Way back in the 70s—80s..I guess…Caidin wrote a fairly good and terrifying Sci Fi on experiments like this that created an ever expanding black hole.
Mathematicians assure us this can’t happen…..
There was a calculation that said there was a finite chance the Trinity test would ignite the atmosphere. It didn’t. Nor did any of the other above ground tests nuclear or thermonuclear. I’d say something was missing in the original calculation.