You're talking about the localized EMP effect that comes with a ground detonation of a nuclear weapon. When people talk about an intentional EMP attack, it is assumed that the detonation would occur at high altitude or even from a sattelite in NEO to maximize the LOS.
It was tested as early as 1962 and caused disruption at least 800 miles away.
Altitude dictates LOS. The electromagnetic pulse will travel through the open air at the speed of light until it is either absorbed or reflected by something else. From 30 miles up, the area affected would be a radius of just under 500 miles. From 120 miles up, 1,000 miles, and from 300 miles up, the radius would be just under 1,500 miles which, if detonated over Kansas would cause damage coast to coast and most of both Canada and Mexico.
Also the pulse happens in whatever time it takes for light to travel from the detonation site to the ground, so it's much closer to a microsecond than a couple or a few days or whatever the good professor said.
Lastly, the yield of a warhead on one of our Minuteman missiles is estimated to be more than sufficient to create a large enough pulse to black out most of our continent.
If we gave a shit what an EMP here might do to the rest of the universe, then we could try to measure how the effect lessens as it travels, but the burst of microwaves traveling at the speed of light from 300 miles away won't be doing much fading in the microsecond of travel between the blast and the earth.
You're talking about the localized EMP effect that comes with a ground detonation of a nuclear weapon. When people talk about an intentional EMP attack, it is assumed that the detonation would occur at high altitude or even from a sattelite in NEO to maximize the LOS.
It was tested as early as 1962 and caused disruption at least 800 miles away.
Altitude dictates LOS. The electromagnetic pulse will travel through the open air at the speed of light until it is either absorbed or reflected by something else. From 30 miles up, the area affected would be a radius of just under 500 miles. From 120 miles up, 1,000 miles, and from 300 miles up, the radius would be just under 1,500 miles which, if detonated over Kansas would cause damage coast to coast and most of both Canada and Mexico.
Also the pulse happens in whatever time it takes for light to travel from the detonation site to the ground, so it's much closer to a microsecond than a couple or a few days or whatever the good professor said.
Lastly, the yield of a warhead on one of our Minuteman missiles is estimated to be more than sufficient to create a large enough pulse to black out most of our continent.
If we gave a shit what an EMP here might do to the rest of the universe, then we could try to measure how the effect lessens as it travels, but the burst of microwaves traveling at the speed of light from 300 miles away won't be doing much fading in the microsecond of travel between the blast and the earth.