EMP: Something new to worry about

[andrew]

I am reading the book One Second After about a small town after a CONUS-wide EMP event. Lots of stuff to worry about there that I hadn't yet folded into my portfolio of worry. It all comes down to these things:

- Water
- Food
- Shelter
- Sanitation

Everything else is gravy.

 

[matt]

Read this article: http://northeastshooters.com/vbulletin/showthread.php?t=61197

 

[RI_John]

How's the book? Good read? I love TEOTWAWKI books, but I can't stomach most of the "prose" (and I use that term loosely!)

I've read Patriots twice, but only for the technical information. Rawles makes Tom Clancy look like Hawthorne.

 

[rg1283]

I finished reading that book this week. Was depressed for awhile after reading it. I do believe that with a faraday cage you can protect your Shortwave Equipment and hopefully intercept the BBC on one of their SW Links. Ham Radio equipment would be no good as far as VHF/UHF Repeaters would definitely be cooked. Local Police/Fire Radio systems may still work, but mobile to mobile or handheld to handheld if your lucky. Forget about the big statewide radio system working.

So now your using HF. Well you might just be talking to yourself on HF.

There is considerable debate on what would work and what would not work after EMP. The main agreement that everyone seems to believe (as I do) the U.S. Power grid will be fried.

Looking at a Map of MA on my wall here, I have realized almost every part of MA has a divided highway (95, Turnpike, 395, 93, etc.).

Drugs would be the biggest issue. One could stock up fairly cheap on basic heart meds that are prescribed. Mostly everyone over 50 seems to take them (Lisinopril, Atenolol. etc.) these are generic drugs.

Anyone who require insulin or expensive specialty drugs would be dead quickly.

My main concern would be what to do with Prisoners currently in Prison and the Mentally Ill that are committed to psych hospitals.

Shortwave Radio (AKA HF) would be key my friends to finding out what is going on. The BBC still has links all of the world, mostly pointing towards Africa that can still be heard.

3 EMP bombs are the worse case scenario. So many variables go into this also. Even more possible now because Obama wants to cut back the Missile Defense System fielding and research $.

 

[ShadeWPI]

Electrical Engineer here, so I am familiar with EMP, it's effects and how its effects would affect our lives.

1) EMP dissipates as the surface area expands (square of distance). Most EMP developments so far have been localized (typically 10s of meters. 100s of meters for Nuclear Weapons)
2) the EMP effect on an item depends on the surface area of the pulse intercepted and the energy in the pulse at that area.
3) EMP causes a massive electrical energy surge by inducing current into conductive materials, this surge causes damage to electronics (much like a lightning strike).
4) A Continental US EMP event capable of disabling the power grid would require extensive amounts of energy. - The "back-bone" of the grid is capable of handling more 1,000,000V @ 1,000A or a Billion Watts of power, but the backbone cables are also hundreds to thousands of miles long.
5) For 3 EMP bombs blanket the US with enough EM energy to "fry" the system, each would need an effective range of about 1,000km, more than a million times the EMP energy released by the Heroshima.
At 1,000km, it takes 3 Trillion Watts to project 1W / m^2. That's 1mW of energy delivered to a 1mm diameter 1m long antenna.

Now, the more likely senerio would be for some much smaller (say 1km range EMP devices) located near sensitive infestructure points intent on disabling, say - the Power Grid "back-bone" - This would fry the power grid and shut down the national power distribution system (small local power distribution systems may be able to get back up in running in a few days to several weeks, but national power would be down for MONTHS. Local broad-cast equipment near the EMP site would be trashed with the effect dropping off in a radial pattern from the site. Small portable electronics distant from the site would be largely uneffected with the less soffisticated devices being the least likely to be damaged (Incandecent flashlights are much less sensitive to EMP than LED lights. Metal cases shield flashlights VERY well though) Aside from power distribution and broadcast equipment, most electronics would not be affected past a few kilometers.

As for the Ballistics Anti-Missile System, other than nuclear weapons, no EMP device capable of this level of damage is physically small enough to be delivered by a ballistic missile. It's a problem of energy storage. To get the trillions of joules of energy you'd need you'd need either Massive Mass and Volume or access to the sub-atomic energy stored within the material.

 

[packingungal]

I am reading the book One Second After about a small town after a CONUS-wide EMP event. Lots of stuff to worry about there that I hadn't yet folded into my portfolio of worry. It all comes down to these things:

- Water
- Food
- Shelter
- Sanitation

Everything else is gravy.

One should always thorougly pre-plan worry.

 

[lafayettela]

Electrical Engineer here, so I am familiar with EMP, it's effects and how its effects would affect our lives.

1) EMP dissipates as the surface area expands (square of distance). Most EMP developments so far have been localized (typically 10s of meters. 100s of meters for Nuclear Weapons)
2) the EMP effect on an item depends on the surface area of the pulse intercepted and the energy in the pulse at that area.
3) EMP causes a massive electrical energy surge by inducing current into conductive materials, this surge causes damage to electronics (much like a lightning strike).
4) A Continental US EMP event capable of disabling the power grid would require extensive amounts of energy. - The "back-bone" of the grid is capable of handling more 1,000,000V @ 1,000A or a Billion Watts of power, but the backbone cables are also hundreds to thousands of miles long.
5) For 3 EMP bombs blanket the US with enough EM energy to "fry" the system, each would need an effective range of about 1,000km, more than a million times the EMP energy released by the Heroshima.
At 1,000km, it takes 3 Trillion Watts to project 1W / m^2. That's 1mW of energy delivered to a 1mm diameter 1m long antenna.

Now, the more likely senerio would be for some much smaller (say 1km range EMP devices) located near sensitive infestructure points intent on disabling, say - the Power Grid "back-bone" - This would fry the power grid and shut down the national power distribution system (small local power distribution systems may be able to get back up in running in a few days to several weeks, but national power would be down for MONTHS. Local broad-cast equipment near the EMP site would be trashed with the effect dropping off in a radial pattern from the site. Small portable electronics distant from the site would be largely uneffected with the less soffisticated devices being the least likely to be damaged (Incandecent flashlights are much less sensitive to EMP than LED lights. Metal cases shield flashlights VERY well though) Aside from power distribution and broadcast equipment, most electronics would not be affected past a few kilometers.

As for the Ballistics Anti-Missile System, other than nuclear weapons, no EMP device capable of this level of damage is physically small enough to be delivered by a ballistic missile. It's a problem of energy storage. To get the trillions of joules of energy you'd need you'd need either Massive Mass and Volume or access to the sub-atomic energy stored within the material.

Thanks for your detailed and easy to understand answer.

 

[n1zfg]

I, too, am a skeptic of a CONUS wide EMP being able to really precipitate TEOTWAWKI.

But I will say that it could have a serious effect. Check out what's been published regarding the "Starfish test" where the army detonated a couple of megatons up in the Van-Allan belts. It pegged all the monitors they had set up for hundreds of miles.

Of course with the tightness of Part 15 emission requirements and the fact that shielding and suppression for it works both ways, I believe the actual effect will be less than what people think.

Even if it were, our society will not permanently turn Amish in the face of such a disaster. I like my creature comforts, including the command of kilowatts of power at the flick of a switch. I'm also willing to bet that I'm not alone in the desire to get that restored as quickly as humanly possible.

 

[mikem317]

A CONUS EMP may be unlikely, but one in a concentrated area like New York City or Los Angleles would create unfathomable havoc.

 

[SemiAutoSam]

If you want to survive an EMP event think of this word.

Faraday Cage / Box.

I make them out of 50 caliber ammo cans and also SAW cans.

I have a spare electrical components in a 40MM can and other smaller items in the 50 and saw cans.

IE for my old cars and trucks: Battery, Starter, Alternator, Distributor.

And more for the more modern car although I'm sure one those I have neglected a component or two.

I take the rubber gasket out of the can and replace it with copper braid and solder it in to the lid where the rubber gasket was.

Then the cans are all tied to a 8 ft ground rod thats pounded into the earth.

 

[andrew]

A lot of people with a lot of letters after their name signed onto that report in '01 talking about the threat of CONUS-wide EMP and its effects on infrastructure. I just finished the book that inspired my OP in this thread and it was very sobering. It made Patriots look like a Sesame Street sing-along in comparison.

 

[ShadeWPI]

Mike,

Definately. In a concentrated area like say, Manhattan, a 1 Mile range EMP pulse would cause complete havoc. There are much better places to initiate an EMP event (I wont describe where, but I was asked by a friend for research into a novel)

Electro-Magnetic Pulse (EMP) is exactly the same as a radio broad-cast, just many, many times more powerful. All conductors will develope both a voltage and current as a result of EMP. The larger the surface area of the conductor, the more voltage and current will be produced. To cause damage, voltage and current my deliver sufficient energy to cause electrical component failure. For a rough estimate of the energy delivered to an electrical circuit, compare it's area to the expanding sphere radiating out from the EMP source (you can get roughly 2x the energy if you "shape" the EMP into an expanding DISK rather than a Sphere) Larger circuits (perticurlarly power distribution infrastructure which is HUGE) are more sensitive due to their increased size.

If you're going to store items in a faraday cage like a .50 Caliber ammo can does help, but I would recommend adding a 1/8" neoprene rubber lining to the interior of the can. Theoretically this isn't needed since the pulse will travel on the "skin" of the metal object, however due to the resistance of the metal of the can, a voltage may build up between the near-side and far-side of the metal can and this voltage could induce a current in compoents in the can if they are touching both sides. Neoprene Insulation will dramatically reduce this effect.

You can do the same thing with your car - add a metal braid from the frame of the car to the ground and then install a metal plate under you car that the braid will rest on when parked and connect the grounding rod to the plate. This will turn your car into a faraday cage and most likely protect the sensitive electronics inside your car.

An EMP pulse will induce a large surge in the residential electrical power distribution and may damage any electronic device attached to the power grid. Surge suppressors will help this, however a typical home surge suppressor is only rated to a few hundred jouls (high end suppressors can be 1500 - 5000 jouls) If you want to protect you whole house, you can invest in a 15-25kj Gas Discharge Tube across the mains into your house. Your neighbors may appreciate this as it will may offer some protection to their houses as well.

Small, metal bodied electronics (metal bodied radios, flash-lights, etc) and small electronics stored in grounded metal containers are unlikely to be effective even at a few hundred meters.

But keep in mind, short of a nuclear weapon, EMP devices of even moderate range are enormous. They are so large that even the military has yet to develop an effective vehicle mounted EMP weapon or bomb capable of disabling a single vehicle. The military has been trying to develop an aircraft deployable "EMP Bomb" for disabling enemy vehicles for more than 15 years and a a Humvee mounted EMP field weapon able to fry basically unprotected remote detonation electronics at 25m would be an invaluable tool against IEDs in Iraq.

 

[Prepper]

Thanks for all that info. Looks like you are saying the effects of EMP won't really end everything as we know it.

Can we really be sure though? I have read somewhere that a nuke detonation within the atmosphere would have a mild EMP effect like you describe. But, something much worse is supposed to happen when the nuke detonates 200 miles up, well outside the atmosphere. Somehow, that is supposed to make the EPM much worse, frying all electronics that are visible to the explosion (over 1000 mile wide area would be visible to a detonation 200 miles up). Sorry, I wish I could remember what the technical terms they were using for what happens when detonation is outside the atmosphere. Any ideas?

If your explanation turns out to be the correct one, then why is almost everyone out there saying a single nuke in the sky would disable most of North America? I'm trying to reconcile the two stories.

 

[Marcus in the Darkus]

Shade WPI, thanks for your informative posts.

 

[ShadeWPI]

Prepper

First, you'll see most of my comments start with "short of a nuclear device" Mostly this is because nuclear devices have immense magnitides of energy that are capable of generating much larger EMP waves than is possible with non-nuclear devices.

Second, a high altitude nuclear device is able to react with the earth's magnatic field lines. Imagin the Earth is a massive magnetic tuning fork and the nuclear weapon is a hammer to hit it.

Third, while even a high-altitude EMP device could affect continent wide electrical power distribution and radio broadcast equipment, these devices are perticuarly succeptible to the effect of EMP. Broad Cast equipment is specifically designed to amplify EM fields (that's how they broadcast/recieve) and power distribution equipment is sensitive because of the huge area the distribution wires cover. Small personal eletronics and most battery powered items lack the sensitivity or size to make they effective targets to such an attack.

This would require using a high-energy (multi-megaton) nuclear weapon in a manner that specifically negates it's primary effect (mass destruction via thermal and over-pressure effects) since a near-ground detonation produces a different effect that is considered "danagerous" to infrastructure equipment out to 8-10km and most high-value government and industrial equipment is already significantly protected from the induced surge effect.
The general population may be without power for months following an orbital level detonation while the infrastructure is repaired and billions to trillions of dollars of equipment might be damaged as a result, most high value assets would be able to opperate.

 

[andrew]

So...I guess I am back to having the shit scared outta me.

 

[Prepper]

Me too. I had a little bit of hope there for a moment. (I never was worried about non-nuke EMP devices since they are pretty much ineffective and the thing of sci-fi [usually bad sci-fi]).

Note to self: Do not install Borg implants in myself. Then I'd be totally screwed if all electronics fry.

 

[ShadeWPI]

Remember, to execute this style of attack you would need:

1) Access to a multi-megaton nuclear device.
2) A trans-orbital delivery system (basically, the ability to place an object into geosynchronous or high orbit. This is roughly 2x the altitude the shuttle flies at.
3) The willingness to knowingly launch such a weapon on the United State with the understanding that you will do little, if any damage to the military capabilities of the US armed forces.
4) Sacricifing such a weapon with no ground-level blast damage. This would me exchanging knocking out power over most of the US for a few months while equipment was replaced instead of targeting a major populated city and causing 10s of millions of deaths.

Also, while this would knock out power infrastructure for an extended period, it is unlikely such a detonation would significantly damage smaller battery powered electronics.

 

[andrew]

And yet, there are end-times whack-jobs like that crazy-ass mofo in Iran that might be willing to sacrifice to take out "The Great Satan"

 

[Pete85]

And yet, there are end-times whack-jobs like that crazy-ass mofo in Iran that might be willing to sacrifice to take out "The Great Satan"

It's the difference between a direct attack, and true terrorism (in the sense that terrorism is intended to cause mass panic and terror, over causing mass casualties). On September 11, 2001 the attack was designed to directly inflict casualties. What if instead of flying the planes into the WTC and Pentagon, they had decided to target main utility hubs? Large masses of people without power, or water, or natural gas, etc for days or months on end. Some people would still die as a result, but the fear and panic stricken on the masses would be the main result. Overall, the effects would be much longer lasting and much wider spread than an attack designed for the purpose of inflicting massive casualties.

 

[ChevyGuy91]

Just a thought, RF or EM is projected Line of Sight. So really you would only have to cover the top and sides of sensitive equipment. Could you just ground some chicken wire or chain link fence and drape it over, say a car or a generator and have it unaffected?

 

[EC1]

Questions

Can a Faraday cage be constructed from say fencing rather than sheet metal? Does the cage need to be continuous or can you build a box with isolated sides and ground each of the 6 sides separately?

 

[SemiAutoSam]

NO

The holes are too large.

IMO a tight mesh would be OK for air circulation but only in the opening of a small hole no larger than 3-4 inches diameter.

This was how the cages where built when I worked for Motorola in the early 1980's.

Amateur Radio operators also use them to test radios.

Basically its a large enclosure that has sealed joints and door.
http://www.unitedstatesaction.com/emp_and_faraday_cages.htm

The material is a tightly woven brass or copper screen just about like the kind of screen on most windows but its bonded to a frame and then soldered together at the joints to make it free of RF leaks.

At least that is what I remember but it was about 30 years ago so I could have forgotten some of the aspects of how they were built.

Info about EMP devices and how to harden buildings against EMP.
http://www.globalsecurity.org/military/library/report/1996/apjemp.htm

http://www.infobunker.com/HERFandEMPthreats.htm

Can a Faraday cage be constructed from say fencing rather than sheet metal? Does the cage need to be continuous or can you build a box with isolated sides and ground each of the 6 sides separately?

 

[ShadeWPI]

What is a faraday cage and how does it work?

A Faraday Cage is a closed loop conductive circuit that minimizes the electro-magnetic field within in in by conducting the field around it.

If you could make a faraday cage out of an ideal super conductor, there would be no field strength within the cage since any field across the conductor would immediately create an infinite current and can cancel the field. Since no ideal super conductors exist, this never occurs, so what actually happens?

the closed loop circuit with finite resistance is exposed to an EM field, the field induced a current, moving charged particles within the circuit to counter sum of external electric field. the lower the resistance, the more charge is moved and the better the field cancellation.

Any hole in the continuous shell becomes a localized EM field. For small holes this field is highly localized and virtually ignored, but larger holes become mini antenna within the cage. Also, round wires in a grid are MUCH less effective than a sheet with round holes punched into it.

In addition, while copper is an effective electric field shield, it is not nearly as effective against magnetic fields while iron or steel is highly effective against magnetic fields but a poor conductor and thus less effective against electric fields. Copper Clad steel is actually one of the more effective shields available.

To answer the question about 6 seperately grounded but individually isolated walls, since a faraday cage functions by conducting the EM field around the surface of the cage, this would be MUCH LESS effective than having them connected together (seperate grounds are each a seperate resistance thus resulting in a differential between the plates, which would generate a field.

A "floating" faraday cage (isolated from ground) in theory has no field strength with the cage, but the cage is equal to the field around it. While this should protect any items within the cage, there is still a transient charging event as the cage "jumps" to the potential of the field and this transient will produce a temperary field.