For an EMP attack to be effective on modern electronics, you need to blow up a multimegaton nuclear bomb close enough for it to take out whomever is using that piece of electronics...
No. Optimal altitude for an EMP attack is actually a few hundred kilometers up. The "base case" usually considered in these scenarios is a nuke going off about 400 km over Omaha. At that altitude, the ionosphere helps you create a "slow" E3 pulse which induces a field in the tens of volts per kilometer at ground level; and since you can see most of the continental US, you have plenty of kilometers to work with.
My understanding could be wrong, but wouldn't this mean exposing a 1 cm wide component (and/or components that have one cm long traces attached) to at least 250 V?
Wouldn't this be expected to destroy not every single component, but enough components to make enough hardware inoperable to collapse all industrial and power generation capabilities? (If you destroy 10% of ICs on only 10% of control boards in a power plant or factory, I'd assume that plant goes down hard and isn't coming up any time soon.)
From what I’ve read about Project Orion, the physical damage from nukes is mostly in the shockwave. The material shockwave doesn’t propagate very far in space, so satellites won’t be blown up by a space nuke.
The EMP is, if I understand right, created by a shockwave in the extremely diffuse plasma of the ionosphere, affecting electrons and ions differently, creating a massive charge separation, and the collapse of that charge separation is what produces the actual EMP. That said, this article is the first I heard of the E1/E3 distinction, so I don’t know enough to be sure of what an EMP would do to satellite electronics.
Naively, this map makes me think that a single such EMP means enough electronics break that every major power plant or industrial plant is down and not recoverable for weeks.
An EMP attack is of course a plausible and realistic, but a rather costly, dare I say, somewhat of a science fiction formulation of an attack.
Any attacker is unlikely to choose the most costliest and fanciful form of attack. Wouldn't it be much more cost efficient to send multiple groups of people to drive around and snipe or blow up equipment of transformer stations at key places?
That doesn't help you if you can't get the fuel for it. Most industrial facilities can't just run on generators. Data centers can in theory, but I somehow doubt those diesel delivery contracts would be fulfilled, and good luck calling around asking for alternatives when the phone networks go down.
It starts to make sense once you know how nuclear EMP attack works. The detonation would happen high in the space (400 km) and would not cause direct effects or radiation on the earth.
EMP pulse in a continent wide nuclear EMP attack is not coming from the nuclear detonation directly. It comes from synchrotron radiation when free electrons in upper atmosphere interact with earths magnetic field
