Perhaps I shouldn’t be proud of this, but I spent some time tonight figuring out what kind of weapon you would need to kill Godzilla (or any other kaiju, I suppose). I saw Garth Edwards' Godzilla last night and I rather liked it. I liked it more than I liked Pacific Rim, but I’m not sure why. I think it might be because I’ve never understood the idea of making giant robots to fight kaiju. We already have excellent weapons to fight large animals – they are called guns.
So I gave some thought to what kind of weapon it would take to bring down the King of the Monsters. I started with some basic assumptions (maybe a lot of assumptions, but it’s fun!).
First, I went with Popular Mechanics’ excellent article on Godzilla’s anatomy (http://www.popularmechanics.com/technology/digital/fact-vs-fiction/the-impossible-anatomy-of-godzilla-16785535). They guess his mass at 160,000 metric tons. An African Elephant can mass up to 7 tons, which makes Godzilla 23,428 times more massive than an African Elephant.
In the old days, an elephant gun would be used to kill an elephant with one shot to the head. Those old howitzers generated about 8,000 foot/pounds of force, or 10,847 joules of force. That means a headshot on Godzilla would need 23K times more than that, or 255 million joules to kill the beast!
The main gun on a M1 Abrams tank generates about 2,624,832 joules of energy, so that’s not enough. However, the BLU-109 Air Force “bunker buster” bomb has a warhead containing 240kg of explosives. That warhead can generate 984 million joules on detonation! Get that in his head and Godzilla is going down.
So, instead of giant robots just use an F-16 with a BLU-109 in guided (JDAM) configuration and go for the headshot. Sorry, Godzilla – you’ve been pwned.
(Wikipedia, Google and Wolfram Alpha were essential to this thought experiment)