What Is an EMP Attack and Why Should You Care?

An electromagnetic pulse (EMP) is a burst of electromagnetic energy that can damage or destroy electronic devices. EMPs can be generated by nuclear detonations at high altitude, by solar flares (called geomagnetic disturbances or GMDs), or by purpose-built EMP weapons. The threat is real, it is taken seriously by the U.S. government, and it is something every homeowner should understand.

How Does an EMP Work?

A nuclear EMP occurs when a nuclear weapon is detonated at high altitude — typically 25 to 300 miles above the earth's surface. The explosion releases a burst of gamma rays that interact with the upper atmosphere, generating a powerful electromagnetic pulse that travels at the speed of light to the earth's surface below. A single high-altitude nuclear detonation over the center of the United States could affect the entire continental United States simultaneously.

The pulse has three components. The E1 component is a fast-rising, high-voltage pulse that lasts only a few nanoseconds but is powerful enough to destroy the microelectronics in computers, phones, vehicles, and appliances. The E2 component is similar to a lightning strike and arrives within a second of E1. The E3 component is a slower, longer-lasting disturbance similar to a severe geomagnetic storm that can damage power grid infrastructure.

What Would an EMP Destroy?

The honest answer is: almost everything electronic. Modern vehicles with computerized ignition systems would stop running. The power grid would fail. Cell towers, internet infrastructure, and communication systems would go dark. Refrigerators, HVAC systems, medical devices, and water treatment facilities that rely on electronic controls would fail. The Congressional EMP Commission estimated that within 12 months of a major EMP event, up to 90% of the U.S. population could perish due to the collapse of critical infrastructure.

Is the EMP Threat Real?

Yes. The Congressional EMP Commission, established in 2001 and reauthorized in 2015, has published multiple reports on the EMP threat and recommended specific protective measures. North Korea has publicly discussed EMP as a strategic weapon. The 1989 Quebec blackout, caused by a solar storm, left 6 million people without power for nine hours and caused $2 billion in damage — and it was a relatively minor geomagnetic event compared to the 1859 Carrington Event, which would have destroyed the modern power grid entirely.

What Can You Do?

The most effective steps for homeowners are: install a whole-home EMP protection device on your electrical panel, store critical backup electronics in a Faraday cage, maintain a supply of emergency food and water that does not require electricity to prepare, and have a plan for extended grid-down living. Our guides on each of these topics go into greater detail.