That EMP pulse disaster theeories are fictional garbage. I’d be much more worried of being vaporized than an emp wave that doesn’t extend much beyond the destruction zone of a nuclear blast.
Some folks assert that we have
satellites that can deliver such pulses in narrow beams and broad beams.
And, iirc, bombs can be engineered to maximize such pulses.
Maybe you need to go back and do a little reading on "Operation Fishbowl", more particularly, a test referred to as "Starfish Prime". This was a high altitude test. Because there is almost no air at an altitude of 400 kilometers, almost no fireball was present. What little fireball that did form was completely spherical in shape. Notable effects: About 1500 kilometers (930 statute miles) away in Hawaii, the electromagnetic pulse created by the explosion was noted as three hundred street lights failed, television sets and radios malfunctioned, burglar alarms went off and power lines fused. On Kauai, the EMP shut down telephone calls to the other islands by burning out the equipment used in a microwave link. This occurred in 1961, when there was no where near the number of semi-conductors in use as we have today, and almost no IC's in use at all. (Today, almost everything has semi-conductors and IC's somewhere in the circuit if there is any electriciy involved in the operation of whatever the piece of equipment might be.) This EMP range was achieved with only a 1.4MT blast.
It is known that the Russians (and their Soviet precursors) tested purposely built EMP weapons that were in the 300MT range. With the entire Russian arsenal being on the market nowadays, I wouldn't bet against someone purchasing an EMP weapon from them - black market or otherwise. (Ever wonder why the Russians and the Chinese still make electronic vacuum tubes? Vacuum tubes can take a hit from an EMP and still function, whereas semi-conductors and IC's can not.)
Raven6