Remember the muntions ship that exploded in the harbor of Halifax, Nova Scotia during world War I? Or the Port Chicago, CA port explosion in 1944? Or the explosion of the ammonium nitrate fertilizer loaded on the cargo ship Grand Comp at Texas City, TX in 1947? Or what nearly happened at the Southern Pacific yards in Roseville, CA in 1973?
According to what I've read, the explosion in Halifax harbor had the force of a tactical nuclear warhead (about the equivalent of 2,000 tons of TNT); it came very close to wiping out the entire town.
Was the Texas city explosion the one that nearly wiped the town off the map and damaged some houses in Galveston?
There is still speculation today about what happened in Port Chicago, CA.
A single crater was left behind by the blast, as if all the explosives on the ship were rigged to go together.
Even the military's reports on the incident are inconclusive as to cause.