MIRV attacks will cover a lot of ground, but those damage zones look a tad exaggerated.
I guess it all depends. I think it is not even close to being accurate.
For example I read once that Nearly one-quarter of America’s 9,962 nuclear weapons are now assigned to the Bangor submarine base on Hood Canal, 20 air miles northwest of downtown Seattle.
I would have expected the blast zone in that area to be much larger.