Features

• Major avalanche natural disasters occur when small slides of snow become one huge, sliding mass. The worst of these events result from built-up snow simultaneously breaking loose from a mountainside. Rapidly accumulating fresh snow causes the fracturing and sliding of weaker layers below. Avalanches are thus most likely to occur during or within 24 hours after a snowstorm that deposits more than 12 inches of snow.
  
  

Fatalities

• Fatalities in these sudden, natural disasters are usually skiers, snowmobile riders and snowboarders. Avalanche disasters kill nearly 150 people a year. In general, the victims themselves trigger 90 percent of avalanches.
  
  

Expert Insight

• Mark Moore of the Northwest Weather and Avalanche Center says that after reviewing more than 20 years of avalanche accidents, he has observed common threads that tie most avalanche natural disasters together: Moore attributes most avalanche-related accidents to ignorance of current weather information on changing conditions. Those who are not aware of increasing winds, temperatures and precipitation changes are more likely to be surprised by avalanches.
  
  

Prevention

• Moore recommends watching out for "bull's eye information," such as cracking or other sounds emerging from the snow, that will warn you of unstable and dangerous conditions. Stay abreast of recent slide notifications for your area, and pay attention to changes in snow-pack conditions as your elevation changes.
  
  

Survival

• There is no way to stop an avalanche once it begins. If you find yourself caught in an avalanche, National Geographic recommends you try to get off the moving slab of snow---not an easy feat. However, if you are on a snowmobile, skies or a snowboard, gather downhill speed and veer left or right and away from the body of moving snow. If you sense you can't escape, look for a nearby tree and grab onto it. If that fails, "swim" your way through the piles of falling snow. After the snow has settled, pushing the snow away from yourself will give you room to breathe. Punch your hand skyward and wait until help arrives.