Initially Published 23 April, 2018
EMP strike/Nuclear detonation
I will cover an electromagnetic pulse device and conventional nuclear weapon detonation separately as they are actually distinct subjects with very different effects. Both EMP and conventional nuclear weapons are nuclear devices however.
Nukes are not easy to build. There is a reason that only eight countries are declared nuclear powers: The US, Russia, China, UK, France, Pakistan, India, & North Korea with Israel and South Africa being suspected but undeclared nuclear powers while Iran is being accused of attempting to develop them. Of those powers, only the US, developed nukes independently. It has been shown that Russia, China, Pakistan, India, and North Korea gained knowledge of nuclear weapon design through espionage while the UK, France, and possibly Israel were given initial designs by the US. What follows is of necessity a very simplistic description and explanation. Number one, I am not a nuclear weapons tech and number two, even if I was I would not put the plans up on the internet. Everything below is available from an open source. A great reference is the Federation of American Scientists (FAS) website on the history of nuclear weapons.
A nuclear device is a very complex weapon to build. It is easy to look at a diagram of Fat Man or Little Boy and say “I could build that” but in fact, you can’t. The tolerances for critical mass are very fine and the explosives that initiate the reaction are very powerful and must be detonated in a very precise sequence or the bomb fizzles because critical mass is not reached. Two types of nukes exist, fission and fusion. A fission bomb gets its explosive force from the energy released when atoms are split and fusion bombs get their explosive force from the energy released when two light atoms are fused to create a heavier atom.
There are essentially two designs for a fission nuke, both developed in World War II and essentially only tweaked since then. Both require fissionable material, typically enriched uranium; enriched because it is processed to separate the richer isotopes. You cannot just dig up some uranium and build a bomb that is why everybody is so concerned about the Iranian centrifuge cascades. The other element used to build a nuke is plutonium which is naturally occurring but is so rare that the plutonium used for nukes is most commonly separated from the nuclear waste generated by what are known as breeder reactors. The two bomb designs can be simplistically described as the gun-device and implosion.
A fusion bomb is one in which a fission device is used as a booster to induce some lighter element, typically a hydrogen isotope such as deuterium or tritium. This elemental hydrogen is compressed to the point where it fuses into helium thus releasing exponentially more energy than a fission device. The first fusion weapon was designed and deployed by the United States and tested in 1952 at Eniwetok Atoll in the Pacific Ocean. The first test of a deliverable fusion design was the Castle Bravo test at Bikini Atoll in 1954. The Bravo test was also the highest yield weapon ever tested (15 MT) by the US although that was a mistake as the yield was about 2 ½ times what they expected. The largest fusion weapon ever tested was the Tsar Bomba tested by the USSR in 1961 with an estimated yield of 50 MT.
There has been much speculation about the use of an EMP device in the past few years and there is also a whole lot of misinformation about exactly how an EMP is generated and what its effects would be. To properly understand what an EMP can do we must understand what an EMP is. A simple explanation is provided by the FAS in their section on EMP. It is:
“A high-altitude nuclear detonation produces an immediate flux of gamma rays from the nuclear reactions within the device. These photons in turn produce high energy free electrons by Compton scattering at altitudes between (roughly) 20 and 40 km. These electrons are then trapped in the Earth’s magnetic field, giving rise to an oscillating electric current. This current is asymmetric in general and gives rise to a rapidly rising radiated electromagnetic field called an electromagnetic pulse (EMP). Because the electrons are trapped essentially simultaneously, a very large electromagnetic source radiates coherently.
The pulse can easily span continent-sized areas, and this radiation can affect systems on land, sea, and air. The first recorded EMP incident accompanied a high-altitude nuclear test over the South Pacific and resulted in power system failures as far away as Hawaii. A large device detonated at 400-500 km over Kansas would affect all of CONUS. The signal from such an event extends to the visual horizon as seen from the burst point.
The EMP produced by the Compton electrons typically lasts for about 1 microsecond, and this signal is called HEMP. In addition to the prompt EMP, scattered gammas and inelastic gammas produced by weapon neutrons produce an intermediate time signal from about 1 microsecond to 1 second. The energetic debris entering the ionosphere produces ionization and heating of the E-region. In turn, this causes the geomagnetic field to heave, producing a late-time magnetohydrodynamic (MHD) EMP generally called a heave signal.”
The physics of an EMP are important and difficult to grasp. To break it down even more, essentially what an EMP does is to induce a very brief, very high-intensity electric current surge in conductive metal. The surge strength depends on a variety of factors but if the EMP is close enough and thus strong enough it will disable or burn out pretty much everything electrical. This is particularly bad in the case of solid-state or transistorized electronics because solid-state electronic cannot be repaired they must be replaced. Traditional pre-transistor electronics fare better than solid-state but are still affected, they are just easier to repair. Additionally, it is possible to induce local EMP effects with conventional weapons. Generating an EMP does not require nukes, just very powerful and wide area EMP effects do.
There are a few ways to defend against EMP and the most effective are shielding and grounding. Shielding is expensive and not completely effective. It is easier to raise the EMP level than it is to shield against them, this is especially so because EMP effects are logarithmic and shielding is not. Grounding is effective but makes equipment immobile. It is conceivable that a powerful enough EMP burst could weld a hammer to an anvil if neither were grounded.
In the case of an actual EMP event you can pretty much expect that just about everything that uses electricity will be useless and lots of conductive objects that are not electronics will be affected to a greater or lesser degree as well. Think about it somewhat like this. If an EMP event were to happen today, the US would instantly be plunged into the late 19th century in terms of technology without all the infrastructure that we have replaced over the last century. Some electronics would survive but the vast majority would not. Just about every car made since about 1965 would not run and could not be made to run without completely replacing the electronics. Electronics which could not be replaced because the factories that make them are crippled and further, the digital memory that stores the designs was probably destroyed in the EMP as well.
That is what an EMP would do. A conventional nuke does something different entirely. A conventional nuke generates an EMP but that is not what causes the most destruction. A conventional nuke destroys things through radiation, thermal, and blast effects. Thermal and blast are pretty bad but it is the radiation that kills people. The radius of effect for thermal and blast from a nuclear weapon are constrained by the size of the weapon, the distance from the explosion, and the intervening terrain. Radiation is also attenuated by distance but its effects are not limited to blast radius as fallout travels with the wind and can kill people hundreds, even thousands of miles away from the blast.
Let’s talk thermal effects first. Thermal effects come from two sources, the heat generated by the nuclear explosion itself and also heat generated by the blast wave as it shock heats the atmosphere. Thermal effects are actually secondary because if you are close enough to get killed by the heat the blast wave is going to catch you and kill you even if the heat doesn’t. The biggest thermal danger from a nuke explosion are the secondary fires started by destroyed infrastructure. An exception is Mt yield weapons in which the thermal radius is much larger than the blast radius and thus can start fires that the blast wave does not immediately snuff out as it destroys the structures and people that are on fire.
Blast effects are what cause the most immediate structural damage from a nuclear detonation. This blast is caused by the overpressure generated as the air is superheated by the detonation itself and propagates outward. The blast actually has two phases the initial outward blast phase followed by a reverse wave as the blast wave recedes and air rushes back towards ground zero as the high pressure bubble created by the detonation collapses. The blast radius attenuates with distance from ground zero. But essentially anything trapped inside the blast radius will be either destroyed or so damaged as to be unusable. Blast is not the killer though, the real killer from a nuke detonation is radioactive fallout.
Video of a nuclear test on typical structures (probably the MET test from 15 April, 1955). The blast itself is at 10:24
Radiation is the big killer from a nuke and its effects are both fast and slow depending on where you are at in relation to the blast and what your level of radioactive exposure is both immediately and also long-term. The radiation produced by a nuke comes in two waves, short-term and long-term. Short-term radiation is the initial pulse of ionizing radiation produced by the blast itself and can kill you fast or slow depending on the dose you receive. Long-term or residual radiation comes mainly from fallout. Fallout is created in two ways, inert material combining with irradiated fission byproducts and neutron induced irradiation. All this fallout will have different half-lives depending on which isotope it is. Some will have half-lives of 1 second or less while other isotopes have half-lives of years, decades, and even millennia. I am not going to attempt to explain the physics involved in how material gets radiated suffice it to say that for my purposes it does. More info on fallout production and creation can be found here at: off the grid news.
Fallout is essentially the material from the ground or water tossed into the air and irradiated by the byproducts of the nuclear detonation. Thus the higher a nuclear detonation occurs the lower the fallout. The lower a detonation the more fallout until it reaches a point where it is buried deep enough that the earth itself tamps and traps the explosion releasing nothing. Most terrorist bombs would probably detonate at or very near ground level and thus produce lots and lots of fallout. Most state delivered weapons would probably detonate anywhere from 500-1,000 feet above the ground to maximize thermal and blast effects while still producing significant fallout. High-altitude EMP detonations produce practically no fallout because the blast wave never reaches the ground.
Either a pure EMP strike or a nuclear strike would be devastating. The EMP would have wider effects but a nuke strike on a major city such as New York, London, Berlin, or Tokyo would not only kill tens of thousands immediately but the repercussions would reverberate around the world economy and could start a monetary collapse. Luckily, nukes are hard to build and even harder to get ahold of. That does not mean they are not available, just that they are difficult to get and it is well known that several terrorist organizations are actively seeking to acquire one. Let us not forget such unstable regimes as North Korea and Pakistan who already have them. Reportedly, several nuclear weapons went missing during the collapse of the Soviet Union in the 90s and have never been accounted for although I do not know for certain that this is true.
Now that we know what the different nuke types are and what they do, how likely is an EMP or nuke detonation. I actually peg this as fairly unlikely. An EMP would be most likely state delivered because of the difficulty in a non-state actor both acquiring and delivering a weapon to high altitude and thus achieving significant EMP effects. While unlikely, such an attack is not impossible. I can envision several scenarios in which a state actor might use nukes, especially given the Obama aadministration’s apparent rush to get rid of the US nuclear deterrent force. While it may be flawed, Mutual Assured Destruction is a strategy that has worked. Nobody will attack us if they are guaranteed to be destroyed immediately thereafter.
The real worry is a terrorist attack with a nuclear device. I say worry because I don’t think that terrorists would hesitate to use a nuke if they get their hands on one. They will also try to hit the most unlikely but highest value target they can find. I simply don’t see terrorists nuking a large city such as New York, London, Paris, Los Angeles, or Washington D.C. Instead I think they would hit a mid-sized city that no one thinks of as a target. Such cities include Nuremberg Germany; Reims, France; Manchester, England; Omaha, Nebraska; or Tulsa, Oklahoma. These are cities that are large but do not pop up as expected terrorist targets and thus I don’t think that national governments are guarding these as closely. Everybody thinks New York or London when they think of terrorist strikes. But the destruction of a city of 400,000-500,000 people would be devastating as well, and they are relatively soft-targets compared to the huge cities. The saving grace is the difficulty in terrorist acquisition of a nuke or nukes.
Given that I think the likelihood of state-sponsored attack is low here are my probabilities.
- Short-term-the next 5 years – State-sponsored-roughly .05% chance; terrorist-roughly 2% chance
- Medium-term-in 5-15 years – State-sponsored-roughly .05% chance; terrorist-roughly 10% chance
- Long-term-more than 15 years from now – State-sponsored-roughly 5% chance; terrorist-roughly 50% chance
I think that eventually terrorists will get their hands on a nuke and when they do they will use it or at least attempt to use it. Of course terrorist use of a nuke would be the dumbest thing they could do as the retaliation would be swift and devastating to not only the terrorists but to the population that hides and supports them.