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SurvivalBlog reader Joe. K. mentioned in a recent e-mail that one of my heroes, Dr. Jack Wheeler, posted a dismissive article about the EMP threat, back in June. (It was posted at Wheeler’s excellent “To The Point News” subscription website: http://www.tothepointnews.com/  )  Wheeler is a fascinating fellow. Back in the 1960s, he swam the Hellespont, climbed the Matterhorn, and went tiger hunting as a civilian in Vietnam during the Vietnam War. All of this before he was 25 years old. He also spent a lot of time living with head hunters in the Amazon jungle. But I digress…  Wheeler’s article, titled “The EMP Annoyance” soft-pedals the EMP threat. Although Wheeler is usually spot-on in his economic analyses, I think that he missed the mark in this case  His main premise is based on the fact that the Starfish Prime EMP high altitude hydrogen bomb test at Johnston Atoll in 1962 caused only transitory power grid and radio disruption 700 miles away in Hawaii. But what he forgets is that those were the days of simpler electronics–when much of America was still primarily using electron tubes and just a few transistors. Modern microcircuits, with their incredibly small gate dimensions are at an order of magnitude greater risk to EMP.

Wheeler is correct in his assertion that terrorists will probably not have access to hydrogen (fusion) bombs–just traditional fission bombs.  Nor will they have access to any means of detonating a nuke at extremely high altitude to maximize its line of sight (LOS) “footprint” area of effectiveness. But nation states like China have both.

Several SurvivalBlog readers have written to ask me about the greatest potential effective range of an EMP-optimized nuclear detonation. The answer is both easy and impossible to determine. Let me explain. First, the easy part. The basic LOS footprint range calculation is really simple. It is essentially the same as the calculation that is used to determine the maximum effective range for a VHF or UHF radio onboard an aircraft. Referring back to one of my unclassified notebooks from my Electronic Warfare (5M) course at Fort Huachuca, I find: Assuming level terrain, the maximum potential radius of LOS in nautical miles (nmi) = square root of the emitter’s altitude (in feet) x 1.056. Hence, that would be 149.3 nmi at 20,000 feet ASL, or 191.8 nmi at 33,000 feet ASL. (A typical jet or C-130’s service ceiling. SurvivalBlog reader “Flighter” mentioned: “…some of the larger business jets such as the Airbus ACJ, Gulfstream, Challenger, and Citation are certificated to fly at or above 41,000 feet. The Sino Swearingen SJ30, is perhaps the highest flyer with a certificated ceiling of 49,000 feet. A dangerous parabolic flight profile could with supplemental oxygen for the flight crew perhaps push apogee to 75,000 feet in a few aircraft models. (Hey, it would be a suicidal flight anyway.) That is probably the highest altitude that could be expected for a terrorist to touch off a nuke–at least in the near future. That would equate to a footprint with a 280 mile radius.

Now on to the part that is impossible to predict: long range linear coupling.  Because telephone lines, power lines, and railroad tracks will act as giant antennas for EMP, the EMP waveforms will be coupled through those structures for many, many miles beyond line of sight (BLOS). Just how many miles BLOS is not yet known. I believe that if it were not for the advent of the Atmospheric Test Ban Treaty and the Outer Space Test Ban Treaty, the DOD and AEC would have had the opportunity to conduct far more extensive tests to further characterize the panoply of potential EMP effects. But those test bans have kept us in the dark. In the absence of practical data, there is a lot guesswork, even among “applied physics” specialist nuclear weapons scientists. We may not know the full extent of the EMP risk until after we see that bright flash on the horizon.

For planning purposes, you can probably safely assume that if you are living more than 280 miles from a major city, then your vehicle electronics will be safe from a terrorist  nuke’s EMP. (Since you will be BLOS to the EMP footprint of a nuke that is set off below 75,000 feet ASL.) Your home electronics, however, anywhere in CONUS might be at risk due to long range linear coupling–that is if your house is on grid power. This, BTW, is one more good reason for you to set up your own off-grid self sufficient power system.

Jim:
See: http://neo.jpl.nasa.gov/ A sub part of this site was mentioned in the article that you posted Friday, but I’d recommend posting this main page of the site.

Let’s look at two more things. 1.) NASA just recently proved they can hit an asteroid with a satellite. Doesn’t that strike you as at least a little odd they would spend the money to do that just for researching the impact? 2.) Now, did you also notice that the military is working on a new type of “bunker busting” nuclear penetration bomb that survives for 100 milliseconds, burrowing into the ground through concrete and steel, and then goes off? Put the two together and you have a far more realistic approach to busting an approaching asteroid than was portrayed in the movies Deep Impact or Armageddon. – Rourke

Mr. Rawles,
I have been enjoying reading your excellent blog. Some thoughts for you on the post from Rourke and the troubles presented by EMP.

Let’s say I build a Faraday cage in my basement, and drive a ground rod just for it. Now let’s say that my home is grounded–most are. If the physical arrangement of my cage is such that I can touch the cage and something else metallic in my basement, such as a washer, dryer, freezer or some such because there are now two separate ground pathways there can be a voltage difference between the two and since I’m touching both I become the conductor for any voltage differences. Does that make sense?

Grounding systems for some large installations can be huge and very complex, but they are all, electrically one system so no voltage differences can exist.
Hope this helps. – Catshooter

Electromagnetic pulse (EMP), is now a commonly know effect thanks to movies showcasing the nuclear version such as Goldeneye (James Bond) and the remake of Ocean’s 11 which shows a non-nuclear version. The real question for survivalists is: what is EMP actually going to do to my valued equipment and what can I realistically do about it? Let’s start with lightening since it is very well understood. We know that lightening will tend to seek out the highest conductive point that is grounded and then seek to flow through a conductor, often back and forth a few times, until the electrical charge imbalance between the cloud and ground is neutralized. To protect buildings, lighting rods have been erected on them historically to channel the electrical current around the building and into the ground.
With EMP the concept of channeling the energy away from what we wish to protect is somewhat similar. EMP is a pulse of energy, and travels through everything. The idea is to shield something from it my placing it in (surrounding it with) a conductive (metal) box that is then grounded (preferably into the earth). The conductive box thus channels a large amount of the electrical energy passing into it down the ground, sparing what is inside of it from the full force of the electro magnetic pulse.
The good news is such a Faraday Cage or Faraday Shielding need not be expensive. A metal file cabinet or inexpensive light weight gun safe will work. I bought a used heavy metal box that I think was originally used to keep coal or sand in. What you want is a complete and connected conductive metal (steel) exterior surface, not a grid or cage with gaps (this is why the term Faraday Cage is actually not a good term since with a cage people think of bars). [JWR Clarifies:  Actually, a cage-like structure would work, but the largest gap in the mesh would have to be less than 1/4 of the wavelength of the expected pulse. Hence, 1/2″ wire mesh should be sufficient.]  Ideally you should connect a very heavy gage electrical wire (monster cable or 220 volt heavy electric wire) to a stand-alone dedicated ground (usually a copper rod drilled in below your basement floor). Some people say connect it to your copper plumbing or steel pipes. The problem with this is that the pipes could act as an antenna and actually channel energy to the Faraday shield. Just talk to an electrician about putting in a ground.
Although the Faraday principal says the electrical items are safe inside as long as they are not connected or touching the exterior shield, I think you still have to worry about the spark gap. Thus my advice is to put your expensive electronic stuff (computer, laptop, night vision, digital camera, radio equipment, etc.) into plastic tubs with plastic lids, and that then into the Faraday Cage. Plastic of course was developed as an insulator for radar in WWII, which due to it’s high voltage had to have an insulator between metal parts so the electricity didn’t just spark through the air (spark gap). Mineral oil has also been used as an insulator in high voltage equipment.
Remember, having anything plugged in, or hooked to an antenna defeats the purpose of shielding around it as you have provided an electrical highway [an unintentional antenna] right in. The use of a [lightning protection fast] fuse on such necessary plugged in equipment is probably your best bet as I fear a circuit breaker is not going to react quickly enough to save delicate equipment. However, I am not an electrical engineer nor am I claiming to be an EMP expert here. I am just trying to apply practical solutions to the problem and welcome the constructive criticism or correct by others who are more knowledgeable and can offer better solutions to the problem. – Rourke   http://groups.yahoo.com/group/survivalretreat

More on the subject:
Understanding EMP: http://www.geocities.com/CapeCanaveral/5971/emp.html  
EMP Bomb: http://www.abovetopsecret.com/pages/ebomb.html 
Faraday Cages: http://www.unitedstatesaction.com/emp_and_faraday_cages.htm#qst 
Duncan Long on EMP: http://standeyo.com/News_Files/NBC/EMP.protection.html