North Korea’s nuclear EMP threat

North Korea’s recent nuclear weapons test is fuelling concerns over a potential high-altitude electromagnetic pulse (EMP) attack which could cripple power supplies and electronic systems across a wide area


HOW EMP ATTACK WORKS

1 Nuclear warhead 
Explodes above Earth’s atmosphere, releasing burst of gamma rays – very high energy electromagnetic radiation

Gamma ray

2 Upper atmosphere
Wave of radiation collides with oxygen and nitrogen atoms at altitude of between 20-40km,
stripping away electrons

Atom

Ejected electron

3 EMP: Electrons interact with Earth’s magnetic field, creating brief but intense burst of
downward-moving radiation


1 2 3

Pulse does not directly kill or injure humans but produces energy surge that can overload and wreck unprotected electrical systems


ESTIMATED AREA AFFECTED*

Height of explosion
500km
200km
50km

Radius of affected area
2,400km
1,600km
800km

CANADA
U.S.
Washington DC
MEXICO

*Explosion over U.S. Midwest



Sources: Congressional Research Service, Business Insider 
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