Galtur Avalanche
OVERVIEW
CAUSES
RESPONSES
MANAGEMENT
50 metres (160 ft) high and traveling at 290 kilometres per hour (180 mph)
powder avalanche
February 1999 in the Alpine village of Galtur, Austria
57 deaths
worst Alpine avalanche in 40 years
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
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.
IMPACTS
Immediate
Long-term
Socio-economic
Environmental
The avalanche caused slope instability, which could a contributing factor to trigger future avalanches
Melted ice that could cause floods
Public infrastructure, including 16 buildings were destroyed/severely damaged
Negative impacts on the local tourism industry
5000 people were evacuated
Tension rises between authorities and affected families
31 people died
Ski resorts were closed in the region, costing the industry 5 million pounds for each day they were closed
Negative headlines in the press of the event damaged the reputation of the Galtur village, which subsequently leads to the decline in popularity as a major tourist destination
The US, Germany, Switzerland and France sent aircraft, sniffer dogs, medical supplies, food & water to support evacuation
The rescuers saved 26 people in 24 hours
Adverse weather conditions (poor visibility) continually hampered the rescue operations
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)
Since the disaster, there has been renewed efforts to improve avalanche knowledge to increase the accuracy the mapping of hazard zones.
Austria had developed a range of avalanche coping means
More avalanche-resistant buildings
A 980 feet avalanche dam built to protect the village
Steel fences constructed on all mountainsides above the village to break up the impact of the avalanche.
Afforestation
Extension of hazard zones
Scientists have considered the effects of land use and climate change to further improve the accuracy of the predictions.