The Sierra Avalanche Center says the trigger of a February avalanche that killed nine backcountry skiers near Lake Tahoe may never be known. The center this week did release a picture showing where the Feb. 17 avalanche near Castle Peak started and where the skiers were buried. A group of 15 s kiers were in a small depression in the terrain that was surrounded by trees and boulders when the avalanche struck. That allowed the snow to pile up, burying some skiers in eight feet of snow. Thirteen skiers were caught in the avalanche. Nine skiers, including six mothers and three guides, died. California Feb 22 Lake Tahoe community mourns victims of California avalanche Extreme Weather Feb 21 Crews recover bodies of 9 backcountry skiers days after California avalanche ...read more read less