Tombstone has its problems. One of the worst is that it is a very small town with abandoned mines under at least part of it. This means that without warning, the ground could collapse.
There are many places like Tombstone in Arizona, though in much worse condition, and you have to be careful around them because they can be deadly. Abandoned mines are some of the most dangerous places you can go, and have more ways of killing a person than you might imagine. Experienced miners treat them like they are booby-trapped.
To top it off, there are so many mineshafts in AZ, nobody knows where they all are. Seems like every year, they swallow a few unlucky off-roaders who drive over the wrong patch of desert.