Anyone have any experience with houses built on sinkholes!?!?!

[Mark Beekman]

I just looked at a Fannie Mae foreclosure and one of the first things I noticed was the caution tape all over the back concrete patio. The entire 10'x10' patio was upended and sloping towards the foundation. It's a split-level condo and the bottom-most level (basement crawlspace) floor was destroyed -- as in CAVING IN! It looked like an IED crater.

Needless to say, this scared me off and I went on my merry way, but now I'm curious. What remedy is there for a condo unit built directly on top of a sinkhole? Is the HOA, insurance company, homeowner, etc. responsible for any repair?

This was a middle unit, with a few units on either side all with shared walls. The other units are, astoundingly, occupied (maybe they don't know?).

Is there any money to be made on something like this?