these bombs are like giant icepicks that use gravity to cut through a structure before detonating.
i actually think we should be able to put a robot on the tip of the bomb that excavates through the structure, so that it's less a question of using the physics of mass to smash your way through in a collision and more like throwing a dart at a mountain that can burrow it's way through it when it gets there like a giant metallic groundhog before letting it rip mid mountain.
i wonder if you could actually trigger an inactive volcano using the same mechanism. that would be pretty brutal.