It was the experienced party's second run on this slope. On their second run the 6th person down the slope - a snowboarder - triggered a large, hard-slab avalanche and was carried 100-150 yards down the slope and stopped on a bench and was on top of the debris. He suffered no injuries and is OK. The rest of the debris continued over the bench to the bottom of the slope with a total of 1,900 vertical feet.
The avalanche was 2.5 - 4 feet deep and 300' wide on a 38 degree east to northeast facing slope around 10,200'. The avalanche broke on the layer of fist-hard faceted snow formed on the snow surface during the first part of January. The slab was hard and composed of both old snow and recently wind blown snow.
Of interest, an explosive test "black hole" from prior testing two days before was noted in the starting zone prior to the avalanche. Prior ski cuts on the slope produced no effect.
