2hats
Dust.
Gravitational binding energy of Earth is order of ~10^32J (ignoring chemical electrostatic/mechanical forces) (†).That's a ground burst. A few miles underground might do it.
Total global nuclear arsenal is order of ~10^19J (as per previous clue).
Not even close (it's as many orders of magnitude out as the energy of an apple dropping from a tree is from the detonation of Little Boy, or your punch is from the energy of a typical hurricane).
† 3GM²/5R = 3*(6.6743*10^-11)*(5.972*10^24)^2/(5*6.371*10^6)