Are sinkholes common? Hmm, yes. They're everywhere.
"Unlike hurricanes or earthquakes, sinkholes aren’t tracked. But CNN
reports that from 2006 to 2010 in Florida alone, there were 24,671
insurance claims for sinkhole damage, totaling a whopping $1.4 billion."
Tin Can Bay, Australia - Beach being swallowed
Five Facts about sinkholes
Lots and lots of sinkholes, and they look like this
The USGS Water Science School - all about sinkholes
The science of sinkholes
Florida brochure - guide to spotting sinkholes
Sinkhole science: a primer
A grounding in sinkhole science
Can we do anything to prevent sinkholes?
"It’s one of those things where they happen, and then you deal with it."
"A lot of the fatal ones I've seen have happened on highways, where
people were driving down the road and drove right into them. A lot of
people who have died in sinkholes were just standing right there when
[the collapse occurred]."