There are many caves and caverns throughout the world.
Would not a shelter built in a cave be far better than one above ground ?
The US Government and agencies has a plethora of underground bases and facilities.
Ther are not enough blast free or fallout free zones in the United States for many to survive above ground, except in special shelters.
In special shelters water and food runs out, the occupants go insane and kill each other, plus there is no TV. :*>
In your own private underground cave shelter YOU control , not some armed guard or government agent.
If you are deep enough in the ground the fallout that settles on the surface cannot harm you.
You must filter the air to prevent fallout from entering your shelter area.
If the fallout particles are caught a safe distance away in air vents then the effects are kept away.
In areas of known caves and caverns, even if there is heavy fallout, your best survival chance may be deep underground. Some will go there .
SOME WILL SURVIVE.
Re: Would not a shelter built in a cave be far better than one above ground?
While I wouldn't want a shelter above ground (above ground is useless in protecting against fallout), as for caves, I'd be afraid of fumes, cave-ins, flooding, but you are right: In extreme circumstances, the cave is better than nothing, and during the big war many will undoubtedly flee to caves and probably survive well enough there. It pays to know in advance where the caves and other natural hide-outs/shelters are in your town.
I wonder if there is a "Cave Registry" of caves and their locations ?
Perhaps some kind soul has this knowledge and will post links.
probably the best info (for your area) would be local knowledge and experience.
(a secret hideout is the best place to not be found or followed) :^>
Re: "I wonder if there is a 'Cave Registry' of caves and their locations?"
http://www.caves.org/pub/journal/PDF/V61/v61n3-Culver.pdf
http://64.233.167.104/search?q=cache:ZuagVcAJlH0J:www.caves.org/pub/journal/PDF/V61/v61n3-Culver.pdf+north+america+caves+map&hl=en
http://www.speleobooks.com/wild.html
If you don't like any of those, search for other North American caves books/maps at:
http://www.google.com/search?hl=en&lr=&q=north+america+caves+map
This one is way cool >>>
http://www.caves.org/pub/journal/PDF/V61/v61n3-Culver.pdf
(distribution map of caves and cave animuels in the Newknighted States)
:')