We skinned up Michigan City with the intention of skiing the due west line of East Bowl (starting around 10,100). Following a previously set traverse, we worked our way past quite a few tracks that dropped into the earlier, steeper NW sections. I started to get cracking when the tracks diminished as I was breaking trail, so we stopped and evaluated the safest way down. I made my way across a very low angle slope towards a flat knoll. Cracks shot and propagated down slope and to both sides. I kept my edge to the flat knoll and stopped. When I looked around, I noticed it had collapsed and that I was near the middle of a slab approx 100 ft across and 50ft vertical. It hadn't moved 2 inches, but was visibly cohesive. My partners communicated what they were seeing from their position, and we decided I should cut back to the left as to maintain a constant visual. From there we slowly worked our way down 1 by 1 in short segments, following the lowest possible angles. At the bottom, my buddy mentioned he thought we had heard a collapse up higher as well, but wasn't certain. Didn't get any pictures as focus was elsewhere ....