User blog comment:GodzillaDestoroyah/A Godzilla sized explosion, Not as big as you think/@comment-24175751-20140704145950/@comment-24974663-20140705022400

Yeah. That was me. I know it's ridiculous to debate physics in a fiction. But Godzilla's body wouldn't undergo fission. It just wouldn't be built to explode like a bomb. But I'm sure a massive melting creature would create enough thermal energy to melt into the Earth's mantle, that's for sure.