Looks like your cake settled after it was iced. It's better to fill and crumb coat then let sit for several hours to settle before applying the final icing.
Your icing could be too thin.
Your cake could have been too warm
Or as Tiggy said, the cake might have settled after being iced.
Looks like your cake settled after it was iced.
This is what went thru my mind the second I saw the pic.
Yeah, first thing I thought was "cake settled".
settled after icing the cake or the board flexed and shattered the icing when it was picked up or moved?
I think it was a combination of the cake settling, the icing sliding a bit, and the crust on the icing cracking because that flimsy Wilton board flexed when you moved the cake.
Crappy cake board.
Just by looking at the border(icing) it seems as if the icing is too thin. When you added the color, you might have added too much. Sometimes that is something to take in consideration. I also always cover my boards with floral paper or contact paper. The moisture from the cake makes uncovered cardboard sag. Hope this helps.