Nuclear Electromagnetic Pulse FAQ

Let’s say you are the leader of some nation with little regard for the lives of others, including citizens of your own nation, and have a small number of thermonuclear weapons along with some high performance missiles. You want to cause something dramatic and unusual with your limited capabilities. Maybe you are an Evil Overlord or a Republic Serial villian and want to perform some experiment in technological resilience and human suffering. You want to do something dramatic and long lasting that will have maximum impact on the course of history. Turns out there’s really only one way to go. You should use your limited resources to attempt to generate a Nuclear Electromagnetic Pulse, or EMP for short. It’s the way to get the most interesting effects from just one weapon.

Because EMP seems to be poorly understood by most of those who have even heard of it, with many exaggerating the risks and others underplaying them, The Board really needs an EMP FAQ. So here it is with pictures and everything:

What is EMP? 

EMP is an effect generated by exploding a nuclear device very high in the atmosphere, from tens up to a few hundreds of kilometers in altitude. This is in the vague “edge of space” territory and is above, sometimes very far above, the radio wave reflecting ionosphere. Remember, its the thick layers of Earth’s atmosphere that make the blast and heat of a nuclear explosion. Nukes themselves are really just very bright and strange flashbulbs that generate lots of odd radiations. In the thin uppermost reaches of the atmosphere, there can be no blast and little heat, but the interaction of a nuclear bomb with the thin atmosphere creates a series of abrupt electromagnetic effects of tremendous power potentially covering a huge area.

Screenshot (12)

The Fast Pulse is the first stage. This picture is taken from the Executive Report of the EMP Commission which you can download here . The report does not specify the weapon yield in this example, but I think it’s at least 300 kT, but less than 1 mT. Whatever the yield, it’s pretty clear that the Commission hates Kentucky and West Virginia. The Fast Pulse is by far the strongest. It is created by gamma and x-rays stripping electrons off of nitrogen and oxygen atoms in the upper atmosphere. These electrons fly off at about 90% the speed of light, which puts them in the beta particle energy range. They don’t stay that fast very long though, they immediately start curving and slowing down. Just remember the Left Hand rule from physics. But all that energy loss from warping and slowing these electrons has to go somewhere, and it comes out as a powerful electromagnetic surge. This is the most damaging part of the EMP. And if you are wondering why the zone of greatest strength is that pink smiley face south of the detonation, that’s magnetic field mojo well beyond the capabilities of The Board’s staff. All you really need to know is that if you do this in Australia, there will be a pink frowny face to the north of the detonation.

Screenshot (13)

The Slow Pulse is most intense directly under the detonation. There’s no smiley face. The Slow Pulse is still pretty fast and abrupt, but is not as strong or widespread as the Fast pulse. It’s caused by neutrons pushing around gas molecules that have only microseconds earlier become ionized by the gamma rays that created the Fast Pulse. These ions are also deflected by the magnetic field, and create a second surge of electromagnetic waves. In the most intense zone of effect it’s really only kind of like a lot of things getting a power surge from a lightning strike and we know how to protect against that, but given the damage from the much stronger first pulse, systems hardened against such power might suffer additional damage.

But wait, there’s more? As you might imagine, Earth’s magnetic field objects to being nuked and as it recovers, it creates even further electromagnetic disturbances. These are similar to the effects of a solar coronal mass ejection. Our technology can usually handle this, but solar activity has been known to cause massive blackouts.

When was EMP discovered?

It really should have been discovered back in 1958 during the higher altitude tests of Operation Hardtack. Scientists noted unusual surges and strange polarizations, but the tests weren’t high enough to generate really strong effects. The first systematic study of EMP began with the USSR’s Project K tests beginning in 1961. The Soviets were considering protecting themselves with a nuclear armed ABM system and quite wisely wanted to know if there were risks with detonating nukes high above their own cities. Read the link and you’ll see they were quite careful, starting with very small bombs and working their way up to 300 kT. The US would be somewhat careless and schedule the fast paced Fishbowl series of tests launched from Johnston Atoll with 1.4 megaton Starfish Prime shot among the tests. Some contemporary sources say Fishbowl was in part mostly about nuking the newly discovered Van Allen Belts just for fun. They are incorrect. Original documents like this once-classified 1962 film clearly indicate that Fishbowl was centered on the use of nuclear weapons for ABM purposes.

The Starfish Prime shot caused the most extensive EMP effect of any test, causing minor damage as far away as Hawaii. This effect was hushed up, as were any effects of the Project K tests. EMP would not become known to the general scientific community until a 1981 series of articles in Science.

Was EMP part of any secret war plans?


Yes! That B-52 isn’t just being tested for hardness against Soviet EMP attacks. It’s also being tested to see how well it will perform over the Soviet Union while an EMP attack from American missiles paves the way for it. All part of the Carter-era Directive 59 plan.

What would an EMP attack look and feel like?

NEMPhawaiiKinda like pretty lights in the clouds like in this picture in Hawaii 1400 km away from the Starfish Prime detonation, the largest high altitude nuclear test. Or maybe like the big fuzzy blue full moon from the Bluegill test in the title background image. Some stargazers would be at risk of temporary flash blindness if they happened to be looking directly at a detonation of the type in the hypothetical attack in the EMP Commission report from the first question. Otherwise you’d just see eerie light and look up to see a strange florescent sphere. In clear daylight you might not notice the detonation and there would be no risk of blindness. You might see some strange things if you looked up.

But you wouldn’t feel anything. There might be a few weird noises in your house. A transformer might explode down the block and wake you up. But otherwise you’d have no idea something so important happened if an attack came without warning.

So my home electronics won’t explode? 


Almost certainly not. We are able to build electronics that are much more safe than systems found on the Starship Enterprise. At most you are going to hear many small crackles and maybe smell some of that “warm electronics” smell like you smell inside of Best Buy. Most damaged devices will just likely stop working with no visible sign of failure. Small isolated devices like watches and pacemakers will not fail.

You can find good information online about making Farady cages to protect your electronics, but they won’t do you any good if your stuff is plugged in.

In fact, if I had one recommendation about what to do with 15 minutes warning of an EMP attack. I would recommend unplugging everything. Power cords, Ethernet cables. Unplug both ends of everything and fill everything that can hold water with all the water it can hold. Because of this next question.

What about the power grid? 

NEMPsubstationThis is the most serious problem. In most of the area influenced by the attack electrical substations will look like this. Even unaffected areas could see long term power loss. Areas of severe damage could lose power for months to years. Emergency backup systems are designed to work only for days after a hurricane or earthquake. This is where the experiment in human suffering begins. When unaffected backup systems run out of supplies, everything we rely of fails. Water pressure and sewage treatment will fail, gas and fuel pipelines will lose pressure. Food will not be delivered to cities. I think predictions of 90% losses in 24 months are probably too high, but EMP is still going to kill. And it will happen slowly.

But if you really still care about your personal electronics even when considering the severity of extended grid loss, go ahead and unplug everything. It will help.

Stop shaming my data kink. How can I save my data? NEMPovens

Optical media like CDs and DVDs should work just fine. If you want to save memory sticks or even your cell phone, just buy some old microwave ovens from Goodwill. They are Faraday cages designed to keep microwaves in, but they will do a lot to keep EMP out. Cut the power cords for extra safety. Many microwave ovens leak small amounts microwaves. Put your phone in every oven you are considering buying. If you get any signal at all inside the oven with the door closed, that oven leaks.

Have fun hoarding your precious data like Gollum while the rest of us spring forth to participate in the heroic struggle of survival and rebuilding.

What about cars and planes? Will they still work?

E-6 Mercury doomsday command plane protected on all sides.

Most aircraft should be able to fly through EMP, with larger military planes doing quite well. Aircraft are pretty much Faraday cages to begin with, and military craft have conductive material across all joints to bend the EMP around the plane. Doomsday Planes like the Mercury, Nightwatch, and Air Force One are hardened against the strongest EMP, which is hard to do because they have so many antennas. Even without hardening, not that many planes would fall from the sky. Observation planes at the Starfish Prime test managed to land safely.

Cars are a different matter. Many people think that any car built after 1983 will fail from medium strength EMP. Between 1979 and 1983 almost every car marketed in the US switched over to electronic ignition control and many believe that EMP disables such systems. This myth is part of the reason every vehicle used in Mad Max: Fury Road had a pre-1983 exterior. While it is true that highest level EMP will fry a good portion of cars, only about 10% of cars will be disabled by mid range EMP. This is in part because the ignition control system is fairly well shielded because such systems when not shielded cause static on the radio.

I really don’t think cars will be much good. A lot of people will be trying to evacuate and with no way to pump gas, the highways will be gridlocked.

So what’s the most helpful thing to have?

NEMPradioThe staff here at The Board thought long and hard about this and it seems that the best thing to have is a connection to the outside world. One of these multiband survivalist radios should be perfect. Put it in an ice chest inside of a closed metal trash can and set the trash can on a board to make a Faraday cage. You’ll need a few months supply of batteries too, but you can store them as usual. You need shortwave and AM capability so you can receive information from far away. If your area is severely affected by EMP, there will be no local FM transmissions for a long time.

What defenses does the US have against EMP?

While EMP has been known to the US military since 1962 no defensive measures were taken during the Cold War other than hardening military and government communications systems. The reason for this is that any anticipated EMP attack would also be accompanied by other types of attack that would cause bigger short term problems than EMP. By hardening communications the US demonstrated that it could still order and launch a counterstrike.

This type of deterrence is still part of US policy. A small scale nuclear EMP strike is likely to be met with a range of responses that could include an all out nuclear strike.

Worrying about hardening civilian infrastructure against EMP only became an issue after the end of the Cold War, and became a major concern after 9/11. If you watch this scary video it looks like we have done nothing and that Obama was trying to kill us all by disbanding the EMP Commission in 2011. The real reason the commission was disbanded is because many of its recommendations were already being implemented at that time. There has been much progress on hardening SCADA control systems and limited stockpiling of vulnerable transformers. Both SPX and Mitsubishi have begun production of the largest substation transformers in the US, making stockpiling easier should there be a perceived need to do so.

Overall, The Board thinks attacks of the type described in the EMP Commission Report are unlikely, but there may soon be a defense against such small scale attacks. The Ground Based Midcourse Intercept system should be fully operational within a year (The Board has covered this here). GBI has the range to reach the high altitudes and match the high angle flight profiles of an EMP attack. There probably should be an additional GBI station on the East coast, but even the current installations in California and Alaska can provide some coverage to the central and eastern US.

The best defense against EMP is dispersed power production. This is already happening in the US largely due to market forces favoring renewables, and deregulating coal will do almost nothing to change this. Low natural gas prices from fracking has led to construction of gas fueled cogeneration plants. Cogeneration plants are small and often located inside cities. They will help cities cut off from the grid.

With EMP, as with other disasters. Dispersion is strength, concentration is weakness.

What would recovery from a nuclear EMP attack be like?

As I said, I think predictions of 90% losses from a single weapon NEMP strike are much to high. Only a three weapon attack that sealed off the coasts could have a chance of reaching that high. Life would still be very grim though. There’d be a global depression too. The entire system of finance, production, and consumption would be disrupted.

But at the same time there would be an outpouring of international aid coming into the US, and later on, regulated commercial investment. This is the main reason I think losses could be held to under 50%. One thing though, the US economy as we know it would be gone. If you think a federation of regional socialist economies governed by a small central state sounds good, that’s likely what we’ll have.

Rebuilding the power infrastructure will mostly be focused on renewables, perhaps even kite power. There will be no opportunistic invasions of the US. There will still be an intact nuclear force.

So, an EMP strike on a large industrialized nation would lead to reduced global emissions and rebuilding largely with green technology? Sounds interesting. EMP attacks as global eco-engineering? That has some appeal to my inner super villain

Additional Questions: 

There’s a lot left out on this post, such as the tube debate and effects on satellites. If you have any questions, ask in the comments. If you know any good sci-fi that covers EMP, let me know.





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