Wonderful post!
I live in Ft Lauderdale and have herd of this mystery and others like it.
There are many different theories about what has happened.
Earth has many magnetic ley lines. I believe that they are stronger at certain times and are constantly changing there energy levels.
this link goes into detail. http://www.crystalinks.com/grids.html

Its like holding a compass while standing at magnetic "North"-- actually in northern Canada and not the "North Pole"... it doesn't point anywhere in particular, since the place it is used to pointing to is at your feet!
You should know that finding magnetic north is not always easy – the spot is actually moving about 10 miles northwest every year. Since it was discovered in 1831, magnetic north has traveled many miles from its original spot!
That being said, i believe that these energy lei lines also change and move. Making it extremely difficult to investigate and figure out what happened during these mysterious events.

Just my 2 cents ;)