See Pictures: The first skier that exited the Aussie couloir skied left toward the Kiwi couloir entrance, stopped, and leaned his shoulder into the slope. That was enough to let a fairly deep slab go which carried the skier slowly for a few meters. The side of the feature that broke was technically northwest facing but on the SW side of Joffre, we think the loading was from the sluff coming out of the couloir above.
Skiing out from and down the Anniversary glacier we saw numerous small naturals on sunny slopes.