Generally the voids in the Florida limestone foundations are filled with water which itself helps to hold up the structure. In times of drought however, as we are experiencing right now the water is depleted and the remaining cave structure is not strong enough to support the house above and falls in. This is what has been labeled here in Florida a "sink hole". They come in all shapes and sizes from hole that are 2-3 feet deep in diameter and a few inches deep to several in Orlando Florida that are now fairly large lakes of a mile or more in size.
Sink holes can occur in almost any area that has a limestone bedrock base but Florida is particularly susceptible to sink holes due to the high rain fall in our area. Lots of the desert southwest has a limestone bedrock like New Mexico and Arizona but lack the rain fall to make sink holes a problem.
Now the million dollar question. "How do you repair a sink hole." There are generally two ways to do this.
The first is filling the void with a slurry of concrete that fills the void and eventually gives the house a solid concrete foundation. This is the most expensive way but is tried and true and is the best way to support the house and surrounding area. The problem with this approach is of course the cost. You may have to use 30 cubic yards of concrete to fill the void or 300 cubic yards there isn't any real way of telling until you start pumping concrete and money down the hole.
The second way is less costly and just as effective which is the pier technology repair of sink hole homes. This repair drives solid concrete piers into the ground and then attaches the concrete foundation to the piers essentially making the home a house built on stilts which are driven into the solid limestone bedrock. The problem with this system is that it leaves the possibility that you will wake up in the morning and walk out your front door into a 30' hole. Your house is still supported but the ground surrounding it has now fallen away.
Of course either way has its pitfalls and supporters. The best solution is to bull doze the house and build in another area....of course there is no guarantee in Florida that any given area does not have a sink hole. Some of the larger sink holes that have appeared were not visible even to ground penetrating radar used to see if there are any sink holes present. If the cavern that collapses is 100' under ground there is no way to predict where or when it will be or collapse.
Just pray that you don't have a sink hole or just enjoy the sunshine and figure that every place has its difficulties.
Hope this helps.
All the best,