@farmerman,
""We've got a high water table and red clay that expands and contracts depending on how much moisture there is in the soil," Keller says. "That expansion and contraction causes cracks in basement wall, and cracks mean leaks."
"I've always been told our soil is not good for basements," says Russell Benson, an Oklahoma City real estate agent on Trulia, in response to a prospective buyer asking why basements were so rare in Oklahoma. "I have sold a few older homes that had basements, but they were never in that great of shape."
"Red clay is susceptible to water and heat. It moves; it causes cracks," he says. "So, you're going to need pumping systems and backup power to run the pumps because eventually the water's going to get in."
"For most homeowners, it just doesn't make sense, moneywise," he says."
http://www.npr.org/blogs/thetwo-way/2013/05/21/185857916/why-oklahomans-dont-like-basements
But, this article also lists fallacies to these arguments.
The local meteorologist were telling everybody, "this thing is to big, if you can not get under ground, get out - leave the area of the tornado." But you gotta have a car and you gotta know how and where to do it. Don't get in a car and get stymied in traffic. Also, don't move into the path of the tornado, where it may change direction to or where it has been.