I always assumed the crawl space under my house was the safest place for us to be in a tornado. I have spent some time in the past few days online reviewing tornado safety and am reading conflicting advice concerning crawl spaces. Some sources are saying that they are NOT safe because the house could shift and you could be crushed. But wouldn't the same be true of a basement?? My crawl space is made of cinder block and mortar and is entirely underground except for the small vents at the top. The access is inside the house and crawl space is about 5 feet deep under the access door and about 2 1/2 feet deep elsewhere. I'm confused and would like input please!

So your crawl space is more like a cellar then.  I am trying to visualize.  I have a crawl space as well ( no basement) the only way to enter is by going outside and crawling under the house.  I think this might be what everyone is talking about when they reffer to crawlspaces.  But that is just my opinion.

http://www.newschannel5.com/global/story.asp?s=6538928

The sample crawlspace picture in this article is almost identical to what I have. And, yes, the access is a panel in the floor that you lift off.