The strong electromagnetic pulse ( EMP ) that results has several components . In the first few tenths of nanoseconds , about a tenth of a percent of the weapon yield appears as powerful gamma rays with energies of one to three mega-electron volts ( MeV , a unit of energy ) . The gamma rays penetrate the atmosphere and collide with air molecules , depositing their energy to produce huge quantities of positive ions and recoil electrons ( also known as Compton electrons ) . The impacts create MeV-energy Compton electrons that then accelerate and spiral along the Earth 's magnetic field lines . The resulting transient electric fields and currents that arise generate electromagnetic emissions in the radio frequency range of 15 to 250 megahertz ( MHz , or fifteen million to 250 million cycles per second ) . This high-altitude EMP occurs between 30 and 50 kilometers ( 18 and 31 miles ) above the Earth 's surface . The potential as an anti-satellite weapon became apparent in August 1958 during '' Hardtack Teak '' . The EMP observed at the Apia Observatory at Samoa was four times more powerful than any created by solar storms , while in July 1962 the '' Starfish Prime '' test , damaged electronics in Honolulu and New Zealand ( approximately 1,300 kilometers away ) , fused 300 street lights on Oahu ( Hawaii ) , set off about 100 burglar alarms , and caused the failure of a microwave repeating station on Kauai , which cut off the sturdy telephone system from the other Hawaiian islands . The radius for an effective satellite kill for the various Compton radiation produced by such a nuclear weapon in space was determined to be roughly 80 km . Further testing to this end was carried out , and embodied in a Department of Defense program , '' Program 437 ''
Starfish Prime
Starfish Prime
High-altitude nuclear explosion