Science: Avalanche Killers

The mining village of Alta. high in Utah's snow-laden Wasatch Mountains, was destroyed by an avalanche in 1874, with the loss of more than 60 lives. The wrecked town remained relatively deserted (the mine had played out anyway) until the skiing boom of the 1930s brought a new kind of life. Now Alta has attractive lodges, and the cars of skiers cram its snow-walled parking lots. But above the town are the same steep slopes that hurled the fatal avalanche.

To prevent similar tragedies, and worse ones, the U.S. Forest Service is applying the science of avalanche control, with its first...