Snowbike triggered D3 at Border Ruffian

About 30 minutes after shooting the video of an ECT that propagated, and about 1/4 mile away from that location, we witnessed 2 riders trigger this D3 avalanche on the Jan 4th facets. Although I hesitate to call it a D3 because it didn't run very far, it had more than enough volume to push a car off a road. The crown was 8ft in more than one place, and debris chunks were bigger than me. When they triggered it, the riders were well below the crown, near the bottom of the small path, on the edge of the trees, where the Jan 4th facets were only 2ft from the surface. Nobody was caught - I'm not even sure the riders were aware they triggered it. 

Pic 1: Examining the crown after the avalanche. I didn't get close to the crown because I didn't trust the hangfire, and I wasn't sure if I could get back out of the deep hole between the crown and the debris. The weak layer was the facets just under the Jan 4th crust, which can be seen in the upper right of the photo.

Pic 2: My sled in the same position, looking the other way along the crown.

Pic 3: Large debris chunks - hard to get a sense of scale, but the rectangular piece in the foreground was about the size of my sled.

Pic 4: Taken by a friend after I took the previous photos, this is me riding away from the site, and gives a better sense of scale of the debris. The crown just above me and also another 60ft behind me was 8ft tall. The debris obscures the view of the slope angle, but you can see a convex roll on the bed surface just behind me, that I estimated to be 40 degrees. Not a large avalanche in terms of how long it ran, but enough volume to be fairly destructive. The trees at the bottom indicate this path can run a bit longer, but just out of the frame of this photo, the vegetation clues decrease and the slope angle tapers off significantly.