From: keivan@brahms.udel.edu (Keivan Esfarjani)
Subject: Re: Nuclear Bomb tests .....
Organization: University of Delaware
Date: Fri, 4 Sep 1992 06:56:30 GMT

In article <1992Sep3.124027.7682@ulrik.uio.no> kambizm@fidibus.uio.no  writes:
>
>I remember there was some speculation at the time connecting
>the earthquak to a Soviet nuclear test. But many scientists
>doubted that how such a chain reaction can cause Tabas some
>thousand kilometers away from the explosion site to experience
>an earthquak. The earthquak was in energy  some hundred times 
>stronger than the original explosion and happenned 36 hours after 
>the test. At the time I took the news as a cold war propaganda, 
>but who knows maybe such things can happen!
>
>                                  Kambiz

Yes, I believe these things CAN happen. All earthquakes are
caused by some instability: The tectonic plates (or whatever they
are called) are in motion with respect to each other, but because
of the friction between them, the motion is not continuous but
occurs "once in a while" , and that occurence is precisely at
the instability point(this is not a geometric point, but a point in time)
Near the instability point, any external 
perturbation(however small) can cause the sliding motion (or the quake).
So even if the intensity of the explosion was very small, and
even though it happened far from the quake site, it could have
caused it. But that does not mean it wouldn't have happened 
without the explosion; it would eventually happen, but probably
later, because the traction force is there and increasing.
So one effect of the explosion would be to release the pressure before    
the traction force between the plates increases more.

As far as the intensity of the quake is concerned, as Mr.
Mehran Kardar (professor of statistical mechanics at MIT) would
tell you, the intensity of the quakes is inversely proportional
to their frequency of occurence. ie: quakes of small intensity
happen very often, and those of large intensity are very rare
(which agrees with our common sense). This phenomenon is in fact
very universal and does not happen only for earthquakes.
(Our electrical engineer ahAlis might know that the noise
power spectrum is inversely proportional to the frequency: this
is the famous 1/f noise) 

Why did I say all that??
Because 1) if nuclear explosions make quakes happen before they are due,
then that shouldn't change much: instead of happening tomorow, they
happen today; and 2) if they make MORE quakes, then it probably 
helps decreasing their intensity: more quakes of smaller intensity
would cause the same displacement as one big quake. (unless the explosion 
itself is very intense and close to the quake site: that would  have 
the reverse effect)

So....
SMALL nuclear explosions might actually be helpful because they MIGHT
cause only small but frequent quakes.
But the question is: are these explosions actually small??
The other question would concern the time scale: how faster do these
explosions make the quake happen? 

OK, let's stop here and leave the response to these questions to geophysicists.

That was the end of our pseudo-scientific programming.

And now back to things more IRANIAN :-)
 
Regards,
K1

BTW the statements above are only mine, they can be right or wrong!
and I don't work for any nukes (although I wish I was!! :-)

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