Wow!

I must say I have NO idea how to practically handle that! I hope our pool installers have a way to deal with it.

After a moment's reflection the doubly scary question comes to mind: How do you know this won't happen again in the future? At what point is the Texas clay considered solid?

I don't have THAT problem in New Jersey. I can't dig down 6" ANYWHERE in my yard without hitting rock--they had to blast to build this development. So nothing moves much ever.