Housing for tornadoes

Whenever I read or hear about tornadoes damaging houses, it is interesting (although a shame) that despite all our modern technology, we are so vulnerable in front of destructive forces of Nature (or at least, destructive from our point of view. Nature may perceive this as a constructive cleansing act). Although I have not done much research, a quick search of tornado-proof housing yields websites (such as this one) that are filled with suggestions on how to use certain “strong” materials. These sites also point out, however, that at the end of the day, the safest thing is to create a “safe house” inside one’s house. This safe house would have very minimal windows, concrete walls, and steel reinforcements.

With the popularity of eco-friendly architecture, I wonder why we can’t go with something more basic and make a safe house in an environment that is a little more appealing than an underground dungeon. Instead of building houses with wood, why don’t we create smooth rolling “hills” and place the houses within them? (Since most regions with tornadoes are flat, this would actually involve adding several feet of sod on top of them). Although this may be expensive, I presume it will be more cost effective in the long run. A great example of what I’m thinking of would look somewhat like a hobbit house, buried within a hill. However, since building hills are expensive, the tornado housing I am thinking of would be a low-story, garden-level/first floor structure embedded in a low man-made hill. I’ve sketched out my idea below: