ulse) A natural or man-made burst of electric or magnetic energy in the atmosphere. With frequencies below the light spectrum, a nuclear bomb, lightning strike or a device designed to emit such a pulse are sources of an EMP. A massive solar eruption (solar flare) can also disrupt communications satellites.
Weaponry specifically designed to target an area with an EMP have been speculation for decades; however, regardless of the type, the distance from the source to an electronic device determines the damage.
Hard drives, SSDs and flash drives are susceptible to EMP damage, whereas optical discs are not. In order to survive an EMP, drives should be stored in a protected container (see Faraday cage