" /> <meta name="Generator" content="Microsoft Word 12" /> <meta name="Originator" content="Microsoft Word 12" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping" /> <style>  </style> Information about the snow cover stability is crucial for avalanche forecasting and for winter backcountry recreation. For a reliable estimation of snow cover stability at all levels of stability and over terrain many stability tests would be required. These tests are time consuming and therefore not practical for backcountry recreationists. Sampling strategy becomes important if spatial variability is considered as a key component of avalanche release. A recently proposed sampling strategy for slope stability estimation allows one to estimate the slope stability with a maximum of four compression tests. However, since backcountry recreationists as well as avalanche professionals during recreation rarely perform stability tests, we wade into this important and controversial question: to dig or not to dig? We review and discuss sampling strategies and methods from the perspective of experienced and less experienced recreationists. Factors were identified which increase or decrease the value of snow cover observations â�� which require digging â�� for recreationists in order to estimate the snow cover stability. These factors include experience level, local observations â�� which do not require digging â�� from previous days and the current day, ability to interpret observations over terrain and across spatial scales as well as cumulative knowledge of the snowpack. In conclusion, the question is not "To dig or not to dig?", but "When to dig?" â�� the latter question we try to answer.<o:p></o:p>   31 Jamieson, B Schweizer, J. Statham, G. Haegeli, P. 2010 Which obs for which avalanche type? Osterhuber, R. and Ferrari, M. International Snow Science Workshop Squaw Valley, California 155-161 17/10/2010 field observations, avalanche character, avalanche danger rating <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="ProgId" content="Word.Document" /> <meta name="Generator" content="Microsoft Word 12" /> <meta name="Originator" content="Microsoft Word 12" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" rel="File-List" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" rel="themeData" /> <link href="file:///C:%5CUsers%5CBruce%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping" /> <style>  </style>At the 2004 ISSW, Roger Atkins proposed thatâ��early in the terrain selection processâ��backcountry travellers could identify which types of avalanches were likely, e.g. wind slab, persistent slab, wet avalanche. These avalanche types are analogous to a set of scenarios in traditional risk analysis. Variations on Atkinsâ�� approach have been incorporated into some public bulletins. The types of avalanches that dominate the danger ratings are called Avalanche Types/Characters/Threats/Concerns/ Situations/Problems by different groups. The latest Swiss brochure for recreation in avalanche terrain suggests different observations for the four different types of avalanche situations. To determine which observations are best for which types of avalanches, a field study was conducted in the winters of 2008-09 and 2009-10 in the Coast Mountains, Columbia Mountains and Rocky Mountains of western Canada. On each field day, an experienced field team rated the local avalanche danger, identified two dominant Avalanche Types and observed a standard set of over 20 quick field observations. The quick observations included avalanches, wind transported snow, snowfall, etc. For correlation analysis, we focussed on two distinct classes of Avalanche Types: 1) Persistent Slabs, as well as 2) Wind Slabs combined with Storm Slabs. While some observations correlated with the local danger when either class of avalanches dominated the danger rating, other observations correlated best when only one of these two classes dominated the local danger rating. These results may help bulletin writers recommend that recreationists focus on certain local observations for better informed decisions. 0 Shea, C. Jamieson, B. 2010 Spatial distribution of surface hoar crystals in sparse forests Natural Hazards and Earth System Sciences 10 1317-1330 06/2010 surface hoar formation, radiation balance, long wave radiation, sky view http://www.nat-hazards-earth-syst-sci.net/10/1317/2010/nhess-10-1317-2010.html 31 Elmer, K. Shea, C. 2010 Imitating nature's hazardous genius Journal of Canada's Avalanche Community Canadian Avalanche Association, Revelstoke, BC, Canada 92 Spring 54-57 04/2010 surface hoar formation 7 Jamieson, B, Haegeli, P. Gauthier, D. 2010 Avalanche Accidents in Canada, Volume 5, 1996-2007 Canadian Avalanche Association, Revelstoke, BC, Canada 429 avalanche accidents, snow avalanches, avalanche education 31 Delparte, D. Jamieson, B. Waters, N. 2010 Evaluating terrain based criteria for snow avalanche exposure ratings using GIS avalanche terrain, GIS Poster presented at conference. Abstract online. Geophysical Research Abstracts. http://meetingorganizer.copernicus.org/EGU2010/EGU2010-8620-1.pdf 0 Gauthier, D. Brown C. Jamieson, B. 2010 Modeling strength and stability in storm snow for slab avalanches Cold Regions Science and Technology 62 2010 107-118 Avalanche forecasting snowpack stratigraphy stability index snow cover stability 0 Floyer, J.A. Jamieson, J.B. 2010 Rate effect experiments on round-tipped penetrometer insertion into uniform snow Journal of Glaciology 56 198 664-672 snow properties, snowpack stratigraphy, snowpack penetrometer, rate effects, compaction zone 0 Shea, C. Jamieson, B. 2010 Star: An efficient snow point-sampling method Annals of Glaciology International Glaciological Society 51 54 64-72 point sampling, variogram, spherical model, spatial correlation The changeable, variable, and fragile nature of snow creates unique samplingÂ challenges. In this paper, we present Star: an efficient, field-usable sampling method for useÂ in point-sampling spatial studies. This paper validates the accuracy of the Star method via aÂ comparative Monte Carlo simulation using 1024 detailed samples of elevation data. As spatialÂ snow studies generally want to find spatial continuity in layers and other properties, we usedÂ variogram ranges to compare the ability of four sampling methods to accurately reveal suchÂ spatial correlation. The other three methods compared to Star represent gridded, griddedÂ random, and pure random methods, whereas Star can be called a linear random method. TheÂ simulation showed Starâ��s accuracy to be comparable to both gridded and gridded randomÂ methods. From this comparative process we introduce a new measure of appropriateness forÂ sampling methods: the correct convergence on a variogram model, which we call correct spatial correlation detection. This directly measures how many sampled areas become correctlyÂ classified with either spatially correlated or non-correlated variance for a given variogramÂ model fit. In this measure, Star performed equivalently to the other methods, and in correctÂ convergence it performed equally to pure random sampling. http://www.igsoc.org/annals/v51/54/t54A028.pdf 0 Schweizer, J. Jamieson, B. 2010 Snowpack tests for assessing snow-slope instability Annals of Glaciology International Glaciological Society 51 54 187-194 snowpack tests, fracture initiation, fracture propagation, Rutschblock Test, Compression Test, Extended Column Test, Propagation Saw Test, spatial variability Information on snowpack instability is crucial for assessing avalanche risk in backcountry operations as well as for operational forecasting of the regional avalanche danger. Since slab avalanche release requires both fracture initiation and fracture propagation in a weak snowpack layer, field observations should ideally provide reliable information on the probability or propensity of both fracture processes. Even simple field observations that do not require digging a snow pit can provide useful information. Traditional snowpack tests include the shovel shear test, the shear frame test, the compression test (CT) and the rutschblock test (RB). Interpretation of the test results for the CT and RB has been improved by considering the appearance or type of the fracture in addition to the score. More recently, two tests have been developed that focus on fracture propagation rather than initiation: the extended column test (ECT) and the propagation saw test (PST). We compare the sensitivity, specificity and unweighted average accuracy of various stability tests. Comparative studies indicate that the RB, ECT and PST have comparable accuracy. For most test methods the unweighted average accuracy of a single test was 70â��90% depending on the dataset. Test methods such as the RB, ECT and PST, which fracture an area large enough to include fracture propagation, are generally more accurate than test methods that fracture smaller areas (e.g. the CT). The threshold-sum method was also less accurate. Even with very experienced observers for the RB, ECT and PST an error rate of at least about 5â��10% has to be expected. Performing a second, adjacent test on the same slope improves test reliability. http://www.igsoc.org/annals/v51/54/a54a105.pdf 31 Shea, C. Jamieson, B. 2010 Some fundamentals of handheld snow surface thermography infrared radiation, snow profile, brightness temperature, snow surface temperature, infrared, thermal image http://www.the-cryosphere-discuss.net/4/1467/2010/ 2 Ross, C. 2010 Testing Fracture Propagation Propensity for Slab Avalanche Forecasting Civil Engineering Calgary, Alberta University of Calgary 179 fracture propagation, weak snowpack layer, avalanche forecasting, snowpack tests, propagation saw test, extended column test The Propagation Saw Test (PST) is a recently developed field test for slabâ��avalanche forecasting. It is designed to test the fracture propagation propensity of a buried weak layer and overlying slab. This thesis reports on two winter field seasons of experimental validation of the PST in the Columbia Mountains of British Columbia, in which nearly 800 PSTs, 200 Extended Column Tests (ECT), and 230 experimental shortâ��scaled PSTs were performed. The PST was found to be efficacious at predicting propagation propensity on the slope scale, with predictive skill often exceeding that of other standard snowpack tests. Compared to the ECT, the PST performed well in deeply buried weak layers where fracture initiation via surface loading was difficult. In deep slabs, where field validation was impractical, PST results were compared to forecasterâ��s expert ratings of propagation propensity. The PST was compared to regional avalanche activity and often appeared indicative of propagation propensity trends on the regional scale. MSc thesis 0 Bakermans, L. Jamieson, B. Schweizer, J. Haegeli, P. 2010 Using stability tests and regional avalanche danger to estimate the local avalanche danger Annals of Glaciology International Glaciological Society 51 54 176-186 snowpack stability tests, avalanche forecasting, snowpack stratigraphy, regional avalanche danger, local nowcast Because public avalanche forecast regions in <st1:country-region w:st="on"><st1:place w:st="on">Canada</st1:place></st1:country-region> are large, ranging from 100 km2 to more than 30,000 km2, there are often areas within each region where the current local avalanche danger differs from the forecast regional danger. Identifying areas where the local danger is higher or lower than the regional rating is useful for recreational backcountry travellers; for those with limited experience, however, this is not always practical. During four winters in the <st1:city w:st="on">Columbia</st1:city>, Coast and Rocky Mountains of western <st1:country-region w:st="on"><st1:place w:st="on">Canada</st1:place></st1:country-region>, field teams performed stability tests and undertook local avalanche danger assessments for comparison against the regional danger ratings. Significant correlations between stability test variables and the local avalanche danger, and between stability test variables and the difference between local and regional danger, indicate potential for improved evaluation of the local danger if stability test results are considered with the regional bulletin rating. Although our analysis shows that a single stability test result cannot reliably be used to estimate the local avalanche danger, it does identify circumstances under which stability tests can help backcountry travellers identify an area of locally higher avalanche danger. http://www.igsoc.org/annals/v51/54/a54a106.pdf 31 Jamieson, B. 2009 Key field observations for supplementing and localizing the avalanche danger rating International Snow Science Workshop Davos, Switzerland 27/09/2009 avalanche danger rating, regional danger, local danger, field observations, scale Snow avalanche danger can vary considerably within forecast regions, especially large regions. Professionals and experienced recreationists routinely use the regional forecast along with local observations to estimate the local avalanche danger. However, some less experienced recreationists are unsure how to interpret the various field observations. To identify some key field observations, we conducted a field study during the winters of 2006-07 and 2007-08 in three distinct snow climates in western Canada: maritime, continental and transitional. Experienced observers rated the local avalanche danger and made 24 observations of weather, avalanche activity and simple manual snowpack tests such as the hand shear test and ski pole test. In all three snow climates, the regional danger rating was better correlated with the local avalanche danger than any single field observation. However, we sought local observations which could supplement and localize the regional forecast. Many of the weather variables correlated better with the regional danger rating than with the local rating, and hence were not useful for localizing the avalanche danger. The key local observations were wind deposits, snow rolls and whumpfs in the maritime snow climate, recent slab avalanching, whumpfs, the hand shear test and cracking at the skis in the transitional climate, and blowing snow, snow surface conditions and probing with the ski pole in the continental snow climate. Explanations will be offered as to why the specific key observations were better correlated with local danger in each snow climate. <o:p></o:p> Abstract and presentation only for Workshop on Avalanche forecasting: problems and future avenues 31 Shea, C. Jamieson, B. 2009 Predicting surface hoar spatial variability in sparse forests using shading in satellite imagery Schweizer, J. van Herwijnen, A. International Snow Science Workshop Davos, Switzerland Swiss Federal Institute for Forest, Snow and Landscape Research WSL. 102-106 27/09/2009 surface hoar, crystal size, crystal growth, sky view, satellite imagery, forest, shading Surface hoar size and location can help predict avalanche trigger points after burial. This paper presents an empirical model to predict the size of surface hoar at the small scale, i.e. less than 10 m, in sparsely forested areas. The model is based on 288 point samples of surface hoar crystals, and uses greyscale values in satellite imagery to map its predictions over a 40-to-100 m scale from a single point observation. When verified in a different surface hoar formation cycle, at a different location and aspect, with crystals sized to more than 7 mm, the model predicted the correct size to within 2 mm of actual size, for 70 percent of the 47 verification points. We present the physical basis for this model through night time surface temperature measurements and sky view photograph masks obtained with a wide angle lens. Beyond helping to describe the small scale variance of surface hoar in commonly skied areas of sparse trees in North America, it confirms processes that drive surface hoar formation anywhere. And although potentially applicable only to areas with trees and weather similar to those examined here, this work demonstrates that with the right conditions surface hoar size can be spatially predicted with reasonable accuracy. 31 Jamieson, B. Schweizer, J. Shea, C. 2009 Simple calculations of avalanche risk for backcountry skiing Schweizer, J., van Herwijnen, A. International Snow Science Workshop Davos, Switzerland Swiss Federal Institute for Forest, Snow and Landscape Research WSL 336-340 27/09/2009 avalanche risk, recreation, avalanche danger, skier triggering, probability of death, triggering odds The avalanche risk from backcountry skiing and its dependence on the regional danger ratings have not been estimatedâ��notably in <st1:place w:st="on">North America</st1:place>. To get around this data gap, we have tried to calculate the risk using an event tree which breaks the avalanche risk to backcountry skiers into the probability of triggering, the probability of being caught in a triggered avalanche, and the probability of death if caught. An expert survey estimated the probability of triggering a potentially fatal avalanche while making fresh tracks in a trigger zone for each level of regional avalanche danger. A previous study found that 40% of people who trigger a potentially fatal avalanche are caught. Based on accident reports, the probability of being killed depends on the avalanche size, the distribution of which is known for skier-triggered avalanches in <st1:country-region w:st="on"><st1:place w:st="on">Canada</st1:place></st1:country-region>. To calculate the daily risk, we modelled making fresh tracks in a specified number of trigger zones as an encounter probability. Based on our assumptions, a person can directly ski a dozen or so trigger zones in a day while the regional danger is Low or Moderate with comparable risk to kayaking. For a person skiing directly 5-10 trigger zones while the avalanche danger is Considerable, the daily risk is likely higher than kayaking and in the range of rock climbing or mountaineering.Â 31 Exner, T., Jamieson, B. 2009 The effect of daytime warming on snow creep Schweizer, J. van Herwijnen, A. International Snow Science Workshop Davos, Switzerland Swiss Federal Institute for Forest, Snow and Landscape Research WSL 271-275 27/09/2009 snow creep, solar radiation, warming, settlement, spontaneous avalanche release Snowpack warming is, besides loading by precipitation and wind-transport, one of the major triggers contributing to natural avalanche release. Established release mechanisms for spontaneous slab avalanches strongly depend on deformation rates in weak layers, which are affected by temperature changes. Once a critical rate is exceeded snow exhibits strain softening and ultimately brittle fracture. Failure of a weak layer is an important prerequisite to slab avalanche release. Critical slope parallel deformation rates may be reached in weak layers on sufficiently steep slopes due to increased creep in the overlying slab, which is heated by solar radiation. Using time lapse photography during the transition from cold mornings to warm sunny afternoons, we monitored vertical and slope parallel displacements of markers on a vertical snow profile on steep slopes. In a case study we present time series of displacements that showed increased snowpack creep and slope parallel deformation rates during solar heating of the near surface layers. 31 Smith, M. Jamieson, B. 2009 Tracking changes in buried melt-freeze crusts Schweizer, J., van Herwijnen, A. International Snow Science Workshop Davos, Switzerland Swiss Federal Institute for Forest, Snow and Landscape Research WSL 107-111 27/09/2009 melt freeze crust, snowpack evolution, near-crust faceting, near infrared photography, temperature gradient Melt freeze crusts are a frequent occurrence in the mid-latitudes, often forming in the snowcover due to rain or wet snow in the fall and insolation in the spring. Such crusts are frequently found at the bed surface of deep slab avalanches. Although faceting and weakening at the boundaries and in the interior of crusts under low temperature gradients has been documented, few long term systematic observations exist. This omission is potentially important, as an understanding of these processes may improve forecasting the strength of deep crusts. For the past two winter seasons, the University of Calgary Applied Snow and Avalanche Research group (ASARC) has monitored naturally occurring crusts in the Columbia Mountains of Western Canada. Properties such as grain form and size, density, temperature and hardness were observed on a weekly basis. Starting in the 2008-09 field season, the specific surface area (SSA) of three crusts was measured weekly using near infrared digital photography, resulting in 23 observations over two months including the transition to near-isothermal snow, where substantial structural changes were observed. This paper details these and other results. 31 Ross, C. Jamieson, B. 2009 Validating the Propagation Saw Test on the slope scale Schweizer., J., van Herwijnen, A. International Snow Science Workshop Davos, Switzerland Swiss Federal Institute for Forest, Snow and Landscape Research WSL 282-286 27/09/2009 Propagation saw test, fracture propagation, slope scale, validation, regional scale, avalanche forecasting, snowpack stratigraphy Over the past few seasons, the Propagation Saw Test (PST) has gained increasing acceptance in some guiding and highway operations in western North America. University of Calgary researchers continued to perform the PST throughout the 2009 winter season in order to further validate the test by building on a previous study. In addition, researchers experimented with column scaling in an attempt to reduce false-stable predictions previously reported for shallow soft slabs. In 2009, more than 600 PSTs were performed in close to 100 snow pits in the Columbia Mountains of British Columbia, Canada to supplement existing data from the previous two winter seasons. At 28 sites in 2009, more than 70 PSTs were performed on 34 layers where fracture propagation was observed (e.g. avalanches or whumpfs) or where fracture initiation was confirmed without propagation. This supplements the 47 sites and 95 tests available to previously validate the PST on the slope scale. An attempt to reduce false-stable predictions of the PST by scaling column length with layer depth below a meter is briefly discussed, supporting the standard test method. A recording standard for the PST is also presented. 31 Smith, M. Jamieson, B. Fierz, C. Lehning, M. 2009 Snowpack forecasting for areas of sparse observations IAMAS, IAPSO and IACS Joint Assemby Montreal, Quebec, Canada 19/07/2009 snowpack modelling, avalanche forecasting, remote weather station, sparse observations Forecasting for avalanche hazard is a difficult endeavor, requiring timely inputs of meteorological and snowpack data. Traditionally in Western Canada, snowpack observations have been provided on a near-daily basis by commercial ski operators, parks and government highway operations. There are, however, an increasing number of areas in use by recreationists which are not well-monitored and suffer from infrequent and sparse data. Such areas often suffer from a paucity of relevant meteorogical observations, further complicating the job of avalanche forecasters. The SNOWPACK model was developed by the WSL Institute for Snow and Avalanche Research SLF and is presently used in an operational capacity for avalanche forecasting in Switzerland. Inputs of wind, temperature, precipitation as well as short and longwave radiation are used to forecast evolution of a number of characteristics of a stratified snowpack including snow depth and temperature, as well as density and grain type. For the past two winter seasons the Applied Snow and Avalanche Research Group at the University of Calgary (ASARC), in partnership with the Canadian Avalanche Centre (CAC) and Alberta Environment, has run SNOWPACK at a data sparse site in the Crowsnest Pass region of Southern Alberta. Both raw telemetry data and results of model runs are made available to forecasters at the CAC, who evaluate the utility of model output as a component in a decision support framework. Model results are compared with manual profiles several times each winter, with initial results showing good agreement with observations. Abstract only. 0 Floyer, J Jamieson, B. 2009 Predicting the fracture character of weak layers from snowpack penetrometer signals Cold Regions Science and Technology 59 2-3 185-192 11/2009 snow penetrometer, fracture character, snowpack stratigraphy, avalanche forecasting, snowpack properties, snow hardness 0 Bakermans, L. Jamieson, B. 2009 SWarm: A simple regression model to estimate near-surface snowpack warming for back-country avalanche forecasting Cold Regions Science and Technology 59 2-3 133-142 11/2009 avalanche forecasting, near-surface warming, diurnal warming, snowpack temperatures, solar radiation, surface energy balance 31 Jamieson, B. 2009 Regional danger ratings and the odds of triggering a potentially fatal avalanche avalanche.ca - The Journal of Canada's Avalanche Community Canadian Avalanche Association, Revelstoke, BC, Canada 89 56-58 07/2009 regional avalanche danger, skier triggering, probability of triggering, odds of triggering Slightly revised for The Avalanche Review 28(1), p.15, (2009). 31 Schweizer, J. Jamieson, J.B. 2009 Guidelines for snow-slope instability tests, European Union Report 43386 for Triggering Instabilities in Materials and Geosystems, FP6. International Symposium on Snow and Avalanches Manali, India 06/04/2009 stability tests, snowpack stratigraphy, avalanche forecasting, fracture initiation, fracture propagation, extended column test, propagation saw test, rutschblock test, compression test Information on snowpack instability is crucial for assessing avalanche risk in backcountry operations as well as for operational forecasting of the regional avalanche danger. Since slab avalanche release requires both fracture initiation and fracture propagation in a weak snowpack layer, field observations should ideally provide reliable information on the probability or propensity of both fracture processes. Even simple field observations that do not require digging a snow pit can provide useful information. Traditional snowpack tests include the shovel shear test, the shear frame test, the compression test (CT) and the rutschblock test (RB). The interpretation of the test results for the CT and RB has been improved by considering the appearance or type of the fracture â�� in addition to the score. More recently, two tests have been developed that explicitly focus on fracture propagation rather than initiation: the extended column test (ECT) and the propagation saw test (PST). We compare the sensitivity, specificity and unweighted average accuracy of various stability tests. The unweighted average accuracy was for most tests 70-90% depending on the diversity of the dataset. In other words, in at least about 10% of the cases the tests did not provide reliable results. Tests such as the RB, ECT and PST, which fracture an area large enough to include fracture propagation, are generally more accurate than tests which fracture smaller areas. http://www.trigs.eu/wp-content/deliverable_441.pdf 31 Birkeland, K. Schweizer, J. Jamieson, B. 2009 Fracture propagation: Recent research and implications The Avalanche Review Amercian Avalanche Association 27 4 28-29, 32 04/2009 fracture propagation, extended column test, propagation saw test, weak layer collapse, shear fracture, avalanche forecasting, weak snowpack layer Full article starts on page 28 of The Avalanche Review, April 2009 0 Jamieson, B. Schweizer, J. Birkeland, K. 2009 An update on applied snow and avalanche science: Selected papers from the 2008 International Snow Science Workshop Cold Regions Science and Technology 59 2-3 103-105 avalanche forecasting, snowpack stratigraphy, FMCW radar, GPR, penetrometer, avalanche dynamics, avalanche rescue 0 Jamieson, B. Haegeli, P. Schweizer, J. 2009 Field observations for estimating the local avalanche danger in the Columbia Mountains of western Canada Cold Regions Science and Technology 58 2-3 84-91 avalanche forecasting, snowpack tests, field observations, classification trees, avalanche danger, scale issues Snow avalanche danger can vary considerably within the forecast regions, especially large regions. Experienced recreationists routinely use the regional forecast along with local observations to estimate the local avalanche danger. However, some less experienced recreationists are unsure how to interpret the various field observations. To assess a systematic approach, we conducted a field study during the winters of 2006-07 and 2007-08 in the Columbia Mountains of western Canada. Experienced observers rated the local avalanche danger and made 24 observations of weather, avalanche activity and simple manual snowpack tests on approximately 130 location-days. Since the local danger was often rated separately for the elevation bands alpine, treeline, and below treeline, the observations could be applied to 272 individual local danger ratings. Fourteen of the potential predictors yielded significant rank correlations with the local avalanche danger. Reflecting their larger scale, many of the weather variables correlated better with the regional danger forecast than with the local rating. In contrast, some snowpack observations including the hand shear and ski pole test correlated better at the local scale than the regional scale. Classification trees using the regional rating plus three of the local observations exhibited a better agreement with the local danger rating than did the regional rating by itself. 31 Shea, C. Jamieson, B. 2009 The role of moisture in surface hoar growth Avalanche.ca - The Journal of Canada's Avalanche Community 88 Spring 61-64 surface hoar, water vapour, diffusion, cloud, vapour pressure, saturation 31 Smith, M. Jamieson, B. Fierz, C. 2008 Observation and modeling of buried melt-freeze crusts. Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 170-178 21/09/2009 melt-freeze crust, avalanche forecasting, snow stratigraphy, snowpack modeling Melt-freeze crusts often occur as a result of wet snow, rain or strong insolation. Past observations have revealed the formation of weak layers at their boundaries, even when the depth-averaged temperature gradient favours rounding. Research has, however, predominantly targeted temperature regimes dominated by kinetic growth. During the winter of 2007-2008 University of Calgary researchers undertook systematic observations of the early December melt-freeze crust that was present throughout much of Western Canada. The data gathered included ongoing measurement of the temperature gradientacross the crust, snow load and shear strength. These observations were used along with meteorological measurements to drive the Swiss SNOWPACK model, a physically based single column model which simulates the evolution over time of a number of microstructural and mechanical properties of the snowpack. We present here the observations from the first year, initial efforts to identify parameters with the greatest influence on mechanical properties and results from model simulations. 31 Jamieson, B. Margreth, S. Jones, A. 2008 Application and limitations of dynamic models for snow avalanche hazard mapping Campbell, C., Conger, S., Haegeli, P. Proceedings of the 2008 International Snow Science Workshop Whistler, BC, Canada 730-739 21/09/2008 avalanche dynamics, basal friction, friction coefficient, Coulomb friction, runout estimation, hazard mapping 31 Floyer, J. Jamieson, B. 2008 Avalanche weak layer prediction from penetrometer profiles In Locat, J., D. Perret, D. Turmel, D. Demurs and S. Leroueil (eds.), Proceedings of the Fourth Canadian Conference on GeoHazards: From Causes to Management Laval University, Quebec. Presse de l'UniversitÃ© de Laval, QuÃ©bec 161-168 20/05/2008 digital penetrometer, snow resistance, snowpack stratigraphy, avalanche forecasting, snowpack layers 31 Jamieson, B. Bakermans, L. Haegeli, P. 2008 Field observations for localizing snow avalanche danger In Locat, J., D. Perret, D. Turmel, D. Demurs and S. Leroueil (eds.) Proceedings of the Fourth Canadian Conference on GeoHazards: From Causes to Management Laval University, Quebec. Presse de l'UniversitÃ© de Laval, QuÃ©bec 543-550 20/05/2008 field observations, avalanche danger, scale issues, spatial scale, avalanche forecasting 31 Jamieson, B. 2008 ASARC's experience with incident peer narratives Avalanche.ca - The Journal of Canada's Avalanche Community Revelstoke, BC, Canada Canadian Avalanche Association 48-49 12/2008 incident, peer narrative, accident report, safety culture, reporting culture 31 Ross, C. Gauthier, D. Jamieson, B. 2008 How To: Propagation Saw Test (PST) Avalanche.ca - The Journal of Canada's Avalanche Community Revelstoke, BC, Canada Canadian Avalanche Association 68-69 12/2008 propagation saw test, PST, snowpack tests, fracture propagation, weak layer, avalanche forecasting 0 Colbeck, S. Jamieson, B. Crowe, S. 2008 An attempt to describe the mechanism of surface hoar growth from valley clouds. Cold Regions Science and Technology 54 2 83-88 surface hoar, valley cloud, stratus cloud, cloud physics, vapour diffusion 31 Bakermans, L. Jamieson, B. 2008 A solar warming model (SWarm) to estimate diurnal changes in near-surface snowpack temperatures for back-country avalanche forecasting. Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 306-314 short wave radiation, snowpack warming, solar radiation, surface energy balance 31 Campbell, C. Bakermans, L. Jamieson, B. Stethem, C. 2008 Avalanche threats and mitigation measures in Canada Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 836-844 avalanche hazard, avalanche terrain, avalanche forecasting, land use, hazard mitigation, avalanche risk 31 Ross, C. Jamieson, B. 2008 Comparing fracture propagation tests and relating test results to snowpack characteristics Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 376-385 propagation saw test, PST, extended column tests, ECT, fracture propagation, fractire initiation, slab thickness, avalanche forecasting 31 Jamieson, B. Haegeli, P. 2008 Can field observations be combined systematically with the regional danger rating to estimate the local avalanche danger? Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 228-237 avalanche danger, avalanche forecasting, field observations, scale issues, spatial scale, regional danger, local danger 31 Morrison, T. L'Heureux, C. Mitchell, V. Quartero, A. 2008 Conceptual design of a digital snowpack probe Avalanche.ca - The Journal of Canada's Avalanche Community 85 78-81 penetrometer, probe, snowpack stratigraphy, hardness, penetration resistance, piezoelectric sensor, avalanche forecasting 31 Exner, T. Jamieson, B. 2008 Can solar warming contribute to dry slab avalanches? Avalanche.ca - The Journal of Canada's Avalanche Community Canadian Avalanche Association, Revestoke, BC. 84 70-73 warming, dry slab avalanches, snow density, settlement, snow temperature Translated and reprinted in Avalanche Press, Japan Avalanche Network, Vol. 2, Nov. 2009. 31 Schweizer, J. Jamieson, B. 2008 Dry-snow slab avalanche release revisited: shear vs. collapse? Geophysical Research Abstracts 10 avalanche release, fracture propagation, collapse, shear, weak layer 0 Gauthier, D. Jamieson, B. 2008 Evaluating a prototype field test for fracture and failure propagation in weak snowpack layers. Cold Regions Science and Technology 51 2-3 87-97 fracture propagation, failure propagation, weak snowpack layer, avalanche forecasting, snowpack test, field test 0 Gauthier, D. Jamieson, B. 2008 Fracture propagation propensity in relation to snow slab avalanche release: Validating the Propagation Saw Test Geophysical Research Letters 35 L13501 fracture propagation, weak snowpack layer, snow slab, avalanche forecasting, fracture arrest, snowpack test 31 Ross, C. Gauthier, D. Jamieson, B. 2008 Field book reference card: PST and ECT tests PST, ECT, Propagation Saw Test, Extended Column Test, Reference card http://wcmprod2.ucalgary.ca/asarc/system/files/PST_ECT_ComboRefCard_081222.pdf 31 Ross, C. Gauthier, D. Jamieson, B. 2008 Field Book Reference Card: Propagation Saw Test (PST). Propagation saw test, PST, Field book reference card 0 Habermann, M. Schweizer, J Jamieson, J.B. 2008 Influence of snowpack layering on human-triggered snow slab avalanche release Cold Regions Science and Technology 54 3 176-182 snow stratigraphy, snow avalanche, avalanche formation, snow stability, skier triggering, numerical modeling 2 Floyer, J. 2008 Layer detection and snowpack stratigraphy characterisation from digital penetrometer signals. Dept. of Geoscience Calgary University of Calgary 31 Fierz, C. Bakermans, L. Jamieson, B. Lehning, M. 2008 Modeling short wave radiation penetration into the snowpack: What can we learn from near surface snow temperatures? Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 204-208 31 Gauthier, D. Jamieson, B. 2008 Predictions of the Propagation Saw Test: Comparisons with other instability tests at skier tested slopes Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 408-414 31 Floyer, J.A. Jamieson, B. 2008 Predicting the fracture character of potential weak layers in penetrometer signals Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 195-208 0 Schweizer, J. Kronholm, K. , Jamieson, B. Birkeland, K. 2008 Review of spatial variability of snowpack properties and its importance for avalanche formation. Cold Regions Science and Technology 51 2-3 253-272 snow cover, snow stratigraphy, snow mechanical properties, snow slope stability evaluation, avalanche formation, avalanche forecasting, spatial variability, skier triggering, numerical modeling, scale http://www.avalanche.org/~nac/NAC/techPages/articles/08_CRST_Schweizer_etal_spatvar.pdf 0 Delparte, D. Jamieson, B. Waters, N. 2008 Statistical runout modeling of snow avalanches using GIS in Glacier National Park, Canada Cold Regions Science and Technology 54 3 183-192 snow avalanches, hazard mapping, geographic information systems, digital terrain model 0 Schweizer, J. McCammon, I. Jamieson, B. 2008 Snowpack observations and fracture concepts for skier-triggering of dry-snow slab avalanches Cold Regions Science and Technology 51 2-3 112-121 snow cover stratigraphy, snow stability evaluation, avalanche formation, avalanche release, skier triggering, stability test, fracture 31 Brown, C. Jamieson, B. 2008 Shear strength and snowpack stability trends in non-persistent weak layers Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 939-947 31 Exner, T. Jamieson, B 2008 The effect of snowpack warming on the stress bulb below a skier Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 415-420 snowpack warming, stress bulb, skier triggering, avalanche forecasting, snowpack stratigraphy 0 Jamieson, B. Campbell, C. Jones, A. 2008 Verification of Canadian avalanche bulletins including spatial and temporal scale effects. Cold Regions Science and Technology 51 2-3 204-213 avalanche forecasting, forecast verification, scale issue, spatial scale, temporal scale, avalanche danger 31 Gauthier, D., C. Ross and B. Jamieson 2008 Validation of the Propagation Saw Test near whumpfs and avalanches Proceedings of the 2008 International Snow Science Workshop in Whistler, BC, Canada 16-21 0 Schweizer, J. Jamieson, B. 2007 A threshold sum approach to stability evaluation of manual snow profiles. Cold Regions Science and Technology 47 1-2 50-59 2 Delparte, D. 2007 Avalanche Terrain Modeling in Glacier National Park, Canada Dept. of Geography Calgary, Canada. University of Calgary 2 Gauthier, D.M. 2007 A practical field test for fracture propagation and arrest in weak snowpack layers in relation to slab avalanche release Dept. of Civil Engineering Calgary, Canada University of Calgary 10 Campbell, C. Bakermans. L. Jamieson, B. Stethem, C. 2007 Current and future snow avalanche threats and mitigation measures in Canada. For Public Safety and Emergency Preparedness Canada. Revelstoke, BC, Canada Canadian Avalanche Association avalanche hazards, avalanche threats, future trends, hazard mitigation 0 Jamieson, B. Zeidler, A. Brown, C. 2007 Explanation and limitations of study plot stability indices for forecasting dry snow slab avalanches in surrounding terrain. Cold Regions Science and Technology 50 1-3 23-34 avalanche forecasting, snowpack stratigraphy, stability index, spatial scale 0 van Herwijnen, A. Jamieson, B. 2007 Fracture character in compression tests. Cold Regions Science and Technology 47 1-2 60-68 fracture character, pops, drops, compression test, avalanche forecasting, sudden planar, sudden collapse, resistant planar, progressive compression, non-planar break 31 Habermann, M., J. Schweizer and J.B. Jamieson 2007 Influence of slab properties on human-triggered snow slab avalanche release. Natural Hazards Section NH7.02: Snow avalanche formation, avalanche dynamics and risk assessment. Geophysical Research Abstracts 9 115-21 avalanche release, avalanche forecasting, slab properties, skier triggering, skier stress, shear stress, weak layer 0 Van Herwijnen, A. Jamieson, B. 2007 Snowpack properties associated with fracture initiation and propagation resulting in skier-triggered dry slab avalanches. Cold Regions Science and Technology 50 1-3 13-22 fracture initiation, fracture propagation, weak snowpack layers, avalanche forecasting, snowpack stability, snowpack stratigraphy 0 Campbell, C. Jamieson,B. 2007 Spatial variability of slab stability and fracture characteristics within avalanche start zones. Cold Regions Science and Technology 47 1-2 134-147 31 Gauthier, D. Jamieson, B. 2007 The propagation saw test Avalanche.ca - The Journal of the Canadian Avalanche Community 83 07-08 60-63 propagation saw test, fracture propagation, avalanche release, avalanche forecasting, snowpack tests, weak layer, slab properties 31 Gauthier, D. and B. Jamieson 2006 Understanding the propagation of fractures and failures leading to large and destructive snow avalanches: recent developments. Proceedings of the 2006 Annual Conference of the Canadian Society for Civil Engineering, First Specialty Conference on Disaster Mitigation Calgary, Alberta 23/05/2006 31 Floyer, J. 2006 An update on digital penetrometer technology. Avalanche.ca - The Journal of Canada's Avalanche Community 79 2006-07 53-55 digital penetrometer, snow resistance, penetration resistance, snowpack layers 31 Jamieson, B. J. Schweizer P. Hägeli C. Campbell 2006 Can stability tests help recreationists assess the local avalanche danger? J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop, Telluride, CO. 468-477 snowpack stability tests, avalanche forecasting, avalanche danger, regional avalanche bulletin, local nowcast 31 Gauthier, D. and B. Jamieson 2006 Evaluating a prototype field test for weak layer fracture and failure propagation. J.A. Gleason (editor), Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 107-116 31 Floyer, J. and B. Jamieson 2006 Empirical analysis of snow deformation patterns below probe tips. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 555-561 31 Brown, C. and B. Jamieson 2006 Evolving shear strength, stability and snowpack properties in storm snow. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 15-21 0 Jamieson, B. 2006 Formation of refrozen snowpack layers and their role in slab avalanche release. Reviews of Geophysics 44 RG2001 snow, avalanche, crystal growth, melt-freeze crust, stratigraphy, grain bonding 31 Bakermans, L. 2006 Infrared communications with dataloggers. Avalanche News 76 47-48 infrared, digital communication, datalogger 31 Bakermans, L. and B. Jamieson 2006 Measuring near-surface snow temperature change over terrain J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 377-386 2 Bakermans, L. 2006 Near-Surface Snow Temperature Changes Over Terrain. Dept. of Civil Engineering Calgary, Alberta, Canada. University of Calgary 31 Gauthier, D. 2006 Puzzling over propagation propensity. Avalanche News 76 44-46 0 Zeidler, A. Jamieson, B. 2006 Refinements of empirical models to forecast the shear strength of persistent weak layers, Part A: Layers of faceted crystals. Cold Regions Science and Technology 44 3 194-205 0 Zeidler, A. Jamieson, B. 2006 Refinements of empirical models to forecast the shear strength of persistent weak layers, Part B: Layers of surface hoar crystals. Cold Regions Science and Technology 44 3 184-193 avalanche forecasting, surface hoar, normal load, strength change, shear strength, empirical model 31 Jamieson, B. 2006 Reflections on near misses and safety culture. Avalanche News 76 18-20 safety culture, near miss, worker safety, reporting culture 0 van Herwijnen, A. Jamieson, B. 2006 Snowpack properties associated with skier-triggering of dry slab avalanches. Natural Hazards Section NH7.02: Snow avalanche formation, avalanche dynamics and risk assessment. Geophysical Research Abstracts 8 06396 0 Jamieson, B. Zeidler, A. Brown, C. 2006 Spatial extrapolation of slab stability indices for snow avalanche forecasting. Natural Hazards Section NH7.02: Snow avalanche formation, avalanche dynamics and risk assessment. Geophysical Research Abstracts 8 09663 31 Jamieson, B., C. Campbell and A. Jones 2006 Spatial and time scale effects in Canadian avalanche bulletins. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 394-492 31 Colbeck, S. and B. Jamieson 2006 Surface hoar growth from valley cloud. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 1-6 31 Campbell, C., and B. Jamieson 2006 Spatial clusters in slab stability and snowpack properties within avalanche start zones. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 44-53 31 Schweizer, J., I. McCammon and B. Jamieson 2006 Snow slope stability evaluation using concepts of fracture mechanics. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 211-218 31 Schweizer, J., K. Kronholm, B. Jamieson and K. Birkeland 2006 Spatial variability – so what? J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 365-377 31 Zeidler, A., B. Jamieson, T. Chalmers and G. Johnson 2006 SAWLEM: Slab and weak layer evolution model. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 228-233 0 Gauthier, D. and B. Jamieson 2006 Towards a field test for fracture propagation propensity in weak snowpack layers. Journal of Glaciology 52 176 164-168 31 Jones, A., B. Jamieson and J. Schweizer 2006 The effect of slab and bed surface stiffness on the skier-induced shear stress. J.A. Gleason (editor) Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 157-164 31 Haegeli, P., I. McCammon, B. Jamieson, C. Israelson 2006 The Avaluator - a Canadian rule-based avalanche decision support tool for amateur recreationists. J.A. Gleason Proceedings of the 2006 International Snow Science Workshop Telluride, CO. 254-263 31 Schweizer, J., C. Fierz and B. Jamieson 2005 Assessing the probability of skier triggering from snow layer properties. Proceedings of the 2004 International Snow Science Workshop Jackson Hole, Wyoming. USDA Forest Service, Fort Collins, CO 192-198 31 Jamieson, B. and P. Langevin 2005 Between a slab and a hard layer: Part 3 - Two field studies of facets growing above wet layers. Avalanche News, Canadian Avalanche Association, Revelstoke, BC. 72 48-51 melt-freeze crust, latent heat, dry-on-wet faceting, faceted snow 31 Jamieson, B., A. Jones and J. Kelly 2005 Comparing regional forecasts of avalanche danger with local “nowcasts” – First results. Avalanche News, Canadian Avalanche Association, Revelstoke, BC. 74 56-59 avalanche danger, spatial scale, avalanche forecast, lead time, local nowcast, regional forecast 31 Jamieson, B. and P. Langevin 2005 Faceting above crusts and associated slab avalanching in the Columbia Mountains. Proceedings of the 2004 International Snow Science Workshop Jackson Hole, Wyoming. USDA Forest Service, Fort Collins, CO 112-120 31 van Herwijnen, A.F.G. and B. Jamieson 2005 Fracture character in compression tests. Proceedings of the 2004 International Snow Science Workshop Jackson Hole, Wyoming. USDA Forest Service, Fort Collins, CO 182-191 fracture character, pops, drops, compression test, avalanche forecasting, sudden planar, sudden collapse, resistant planar, progressive compression, non-planar break

Short video of a presentation on Pops and Drops http://vimeo.com/22219643

2 van Herwijnen, A.F.G. 2005 Fractures in weak snowpack layers in relation to slab avalanche release. Dept. of Civil Engineering Calgary, Alberta, Canada. University of Calgary 0 van Herwijnen, A.F.G. Jamieson, B. 2005 High-speed photography of fractures in weak snowpack layers. Cold Regions Science and Technology 43 1-2 71-82 fracture, weak snowpack layer, slab avalanche release, fracture propagation Â Abstract online at <a href="http://www.cosis.net/abstracts/EGU04/01710/EGU04-J-01710.pdf">Geophysical Research Abstracts 6, 01710.</a> 31 Campbell, C.P. and B. Jamieson 2005 Spatial variability of rutschblock results in avalanche start zones. Proceedings of the 2004 International Snow Science Workshop Jackson Hole, Wyoming. USDA Forest Service, Fort Collins, CO 288-297 31 Jamieson, B. and J. Schweizer 2005 Using a checklist to assess manual snow profiles. (yellow flags) Avalanche News, Canadian Avalanche Association, Revelstoke, BC. 72 57-61 0 Zeidler, A. Jamieson, B. 2004 A nearest-neighbour model for forecasting skier-triggered dry-slab avalanches on persistent weak layers in the Columbia Mountains, Canada. Annals of Glaciology 38 166-172 avalanche forecasting, nearest neighbour, snowpack stratigraphy, snowpack stability index, persistent weak layer 31 Jamieson, B. 2004 Between a slab and a hard layer: Part 2 - The persistence of poorly bonded crusts in the Columbia Mountains. Avalanche News, Canadian Avalanche Association, Revelstoke, BC. 71 34-37 melt-freeze crust, facets, persistent weak layer, grain size, surface hoar 31 Jamieson, B. 2004 Between a slab and a hard layer: Part 1 - Formation of poorly bonded crusts in the Columbia Mountains. Avalanche News, Canadian Avalanche Association, Revelstoke, BC. 70 48-54 melt-freeze crust, faceted snow, dry-on-wet faceting, persistent weak layer 31 Zeidler, A. B. Jamieson 2004 Computer assisted avalanche forecasting: human-triggered avalanches. Proceedings of the Western Snow Conference (April 2004). Vancouver, BC, Canada avalanche forecasting, skier-triggering, nearest neighbours, snowpack properties Computer-assisted avalanche forecasting has become a valuable tool in some forecasting operations in Canada. Avalanche forecasting models are based on statistical, numerical and/or rule-based methods, but usually predict natural rather than skier-triggered avalanches. A nearest neighbour forecasting model for skier-triggered avalanches on post storm weak layers was improved by adding snowpack properties including a stability index to meteorological variables. However, a skier stability index did not improve the forecasting success on storm snow instabilities. The best forecast could be achieved by using meteorological parameters. http://www.westernsnowconference.org/proceedings/pdf_Proceedings/2004%20WEB/Zeidler,%20A.,%20and%20B.%20Jamieson_Computer-Assisted%20Avalanche%20For.pdf 2 Zeidler, A. 2004 Forecasting skier-triggered avalanches in the Columbia Mountains of Canada. Dept. of Civil Engineering Calgary, Alberta, Canada. University of Calgary 0 Jamieson, B. Fierz, C. 2004 Heat flow from wet to dry snowpack layers and associated faceting. Annals of Glaciology 38 187-194 heat flow, snowpack stratigraphy, melt-freeze crust, faceted crystals, kinetic metamorphism, dry-on-wet faceting 0 Lehning, M. Fierz, C. Brown, R. Jamieson, B. 2004 Modelling instability in the Swiss snow cover model SNOWPACK. Annals of Glaciology 38 331-338 snowcover modeling, snowpack instability, avalanche foroecasting, snowpack stratigraphy 31 van Herwijnen, A.F.G. B. Jamieson 2004 More results on fracture characterization in compression tests. Avalanche News, Canadian Avalanche Association, Revelstoke, BC. 68 38-41 fracture character, progressive compression, resistant planar, sudden planar, sudden collapse, break 0 Jones, A.S.T. and B. Jamieson 2004 Statistical avalanche-runout estimation for short slopes in Canada. Annals of Glaciology 38 363-372 0 Johnson, B.C. B. Jamieson R.R. Stewart 2004 Seismic measurement of fracture speed in a weak snowpack layer. Cold Regions Science and Technology 40 1-2 41-45 fracture speed, fracture propagation, weak snowpack layer, seismic, geophone, snowpack stratigraphy 31 Campbell, C. B. Jamieson P. Haegeli 2004 Small scale mapping of stability: If not, why not. Avalanche News, Canadian Avalanche Association, Revelstoke, BC 71 45-49 spatial scale, snowpack stability, stability tests, process scale, measurement scale 2 Campbell, C. 2004 Spatial variability of slab stability and fracture properties in avalanche start zones. Dept. of Civil Engineering Calgary, Alberta, Canada University of Calgary 31 Schweizer, J. and B. Jamieson 2003 Snow stability measurements. Proceedings International Seminar on Snow and Avalanche Test Sites Grenoble, France 317-331 CEMAGREF Editions 22/11/2001 0 Chalmers, T. Jamieson, B. 2003 A snow-profile-based forecasting model for skier-triggered avalanches on surface hoar layers in the Columbia Mountains of Canada. Cold Regions Science and Technology, Special issue, International Snow Science Workshop 2002 37 3 371-381 surface hoar, snowpack stratigraphy, avalanche forecasting, strength change, normal load 31 Stethem, C., D. McClung, B. Jamieson and P. Schaerer 2003 Avalanche Hazard Mapping in Canada Proceedings of 2002 International Snow Science Workshop Penticton, Canada (J.R Stevens, editor), BC Ministry of Transportation, Victoria, BC 555-560 31 van Herwijnen, A. and B. Jamieson 2003 An update on fracture character in stability tests. Avalanche News, Canadian Avalanche Association, Revelstoke, BC 66 26-28 fracture character, compression test, progressive compression, resistant planar, sudden planar, sudden collapse, break 31 Schweizer, J. and B. Jamieson 2003 Contrasting stable and unstable profiles with respect to skier loading Proceedings of 2002 International Snow Science Workshop Penticton, Canada (J.R Stevens, editor), BC Ministry of Transportation, Victoria, BC 499-501 31 Jones, A.S.T. and B. Jamieson 2003 Estimating the average friction coefficient in a simplified avalanche dynamics model for short slopes in Canada. Proceedings of the Third Canadian Conference on Geotechnique and Natural Hazards, June 2003 Edmonton, Canada 309-316 Canadian Geotechnical Society 31 Zeidler, A. and B. Jamieson 2003 Estimating the strength of faceted snow layers for an avalanche forecasting model Proceedings of 2002 International Snow Science Workshop Penticton, Canada (J.R Stevens, editor), BC Ministry of Transportation, Victoria, BC 130-137 31 Chalmers, T. and B. Jamieson 2003 Forecasting shear strength and skier-triggered avalanches for buried surface hoar layers. Proceedings of 2002 International Snow Science Workshop Penticton, Canada (J.R Stevens, editor), BC Ministry of Transportation, Victoria, BC 138-140 Extended abstract 31 Jamieson, B. 2003 Fracture propagation and resistance in weak snowpack layers. Avalanche News, Canadian Avalanche Association, Revelstoke, BC. 67 36-43 fracture propagation, fracture resistance, weak snowpack layer, remote triggering, skier triggering 31 van Herwijnen, A. and B. Jamieson 2003 Interpreting fracture character in stability tests Proceedings of 2002 International Snow Science Workshop Penticton, Canada (J.R Stevens, editor), BC Ministry of Transportation, Victoria, BC 514-520 31 van Herwijnen, A. and B. Jamieson 2003 Notes on Fracture Character scheme used by U of C ASARC Avalanche Research Group. See also van Herwijnen and Jamieson, 2003 in Avalanche News 66. 31 Jamieson, B. and A. van Herwijnen 2003 Preliminary results from controlled experiments on the growth of faceted crystals above a wet snow layer Proceedings of 2002 International Snow Science Workshop Penticton, Canada (J.R Stevens, editor), BC Ministry of Transportation, Victoria, BC 337-342 Reprinted in Avalanche News 64, 32-37 31 Jamieson, B. 2003 Risk management for the spatial variable snowpack. Avalanche News, Canadian Avalanche Association, Revelstoke, BC 66 30-31 risk management, slab avalanche, spatial variability, uncertainty, margin of safety, trigger point 0 Schweizer, J. Jamieson, J.B. Schneebeli, M. 2003 Snow avalanche formation. Reviews of Geophysics 41 4 1016 snow avalanche formation, slab avalanche release, snowpack stratigraphy, avalanche forecasting, weak snowpack layer, snow metamorphism 0 Schweizer, J. and B. Jamieson 2003 Snowpack properties for snow profile analysis. Cold Regions Science and Technology, Special issue, International Snow Science Workshop 2002 37 3 233-241 0 Stethem, C., B. Jamieson, P. Schaerer, D. Liverman, D. Germain and S. Walker 2003 Snow avalanche hazard in Canada - A review. Natural Hazards, Special Issue on An Assessment of Natural Hazards and Disasters in Canada 28 487-515 31 Stewart, K. and B. Jamieson 2003 Spatial variability of slab stability in avalanche start zones Proceedings of 2002 International Snow Science Workshop Penticton, Canada (J.R Stevens, editor), BC Ministry of Transportation, Victoria, BC 544-548 31 Campbell, C. and B. Jamieson 2003 Spatial variability of stability and fractures in avalanche start zones: Results from the winter of 2002-03. Avalanche News, Canadian Avalanche Association, Revelstoke, BC 66 23-25 spatial variability, stability test, rutschblock test, fracture character, snowpack stability 2 Jones, A.S.T. 2002 Avalanche Runout Prediction for Short Slopes. Department of Civil Engineering Calgary, Canada University of Calgary 0 Jamieson, B. and C. Stethem 2002 Snow avalanche hazards and management in Canada: Challenges and progress. Natural Hazards 26 1 35-53 31 Jamieson, B., T. Geldsetzer and C. Stethem 2001 Case study of a deep slab instability and associated dry slab avalanches Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 101-108 31 Chalmers, T., B. Jamieson 2001 Contrasting stability trends of two surface hoar layers in the Columbia Mountains Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 94-100 0 Chalmers, T. and B. Jamieson 2001 Extrapolating the stability trends of buried surface hoar layers from a study plot. Cold Regions Science and Technology 33 2-3 163-177 0 Jamieson, J.B. and C.D. Johnston 2001 Evaluation of the shear frame test for weak snowpack layers. Annals of Glaciology 32 59-69 31 Geldsetzer, T. and B. Jamieson 2001 Estimating dry snow density from grain form and hand hardness. Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 121-127 Reprinted in the Avalanche News 62, 45-51. 0 Jamieson, B. Geldsetzer, T. Stethem, C. 2001 Forecasting for deep slab avalanches. Cold Regions Science and Technology 33 2-3 275-290 deep slab avalanche, melt-freeze crust, faceted crystals, avalanche forecasting, shear frame stability index 31 Schweizer, J. and B. Jamieson 2001 Field observations of skier-triggered avalanches Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 192-199 31 Johnson, B.C., B. Jamieson and C.D. Johnston 2001 Field data and theory for human-triggered "whumpfs" and remote avalanches. Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 208-214 Reprinted in Avalanche News 61, 20-26 31 Jones, A.S.T, B. Jamieson and M. Wiegele 2001 Forecasting factors for skier-triggered avalanches at a helicopter skiing operation. Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 184-191 2 Chalmers, T. 2001 Forecasting shear strength and skier-triggered avalanches for buried surface hoar layers. Dept. of Civil Engineering Calgary, Alberta, Canada University of Calgary 109 0 Jones, A.S.T. and B. Jamieson 2001 Meteorological forecasting variables associated with skier-triggered dry slab avalanches. Cold Regions Science and Technology 33 2-3 223-236 31 Jamieson, B. 2001 Snow avalanches. A Synthesis of Geological Hazards in Canada. Bulletin 548 G.R. Brooks (ed.). Geological Survey of Canada 81-100 snow avalanche, avalanche hazard, slab avalanche, avalanche forecasting, static defence 0 Schweizer, J. and B. Jamieson 2001 Snow cover properties for skier-triggered avalanches. Cold Regions Science and Technology 33 2-3 207-221 31 Johnson, G. and B. Jamieson 2001 Strength changes of faceted snowpack layers in the Columbia and Rocky Mountain snowpack climates in southwestern Canada. Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 86-93 Reprinted in the Avalanche News 62, 10-21 0 Colbeck, S.C. and B. Jamieson 2001 The formation of faceted layers above crusts. Cold Regions Science and Technology 33 2-3 247-252 31 Colbeck, S.C. and B. Jamieson 2001 The formation of faceted crystals above crusts. Proceedings of the International Snow Science Workshop, October 2000 Big Sky Montana American Avalanche Association, PO Box 1032, Bozeman, Montana, 59771, USA 239 Extended abstract 31 Johnson, B. Crane Bruce Jamieson Colin D. Johnston 2000 Field studies of the cantilever beam test. The Avalanche Review 18 6 8-9 cantilever beam test, snowpack test 2 Johnson, G.T. 2000 Observations of Faceted Crystals in Alpine Snowpacks. Dept. of Civil Engineering Calgary, Alberta, Canada University of Calgary 98 2 Johnson, B.C. III. 2000 Remotely Triggered Slab Avalanches. Dept. of Civil Engineering Calgary, Alberta, Canada University of Calgary 98 0 Jamieson, J.B. and J. Schweizer 2000 Texture and strength changes of buried surface hoar layers with implications for dry snow-slab avalanche release. Journal of Glaciology 46 152 151-160 0 Wilson, Adrian, Jürg Schweizer, Colin Johnston and Bruce Jamieson 1999 Effects of surface warming on a dry snowpack. Cold Regions Science and Technology 30 (1999) 59-65 31 Jamieson, Bruce and Torsten Geldsetzer 1999 Patterns in unexpected skier-triggered avalanches. Avalanche News 58 7-17 slab avalanche, skier triggering, avalanche terrain, remote triggering Also reprinted in The Avalanche Review 18(3) 4-7. 31 Jamieson, Bruce 1999 Skier triggering of slab avalanches: Concepts and research. The Avalanche Review 18 2 8-10 slab avalanche, skier triggering, group triggering 31 Jamieson, Bruce 1999 The compression test - after 25 years. The Avalanche Review 18 1 10-12 compression test, snowpack stability test 31 Schweizer, Jürg, Bruce Jamieson and David Skjönsberg 1998 Avalanche forecasting for transportation corridor and backcountry in Glacier National Park (BC, Canada). Erik Hestnes, Norwegian Geotechnical Institute, publication 203 Proceedings of 25 Years of Snow Avalanche Research (Voss, May 1998) 238-244 31 Geldsetzer, Torsten Bruce Jamieson Colin Johnston 1998 Experience with microphotography of buried surface hoar. The Avalanche Review 17 2 6-8 surface hoar, microphotography Also presented at the Technical Meeting of the Canadian Avalanche Association, May 1998. 31 Davis, Robert , Bruce Jamieson and Colin Johnston 1998 Observations of buried surface hoar in British Columbia, Canada: section analysis of layer evolution and associated strength measurements. Proceedings of the International Snow Science Workshop Sunriver, Oregon Stevens Pass Ski Area, P.O. Box 98, Skykomish, WA 86-92 0 Jamieson, J.B. and C.D. Johnston 1998 Refinements to the stability index for skier-triggered slab avalanches. Annals of Glaciology 26 296-302 31 Jamieson, B. and G. Brooks 1998 Regional snow avalanche activity and locations of known fatal accidents in Canada (1863-June 1997). A map published by Geological Survey of Canada. Open File 3592. 31 Jamieson, Bruce and Colin Johnston 1998 Snowpack factors associated with strength changes of buried surface hoar layers Proceedings of the International Snow Science Workshop Sunriver, Oregon Stevens Pass Ski Area, P.O. Box 98, Skykomish, WA 74-85 Also, reviewed and revised for Cold Regions Science and Technology 30(1999), 19-34. 31 Jamieson, Bruce Colin Johnston 1998 Snowpack characteristics for skier triggering. Avalanche News 55 31-39 slab avalanche, skier triggering, snowpack characteristics, snow slab properties, weak layer properties Also presented at the Technical Meeting of the Canadian Avalanche Association, May 1998. 31 Auger, Tim and Bruce Jamieson 1997 Avalanche probing revisited. Proceedings of the October 1996 International Snow Science Workshop Banff, 118-125. Canadian Avalanche Association, Revelstoke, BC, Canada. 295-298 Also reprinted in Avalanche News 49, 16-19 31 Schweizer, Jürg, David Skjönsberg and Bruce McMahon 1997 Experience with stability evaluation for a surface hoar layer during winter 1995-96 at Rogers Pass, British Columbia, Canada. Proceedings of the October 1996 International Snow Science Workshop Banff, Canada Canadian Avalanche Association, Revelstoke, BC, Canada. 118-125 31 Jamieson, Bruce and Tim Auger. 1997 Improved probing for buried avalanche victims. Proceedings of the SAR Scene Conference Sault Ste. Marie Government of Canada, Ministry of Public Works 93-5/1997E 211-218 31 Jamieson, Bruce Colin Johnston 1997 Mechanisms for strength changes of buried surface hoar layers. Avalanche News 53 7-11 surface hoar, weak snowpack layer, snowpack stratigraphy, load, overburden, crystal penetration, superstratum, substratum 31 Davis, R., B. Jamieson, J. Hughes and C. Johnston 1997 Observations on buried surface hoar- persistent failure planes for slab avalanches in British Columbia, Canada Proceedings of the October 1996 International Snow Science Workshop Banff, Canada Canadian Avalanche Association, Revelstoke, BC, Canada. 81-85 31 Schweizer, Jürg. 1997 Preliminary results on controlled shear experiments. Proceedings of the October 1996 International Snow Science Workshop Banff, 118-125. Canadian Avalanche Association, Revelstoke, BC, Canada 195-197 31 Jamieson, Bruce and Colin Johnston 1997 The compression test for snow stability. Proceedings of the October 1996 International Snow Science Workshop Banff, 118-125. Canadian Avalanche Association, Revelstoke, BC, Canada Also abridged for Avalanche News 49, 12-15 31 Jamieson, Bruce Colin Johnston 1997 The facet layer of November 1996. Avalanche News 52 10-15 faceted crystal, weak snowpack layer, melt-freeze crust, Columbia Mountains, persistent weak layer 31 Geldsetzer, Torsten Bruce Jamieson Colin Johnston 1997 Visible changes in buried surface hoar over time. Avalanche News 52 16-17 surface hoar, microphotography, persistent weak snowpack layer 2 Jamieson, Bruce 1995 Avalanche prediction for persistent snow slabs. Dept. of Civil Engineering Calgary, Alberta, Canada University of Calgary 275 31 Jamieson, Bruce Colin Johnston 1995 Interpreting rutschblocks in avalanche start zones. Avalanche News 46 2-4 rutschblock test, snowpack stability test, avalanche forecasting, snowpack stratigraphy 31 Jamieson, Bruce and Colin. Johnston 1995 Monitoring a shear frame stability index and skier-triggered slab avalanches involving persistent snowpack weaknesses Proceedings of the International Snow Science Workshop at Snowbird 14-21 31 Stethem, C., P. Schaerer, B. Jamieson, J. Edworthy 1994 Five Mountain Parks Highway Avalanche Study. Proceedings of the 1994 International Snow Science Workshop in Snowbird, Utah. 72-79 31 Jamieson, Bruce 1994 Transceivers and Avalanche Safety. Avalanche News 42 8 avalanche transceivers, avalanche beacons, survival rate, survival time 31 Jamieson, Bruce and Colin. Johnston 1993 Experience with rutschblocks Proceedings of the International Snow Science Workshop (Oct. 1992) Breckenridge, Colorado 150-159 4/10/1992 rutschblock test, ski block test, spatial variability, slope angle effect During the winters of 1990-1992, rutschblock technique and limitations, variability and precision of rutschblock scores, and applications of rutschblocks to slab stability evaluation were studied in the Cariboo and <st1:placename w:st="on">Monashee</st1:placename> <st1:placetype w:st="on">Mountains</st1:placetype> of western <st1:country-region w:st="on"><st1:place w:st="on">Canada</st1:place></st1:country-region>. The time required for each test was, under many conditions, reduced to 10 minutes or less by using cords, specialized saws or the tails of skis to cut the two sides and the upper wall of the rutschblock. The median rutschblock score was 4 or less on most days when one or more large dry natural slab avalanches were reported by helicopter skiing guides operating within 30 km of the study area. Also, median rutschblock scores were 4 or less near slabs that had been ski-released and individual scores up to 5 were recorded near recently ski-released slabs. On slopes of 20Â° to over 40Â°, median rutschblock scores correlate well with a Swiss stability index; however, rutschblock scores on slopes below 20Â° are inconsistent with the correlation suggesting a minimum angle for rutschblocks of approximately 20Â°. In spite of natural variability of rutschblock scores on a particular slope, decreasing the slope angle by 10Â° tended to increase the rutsehblock score by 1. A tendency for higher and more variable scores was noticed near the top of several slopes. Slightly abridged for Avalanche Review 11(2), 1, 4-5 31 Jamieson, Bruce Colin Johnston 1993 A progress report on studies of persistent slab instabilities. Avalanche News 40 10-13 persistent weak snowpack layer persistent instability slab avalanche 0 Jamieson, J.B. and C.D. Johnston 1993 Rutschblock precision, technique variations and limitations. Journal of Glaciology 39 133 666-674 0 Jamieson, J.B. and C.D. Johnston 1993 Shear frame stability parameters for large-scale avalanche forecasting. Annals of Glaciology 18 268-273 31 Jamieson, Bruce 1993 Snow slab layers and stability: a summary of some recent research and experience. Avalanche News 41 2-3 Reprinted in The Avalanche Review 12(5), 1-3 and in ACMG News 4, Winter 1994, 4-5 0 Jamieson, J.B. and C.D. Johnston 1992 A fracture-arrest model for unconfined dry slab avalanches. Canadian Geotechnical Journal 29 61-66 31 Jamieson, Bruce Colin Johnston 1992 Rutschblock technique and interpretation. Avalanche News 37 3-7 Reprinted in Avalanche Safety Course Manual (Canadian Avalanche Association, 1993-1996) and in Avalanche Instructor's Manual (National Ski Patrol, 1995). 0 Jamieson, J.B. and C.D. Johnston 1992 Snowpack characteristics associated with avalanche accidents. Canadian Geotechnical Journal 29 862-866 31 Jamieson, J.B. and C.D. Johnston 1991 The width of unconfined slab avalanches based on field measurements of slab properties . Proceedings of the International Snow Science Workshop (Oct. 1990) Bigfork, Montana 234-244 31 Jamieson, Bruce Colin Johnston 1991 The width of unconfined slab avalanches. The Avalanche Review 10 2 3-6 0 Jamieson, J.B. and C.D. Johnston 1990 In situ tensile tests of snowpack layers. Journal of Glaciology 36 122 102-106 31 Jamieson, J.B. and C.D. Johnston 1989 In situ tensile strength measurements of alpine snow. Proceedings of the International Snow Science Workshop (June 1988) Whistler, B.C. 103-112 2 Jamieson, J. B. 1988 In situ tensile strength of snow in relation to slab avalanches. Dept. of Civil Engineering Calgary, Alberta, Canada University of Calgary 142