Storm cellars are underground structures that are either located below buildings, or are built underground near houses or other such buildings. They are reinforced structures into which residents can go for protection from a strong wind storm. They are common in areas that often have tornadoes and hurricanes.
A typical storm cellar for a single family would be built nearby the home. It might have a floor area of eight by twelve feet, (2.5 x 3.5 m) and an arched roof like that of a quonset hut—but it would be entirely underground. In most cases the entire structure would be built of blocks faced with cement and rebar through the bricks for protection from the storm doing this makes it almost impossible for the bricks to fall apart. New ones sometimes are made of septic tanks that have been modified with a steel door and vents. Most storm cellars would be reached by a covered stairwell. At the opposite end of the structure there would be conduits for air that would reach the surface, and perhaps a small window to serve as an emergency exit and also to provide some light.
A storm cellar may also be used to store canned goods for emergencies or for a long period of time.
The Secure Home, Joel Skousen, Swift Learning Resources; 3rd ed, 1999 (ISBN 1-56861-055-6)