...a plonge into a magma pool = fatal? I'm surprise uncle Walt has no one calling him a Thor hater for that.
...I mean, really? Trying to start something with what Walt has written? Ahem...it's called "drama", in case you are wondering. Thor's dialogue was for dramatic effect. How dramatic would it have been if he said "I better call Mjolnir because a lava bath, although harmless, I would still have to shampoo my hair 10 times just to get the sulfur out of my hair...such a drag...hurry mjolnir"! Besides, Thor said - "before the fall becomes a fatal one", not really a 'plonge' (what the heck is a 'plonge'?) into a magma pool. I reckon Superman wouldn't want to fall a thousand feet drop mere moments after waking up in mid-air...geez! Do we have to explain everything to you Supes fanboys?