This is an update to Ron's report from yesterday. I went out with Apex Pro Patrol today to get better observations and do a fracture profile. It appears to have intitally triggered a windslab on the Jan 30th layer 80 cm down. The main body then went full depth and full path. Main failure plane looks to be the old melt freeze crust from November 22 which is 20 to 30 cm thick where present, or to ground where it's not. There's a 15 to 20 cm layer of well developed surface hoar at the base of the pack regardless of the presence of the melt freeze layer. This particular slope is notorious for it's large fetch and convex shape and is a well known performer. If you look through the photos, you can see that there's still some significant hangfire on both sides of the slide. There are very long cracks in the slope extending out to 100m. The ski tracks on the slope are only 10m from the end of these cracks. The snowmobile tracks are well within them. We did some tests and got hard sudden results down 80 cm. 2x ECTP24 down 80 on facets and old surface hoar. The sledders who triggered the slope are claiming that they did so on purpose to make it safer, which is an interesting concept. I've listed it as accidental.
Source: Avalanche Canada MIN