Can any one tell me what the Diameter of an E.M.P blast would be? For the sake of discussion say a blast over a large city like Los Angeles California. And would mountians and valleys make any difference?

How many megatons is the bomb and and at what altitude is it set off?

1 megaton at an altitude of 48 miles (if I remember correctly) over the center of the midwest US will create a strong pulse that will cover the entire US of A.

1 megaton exploded at 10,000 ft over a city will have a 10 - 20 mile blast effect. It will have a fallout footprint of 30 miles upwind, 50 miles cross axis, and 350 miles downwind. Hills and mountains will deflect the blast waves and affect the wind patterns irt fallout and the wind that will draw oxygen into the NuDet. Nagasaki, Japan was a good example of this.

The type of material (weight) will greatly affect the Fallout Footprint. The greater amount of radioactive particles that are blown into the upper atmosphere, will be inert (radioisotope) when they come back down to earth.

There is an EMP map that can be found at www.standeyo.com
That article came out last month so you may have to search the archives to find it.

What a Single Nuclear Warhead Could Do

find out how to protect yourself from an EMP attack





November 24, 2008
By Brian T. Kennedy
Wall Street Journal

As severe as the global financial crisis now is, it does not pose an existential threat to the U.S. Through fits and starts we will sort out the best way to revive the country's economic engine. Mistakes can be tolerated, however painful. The same may not be true with matters of national security.

Graphic: An EMP blast would have far-reaching consequences for the US, affecting nearly the entire country.

Although President George W. Bush has accomplished more in the way of missile defense than his predecessors -- including Ronald Reagan -- he will leave office with only a rudimentary system designed to stop a handful of North Korean missiles launched at our West Coast. SomePolitician PHRASECENSOREDPOSTERSHOULDKNOWBETTER. will become commander in chief of a country essentially undefended against Russian, Chinese, Iranian or ship-launched terrorist missiles. This is not acceptable.

The attacks of Sept. 11, 2001, have proven how vulnerable we are. On that day, Islamic terrorists flew planes into our buildings. It is not unreasonable to believe that if they obtain nuclear weapons, they might use them to destroy us. And yet too many policy makers have rejected three basic facts about our position in the world today:

First, as the defender of the Free World, the U.S. will be the target of destruction or, more likely, strategic marginalization by Russia, China and the radical Islamic world.

Second, this marginalization and threat of destruction is possible because the U.S. is not so powerful that it can dictate military and political affairs to the world whenever it wants. The U.S. has the nuclear capability to vanquish any foe, but is not likely to use it except as a last resort.

Third, America will remain in a condition of strategic vulnerability as long as it fails to build defenses against the most powerful political and military weapons arrayed against us: ballistic missiles with nuclear warheads. Such missiles can be used to destroy our country, blackmail or paralyze us.

Any consideration of how best to provide for the common defense must begin by acknowledging these facts.

Consider Iran. For the past decade, Iran -- with the assistance of Russia, China and North Korea -- has been developing missile technology. Iranian Defense Minister Ali Shamkhani announced in 2004 their ability to mass produce the Shahab-3 missile capable of carrying a lethal payload to Israel or -- if launched from a ship -- to an American city.

The current controversy over Iran's nuclear production is really about whether it is capable of producing nuclear warheads. This possibility is made more urgent by Iranian President Mahmoud Ahmadinejad's statement in 2005: "Is it possible for us to witness a world without America and Zionism? But you had best know that this slogan and this goal are attainable, and surely can be achieved."

Mr. Ahmadinejad takes seriously, even if the average Iranian does not, radical Islam's goal of converting, subjugating or destroying the infidel peoples -- first and foremost the citizens of the U.S. and Israel. Even after 9/11, we appear not to take that threat seriously. We should.

Think about this scenario: An ordinary-looking freighter ship heading toward New York or Los Angeles launches a missile from its hull or from a canister lowered into the sea. It hits a densely populated area. A million people are incinerated. The ship is then sunk. No one claims responsibility. There is no firm evidence as to who sponsored the attack, and thus no one against whom to launch a counterstrike.

But as terrible as that scenario sounds, there is one that is worse. Let us say the freighter ship launches a nuclear-armed Shahab-3 missile off the coast of the U.S. and the missile explodes 300 miles over Chicago. The nuclear detonation in space creates an electromagnetic pulse (EMP).

Gamma rays from the explosion, through the Compton Effect, generate three classes of disruptive electromagnetic pulses, which permanently destroy consumer electronics, the electronics in some automobiles and, most importantly, the hundreds of large transformers that distribute power throughout the U.S. All of our lights, refrigerators, water-pumping stations, TVs and radios stop running. We have no communication and no ability to provide food and water to 300 million Americans.

This is what is referred to as an EMP attack, and such an attack would effectively throw America back technologically into the early 19th century. It would require the Iranians to be able to produce a warhead as sophisticated as we expect the Russians or the Chinese to possess. But that is certainly attainable. Common sense would suggest that, absent food and water, the number of people who could die of deprivation and as a result of social breakdown might run well into the millions.

Let us be clear. A successful EMP attack on the U.S. would have a dramatic effect on the country, to say the least. Even one that only affected part of the country would cripple the economy for years. Dropping nuclear weapons on or retaliating against whoever caused the attack would not help. And an EMP attack is not far-fetched.

Twice in the last eight years, in the Caspian Sea, the Iranians have tested their ability to launch ballistic missiles in a way to set off an EMP. The congressionally mandated EMP Commission, with some of America's finest scientists, has released its findings and issued two separate reports, the most recent in April, describing the devastating effects of such an attack on the U.S.

The only solution to this problem is a robust, multilayered missile-defense system. The most effective layer in this system is in space, using space-based interceptors that destroy an enemy warhead in its ascent phase when it is easily identifiable, slower, and has not yet deployed decoys. We know it can work from tests conducted in the early 1990s. We have the technology. What we lack is the political will to make it a reality.

An EMP attack is not one from which America could recover as we did after Pearl Harbor. Such an attack might mean the end of the United States and most likely the Free World. It is of the highest priority to have a president and policy makers not merely acknowledge the problem, but also make comprehensive missile defense a reality as soon as possible.

Mr. Kennedy is president of the Claremont Institute and a member of the Independent Working Group on Missile Defense.

http://online.wsj.com/article/SB122748923919852015.html

wildman 800
I knew I could count on you for an answer to my question Thanks.

That all sounds very scary, but isn't high on my priority list of things to prep for. I am much more concerned about the unemployed drug addict looking for $$ for his next fix. (great topic for another thread...home invasion defense)

"find out how to protect yourself from an EMP attack"...that article doesn't say much about personal protection from an EMP. Apparently, "The only solution to this problem is a robust, multilayered missile-defense system." Where do I get one of those?

I would recommend putting an ad in Craigslist for free non-working microwave ovens, and get a couple to stash away some spare electronics, like a laptop, emergency radio, ham radio, CB, walkies, etc. I have read that the shielding that keeps microwaves from escaping also make it EMP proof.

It really doesn't take a whole lot to shield from EMP. I've read that even a close screen material can do it.

This is a rather old article about it, but has a decent section about the Faraday box. As far as I know it is effective - someone out there can educate me if I'm mistaken.
Or this one.

Sounds to me like a good quality gun safe, with carpeting on the inside, should do it. You could cover the door gap with metal screening or tin (excuse me, aluminum) foil if you were really paranoid. Not that I've been considering it or anything, just thinking out loud...

20MTs at 200 miles up? I can't really take (preparing for) this EMP seriously. There is only 1 country on the planet that has ever had an operational capability to haul a 20MT warhead into space.

Since such a weapon would have to be not just a relatively simple fission device but a fusion device -- and a reasonably heavy one at that -- it's beyond the technical grasp of just about every country but 1 for the foreseeable future. Only Russia makes rockets big enough to move a payload that large into space. Shahab-3? Let alone from a freighter? Please.

The largest weapon the US has ever put on an ICBM was under 5MT. Russia reportedly maintains 30 SS-18's with 20MT warheads so they do have the capability (though most maintain that those missiles are destined for bunker-buster missions). However, if those are launched at us, everything else is coming as well. There isn't much preparation you can do to prepare for that. EMP will be the least of your worries.