Equipment Became Better in Backcountry Skiing-Did Severity of Injuries Decrease? An Analysis from the Swiss Alps.

Background: Large technical developments in avalanche transceivers as well as in ski-shoe-binding units should make backcountry skiing a safer sport and as a consequence, yield to a decrease in the number and severity of mountain emergency events. Methods: From 2009-2018, a total of 3044 mountain emergencies (953 females and 2091 males) were identified from the SAC (Swiss Alpine Club) central registry while backcountry skiing. These were classified descriptively by cause, whereby the severity of the mountain emergency was quantified with a NACA-Score (National Advisory Committee for Aeronautics Score). Results: A total of 1357 falls (44.6%), 558 emergencies caused by avalanches (18.3%), 408 cases of blocking (13.4%), 214 cases of illnesses (7.0%), 202 cases of losing way (6.6%), 138 cases of a crevasse accident (4.5%), and material failure in 30 cases (1%) were registered. For the remaining 137 cases (4.5%), no classification or rare forms were detected. No substantial sex differences were found in severity of injury, however looking at the two endpoints of the observed time frame, a significant increase in NACA-Score from 2009 to 2018 (2.1 ± 1.8 up to 2.6 ± 2.1, p < 0.01) was detected. Conclusions: The increase in the severity of mountain emergencies while backcountry skiing in the last decade might be due to the fact that too many inexperienced absolve backcountry tours. The tendency might be promoted by the improved material in the way that it seems easier to absolve a tour while underestimating potential hazards.

Tree-ring reconstruction of snow avalanche activity: Does avalanche path selection matter?

In the current context of anthropogenic global warming, one of the purposes of dendrogeomorphic analyses is to provide long and continuous chronologies of mass movements, so as to detect potential trends or shift related to increasing temperatures. However, on documented slopes, the comparison between historical archives and tree-ring records suggests that dendrogeomorphic reconstructions systematically underestimate the natural activity of the process under investigation. In the specific case of snow avalanches, underestimation generally amounts to 50% and the main causes generally given for this difference are related to the magnitude of past events. In this study, we hypothesize that the morphometric characteristics of avalanche paths and their forest cover could have significant impacts on the length and reliability of tree-ring reconstructions. In order to test this hypothesis, we selected four adjacent, albeit differently structured, avalanche paths from the Queyras massif (French Alps), with the aim to compare their potential for a continuous reconstruction of past avalanche activity. On the most active avalanche paths characterized by high-altitude release areas (covered only by shrubby vegetation), tree-ring reconstructions do not exceed one century in length, with recurrence intervals of high magnitude events >25 years. By contrast, on forested couloirs where lower slopes and forest coverage up to the release areas limits the intensity of events, the frequency of reconstructed snow avalanches is 2.5 times higher, the reconstructions span longer periods and the convergence rate with historical archives attest to the reliability of the dendrogeomorphic approach. These results suggest that a careful selection of couloirs is essential and that priority should be given to forested sites as (i) they allow for exhaustive and (ii) reliable reconstructions over (iii) long periods of time.

Body Positioning of Buried Avalanche Victims.

OBJECTIVE: The immediate medical management of buried avalanche victims will to some extent be dictated by the victim's body positioning in the snow. Medical personnel are trained to assess and manage victims in a supine body position. Furthermore, avalanche first responders are trained to handle extricated avalanche victims carefully out of concerns for causing hemodynamic instability or for aggravating spinal injury. Thus, locating and extricating avalanche victims in positions other than supine has the potential to complicate immediate medical management. To our knowledge, the current medical literature does not detail the body positioning of buried victims. METHODS: In order to ascertain the most common body positioning of buried avalanche victims we reviewed the avalanche incident database of the Colorado Avalanche Information Center (CAIC). This comprehensive database strives to track over 160 fields of information for each avalanche victim, including the body and head positioning of buried victims. RESULTS: Head positioning was recorded for 159 buried victims. We found that 65% of buried avalanche victims were found with their heads in a downhill position, 23% with their heads uphill and 11% with their heads in the same level as the rest of their bodies. Body positioning was recorded in 253 victims. 45% of victims were found lying prone, 24% supine, 16% were sitting or standing and 15% were found lying on their sides. We identified 135 victims where both head and body position was registered. 40% of victims were found prone with their heads in a downhill position CONCLUSIONS: The majority of victims will be extricated with their heads in a downhill position. Moreover, almost half of victims will be found prone. We believe this will have significant impact on the immediate medical management. We believe current training in avalanche medical rescue should emphasize managing victims in non-supine positions. Finally, our findings may represent another benefit of modern extrication techniques.

Risk of Avalanche Involvement in Winter Backcountry Recreation: The Advantage of Small Groups.

OBJECTIVE: Avalanches are the primary hazard for winter backcountry recreationists and cause numerous deaths and injuries annually. Although recreationists usually travel in groups, there is little empirical knowledge on group-related risk factors. This study aims to explore the relative risk of avalanche accidents with respect to group size and to discuss underlying reasons for different risk levels. METHODS: We compared backcountry usage data in regions in Switzerland and Italy with avalanche accident data in these regions. RESULTS: We found higher avalanche risk for groups of 4 or more people and lower risk for people traveling alone and in groups of 2. The relative risk of group size 4, 5, and 6 was higher compared with the reference group size of 2 in the Swiss and Italian dataset. The relative risk for people traveling alone was not significantly different compared with the reference group size of 2 in the Italian dataset but was lower in the Swiss dataset. CONCLUSIONS: These findings are in accordance with avalanche safety recommendations regarding the higher risk of large groups but not regarding lower risks of people traveling alone in avalanche terrain, which is not recommended and requires great caution. Further studies on backcountry usage are necessary to improve our understanding of human behavior and risk factors. New techniques (eg, video monitoring) may be useful for acquiring reliable data on backcountry usage.

A data-based model to locate mass movements triggered by seismic events in Sichuan, China.

Earthquakes affect the entire world and have catastrophic consequences. On May 12, 2008, an earthquake of magnitude 7.9 on the Richter scale occurred in the Wenchuan area of Sichuan province in China. This event, together with subsequent aftershocks, caused many avalanches, landslides, debris flows, collapses, and quake lakes and induced numerous unstable slopes. This work proposes a methodology that uses a data mining approach and geographic information systems to predict these mass movements based on their association with the main and aftershock epicenters, geologic faults, riverbeds, and topography. A dataset comprising 3,883 mass movements is analyzed, and some models to predict the location of these mass movements are developed. These predictive models could be used by the Chinese authorities as an important tool for identifying risk areas and rescuing survivors during similar events in the future.

Risk assessment in winter backcountry travel.

OBJECTIVE: Risk assessment is an important part of safe backcountry travel in avalanche terrain. The purpose of this study was to determine and compare the ability of backcountry travelers to accurately estimate the avalanche danger for their destination and time of travel. METHODS: We surveyed 353 winter backcountry users, asking them to rate the avalanche danger for their destination that day. We then compared this estimation to the Utah Avalanche Center daily advisory for that specific location, aspect, and elevation. Tendency to underestimate the avalanche danger was then compared across 6 different sports (backcountry skiing, backcountry snowboarding, snowshoeing, snowmobiling, out-of-bounds skiing, and out-of-bounds snowboarding) as well as across age, gender, and subject participation in an avalanche safety course. RESULTS: A comparison across different sports, adjusted for age and gender, showed that snowshoers were 7.11 times more likely than skiers to underestimate the avalanche danger (95% CI, 2.95, 17.11). This difference was maintained after adjusting for past education in an avalanche safety course (odds ratio, 5.74; 95% CI, 2.28, 14.46). Snowmobilers were also significantly more likely to underestimate the avalanche danger when compared to skiers (odds ratio, 3.11; 95% CI, 1.12, 8.24), but these differences ceased to be significant when the data were adjusted for avalanche safety course (odds ratio, 2.39; 95% CI, 0.84, 6.74). While there was a trend for women and older age groups to underestimate the avalanche danger when compared to men, these trends were not significant. CONCLUSIONS: Snowshoers and snowmobilers are groups that tend to underestimate avalanche danger when traveling in the backcountry. These groups may be unknowingly assuming a higher risk and should be targeted for avalanche education and awareness.

Dealing with the white death: avalanche risk management for traffic routes.

This article discusses mitigation strategies to protect traffic routes from snow avalanches. Up to now, mitigation of snow avalanches on many roads and railways in the Alps has relied on avalanche sheds, which require large initial investments resulting in high opportunity costs. Therefore, avalanche risk managers have increasingly adopted organizational mitigation measures such as warning systems and closure policies instead. The effectiveness of these measures is, however, greatly dependent on human decisions. In this article, we present a method for optimizing avalanche mitigation for traffic routes in terms of both their risk reduction impact and their net benefit to society. First, we introduce a generic framework for assessing avalanche risk and for quantifying the impact of mitigation. This allows for sound cost-benefit comparisons between alternative mitigation strategies. Second, we illustrate the framework with a case study from Switzerland. Our findings suggest that site-specific characteristics of avalanche paths, as well as the economic importance of a traffic route, are decisive for the choice of optimal mitigation strategies. On routes endangered by few avalanche paths with frequent avalanche occurrences, structural measures are most efficient, whereas reliance on organizational mitigation is often the most appropriate strategy on routes endangered by many paths with infrequent or fuzzy avalanche risk. Finally, keeping a traffic route open may be very important for tourism or the transport industry. Hence, local economic value may promote the use of a hybrid strategy that combines organizational and structural measures to optimize the resource allocation of avalanche risk mitigation.

Rescue missions for totally buried avalanche victims: conclusions from 12 years of experience.

The planning and execution of avalanche rescue missions to search for totally buried avalanche victims are mostly based on personal experience and preference, as evidence-based information from literature is almost completely missing. Hence, the aim of this study was to identify major factors determining the survival probability of totally buried victims during avalanche rescue missions carried out by organized rescue teams (Austrian Mountain Rescue Service, Tyrol). During the 12-year period studied, 109 totally buried persons (56 off-piste, 53 backcountry), were rescued or recovered; 18.3% survived to hospital discharge. Median depth of burial was 1.25 m; median duration of burial was 85 min. The majority (61.6%) of the rescue missions were conducted under considerably dangerous avalanche conditions. The probability of survival was highest when located visually and lowest for those located by avalanche transceiver; survival did not significantly differ between those found by rescue dogs and those located with avalanche probes. Multivariate analysis revealed short duration of burial and off-piste terrain to be the two independent predictors of survival. Whenever companion rescue fails, snow burial in an avalanche is associated with extraordinarily high mortality. Searching the avalanche debris with probe lines seems to be equally effective as compared to searching with rescue dogs. The potential hazard for rescuers during avalanche rescue missions comes mainly from self-triggered avalanches, hence thorough mission planning and critical risk-benefit assessment are of utmost importance for risk reduction.

[Avalanche emergencies. Review of the current situation]. / Der Lawinennotfall. Eine aktuelle Ubersicht.

In North America and Europe around 140 persons die every year due to avalanches, approximately 35 in North America, 100 in the European Alps, and 5 in other parts of Europe. Most of the victims are skiers and snowboarders. This article outlines the specific pathophysiology of avalanche burials, such as hypoxia, hypercapnia, and hypothermia and also other factors which influence survival. Strategies to minimize the mortality due to avalanches and the on-site treatment of buried persons are discussed. Finally, possibilities to reduce the number of avalanche deaths are pointed out.