Doesn't matter where you are. East coast, west coast. He was an idiot for traversing there.
Terrain trap below with multiple obvious strainers and fresh snow on top of a tailing pile...
...a TAILING PILE! The reason tailing piles slide is because the whole ground layer is a made of up gravel.
Sucks to be the kid, and glad he is ok. But common sense says thats a shitty place to be.