How Accurate Are Seismic Estimates of Nuclear Test Yields?

[Orion1]

I thought this would be an interesting video for physics majors to watch:

http://www.spikedhumor.com/articles/28850/Underground_Nuclear_Explosions.html"
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[Astronuc]

That demonstrates how fluid the ground really is. Some of those displacements are fairly substantial.

 

[Orion1]

I am enquiring as to what the explosive yield is for the new North Korea nuclear weapon?
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[Astronuc]

I believe the yield is likely in the kT range, particularly if it is only nuclear, i.e. fissile. I don't believe NK has developed a thermonuclear weapon - well hopefully not - but that would be the next step.

 

[Morbius]

I am enquiring as to what the Megaton yield is for the new North Korea nuclear weapon?
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Orion1,

I would also concur with Astronuc.

Thermonuclear weapons, also known as "hydrogen bombs" or "H-bombs" can have
yields that are in the Megatonnes.

That's NOT what the North Koreans have, or claim to have. They claim to have
"A-bombs"; the type of weapons the USA developed in World War II and dropped
on Hiroshima and Nagasaki.

It takes a "A-bomb" to trigger an "H-bomb"; so you have to develop one before the
other.

As Astronuc points out, "A-bombs" have yields measured in "kilotonnes".

The bomb the USA dropped on Hiroshima was about 15 kilotonnes, and the
bomb that was dropped on Nagasaki, and its twin tested at Trinity; were about
20 kilotonnnes.

Any weapons developed by a nascent nuclear weapons state like
North Korea would probably have yields similar to the first weapons
developed by the United States; i.e. 10-20 kilotonnes.

Dr. Gregory Greenman
Physicist

 

[berkeman]

I thought this would be an interesting video for physics majors to watch:

http://www.spikedhumor.com/articles/28850/Underground_Nuclear_Explosions.html"
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What were those pre-fab buildings on stilts? Looked like they survived pretty well.

 

[pippo90]

i don't get it? the world is against north korea even getting a nuclear research program and the UN hassels them when the UN has who knows how many nukes! and anyways NK isn't stupid enough to nuke anyone especailly when they know that their coutry could be leved in less than a week by all the nukes the UN has

 

[Astronuc]

The UN does not have nuclear weapons. The nuclear weapons are under the control of the those nations which have the capability of designing and manufacturing them.

 

[Orion1]

South Korea's seismic monitoring center alleges there was indeed a magnitude 3.6 quake.

A seismic wave of magnitude 3.58 had been detected in the district of Gilju in North Hamkyung province.

h = -2,000 meters (below the surface).

M - Richters
3.5 = 178 metric tons
4.0 = 1 kiloton

1 kt TNT explosion is roughly equivalent to a magnitude 4 earthquake.
1-kiloton nuclear explosion would produce a magnitude in the range of about 4.0 to 4.5 on the Richter scale

I calculate the first NK test yield at 1 kiloton.

Reference:
http://en.wikipedia.org/wiki/Moment_magnitude_scale
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[Morbius]

I calculate the first NK test yield at 1 kiloton.

Reference:
http://en.wikipedia.org/wiki/Moment_magnitude_scale
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Orion1,

The current reports are that the NK weapon was about 550 tons or ~1/2 kiloton.

As the Wikipedia article you stated states at the end; these formulas are not very
useful for estimating yields. The local geology has a big impact on how much
the energy of the bomb couples into seismic waves, and how those waves propagate.

Estimating the yield of a nuclear test from seismic data is much more complex
than what is found in the Wikipedia article, and they acknowledge that.

Dr. Gregory Greenman
Physicist