What Is An EMP Bomb?

During a hearing on October 12, experts warned the US House of Representatives that an EMP bomb, likely from North Korea, could kill as many as 90 per cent of all Americans within a year. But what is an EMP bomb? And could such a weapon really be that devastating?

Peacekeeper Missile Defence System. via Wikimedia Commons.

What Is EMP?

EMP stands for electromagnetic pulse, which is considered a short burst of electromagnetic radiation. This kind of burst can come from a variety of sources, including our own sun, but in this case we’re talking about a pulse from a nuclear detonation that occurs at an extremely high altitude.

When a nuclear explosion occurs in space above a target, three types of electromagnetic pulses follow: E1, E2 and E3. An E1 pulse involves high-energy gamma rays colliding with air molecules nearly 32km above, then raining down electrons that get pulled in by Earth’s natural magnetic field. An E2 pulse comes from high-energy neutrons that get fired in every direction, and an E3 pulse occurs due to the size of the nuclear fireball itself affecting the Earth’s magnetic field. As nuclear physicist Dr Yousaf Butt explains, these pulses affect everything in line of sight of the nuclear blast. For example, a blast at 97km up can affect a 1127km radius on Earth. However, there is a “safe space” that is unaffected by all three pulses almost directly below the blast thanks to the Earth’s magnetic field.

What Can It Do?

EMP bombs do not cause casualties directly. The blast happens much too far away from people. Their power comes from interfering, disrupting or damaging electronic equipment. That could mean power grids going down, cars and planes losing power, computer systems going berserk, and possibly even losing emergency backup power at facilities such as hospitals. It sounds pretty scary, and EMP blasts are a significant threat, but the effects are largely untested and exaggerated through pop culture and inflammatory claims by politicians.

Still, we are certain about some aspects of nuclear-based EMP detonations. According to Butt, each of the three different types of pulse – E1, E2 and E3 – affect various types of electrical systems in different ways. E1 affects local antennas, short cable runs, equipment inside buildings, integrated circuits, sensors, communication systems, protective systems and computers; E2 is similar to a lightning strike (so not as damaging since people know how to deal with it), and affects longer conductive lines, vertical antenna towers, and aircraft with trailing wire antennas; and E3 affects power lines and long communications lines such as undersea and underground cables, which could wreak havoc on commercial power and landlines. Overall, most of the damage would come from E1 and E3 pulses disrupting the technology people have come to rely on. Post-blast, generators may be able to still provide power, but for the most part, people would not have access to electricity. This could be devastating, or it could be extremely inconvenient until it’s fixed – it’s all speculation.

Should People Be Worried?

An EMP attack on the US by North Korea is probably more likely than a direct nuclear ICBM attack. Why? An EMP bomb requires a heck of a lot less accuracy to be effective. As long as it goes off somewhere above the US they have sunk America’s battleship, so to speak. And high-altitude ICBMs are difficult to stop compared to those that come in lower, such as ground-based nuclear attacks. America’s Ground-based Midcourse Defence missile system (GMD) is capable of reaching into space, but other systems such as THAAD or Aegis would have a much harder time.

But again, the specifics of EMP bombs and what would happen post-blast are still up in the air, and, for the most part, exaggerated. In 1962, the STARFISH PRIME weapons test – which involved firing a 1.4 megaton nuke 400km above the Pacific – caused quite a commotion. Electromagnetic surges travelled as far as Hawaii, around 1450km away, causing damage to some telephone company equipment, making streetlights flicker, and even messing with people’s garage doors (they started to open and close by themselves). But there were no power outages, the phone lines stayed up, and there was no radio interference throughout the entire event.

In another example, the EMP Commission tested the effects of electromagnetic pulses on 37 cars and 18 trucks in a laboratory environment. Jeffrey Lewis at Foreign Policy explains:

While EMP advocates claim the results of an EMP attack would be “planes falling from the sky, cars stalling on the roadways, electrical networks failing, food rotting,” the actual results were much more modest. Of the 55 vehicles exposed to EMP, six at the highest levels of exposure needed to be restarted. A few more showed “nuisance” damage to electronics, such as blinking dashboard displays.

So that claim that an EMP bomb would kill off 90 per cent of Americans is almost certainly total garbage. For one, Kyle Mizokami at Popular Mechanics points out that the source of that information is a quote from Congressman Roscoe Bartlett describing a science-fiction novel he had read called One Second After – not real data of any kind. Also, Bartlett was so freaked out by the idea of the nation’s power grid going down, he went off the grid to live off the land. Not exactly a reliable source of information to say the least. The truth is, nobody really knows if an EMP bomb could take out America’s power grid, or how large of a bomb would be necessary to accomplish such a feat, and at what altitude. Even if North Korea were to strike, it’s unlikely they’d have a weapon large enough to send the US back to the stone age. And they’d most certainly only get one shot to do so…

That said, the US is still somewhat vulnerable, and the country now lacks an official way to prepare for such an attack. On September 30 of this year, the Trump administration shut down the Congressional Commission to Assess the Threat to the United States from Electromagnetic Pulse after it had been in operation for over 16 years. Members of the former commission, including Dr William R. Graham and Dr Peter Vincent Pry, have been trying to appeal to the administration to get things back on track. They suggest the US’ infrastructure is not prepared for an EMP attack, and believe US intelligence has been underestimating North Korea’s nuclear capabilities. After all, it is possible to protect against such attacks, but the costs for such a shield would be in the billions and likely take years to implement. For now, rest easy knowing an EMP strike would not kill 90 per cent of the people in the US.