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Galtur Avalanche (OVERVIEW (50 metres (160 ft) high and traveling at 290…
Galtur Avalanche
OVERVIEW
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February 1999 in the Alpine village of Galtur, Austria
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CAUSES
Further snow storms caused by cooled air from the Tropics and cold Arctic air, created a large snow pack on the mountains above Galtur.
Freeze thaw conditions created a weak layer on top of the existing snow layer. Further snow was then deposited on top
Northwest winds also piled the snow the increasing depths
This put a lot of shear stress on the weak layer underneath the new snow pack. Inevitably, the weak layer failed and caused the powerful powder avalanche to crash down the mountainside, picking up more snow and speed as it went. During the event, there was also the presence of winds of 120km/hour, causing this layer of snow to at a high speed.
January 1999: a series of storms occurred, bringing 4 meters of fine snow that formed a huge snowpack on the mountains above Galtur
MANAGEMENT
Galtur was hazard zoned, with the risk levels being categorized into three colors
However, the green zone was the area that was the worst hit.
→ Red zones: highly vulnerable to avalanches (no development permitted in these areas)
→ Yellow zones: moderate risk to avalanches (development is allowed but structures must be built to resist avalanches)
→ Green zones: avalanche-safe (development is permitted with no reinforcement required)
The hazard zoning is based nearly entirely on the historical record, and there was no evidence of avalanches traveling so far on this track in the past.
However, the green zone was the area that was the worst hit.
RESPONSES
Immediate
The US, Germany, Switzerland and France sent aircraft, sniffer dogs, medical supplies, food & water to support evacuation
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Destroyed transport infrastructure meant that a response by road was not possible for 3 days → rescue operation was only feasible by air (however, crew had to fly below tree line in order to not create an additional avalanche risk)
Long-term
Since the disaster, there has been renewed efforts to improve avalanche knowledge to increase the accuracy the mapping of hazard zones.
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Scientists have considered the effects of land use and climate change to further improve the accuracy of the predictions.
IMPACTS
Socio-economic
Public infrastructure, including 16 buildings were destroyed/severely damaged
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Environmental
The avalanche caused slope instability, which could a contributing factor to trigger future avalanches
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