Galtür Avalanche

The Galtür Avalanche was an avalanche that occurred on February 23, 1999 in the Alpine village of Galtür, Austria.It took less than one minute to hit Galtur. At 50 m(164 ft) high and traveling at 290 kph (186 mph), it hit with the force of a bomb, overturning cars, ruining buildings and burying 57 people. By the time rescue crews managed to arrive, 31 people-locals and tourist had died. This Avalnche was considered the worst Alpine avalanche in 40 years. Three major weather systems originating from the Atlantic accounted for large snow falls totaling around four meters in the area. 'Freeze-thaw' conditions created a weak layer on top of an existing snow pack, further snow was then deposited on top. This, coupled with high wind speeds creating large snow drifts, caused roughly 170,000 tons of snow to be deposited.

The zones

Like most populated regions of the alps, Galtür was hazard zoned according to the perceived risk into red, yellow and green areas.

• Red Zone- Highly vulnerable to avalanches; no development permitted
• Yellow Zone- Moderate risk; development is allowed but must be reinforced to resist an avalanche.
• Green Zone- Avalanche safe; development is permitted with no reinforcement required.

The cause

In January 1999 a series of storms occurred bringing with them 4 m (13 ft) of fine snow and forming a huge snowpack on the mountains above Galtur. Later that a month a melt-crust developed- the upper layers melting during the day and refreezing at night.The cause of the avalanches puzzled scientists for a long period of time. Although the area was prone to avalanches, never before had they occurred on such a scale as this, reaching the village. A complex sequence of events led to the event: 4000 km away, on January 20, an Atlantic storm was forming. Turbulent warm air from the tropics headed north, and, cooling, it swung back towards Europe. This started a series of storms. Combined with cold arctic air coming from the north, there was a very dry, light snowfall exceeding 4 meters. A massive snowpack formed on the mountains above Galtür. Northwest winds piled the snow to increasing depths. At Galtür, it bonded with ice and hence lasted longer than they were generally known to. The resulting powder avalanche contained a central layer scientists were not previously aware existed. Known as the saltation layer, it was primarily responsible for the destruction of buildings. As new snow fell, the melt-crust became unstable until, on February 23, it failed and caused an enormously powerful powder avalanche to crash down the mountainside, picking up more and more snow as it went.

The avalanche

The avalanche occurred on February 23, 1999 at 8:00 AM in Austria, when the frozen layer of snow (melt-freeze-crust) failed. It finished at 8:02 AM Due to the cold conditions, snow with a very low density (between 50 and 70 kg/m³) was formed. This caused a massive powder avalanche traveling at around 186 mph (290 km/h) down the mountainside. As it travelled down the mountain, the avalanche picked up twice the amount of the initial snow volume of around 170,000 tonnes. The avalanche was estimated to contain around 300,000 metric tonnes of snow. The avalanche went into the village's Green Zone, destroying seven modern buildings and causing extensive primary damage. Many people died of asphyxiation from inhaling and suffocating on the aerosol-type snow due to its low density.

Aftermath

Soon after the avalanche rescuers began to look for survivors; in 24 hours the rescuers saved 26 people. A rescue dog, Heiko, amply proved the value dogs have in avalanche rescue, saving many lives, and another dog; a Labrador-Alsatian cross named Jack that was buried under snow for 24 hours. The day after the avalanche, 31 people were all confirmed dead. Outraged families demanded to know why the avalanche penetrated the supposedly safe zones and devastated Galtür. However, 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. Since this disaster there have been renewed efforts to improve avalanche knowledge and forecasting so that hazard zones can be accurately predicted. This is particularly important if land use or climate changes render past information less useful. Response has included the extension of the hazard zones, with steel fences constructed on all mountainsides above the village to break up the areas where unstable shelves can form, creating smaller shelves overall that reduce the size and scale of any future avalanches. A 300m avalanche dam directly protects the village.

Green Zone

As in the region, Galtur is risk-zoned for avalanches; but it was the safe, Green Zone that was the worst hit. The Austrian government asked for assistance and thousands of people were airlifted out, using helicopters from both Europe and the USA. Since then the risk zones have been extended, steel fences have been erected on the surrounding slopes to create smaller areas to reduce the extent of an similar disasters.

In Popular Culture

The avalanche attracted media attention from all over the world, mostly due to the magnitude of the rescue operation. It was also profiled on National Geographic's Seconds From Disaster in the episode "Alpine Tsunami".