>>That said, explosions are funny things - I was taught that the forces generated usually follow the path of greatest resistance, which is a bit counterintuitive. You can, for example, use explosives to fell trees: http://www.fs.fed.us/t-d/pubs/pdfpubs/pdf08672325/pdf08672325dpi72.pdf
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>I was once told by the Ontario Fire Marshall, that there is technically no such thing as an explosion; only rapid burning. Although he did point out that if it was rapid enough that he couldn't outrun it, he'd be willing to accept the use of the word.

Tsk, tsk... the narrow-sighted specialist. Does he know there are explosions entirely without fire? Try boiling an egg in a microwave. Or an ampoule under a lens, using just sunshine.