Avalanche! How Trees Hold the Secrets of the Past…

Jen Dickie

Stob Ghabhar, Scotland. This image was taken from the Geograph project collection. See this photograph's page on the Geograph website for the photographer's contact details. The copyright on this image is owned by Richard Webb and is licensed for reuse under the Creative Commons Attribution-ShareAlike 2.0 license. Last month, tragedy struck in the Scottish Highlands when an avalanche swept four climbers to their deaths. The experienced mountaineers were descending the Bidean Nam Bian peak on the southern side of Glencoe when the avalanche hit, causing them to fall 1000ft (c. 300m) before being buried under dense snow.  In a report for The Independent, Richard Osley describes how the tragedy occurred shortly after the Scottish Avalanche Information Service (SAIS) issued a warning that human-triggered avalanches were likely in the Glencoe area and the risk was rated as ‘considerable’.  The SAIS reported that on the day of the avalanche, there did not appear to be much depth of snow on the hills of Glencoe, however, there were areas of “mainly hard, unstable windslab” that overlay “a persistent softer weaker layer”; in these conditions more compact blocks of snow can separate from the surrounding snow resulting in a ‘Slab Avalanche’, this type of avalanche is responsible for the majority of avalanche-related fatalities.

As the popularity of the winter sports industry grows, there is increasing pressure on scientists to predict where and when avalanche events will occur.  Dedicated research centres such as the Swiss Institute for Snow and Avalanche Research are continually improving our understanding of avalanche formation and dynamics and therefore providing increasingly reliable warning services, however, they highlight that we are still unable to accurately predict “why, when and where an avalanche will be released”.

In an article for Area, Mircea Voiculescu and Alexandru Onaca describe how they have applied dendrogeomorphological methods to assess snow avalanches in the Sinaia ski region in the Romanian Carpathian Mountains.  By combining climatological and nivological (physical properties of the snow) analyses with information on disturbances recorded in tree growth, they argue that historical avalanche activity can be reconstructed, including the frequency, magnitude and return-period characteristics of the events.  This knowledge, they argue, can be used to make assessments of risk in areas such as the Carpathian Mountains, where the geomorphological understanding of local avalanches is limited.

As winter sports become more popular with non-expert communities, there is growing pressure to identify high risk areas and to provide appropriate warning systems that non-experts can understand.  It is clear that real-time observations and local knowledge are key to identifying avalanche risk, however, this research shows that by combining different techniques and approaches, we can increase our knowledge and understanding of hazards such as avalanches, and provide essential risk information to previously unmonitored regions such as newly established winter sports resorts.

books_icon Mircea Voiculescu and Alexandru Onaca, 2013, Snow avalanche assessment in the Sinaia ski area (Bucegi Mountains, Southern Carpathians) using the dendrogeomorphology method, Area 45 109–122 doi: 10.1111/area.12003

60-world2 Four climbers die in Glencoe avalanche, The Independent, 20th January 2013

60-world2 SportScotland Avalanche Information Service, accessed on 18th January 2013

60-world2 The WSL Institute for Snow and Avalanche Research SLF, accessed on the 18th January 2013

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