Colorado! Well I'm partial, but all of the areas surrounding Colorado are good too. These areas don't have earthquakes or hurricanes. I wouldn't look east of colorado though because then you have to worry about tornadoes. Also something to look for is a place with mild winters. You do not want to be located somewhere that suffer sever ice storms on a regular basis because they often cause power outages. Good luck with your search!
I think there isn't anywhere that can be considered completely disaster-free. Even if disasters aren't common in an area, there is no guarantee that something won't happen. That said, some places that DO have earthquakes regularly might not actually be a bad location, since things are built to withstand the earthquakes.
In the IT world, and hosting world, Texas seems to be the clear winner of reliability. That's why some of the largest hosts in the world, like Hostgator, are based in Houston with server farms all over Texas. If I were to need a reliable disaster recovery area, Texas would be at the top of the list.