I think the reporterette doesn’t know what “explosion” means. It wasn’t an explosion in the normal sense (unless somebody set a depth charge off IN the tank). It appears to be an overpressure situation with the remarkable failure of 100% of the circumferential weld attaching the tank walls to the base.
“..overpressure situation ..”
I suppose that’s possible, but it’s hard to imagine the tank would have no overpressure relief valve. It gets hot as hell out there, and I guess water is added and subtracted all the time, probably from a fairly large pipe. That just didn’t look like a ~~3 psi overpressure explosion to me.