Set it off high in the atmosphere and there go all Electrical devices in good part of US and Canada including all cars, ships, tractors etc. I think thebdeath toll is supposed to be 75% or so in affected area due to starvation, lack of medical care and breakdown in society. Not much of anything will work in area hit by EMP.
that book 1 second after that seems to be the primary source for everyone’s emp worries is completely absurd and exaggerated and was basically written for some lobbyists to secure a lot of grant money for certain clients
There are two and possibly 5 countries with the wherewithal do successfully pull off a hemp detonation IF it was not intercepted in route—one or a few missiles head this way you can bet that there will be enough countermeasures to stop or at least limit the damage...the norks are far from able to pull this off anytime soon
Also, emp effects are based on long circuits pushing up enough energy to fry stuff....power grid is vulnerable but most vehicles, even modern, would be largely unnaffected, as would generators and other electronics that are not plugged in
I know from personal experience parts of out power grid are protected with basically giant fuses and much of it would be brought back online fairly quickly
If you want something credible to worry about then worry about the c&c systems of the power grid, banking ssytem, and toher critical infrastructure being hacked...there is stuff there that should keep you from sleeping well