If you are talking about the cracking that is left normally on the terrain, that's definitely a bug! I wanted to fix this for awhile now, but it required a hefty solution to fix. We should see this fixed in a future beta update.
I bet that's a nasty bug to fix properly...
I can think of about three conditionals and a need to locate an arbitrary best place to put the effect in that fix, and that's a lot for one bug.