Wait, Merton is a mistranslation of Meltdown from FF6, right? Assuming this, Meltdown could possibly be referring to a reactor being blown up. I happen to remember, in the area after you blow up the first reactor, right before Cloud has to battle the bunch of MPs by himself, there is a railing in the foreground, and the camera is placed in such a way that you can't see beyond the railing. From what I remember, it's pretty high up in the air, and that would mean that there is a big sight beyond the railing, which you can't see?

I say that area which probably has a name that I can't remember, with fire spewing in from the doorway that you got out of the first reactor from.