That just means you need a second nuke to blow a hole that allows the gas to escape & lave to flow in, and a 3rd nuke to collapse the hole before the lava gets

That just means you need a second nuke to blow a hole that allows the gas to escape & lave to flow in, and a 3rd nuke to collapse the hole before the lava gets too far. It's all there in my book, "How to nuke your way out of any problem"