Avalanche trackers in Europe, alarmed by a spate of deadly snowslides in the Alps, are gearing up for more high-tech methods to forecast a menace that has claimed at least 50 lives in the past month.
Among the new techniques being put into more widespread use are radar and computer modeling.
Radar, widely used in weather forecasting, increasingly is being adapted to measure the snowpack, says Lucian Roland of the Austria Institute for the Control of Avalanches and Torrents in Innsbruck, Austria. The radar, loaded on the back of a truck and transported to a potential danger site, can "see" the snowpack in as many as 60 sections for analysis.
Computer modeling, which compares such weather characteristics as wind and snowfall with past data, can help estimate the stability of snow, and the size and probability of an avalanche.
While such techniques are coming into vogue in Europe, they are not yet widely used in the United States, avalanche specialists say.
"Europe has many more years of history than we do, and a lot of data from many years back," says Nick Logan, associate director of the Colorado Avalanche Information Center in Denver. "We are starting to build up our database to use this new tool," he adds.
In Switzerland, Charles Wuylloud, director of natural disaster control in Valais, a canton hit hard by recent avalanches, says he hopes to get more money for a system of sensors throughout the mountain area. The system would use microphones to record and transmit information about snow conditions. "But there's a lot we don't know about the mechanism and complexities of snow," he admits.
New techniques aside, the weather is the determining, and unpredictable, force. Recent snowfall in the Alps - a mountain range that extends from southern France through Switzerland, Italy, Germany, and Austria as far as the former Yugoslavia and Albania - was the heaviest in at least 20 years. Some weather analysts say it's the worst in half a century.
"Four weather fronts within a few weeks brought heavy snow, and it was blown by northwest winds so it accumulated on the sheltered side of the mountains," explains Martin Schneebli of the Swiss Federal Institute for the Study of Snow and Avalanches in Davos, Switzerland.
But it is not just quantity, but quality that makes a destructive avalanche, forecasters say. The winds left layers of light powder - wonderful for skiing, but dangerous because it slides more easily.
"When it begins to slide, it picks up speed at a tremendous rate. It displaces the air before it, making it very powerful and destructive," says Cecile Coleou, of the Center for the Study of Snow in Grenoble, France.
"It was like a cloud surrounding us ... you couldn't see anything around you," says Christiane Erlich, describing a Feb. 20 avalanche at a Swiss resort. No one was hurt.
Such powerful, powdery ava-lanches, which can reach speeds of 200 miles per hour, are common in Colorado, explains forecaster Logan. "The difference is that the avalanches here don't create such large air blasts in front of them because the mountain valleys here are not as steep as those in Europe," he says.
The vertical drops in the Alps cause avalanches to gather speed and become an uncontrollable hazard. An avalanche in Chamonix, France, that killed 10 people last month, crashed down the mountain into the valley. Then the avalanche's force pushed it up the other side of the valley into an "avalanche free zone," an area previously thought to be safe.
Traditional methods of avalanche protection have proved insufficient in the face of the unusual amounts of snow accumulation this winter, experts say. Alpine countries use a combination of various methods, including metal and stone barriers, terracing and netting, human observation, and snow sampling. In addition, ski stations routinely shoot explosives into potential avalanche sites to reduce the buildup of snow and to cause a controlled snowslide. (Similar methods are used in America's snowy areas, Logan says.)
After the devastating winter of 1950-51 when 340 serious avalanches were registered, Switzerland built some 250 miles of snow barriers. That winter claimed 240 lives in Alpine towns across Austria and Italy as well, impelling those countries to undertake similar systems of snow containment.
Despite modern control efforts, on average in Switzerland about two dozen people each year are felled by what is known here as "white death."
Like Colorado, Europe's Alpine countries also try to limit the danger by forbidding building in avalanche zones, although some towns and chalets predate those restrictions. Until this winter, no person inside a building had been killed in a snowslide in 11 years, the Davos-based Swiss avalanche center says.
Colorado's average 2,000 yearly avalanches typically fall in backcountry areas, where people are skiing, backpacking, and snowshoeing, Logan says. "We rarely get an avalanche that strikes a town," he notes.
In Europe more avalanches fall in occupied areas, although many of the villages are sparsely inhabited during the nontourist season. "The difference now is that you have many more tourists coming to these areas, mainly to ski, so when you do have such a catastrophe, it claims many more lives," Mr. Roland says.
But with agriculture on the decline and tourism the chief means of income in many Alpine areas, avalanche forecasters agree they must hone their techniques to ensure that avalanches are less frequent and less deadly.