[SunkenCiv]

It's not unclear at all. It would. Early in the 20th century, a midair detonation over Lake Michigan knocked out at least six municipal power generators of the time, sent a surge up the Grand River channel in Grand Haven, lit the surrounding surface of the Earth for miles, and was so evident people ran out of their homes into the night, sure that the world was ending, as far inland as Battle Creek. This was a small, transient event that left no other traces.

[Toddsterpatriot]

I don't recall a lot of communications networks being used after Hammerfall. Power generation either, except at the nuclear power plant.