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World of Science | Review ISSW2018: Avalanche accidents

What's happening in snow science?

by Lea Hartl 02/20/2020
The International Snow Science Workshop (ISSW) brings together scientists and practitioners from a wide range of snow-related fields every two years. New findings and research results are presented in various thematic blocks - so-called sessions. We break the whole thing down into more or less digestible morsels and summarize the sessions of the ISSW2018 for you every two weeks.

Special Topic Avalanche Accidents (Session 13)

The contributions in this session can be divided into two main categories: On the one hand, individual avalanche periods or avalanche accidents are discussed that were "special" in some way - for example, due to particularly high damage or extreme weather conditions. On the other hand, several research teams or LWDs focus on the long-term development of avalanche accident statistics in their region and corresponding statistical patterns with regard to: "Who? How many? When? Why?"

Individual events, catastrophic avalanches, extreme situations

On the occasion of the 50th anniversary of the founding of the Austrian Board of Trustees for Alpine Safety (KURASI), the two avalanche accidents that were decisive for this foundation were remembered: On January 3, 1965, a group of Dutch youths were caught in an avalanche on the road between Obertauern and the Hotel Scheidegg. 3 people lost their lives. On March 2 of the same year, a coach was pushed off the road by an avalanche not far from the first accident site. 14 passengers died and many more were injured. The second accident also had legal consequences, as the road was open at the time of the accident, and ultimately led to the founding of the KURASI, which has had a cross-organizational, documentary function ever since. In addition, the board of trustees - on the basis of its own now very extensive database - makes recommendations for the prevention of alpine accidents. (The catastrophic avalanches in 1965 near Obertauern and the 50th anniversary of the Austrian Board of Alpine Safety, Höller, O13.3)

One avalanche accident in the recent past that those affected hope will lead to changes in dealing with the risk of avalanches is the accident in Sölden in 2015, in which two young racers from the USA lost their lives. The families of the victims have founded an organization that raises awareness, particularly in the USA and in racing. At the ISSW, the mother of one of the victims called for the danger level scale to be redesigned so that LWS 3 should already represent the maximum, potentially fatal warning level. In addition, communication of the danger and the secured and unsecured areas in the ski resorts must be improved. She also criticized the often trivializing, powder-heavy marketing of many ski resorts (Soelden 2015 avalanche: What can be learned, Berlack, no extended abstract).

The avalanche that destroyed a hotel in Rigopiano (Italy) in January 2017 also had legal repercussions. As part of the investigation and court proceedings, experts were called in to clarify how the avalanche occurred and to investigate the collapse of the hotel from a structural engineering perspective. In a session contribution, they explain the "forensic" avalanche investigation that takes place after a large damaging avalanche.

The corresponding snowpack investigations were not only complex due to the terrain and existing avalanche risk, but also had to be carried out as quickly as possible before conditions changed too much. In addition to the usual snowpack investigations, the avalanche path was measured in detail and forest damage was precisely recorded, as this allows conclusions to be drawn about the avalanche dynamics. Dendrochronological studies can theoretically provide indications of the frequency of large avalanches in certain avalanche paths, but in this case it was concluded that the avalanche was so large that it would have destroyed all the trees that could have "experienced" earlier, similar avalanches. Geomorphological, geophysical and GIS-based investigations indicate that there may have been large avalanches at the accident site in the past, but that these rarely occur (The 18th January 2017 Rigopiano avalanche disaster in Italy - Analysis of the applied forensic field investigation techniques, Chiambretti et al, O13.4).

Less tragic, but spectacular from a weather perspective, was the heavy precipitation in Lower Austria in April 2017. The LWD Lower Austria reviews this event: After the daily situation report had already been discontinued at the end of March, the third week of April was a wake-up call. Over 200 cm of fresh snow fell in 30 hours. On April 20, LWS 5 was issued in the Ybbstal Alps - very, very unusual for Lower Austria - and some roads were closed. Sliding snow avalanches were the main problem. No people were injured and the tone in the (German-language) review by the LWD Lower Austria seems more pleased and fascinated than concerned - when compiling this summary, this was a welcome change between all the not at all pleasing disaster reports (Avalanche Danger Level 5 in Lower Austria in April 2017 - a Case Study, Studeregger et al., P13.6.).

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Avalanche accidents in Austria: figures and statistics

Scientists from the Institute of Statistics at the University of Innsbruck have unleashed their statistical power on the spatial and temporal distribution of fatal avalanches in Austria in the period 1967/68 - 2015/16 (Spatial and temporal analysis of fatal off-piste and backcountry avalanche accidents in Austria with a comparison of results in Switzerland, France, Italy and the US, Pfeifer et al, O13.1). Main result: Contrary to popular belief that the number of avalanche fatalities remains constant, there was an increase from the late 1960s to the mid-noughties, followed by a slight decrease in recent years. The frequency of accidents with more than one fatality has decreased significantly, which the authors speculatively attribute to better training and adapted behavior of winter sports enthusiasts (e.g. skiing alone).

In a second analysis section, the accident statistics are broken down by region and municipality. The authors identify two hotspots where a particularly high number of accidents occur: The Arlberg/Silvretta region (including the municipalities of St. Anton, Lech, Ischgl, Galtür) and the rear Ötztal and Stubai Alps (including the municipalities of Sölden, St. Leonhard, Längenfeld, Silz, St. Sigmund i. Sellrain, Neustift).

KURASI, which is strongly represented in this session, also analyzes statistics (Accidents related to snow in alpine terrain, Walter et al., P13.3). In addition to the accident location and type of accident, the KURASI database also records, where possible, whether people were on the ascent or descent when an avalanche occurred, as well as details of the rescue measures and the age and gender of the victims. Between 2005 and 2018, 2,200 men and 410 women were involved in avalanche accidents.

The KURASI data is also used in another study that uses statistical methods to find out whether avalanche accidents are particularly frequent when many tourists are visiting Austria. Accident figures are compared with vacation periods and overnight stays. The results do indeed indicate that more accidents occur when there are more people. In order to really separate this from other factors (weather, snow), further investigations are necessary (Statistical investigation of avalancheaccidents using natural and touristic impact factors, Fromm et al., P13.5).

Avalanche databases in other countries

Not every country where avalanche accidents occur has such a comprehensive, centrally collected database on these incidents. On the contrary - in many regions outside the Alps and North America, studies on avalanche accidents have only recently become a research topic at all.

One article, for example, summarizes what is known about avalanches in Bulgaria: compared to the Alps, quite little (Avalanches in Bulgaria - Human and nature perspective, Panayotov, O13.5). Historical records mention avalanches mainly in the context of forest damage. There is still no central database recording avalanche accidents in Bulgaria or mapping of avalanche tracks. Since 2000, the Bulgarian Extreme and Freeskiing Association (BEFSA) has operated an unofficial database, into which information from social media is also fed. The authors emphasize the importance of accident recording for future accident prevention.

In the Romanian Carpathians, avalanche accidents have been documented since 1968/69, in connection with the founding of a Romanian mountain rescue organization. From 1968/69 to 2016/17, 152 avalanche accidents are known in which 154 people lost their lives. Since the 2003/04 season, there has been a nivometeorological department in the Romanian Meteorological Service, which operates an avalanche warning program in cooperation with the Snow Research Center in Grenoble. Since its introduction, as well as the introduction of blasting measures for infrastructure protection, training programs and a generally increasing awareness among the population, the number of accidents has decreased significantly according to this session article (A History of snow avalanche accidents in the romanian carpathians, Voiculescu. No extended abstract)

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The mountain rescue service also records avalanche accidents in Slovakia. In the last 20 years, 67 people have lost their lives in avalanches here. As in other countries, efforts are being made to document alpine accidents as completely as possible, but reconstructing historical events is difficult due to a lack of reliable records. In future, they would like to work together with their Polish colleagues to record avalanche accidents throughout the Tatra Mountains. Avalanche accidents in Slovakia mainly occur where there are particularly large numbers of people in the winter mountains, for example near ski resorts (20 years of avalanche incidents in Slovakia - comprehensive overview, Biskupič et al, P13.4).

No official figures on avalanche accidents are available from Russia, but a team of researchers has tried to gather as much data as possible from various sources (Avalanche accidents in Russia Seliverstov et al., P13.7). The first documented avalanche accident in Russia occurred in 1370 in the city of Nizhny Novgorod, where snow apparently fell down a riverbank and damaged a monastery. In the 1930s and 1940s, there were several catastrophic avalanches in mountain regions, some of which killed over 50 people. Since the early 1990s, the average number of avalanche fatalities has been around 10 per year, mostly affecting locals who are not traveling for winter sports reasons. This has only changed in the last decade: Most of the victims are now tourists. The typical avalanche victim profile also changes over the course of the year: In March, when most skiers are out and about, they are the ones most affected. In February, there are many accidents in which roads are buried. In January, it is mainly local children who die, as they are on vacation at this time. In July - peak season for mountaineers on the higher peaks, where avalanches can also occur in summer - mountain tourists are the most frequent victims.

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Pyrenees

Apart from the Austrian Alps, the Pyrenees were the most strongly represented region in this session. A contribution from Andorra presents detailed records of a road safety program that has been documenting where and how much blasting has taken place since the 1980s, and whether and what kind of avalanches were triggered. A comparison of this data with the weather conditions on the respective day shows - unsurprisingly - that there is a correlation between blasting activity or the risk to the roads in question and a lot of fresh snow. Less clear but also present is a correlation with windy weather after snowfall (Evaluation of 30 years of Nivo-Meteorological and avalanche data in Andorra, Apodaka et al., P13.1). The very active avalanche warning service of the Val D'Aran in the Spanish central Pyrenees has been intensively engaged with its "customers" or the users of the local LLB and is involved with two contributions:

"For avalanche warning services today, communicating effectively with end users is a bigger challenge than writing a bulletin." In this context, four different incidents are examined in more detail, in which different user groups were exposed to different types of avalanche problems (Reanalyis of recent avalanche accidents in Val D'Aran, Central Pyrenees: A communication challenge for different user groups, Gavaldà et al, O13.2).

  • Two well-equipped Finnish freeriders were affected by an avalanche of old snow in the variant terrain, which had been triggered by other people above them. Several groups were on the same slope. The Finns stated that they had not found the LLB for the area on the internet. Due to the language barrier, there were communication difficulties between those affected and the rescue services.

  • Ski tourers triggered an avalanche on a standard tour. They had read the LLB, which indicated an old snow problem, but decided on a specific descent after seeing another group skiing similar terrain.

  • On a guided ski tour in rarely used terrain, the very experienced guide triggered an avalanche and was partially buried. The LLB had pointed out critical conditions and the group was moving in the indicated danger zones.

  • A member of a group of snowshoe hikers was hit by a wet snow avalanche coming from above during a walk (no serious injuries). The group had no experience in the winter mountain environment and was not aware of any danger.

These incidents are used to identify similarities and differences between the various user groups. Based on this, ideas are then developed on how to better get the LLB message across to different people:

In order to reach freeriders and off-piste skiers, closer cooperation with the ski resorts is desired. These could display the LLBs prominently, for example. It is also particularly important for this user group, which often consists of tourists, to offer the LLB in English in addition to the local language and to ensure that it is easy to find online.

The "typical" ski tourers in the Pyrenees read the LLB but, according to the study, often do not have enough experience to translate it into appropriate decision-making in the terrain. One of the reasons for this is that although there is a long mountain sports tradition in the region, avalanche training has only been offered for a comparatively short time. Ski touring is a relatively new sport. In addition, heuristic traps are a particular problem in this user group, such as "scarcity" - people want to ski powder when the rare opportunity presents itself, or "social facilitation" - the others are doing it too! The authors suggest integrating the heuristic traps into the LLB and investing more in avalanche education programs. In the case of the guided group or professional users, the human factor should also be addressed to a greater extent. On the one hand, with regard to the heuristic traps, and on the other, through increased application of the concept of "strategic mindsets" in training and management.

For completely inexperienced groups who have never thought about avalanches before, it makes the most sense to strengthen cooperation with the hotel industry and rental stores. For example, it could be introduced that snowshoes can only be rented together with safety equipment, or similar measures could be taken to raise awareness.

Another article by LWD Val D'Aran analyzes avalanche accidents in the area in relation to the avalanche problems prevailing at the time of the accident, danger levels, terrain type and results of the AVALUATOR Trip Planning Tool (similar principle to Stop or Go, 3x3). Finding: Most - but not all - accidents occur in complex terrain with LWS 3 and AVALUATOR result "Not recommended" (ATES mapping and typical Problems in Avalanche Accidents or Close-calls in Val d'Aran, Central Pyrenees, Seira et al, O13.6).

Conclusion

"Avalanche accidents" is again one of the broader session topics with a lot of room for interpretation as far as the specific content of the contributions is concerned. Nevertheless, two main topics emerged - "special" individual cases and statistical evaluations of long time series. This shows that the same rule of thumb applies in avalanche research as in many other fields of research: The detailed evaluation of individual events (case studies) is essential for process understanding, as well as method and model development. However, the significance of such events can only be reliably classified in the overall picture if the large-scale patterns and temporal development of this overall picture are understood. This in turn requires a comprehensive and reliable data basis, and creating this is anything but trivial.

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This article has been automatically translated by DeepL with subsequent editing. If you notice any spelling or grammatical errors or if the translation has lost its meaning, please write an e-mail to the editors.

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