Sinkholes need not breach the surface to do damage. Unless there is a new wieght like a building or road traffic huge caves can develop below the surface and go unnoticed on top.

This isn't just a Florida thing. Think way back to... a few weeks ago and last fall when gas lines were popping and whole neighborhoods were being evacuated. The recent quake swarm in central AR. The 3+ quake just off the coast of Mobile AL.

This is going to get worse.