The quiet was deceptive. Two hundred meters wide, the avalanche that swept the Chamonix Valley last Tuesday was the worst the region had seen in 90 years. It killed 12 people, splintering its way through a pine forest, smashing 23 chalets and crushing cars like soda cans. Rescuers arrived on the scene within the hour, and managed to save more than 20 people from the snow and rubble. Police, firefighters and soldiers used avalanche dogs and sensors to hunt, first for survivors, then, later, for bodies.

The Peclerey tragedy is the worst disaster in what has been the snowiest European winter in 14 years. The snow has clogged highways and halted train lines from Rome to Romania, forcing hundreds of evacutions–and killing people. The day before the Chamonix disaster, three died in an avalanche in Wengen, a Swiss resort. In western Austria, the biggest snowfall in decades stranded 25,000 tourists for five days. And three days after the Peclerey disaster, two new avalanches in the French Alps killed five more people.

Last week’s disaster, says Francois Sivardiere, president of France’s National Association for the Study of Snow and Avalanches, was an ““aerosol’’ avalanche, caused when fresh snow–in this case, 1.8 meters in four days–gets too heavy to support its own weight. Chamonix-based meteorologists study the snow daily for signs of potential avalanches, rating the danger on a scale from 1 to 5. Last Tuesday it was a 5.

But all the preparation in the world can’t eliminate the risks of living in the mountains. One of the men killed last week was Daniel Lagarde, a local mountaineer. His expertise couldn’t save him, his wife or his 3-year-old daughter. But it may have spared his 12-year-old son, RaphaEl, who was rescued 12 hours after the avalanche. The boy told doctors his father had taught him what to do if caught in an avalanche: sit quietly, and save your energies for rescue.