I don't believe hell is in the center of the earth. I think it doesn't exist in this dimension, but in one outside of our own, and therefore is not located inside the earth. It's very real, as Heaven is, but as far as I can tell from Scripture, it is not located within the confines of the physical universe we know.

In this video clip, Randy Alcorn answers the question,"Is Hell a real place, and is it our default destination?"

Jesus spoke of Hell as a literal place, describing it in graphic term.