Riders reported cutting across this slope and then an hour later a different snowmobiler triggered it. It was a couple hundred feet wide and debris stopped just above groomed trail. The rider that triggered it was caught and deployed his airbag and able to escape, but his sled was towed back to town.
Number of slides
Soft slab avalanche
u-An unintentional release
I - Interface between new and old snow
Slab Thickness units