In 1971 there was another what if we nuke this going on, this time in the Aleutian islands, directly on top of an active volcano chain and part of the ring of fire. A 5 megaton nuke was set off 6000 feet under Amchitka island. This was the largest underground test ever on US soil. Not being that long after the great 9.2 Alaska earthquake there was lots of doomdayers saying this could at worst crack the mantle and set off unheard of devastating quakes and title waves.
My electrician apprentice teacher worked on that project and actually had a hand in wiring that bomb up. Most everybody wanted off the island before they set it off but he volunteered to stay. Was a hell of a show i understand but other than some poor marine mammals washed up on the beach, nothing serious happened.IInterestingly enough the environment organization Greenpeace was born out of this test
https://en.m.wikipedia.org/wiki/Cannikin