DENVER (AP) - The kind of avalanche that killed five people in Colorado over the weekend is among the most difficult to predict and trigger, and it's dangerous because of the amount of snow normally involved.
Saturday's slide near Loveland Pass is called a deep persistent slab avalanche, and it was the kind of avalanche that backcountry snowboarders and skiers were warned of in the area that day. It's also the same type of avalanche that killed a snowboarder Thursday near Vail Pass.
"Unfortunately, we were warning about the exact problem that these fellows became entangled with," Ethan Greene, director the Colorado Avalanche Information Center, said Monday.
Besides the four snowboarders and a skier who died, one other man in the group was buried but survived. Some were on snowboards that can be split in two for climbing up slopes. All had avalanche beacons, used to locate people buried under the snow.
Deep persistent slab avalanches get their start after a weak snow layer falls, typically early in the season, and causes a structural weakness in the snowpack, Greene said. They're triggered when the bond breaks between the slab being released and the underlying persistent weak layer. The problem layers can be buried deep within the snow.
A Denver Post photo of investigators at the site of Saturday's slide shows that the area where the snow broke off is above their heads in one location.
Exactly where such slabs could break up is hard to predict. In Thursday's slide, multiple people had crossed the area before the slide occurred, Greene said.
The slide happened on public forest land open to anyone willing to hike uphill for the thrill of skiing and snowboarding in fresh snow for free. Greene said it's up to users to assess the risks, carry their own rescue equipment and make educated decisions about how much risk is too much.
Typically, avalanches aren't as common in the spring, but new snow in Colorado's mountains have created avalanche conditions more like those usually seen in the winter.
The Post reported that the four snowboarders and one skier killed Saturday had participated in a fundraiser for the avalanche center in Dillon a day earlier. Greene said someone from the center spoke to the group, but Saturday's outing in the Sheep Creek area wasn't part of any fundraiser for the center.
The Clear Creek County sheriff identified the victims as Christopher Peters, 32, of Lakewood; Joseph Timlin, 32, of Gypsum; Ryan Novack, 33, of Boulder; Ian Lamphere, 36, of Crested Butte; and Rick Gaukel, 33, of Estes Park. The sixth person, identified by friends as Jerome Boulay, didn't need to be taken to a hospital, said Sheriff Don Kreuger.
Eleven people have died in avalanches in Colorado this season.
Saturday's was the deadliest in the state since 1962, when seven people were killed in a slide that wiped out several homes in the town of Twin Lakes near Independence Pass.