I've got a question for you explosion junkies out there.
Not surprisingly, Wikipedia has a list of "Largest Artificial Non-Nuclear Explosions," including such oldies-but-goodies as the explosion of ammunition ships in Halifax in 1917 and Port of Chicago (San Francisco Bay Area) in 1944, which were both in the several kiloton range. (I wouldn't be surprised if the record wasn't actually held by some colossal Soviet screw-up that got covered up.)
But Gerdec isn't yet included on the list. Any estimates of where it would stand?