Although basements are one of the best places to stay safe during a tornado, fewer than one in 10 Oklahomans have access to cellars. This is because the soil in the state is mostly made of clay, and clay can be fickle as a foundation for buildings, The Atlantic explains. “There is a chance your house, its basement surrounded by glorified mud, will eventually simply topple into itself,” the magazine says.
Compounding the problem is Oklahoma’s bedrock below the clay, which is limestone. Drilling steel reinforcements into the bedrock doesn’t work well because dry limestone becomes flaky. Plus, a steel-reinforced shelter can cost thousands of dollars, much more than most families can afford.