The outside balconies of the middle building collapsed first and took out the columns of the entire building that collapsed. A sinkhole didn't cause the building to collapse, but may have caused the balconies to collapse. The entire state is built on limestone, which dissolves in rainwater.
I think it's a foundation failure that caused the balconies to collapse. There was a lawsuit by the condo dwellers about cracks in their walls. The whole complex was settling for 40 years. But the foundation engineer that stamped it in 1980 will not be to blame. It is the nature of foundation engineering. I'm sure they drilled a few holes and found no karst, and built a foundation four times stronger than necessary, as per standard. And his stamp came with a clause indemnifying him about unseen hazards under the building, because you can only know what's down there right where you do your test drilling.
Who will be liable are the building inspectors and engineers who inspected the building for the lawsuit over the last five years and didn't order everybody out.
