A 21-year-old skier survived being buried up to the neck in an off-terrain avalanche at Sundance Mountain Resort on Saturday afternoon, police say. His ski came off and he slid under a rope into what Sgt. Spencer Cannon with the Utah County Sheriff's Office described as clearly marked and closed off terrain. Once he was in the roped-off area, Cannon said, an avalanche came down on him, burying him up to the neck.