The Basics of EMP: What is it, how likely, and how to prepare?

Google is on fire with people searching for information about EMP. What is an EMP? How do EMPs work? What happens during an EMP? Discussion about the book, One Second After, by William Forstchen, is making the rounds again, not only in prepper circles this time though.

I read it, years ago. At the time, the story describing life in a small town following an electromagnetic pulse (EMP) terrified me. I even reviewed it.

But here’s the thing.

I no longer believe that scenario is realistic.

This doesn’t mean I don’t think there is an EMP threat. I do. But I think localized events are more probable.

It just doesn’t make sense that a foreign power would destroy valuable infrastructure in that way.

They render it useless to us, yes, but also to them. They’d have to be idiots.

Nevertheless, knowledge is power, so in this article, I more thoroughly develop my reasoning about why a nationwide grid-down SHTF EMP scenario is just fun fiction. Plus, we’ll cover what you need to know to understand the basics of EMP and links to a comprehensive article with pictures about how to make a faraday cage.

What is an EMP?

An electromagnetic pulse (EMP) is a burst or wave of energy that creates an electromagnetic field. This field can cause damaging current and voltage surges within electrical systems. Anything in the vicinity of the origin of the burst is subject to its impact. The scope of its impact depends on how powerful the EMP is or is designed to be.

What causes an EMP?

EMPs can be naturally occurring or the result of a man-made device. The two main potential causes for a large EMP in our modern society, and the ones this article will focus on, are geomagnetic storms from Coronal Mass Ejections (CMEs) and device detonation (nuclear or non-nuclear) resulting in EMPs or HEMPs, high-altitude electromagnetic pulse. Here is a high-level summary in chart form:

We’ll look at CMEs first.

What is a Coronal Mass Ejection (CME)?

A coronal mass ejection (CME) is a stream of plasma magnetic material produced from a solar flare that moves outward from the sun at the speed of light. Carried on the solar wind, it can move in any direction from the Sun. They make for extraordinary viewing and rich scientific study.

It’s important to note that not all solar flares result in a CME, and not all CMEs are the result of a solar flare. But, a solar flare is still the most likely cause, and on average, the larger the flare the larger the potential CME. However, it’s mostly academic until Earth gets in the way. That’s when things can get a bit dicey.

What happens when a CME hits Earth?

When a CME collides with Earth it creates fluctuations in Earth’s electric and magnetic fields. The consequences from these fluctuations can be unnoticeable to aggravating to grid-down SHTF.

That last part sounds freaky, but CMEs actually occur quite often, and even when they do strike the Earth they cause little to no damage.

In fact, if you’ve seen pictures of the Northern Lights (aurora borealis) then you’ve witnessed one of the harmless effects. Those beautiful light shows begin as massive eruptions on the sun that hurl a CME in our direction.

That being said, a CME of large enough scale striking the Earth’s atmosphere could create disruptions in the electric and magnetic fields of Earth similar to those created by a HEMP (up next in our discussion).

How you ask?

How CME’s create disruptions

Well, when highly charged plasma particles from the surface of the sun crash into the Earth’s magnetosphere, it induces an electrical current in long lines of metal, like wires and pipes. This induction of current will destroy the transformers needed for power transmission on the grid, essentially wiping out the ability of the power grid to remain operational.

And then, at the far end of the CME worst-case scenario spectrum, is the one intense enough to potentially cause the Earth’s magnetic field to shift its alignment unpredictably. TEOTWAWKI, anyone?

What are some examples of CMEs from history?

Here are three examples from history:

1. In 1859 an enormous CME caused what we now refer to as a Solar Superstorm. This event was called the Carrington event after the amateur astronomer who witnessed the flares through his telescope, caused the northern lights to be seen as far south as Cuba AND made compasses and telegraphs fail across the globe.
2. In 1967, the US Air Force thought the USSR had jammed some of its surveillance radars; that’s considered an act of war, by the way. Serious stuff. The real culprit was a solar flare so powerful it could be seen with the naked eye. Military space weather forecasters saved the day there.
3. In 1989, Quebec, Canada lost its electrical grid, Toronto Stock Exchange trading stopped, caused an inflight sensor malfunction on the Space Shuttle Discovery, and is believed to have caused the demise of the Solar Maximum Mission satellite.

More recently, Space X lost most of a batch of satellites a day after launch as a result of a geomagnetic storm. Not, interestingly enough, because of damaging circuits or other electronic systems, but because the storm significantly increased atmospheric drag.

Our world is so much more technologically interconnected, so much more dependent on technology for critical infrastructure for simply every aspect of our lives, a Carrington-type event would have significantly more severe and far-reaching consequences.

What are the odds of a major CME event?

The odds of a massive CME striking the Earth are difficult to calculate. The easy odds are that the chances of it happening are 100%. It has happened before, it will happen again. The hard odds are whether or not it happens at a time when human civilization cannot withstand it…like now.

Is there any good news about a CME?

Yes, actually there is good news. Since first optically observed in 1971, scientists continue to make great strides in their ability to predict them and their potential impact on life on earth.

In fact, on the homepage of NOAA’s Space Weather Prediction Center is a scale that provides current space weather conditions with respect to radio blackout impacts, solar radiation impacts, and geomagnetic storm impacts.

If you’re a space weather geek, or just curious, you could spend a lot of time on that website.

So, we know the solar cycles. We know when the sun is going to throw a major tantrum. We even have a severity scale to rank them. In other words, we’re not going to be blindsided.

Now let’s talk about HEMPs. It’s the one that concerns preppers and government officials the most.

What is a High-altitude Electromagnetic Pulse (HEMP)?

As its name suggests a HEMP is simply an EMP detonated high in the atmosphere.

What happens when a high-altitude nuclear EMP weapon explodes?

While all nuclear weapons create EMP, when detonated at a high altitude the EMP generated is so massive that it can destroy electronics and permanently knock out the power grid across the entire country.

What are some examples of HEMPs in history?

The first true tests of HEMP devices occurred in 1962, an event called Starfish Prime, when a 1.4-megaton thermonuclear bomb was detonated 25 miles above the surface of the Earth over the Pacific Ocean. This extremely small device (in today’s terms) damaged six satellites and knocked out streetlights and other electrical equipment in Hawaii, more than 800 miles away.

In that same year, the Soviet Union detonated a much smaller device (only 300 kilotons) in space over Kazakhstan. The resulting EMP was reported to be many times greater than that of the US tests over the Pacific Ocean due to the landmass below and the stronger magnetic fields in that specific area.

According to scientists within the US government, a large nuclear device detonated roughly 300 miles above Kansas could result in an EMP spanning the entire mass of the continental United States.

What are the odds of a HEMP attack?

Even though we can answer the question, what is an EMP and how does it work, the odds of a HEMP attack upon the United States are unknown.

Up until the recent past, very few nations had the capability of an attack, but as each year passes and the knowledge needed to complete such a mission becomes more available, the odds increase. Currently, China, Russia, North Korea, and likely, Iran, have sophisticated weapons that have been designed specifically to create an EMP.

One likely scenario involving an EMP attack would be carried out by a terrorist group, such as ISIS or a similar, radical group.

Is there any good news about a HEMP?

That depends on who you ask. Some say that an attack like that on the United States is about as bad as it gets.

I’m sorry. There’s just really not any good news when it comes to HEMPSs.

Admittedly, there is a distinct lack of information available about EMP and its effects; most of what we know is from nuclear tests, both American and Soviet, in the 1960s. Data and information after that period are still highly classified, so all we have to go on is what has been declassified from this earlier era of tests.

However, this information, along with a few pieces of recent data, is enough to make some reasonable projections.

How would life change if a HEMP occurred today?

Not for the better.

Experts predict that 90% of Americans would be dead within one year. The reason for this is the extreme dependence on electricity and the delocalization of resources, like food, water, and sanitation abilities.

The moment a large EMP wipes out earthly electronics there will be massive death. Consider these EMP effects:

• Everyone utilizing any method of flight may suddenly find themselves falling to the earth.  Although no hard numbers are available for how many people are in the air at any given moment, it’s probably close to 1 million.
• At the same moment, it’s quite possible that all vehicles traveling will suddenly lose power.  Many won’t be able to brake or steer properly, creating massive casualties globally.
• Millions of people worldwide that depend on machines to perform life support functions will begin to perish within moments of the EMP.
• Immediately after the EMP the world’s supply chains are finished. Famine-stricken areas around the world will have received their last shipment, and drought-stricken areas their last water. In the United States grocery stores will most likely have stocked their shelves for the last time and larger non-farming-based communities will begin a rapid decline.

In a matter of days, the socioeconomic societies of Earth will crumble and fail.

Most estimates state that the loss of electrical power would last weeks or months until restored. I don’t believe these estimates to be accurate and feel that with all of the other concerns that will be present, re-establishing power across the country will be low on the list.

Read this post for tips about what to do immediately after an EMP.

How do we protect our electronics from the effects of EMP?

The easiest way to protect your devices from the effects of EMP is to construct a Faraday Cage. In simplistic terms, you can build a Faraday Cage by constructing a metal container that can be closed relatively tightly. Inside this container, you would install some form of insulating material such as Styrofoam. 

As long as the container closes relatively tightly and the insulating material covers all metal surfaces, any items inside the container are reasonably well protected from the effects of an EMP. When the EMP strikes the cage it will simply conduct itself around the metal exterior, not passing through the insulation to the devices inside. If the container is open, the EMP will certainly have a good chance of striking the items inside.

Faraday Cages can be scaled up large enough to protect items as large as vehicles as long as proper insulation is used. A large metal shipping container insulated with several inches of Styrofoam insulation could easily protect hundreds or even thousands of small devices or many devices ranging in size.

Read more about protecting electronics and find instructions with pictures for building a Faraday Cage here.

What should I do?

Begin your preparations now by becoming self-sufficient. Develop your own power sources via solar and wind power devices. Ensure you have all of the necessary knowledge and materials to repair these devices after an EMP and obviously ensure the spare parts are protected against EMP. Learn to live off of food that you have grown and processed animals you have hunted or bred for livestock. In other words, you need to begin preparing now to do it on your own.

What are your thoughts on the likelihood of an EMP occurrence?

Originally published June 15, 2012; updated and revised by Team Survival Mom.