from Survival Blog:
Electromagnetic Pulse (EMP) is a serious national threat with growing public awareness. A high-altitude atomic/nuclear explosion sends electrons plowing through the earth’s magnetic field lines and thus generates powerful radio waves that impact the earth below the explosion within a radius of many hundreds to thousands of miles.
The peak field strength is immense, on the order of 50 kilovolts per meter, and covers a very broad frequency spectrum, from very low frequencies, past 100 MHz; but the first wave (named E1) is evanescent, over in a mere microsecond or so. There are additional, slower incident waves– E2 and E3, but these are more of a powerline problem and are not addressed in this article. (I will write on this aspect in a later article.)
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