Do all devices go out at the same time in an EMP attack?

Question

Is there an order in which different kinds of (unshielded) electric devices go out in the event of a high altitude EMP? For example, first small gadgets, then electric vehicles, then grids. Or do all unshielded devices go out pretty much at the same time, seemingly instantaneously, with no specific order or delays depending on the type of device?

Answer 1

Last summer, a lightning bolt struck a tree right outside my apartment building (so close that I hit the floor). As you may be aware, lightning creates a small EMP blast. The power went out momentarily and when it came back on, my desktop PC would not boot and my TV no longer had sound (yes, everything was plugged in to a very nice APC UPS). The PC turned out to be a fried motherboard. A week or so later I noticed that my Wi-Fi was flaky. It was constantly dropping connections. That could be unrelated, but I threw it on the insurance claim as well. I wasn't the only one affected. My upstairs neighbor swears he saw a small ball of lightning in his bedroom, and he lost his TV, cable box, and cable modem. Another neighbor lost the DSL modem and a TV as well, but the worst (IMO) was the car that was parked directly under the tree. I don't know what fried on it, but it wouldn't start after that and had to be towed to a mechanic.

So to actually answer your question; anything that is going to be affected is immediately affected (well, immediately as in tens of microseconds). However, a device may sort of function after it's been affected and it may take a while to notice that it has failed (like my Wi-Fi router). So, an example might be a radio that is no longer able to receive but can still transmit, or maybe that radio can only send/receive on certain wavelengths.

If you had several circuits carrying current to a device, and only some of those circuits were blown out by the EMP blast, the remaining circuits could fail if the device they were powering drew too much current for the remaining circuits to handle. I can't speak for military or "hardened" devices, but I know consumer and professional electronics just aren't designed that way. In a consumer device, there is one power circuit, and if it doesn't go in the EMP pulse, it's 100% fine afterwards. In a commercial device (like the APC switchable UPS's I use at work), there are redundant power supplies. If one goes, the other is designed to handle 100% of the load. Designing something to only work if both PSU's are running would be silly (because it would be less dependable, not more).

Answer 2

All direct effects happen at practically the same time (light speed from the EMP source still apply).

That said, if you will burn longer tracks on PCB, tracks in complicated devices would get burnt immediately - because these are thin and delicate. On the other hand, tracks on PCB in an old car might get only some damage, and electronic connected to them might be hardy enough not to fail immediately. In such case, a damaged diode or track might function correctly for some time, it's condition worsening with use, until complete fail.

Answer 3

EMPs work by creating rapidly changing electrical and magnetic fields. When these come into contact with electronics they induce a power surge that may fry electrical components. All modern electronics have weak/sensitive components that will fry instantly.

EMPs are also quick so if an electronic component doesn't instantly fry from it then it will most likely keep working, unless it is badly damaged and over a few seconds it keeps getting worse until it dies out.

Note: Weaker EMPs may simply force devices to restart since they won't fry the components but simply mess with the bits making the device run into a "Blue Screen of Death" or similar.

Edit: Since Tim added some real life experience I thought I could add some experiences I've had with lightning

One day when I was walking back home while listening to music a lightning hit kinda close and I heard some interference before finally hearing the thunder. I guess the current induced by the EMP wasn't strong enough to fry anything but only to create interference in the wires.

I've also had experience with lightning affecting devices connected to the grid.
The first time this happened my TV got fried and after that I got a UPS.
Now that I have a UPS whenever a lightning strikes, my UPS just shuts off, protecting my devices, and I have to restart it. The UPS has a battery so the devices can keep running with it powered off.

Answer 4

EMP won't kill everything

It'll be totally hit-and-miss what gets nailed by EMP. A row of police cars, all same make/model, might all get their PCM (engine) computer killed except for one, while two more parked at a different angle might work fine except for power windows and radio. Boeing aircraft might be flyable (with the DirecTV and FMC not working) while 75% of Airbus aircraft are heavily damaged.

The power companies may find many of their Eaton controls took a hit but very few of their GE's.

A bunch of railroad lines, using older tech, may be totally unaffected, while the railroads are unable to control trains from their central dispatching centers and must go back to "old-school".

In case you catch what I'm implying, engineering mentality and build quality matters. I expect Boeing to be thinking hard about this, since a lot of their business is warplanes or military derivative of commercial airframes, like Air Force One and other VIPs, P-8 Poseidon, KC-767, etc. Eaton vs GE, no idea, it's just a made-up example.

You just don't know until you pop a nuke over one, and you're not going to do that, unless you take a serious disliking to the Test Ban Treaty.

Answer 5

An Electromagnetic Pulse is a brief magnetic field.

When electrically conductive materials (like wires) pass through a magnetic field it causes electricity to flow through the materials. This is how a generator creates electricity.

In an EMP attack the idea is to create a very strong magnetic field that causes electricity to flow in wires and circuitry. The attacker is hoping to cause enough power to flow to burn out components. It doesn't matter if the device is plugged in or not, though long wires like power lines can build up more of a power surge if they are lined up right with the magnetic field, which can send a surge through an outlet.

Magnetic fields travel at the speed of light, so from an observer's perspective it will appear to affect everything at the same time.

Devices won't go down at the same time though, it will depend on how well they handle the pulse. If they're magnetically shielded the pulse might not be strong enough to affect it, or the pulse won't create enough power flow in some devices to hurt it. A weaker pulse can just cause the device to crash or reset.

Answer 6

If what you have is a single, strong pulse, then the timing differences are going to be based on physical distance from the source and the propagation of the wave. Since the wave travels at pretty near the speed of light, for practical purposes it's instantaneous unless the distances involved are quite large. Depending on their sensitivity to EMPs and the strength of the pulse, devices might catch fire, suffer component damage, suffer transitory malfunctions, or be unaffected. Devices may be affected differently depending on whether they are running or not at the time the pulse happens.

If, on the other hand, you have a series of pulses, then all of the above applies with the addition that devices that suffer only minor damage or transitory effects may have those effects stack up over time to cause actual failures. In this case, the less shielded/more susceptible devices will likely fail first, followed by incremental failure of the tougher devices as the pulses continue.

How "tough" a device is can be roughly determined from three factors: How easy it is to damage the components, how much wire is oriented in such a way that it will pick up voltage as the EMP goes past, and what percentage of the EMP can reach the device (faraday cages and distance can make a big difference.)

Examples:

• The power grid is made of exceptionally tough components, but it has miles of wire that act like giant antennas and pick up massive amounts of induced current. One, extra-large solar flare in 1859 plus miles of wire resulted in some telegraph offices on half the globe literally catching fire. (And, apparently, some of the ones that survived being able to send messages for a while without the power supply being hooked up.)
• Your phone has much less wire and won't pick up nearly so much stray power, but its components are much more delicate and it doesn't take as much to damage them.
• Put your phone inside an unplugged microwave, and the faraday cage that normally keeps the microwaves in will, instead, keep the EMP out (unless it's really, really powerful, but past a certain point it becomes more death-ray than EMP)
• A series of light pulses could fry the phone without causing any significant trouble to the grid.
• One, big pulse tuned to probably something in the ELF frequency range could toast the power grid without the phone even noticing. (Unless it was plugged into said grid at the time, obviously.)

Answer 7

As the other noted, the EMP blast propagates from origin with the speed of light and its intensity decreases with a square of radius.

Also, some components are more vulnereable to the overload - microprocessor on the weak part, thick copper wire on the tough side.

The mode of failure matters.

1. Direct failure: The working part is the one that was EMPed. Such devices, no matter their size, comlexity or age, will fail almost immediately the shockwave hits them. Fine electronics will fail instantly, tougher ones will last fractures of a second.
2. Delayed failure: The EMPed part is a component of a more complex device. In this case the device will fail when the EMPed part is needed for the first time. Say there is really old car and EMP fried its alternator only. The car is working until it drains all the power from its battery.
3. Failure initiation: The EMP overloaded some parts and their lifetime was significantly reduce. Or the EMP killed some part that was backed up by different part which is now constantly overloaded. After some time the now-overloaded part fails. Say there is powerline divided into several parallel and insulated lines and because of the overload part of it was overheated, several wires were cut and welded together. In the wounded part the current is higher than in the untouched wires and is heating up. At some point it will break.

tl;dr: The EMP damage front is moving with a speed of light. Before and after, no damage is dealt. The effect of the damage, on the other hand, may be dealyed with the respect to what was damaged and how serious the damage was.

Answer 8

For the most part EMP would fry anything solid state whether plugged in or not. For complete EMP immunity go old school technology- Vacuum Tube.. they are completely immune.

EMP is seen as a secondary effect of all types of nuclear weapons, and was a problem in the very first nuclear weapons test in July, 1945. The official technical history for that first nuclear test in 1945 states, "We can understand the difficulty of transmitting signals during the explosion when we consider that the gamma rays from the reaction will ionize the air and other material within hundreds of yards. Fermi has calculated that the ensuing removal of the natural electrical potential gradient in the atmosphere will be equivalent to a large bolt of lightning striking that vicinity. . . . All signal lines were completely shielded, in many cases doubly shielded. In spite of this many records were lost because of spurious pickup at the time of the explosion that paralyzed the recording equipment."

As I stated on another page on this site, consider this Cold War era quotation from a widely-read and highly-respected publication: "The United States is frequently crossed by picture-taking Cosmos series satellites that orbit at a height of 200 to 450 kilometers above the earth. Just one of these satellites, carrying a few pounds of enriched plutonium instead of a camera, might touch off instant coast-to-coast pandemonium: the U.S. power grid going out, all electrical appliances without a separate power supply (televisions, radios, computers, traffic lights) shutting down, commercial telephone lines going dead, special military channels barely working or quickly going silent." -- from "Nuclear Pulse (III): Playing a Wild Card" by William J. Broad in Science magazine, pages 1248-1251, June 12, 1981.

The reason that EMP is getting more attention now is that the critical infrastructure that sustains our lives is becoming increasingly sensitive to the effects of EMP. This is happening because electronics equipment is becoming more sensitive to EMP all the time, and critical infrastructures are becoming increasingly dependent upon electronics.

The next myth is what I call the either-or myth with regard to electromagnetic shielding. The myth is the belief that either an electronic device is resistant to EMP or that it must be enclosed in a military-grade faraday cage. This myth is so bizarre that I heard it for years before I realized that many people actually believe it. Unfortunately, many of the "professionals" working in the EMP field seem to be responsible for spreading this myth through careless comments.

Of course, it is always better to have as much shielding protection as possible, and the means to obtain a high level of electromagnetic shielding are well known. The problem is that a maximally effective shield is often simply neither affordable nor practical.

If a device has a damage threshold of an EMP field of 20,000 volts per meter, then reducing the electromagnetic field by a factor of 3 or 4 will be enough to protect it from known weapons, and shielding it by a factor of 10 will protect it from the super-EMP weapons that are believed by many to exist. A very efficient 80 db. faraday cage would reduce the EMP by a factor of 10,000. In other words, it would reduce a 20,000 volts per meter EMP field to 2 volts per meter. This high level of shielding is necessary for some applications, but not for the average consumer (except for the most critical electronics such as an emergency radio receiver). For many applications, an imperfect shield is quite helpful and may be all that is necessary. (In some cases, though, such as an expensive solar panel system, it makes sense to try to get as close as possible to military grade protection since a functioning solar power system may determine whether you have electricity or not.)

and:

When EMP (or lightning) hits the ground, the currents tend to spread out horizontally. These ground currents can do great damage, especially to underground cables of all kinds. Metal conduits are of little help, and may actually make the situation worse by providing a path for underground currents which can, in turn, induce large voltage spikes on the underground lines inside of the conduits. A large amount of damage has actually occurred due to these underground currents, due to both lightning strikes and nuclear EMP. This is one reason that so much of the information on the internet on grounding and on underground cabling is pure nonsense. Large variations in soil conductivity makes the ground current situation even more complex.

Source: Jerry Emanuelson, B.S.E.E. Futurescience, LLC

Answer 9

Most of the answers dance around the real issue, I think. If I break "a component" of a computer, when will the computer stop working? Well, obviously it might stop immediately, it might stop after a couple of minutes, or it might not ever fail. It depends on the component, right? So, if instead of me breaking it, it "fries" due to EMP, do you think the possible range of behaviors are any different? As said, the currents created in conductors due to an EMP are immediate and quickly over. The damage may be so severe that the circuit is then shorted or it may have damaged the circuit so that it will soon fail or the damage may be marginal so that, for example, instead of a mean time between failures of 100,000 duty cycles, it's been reduced to 1,000. Or perhaps its been damaged so that the next time it sends current to a particular device, it shorts. Keep in mind that anything which absorbs the EMP (which has to happen to do damage) will also (to some extent) shield other devices in its "shadow". Perhaps you've seen the photographs of Hiroshima, where people's silhouettes have been burned onto walls and roadways? Those same pictures show some buildings still standing when most everything else was flattened. My point here is it's neither all-or-nothing, nor is it gradual. To some extent it will be random (depending on what the device is doing at the instant it happens and where exactly it is (as well as what is around it).) Consider it to be a statistical thing. Let's say cell phones. There will be some distance inside of which everything will surely fry. Beyond that there will be distances with decreasing probability of failure (average failure rate will decrease with distance as 1/r²) until at some distance there's a low probability of damage. A very important qualification: Most nuclear weapon EMP scenarios include the interaction between the initial EMP and the Earth's ionosphere which can distribute the EMP over a very wide area. In that scenario, the damage would be literally hit and miss and hit and miss...

Answer 10

Capacitors could soften the blow of an EMP strike. They store extra charge, devices with lots of strong/solid caps might survive an EMP blast. But they might fail tomorrow due to wear of rapid and high voltage charge. Microcontrollers, if detached from any other circuitry, will probably survive due to the small area they have. Also if the frequency is kind of low, very thin lines in the microcontrollers may not get charged at all (not 100% sure about this part). Due to these conditions a device can fail tomorrow after surviving an EMP strike. But it should be relatively easy to replace capacitors to get it to working condition.