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Newt is not the only one worrying about EMP

here is another item from Janes:

UK urged to prepare for EMP threat.
The UK House of Commons Defence Committee (HCDC) has warned of the potential danger posed by a deliberate electro-magnetic pulse (EMP) attack, pointing – in a report published on 22 February – to Iran and non-state actors as particular threats. Citing evidence given by the US EMP Commission, the HCDC stated that “Iran, in particular, is reported to have been conducting what appear to be missile tests to simulate a nuclear EMP strike”

It sort of makes me glad that I and my own computers are in an out of the cross-hairs corner of the world…

28 comments to Newt is not the only one worrying about EMP

  • Eddie Willers

    Hup! Time to dust off those thermionic vacuum tubes (aka ‘valves’) for 100% EMP resistance.

    Come to think of it, isn’t China the only valve manufacturer these days?

  • Laird

    Dale, you may think you’re “out of the crosshairs”, but a nuclear device detonated about 100 miles over the center of the US would fry just about every electronic device in the country, to say nothing of the grid. If you haven’t read Forstchen’s One Second After (a novel about the likely effects of such an attack), I recommend it to you.

  • Dale Amon

    Well, actually, I am somewhere outside Belfast in the land between country and suburbia, ie a half mile walk to a mall and I can see farms on a hill in the distance. I suspect the Iranian threat to London is not a missile (yet) but something in an airccraft or even just in the heart of ‘The City’ at ground level.

  • Laird

    Apologies, Dale, I thought you were still in the US (hiding out in Montana or some such!). The EMP pulse from a ground-level nuclear device in London probably wouldn’t affect you, but an atmospheric one likely would.

  • stephan

    A little confused here. If these are the devastating effects of an atmospheric nuclear blast, then why did none of the major U.S, Russian, French, etc atmospheric and space based nuclear tests not cause such effects over wide swathes of the world. No sarcasm here, I honestly would like to know what prevented that in test cases?

    I mean, I know most of them were tested over empty ocean, etc, but wouldn’t some of the effects have spilled over to Civilized land? Especially if just one weapon can supposedly wipe out the enormous surface area of the entire Continental U.S grid?

  • stephan

    For example, the 50 megaton Tsar Bomba test was an atmospheric explosion that exploded within only a few hundred miles of cities, town and electrical grids. Yet it, as far as I know, didn’t cause major blackouts.

  • Dale Amon

    The airburst tests were all at altitudes required to maximise the triple point effect for the particular bomb size. air bursts are used because the reflect shock wave merges with the original shock wave to form a wall of double the overpressure that sweeps along at ground level and maximises the blast damage.

    EMP effects are maximised by exploding at very high altitudes, so high in fact that there is no blast damage on the ground.

    There was such a test series at Johnston Island in the early 60’s and it took out electrical and electronic devices as far away as New Zealand and Hawaii.

    This was not much advertised at the time…

  • Ben

    The system was more rugged back then and they did still experience problems.

    http://en.wikipedia.org/wiki/Electromagnetic_pulse has a lot of nifty stuff with the nuclear testing history of EMP’s.

  • Ben


    The relatively small magnitude of the Starfish Prime EMP in Hawaii (about 5600 volts/metre) and the relatively small amount of damage done (for example, only 1 to 3 percent of streetlights extinguished)[10] led some scientists to believe, in the early days of EMP research, that the problem might not be as significant as was later realized. Newer calculations[9] showed that if the Starfish Prime warhead had been detonated over the northern continental United States, the magnitude of the EMP would have been much larger (22 to 30 kilovolts/metre) because of the greater strength of the Earth’s magnetic field over the United States, as well as the different orientation of the Earth’s magnetic field at high latitudes. These new calculations, combined with the accelerating reliance on EMP-sensitive microelectronics, heightened awareness that the EMP threat could be a very significant problem.

  • Dale Amon

    I might add that you can build a non nuclear EMP bomb in your garage, assuming that your garage has the requisite high explosives laying about.

    You need a high strength magnetic field and the explosion needs to compress and direct that magnetic field in a pulse in the direction of the shaped charge (if I remember the details correctly).

  • Ken Mitchell

    Why didn’t the old-time nuclear explosions cause a massive EMP problem? Because electronics back then were over-engineered by a LARGE factor. Today, things are designed to such close tolerances that even a little electronic overstress can cause major problems. Solar flares – and not even BIG solar flares – cause problems.

    One of the problems caused by computers is our arrogance in saying “this only needs to be THIS tough”, and then designing gadgets to exactly that spec. This saves pennies immediately, but might cost megabucks in the long run.

  • Micha Elyi

    Someday, our Samizdata.Net hosts will get the tabbing sequence on their pages worked out…

    Can this EMP vulnerability be removed by individual efforts via the marketplace or are libertarians defeated and a big government programme is required?

  • iougt0t8o89yt

    An emp attack may or may not happen. A large solar flare that will destroy the grid (but not electronics) is statistically certian to happen. We need to stockpile transformers to restore the grid and we are not doing that. Transformers take along time to make and there is little capacity to make them. Imagine no electricity for a year. Mass starvation. But it gets worser… The problem is that nuclear reactors need power to run the cooling ponds or radioactive materialis will start burning and leaking into the atmosphere. A nuclear catistrophe is currently designed into the earths future:


  • The non-nuclear version is called an Explosively Pumped Flux Compression Generator. Probably a bit beyond the average garage workshop.

    You can protect most things if you put them in Faraday Cages. But they can’t be plugged into an electrical outlet. The pulse will travel along the power grid. There are things you can do if you have working generators, but in general you just protect things for use after the EMP is gone.

    So are you going to run out and buy a spare PC? and a generator to run it? There won’t be a net to connect to for a long time. And the fact that every refrigerator will stop working will be a little higher priority. (Most cities contain about 3 days worth of food – a good chunk of which is perishable.) You might want to protect that hand-crank radio. But if you are worried about EMP, even that probably isn’t the first thing you should be doing.

  • SChaser

    A few facts…

    Nuclear EMP from an exo-atmospheric burst would have catastrophic effects for at least three reasons, only two of which apply to a solar coronal mass ejection (CME) event:

    1) A very high frequency (1ns rise time) electromagnetic pulse of extreme amplitude (discussed above) would be devastating to modern microelectronics. The >1GHz frequencies would get through a lot of shielding (such as a car’s metal structure).

    2) A huge, slower magnetic field pulse would mimic a very big CME event, taking out electrical (as opposed to electronic) systems. If detonated over the north central US, it would take out most of the high voltage transformers in the US power grid (needless to say, smaller Britain/Ireland would be devastated if targetted). New transformers would have to be manufactured as replacements before the grid would come back up.

    3) The large beta radiation flux (i.e. high energy electrons) would go into orbit in the earth’s magnetic field, irradiating everything in space that passed through the bands, for months after the event. This would destroy, either instantly or over a few hours to days to weeks, almost all satellites in orbit except those very high up. It would also kill, within an hour, all astronauts in low earth orbit. A CME would have similar, although lesser, effect, with different particles (protons, I believe).

    One Second After is a good book, but exaggerates the effect. Not every microelectronic device would be fried. Not every modern (microelectronic controlled) vehicle would be disabled. Not every radio or telephone would die. Many military systems are hardened against these effects and would not be affected.

    In addition, satellites and astronauts directly exposed to the explosion would suffer instantaneous damage, even (I think) at geosynchronous altitudes.

    Even a small fission nuke can cause these effects.

  • Man Mountain Molehill

    Fortchen might have overstated the case. The analysis I saw claimed 3 high altitude bursts of fairly large (hydrogen) weapons would take out 90% of the continental US power grid.

    Other sources give the field strength at ground level at 100kV/meter. This is huge, but not all of it will get into typical electronics. A computer already has about 30 to 40 dB of shielding, so even if the full 100kV pulse gets coupled to the outside of the case (unlikely, given effective antenna efficiency), the internal amplitude will be reduced to 1 to 3kV. Computers are already designed to withstand electrostatic discharge in this range, so maybe no permanent damage. (ESD and EMP have roughly similar time constants)

    Mission critical military electronics is designed to withstand EMP. See the B1 bomber spec, among others.

  • wolfwalker

    One other thought on “Why didn’t the old-time nuclear explosions cause a massive EMP problem?”

    The last airburst nuclear tests were in the mid-1960s, right? At that time, virtually all electronic systems and gadgets were vacuum-tube-based. The great transistor revolution didn’t happen until a few years later. Aren’t vacuum tubes MUCH more resistant to EMP than transistor circuits?

    And a question: what would be the effect of an EMP burst on light-based circuits such as fiber optics? What would be the effect on flash memory?

  • Alb

    Will we have the capacity to obliterate Tehran if Iran attacks us? Do we have the capacity to tell our nuke subs to go into action even if London burns?

    If we can get our nukes off to wipe out the little rat who runs Iran, that’s the only thing that matters in the end. Thus we need to make them aware of what war will do to their bid to be the ruler of the muslim world.

  • cbinflux

    Trouble is, the ‘little rat’ is a 12th Imam believing lunatic.

  • Look, Forstchen’s book is nonsense. He didn’t do his research. I gave a scratch calculation a couple of years ago, and other criticisms of his approach to the EMP threat in two blog posts.


  • SChaser

    Not only are higher frequencies easier to block, but 1 GHz is not that great. An aircraft weather radar tends to work at around 9 GHz, and while they should be turned off after landing they are occasionally left on. The power density from these close by is far higher than the likely average power from an EMP from even a large weapon over the USA, yet they don’t actually damage nearby electronics, except perhaps the most vulnerable.

    Likewise any lower-frequency pulse would have to have far more energy than any likely source to do the kind of damage you suggest.

    Forstchen’s work is garbage, as I explain in the articles linked above.

  • Ben

    Since it was an entertaining novel about a worst case scenario I don’t think it was “garbage” any more than any other historical fiction based novel. A book about some spotty electrical grids while people curse at brownouts but generally behave themselves would be kind of lame.

  • Laird

    Doubting Rich, nowhere do you give your qualifications to give a “scratch calculation” of the effects of an EMP pulse, and there are engineers and scientists hanging around this site who are far more qualified than I to respond to your criticism, but in their absence I’ll take a stab at it. I think you’re completely wrong. (In other words, I am doubting you, Rich!)

    First of all, you seem to be ignoring the amplifying effect of the earth’s magnetic field, which was described fairly well in the Wikipedia article Ben linked about. It’s not simply the gamma radiation initially emitted by the nuclear device which is so destructive, it’s the cascading and cumulative effect of the three separate phases of the pulse.

    You also seem to make the assumption that the EMP pulse will affect structures on the planet’s surface in some qross physical way (c.f. your comment “I am not sure how the good professor ever thought that something that fried all electronics, even the shielded ones in a car or an electrical substation 1500 miles away, wouldn’t hurt at least some of the people 300 miles below, who were receiving 25 times the power.”). But it isn’t that the pulse “fries” all electronics, only the extremely sensitive ones upon which nearly all of our technology now relies. We know it doesn’t much effect vacuum tubes or older, more robust, forms of technology. Why do you think it would be felt by a human simply because it destroyed a transistor? An impact which squashed a gnat wouldn’t even be felt by a human. Besides, my understanding is that gamma radiation is imperceptible, but nonetheless fatal.

    My opinion isn’t worth much; I’m not a scientist or engineer. But I think the opinion of the US EMP Commission is worthy of some respect. There are some highly qualified people on that commission, and I’m sure that their staff was equally capable. Their 2004 Report was full of phrases such as “catastrophic impact”, “unprecedented cascading failures of our major infrastructures”, and “damage that could reach large-scale, long-term levels.” Their more detailed follow-up report in 2008 was equally chilling. Frankly, I give their analysis and conclusions much more credence than your “scratch calculations”.

  • anona

    The item that many people are missing is that there is only so much energy in an emp type weapon. No matter the size they only have a specific amount of power.
    Every increase of the area affected reduces the amount of energy recieved per unit of area by the inverse of square of the change. Example: 100 units of energy over 1 square foot becomes 25 units per square foot when the size (length and width) is doubled (now 4 square feet). Add to the equation the effects of distance; since energy doesn’t ‘free ride’ and atmosphere (density and contamination such as humidity and/or dust, provide effective damping effects.
    As for transmission through wire; a 100 mile run of power line can result in a 50% loss in power at the other end of the line from transmission loss (internal resistance in the lines themselves, plus coupling and switching losses). Also not mentioned is the wavelenght of the pulse. If it is not matched by the lenght of wire it’s on, it will self attenuate as heat due to the fact that there is no physical transmitter (in this case) to reflect back into. A mismatch in wavelenght to antenna lenght results in no/poor transmission and power reflection back to the transmitter or transformation to heat.
    As to the results of a “commision”; be very wary of rent-seeking. It’s very easy to have a comission “find’ the problem the sponsor desires, and then having “found” the problem; seek funds to come up with numerous ‘studies” and white papers to find a “solution’ to the stated problem

  • SChaser

    Doubting Rich writes “Not only are higher frequencies easier to block, but 1 GHz is not that great. An aircraft weather radar tends to work at around 9 GHz, and while they should be turned off after landing they are occasionally left on. The power density from these close by is far higher than the likely average power from an EMP from even a large weapon over the USA, yet they don’t actually damage nearby electronics, except perhaps the most vulnerable.”

    Four problems with your analysis:
    1) Higher frequencies can get through smaller gaps in shields than lower frequencies. A lot of equipment is shielded for lower frequencies. Aircraft weather radar operates at quite low energy ( US government report(Link) on the phenomenon. It does the calculations you want and arrives at far more alarming (but correct) conclusions than you do. It explains why.

    BTW, the US govt (at Sandia Labs in Albuquerque) conducts EMP testing of all sorts of things using accurately simulated EMP. They actually know, not only from physics, but also from experiment, that EMP is an enormous problem.

    “Forstchen’s work is garbage, as I explain in the articles linked above”

    Forstchen is writing dramatic fiction. Since he is not well trained in the physical sciences, he makes the sorts of mistakes that you ridicule, which are irrelevant to the effects he describes, since he took them from people skilled in the field (see report above). He is mostly correct – he hypothesizes two or three HEMP bursts over the US (I think two, not sure) along with attacks on countries that might come to the aid of the US or provide replacement parts. Forster exaggerates the effect (100% disabling of all micro-electronics based equipment, primarily). But, a significant EMP attack against the US would kill a lot of people, and the death toll could reach into the millions, as our just-in-time supply chain for food, fuel and pharmaceuticals could be disabled for (potentially) months.

    The power grid problems are also very significant, because extremely large custom-made pieces of equipment (such as transformers and generators) are destroyed. These cannot be replaced for quite a few months, especially if a lot are lost at once. Major portions of the grid will be out for months.

  • SChaser

    Oops.. something got garbled. For sure, read the USG report, and keep in mind that a lot of experts on this (including a PhD relative of mine) have worked on this problem and done lots of experiments, and their experience went into that report.

    Anyway, back to the issues:

    2 – Bypass capacitors in filters, at higher frequencies move towards inductive, reducing or eliminating their effect.

    3 – Series inductors in filters can be bypassed by higher energy capacitively coupling around it or radiating around it.

    4 – Earth’s magnetic field effect on focusing the effect

    Regarding aircraft-borne radar – they are quite low power. A search radar in the maritime patrol aircraft I once crewed had only about 1KW of average energy, and about 160kW of peak power – in other words, it was almost exactly a microwave oven, except it sent the energy out. They don’t operate a couple of feet from consumer and industrial electronics either – they, unlike the EMP effect, do suffer from 1 over r-squared.

    If your calculations used the 1/r-squared law, they are wrong. The electric field pulse is generated over a wide area of the upper atmosphere, putting the ground beneath it in the near-field, resulting in effectively zero loss with distance.

  • SChaser

    Someone asked why no big EMP problem with atmospheric tests….

    EMP does result from atmospheric tests, but it is of much lower amplitude.

    The kind of attack we are discussing is HEMP (High altitude burst Electromagnetic Pulse). This has very different physics – see Wikipedia or the government pdf report.

    Military equipment designed to fight on a nuclear battlefield is shielded against intra-atmosphere EMP. SO are other facilities such as some critical infrastructure – I’ve seen the EMP vault at our local Emergency Operations Center – it is underground, made of thick steel, and has copper fingers all around the vault door to help with shielding.

  • AmandaK

    There is some really great conversation going on here about EMP. Has anyone ever heard about EMPact America? They have a radio show every Wednesday and this Wednesday a man named Dr. George Baker is going to be on their show at Noon Eastern Time to talk about this topic. It should be very informational and interesting to listen to. Here’s the link if you’d like to take a listen: http://empactradio.org/archives/episode91-dr-george-baker/