I need to demonstrate that any air explosion (fireworks, natural gas
explosion, etc.) sends shock waves or a vector through the ground as
well as through the air.  The air part is easy, but I need
authoritative text(s) to demonstrate that some portion of that energy
is transferred through soil.

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Request for Question Clarification by pafalafa-ga on 19 Feb 2006 07:14 PST

jmpollock-ga,

The answer to your question will depend, in large measure, on what it
is -- precisely -- that you want to demonstrate, and what type of
information would be deemed demonstrative.

You might want to have a look at this paper:


http://www.gvu.gatech.edu/animation/Papers/yngve:2000:AE.pdf
Animating Explosions


I'm not sure the math/modeling will be of interest, here, but the
article has quite a number of excellent images demonstrating the
transfer of energy of exposions under a variety of different
conditions.

Let me know if this is helpful.  And if it's not, please explain in
what ways it falls short, so we can better understand what you need.

Thanks,

pafalafa-ga

Hmmm? 

   The only authoritative reference needed to assert that some
*portion* of the energy gets transferred into the soil is high school
level physics. For instance, suppose a firecracker explodes in midair
at some height above ground. The shock wave radiating from it through
air carries energy & momentum. As the wave strikes the ground it very
surely does interact with the soil. There is an exchange of both
energy and momentum. There's really no way to avoid it.

I'm a trial lawyer and I have to prove this to a Judge and Jury.  
What texts, treatises,etc.  prove that point?

Is this an actual point of contention in some litigation you're dealing with?

Let's put it this way: Have you ever been inside your house, with all
the windows & doors closed, but were also able to hear sounds
originating from outside?

   This is because sound waves carry energy, and when they strike the
walls of your house they excite the material of which the walls are
made and the sound wave is propagated through the walls, where the
energy further excites the interior air which conducts the wave to
your ear.

   So if you are in court and someone claims that *no* portion of the
energy from an airburst can penetrate into the soil, ask in return if
it's reasonable to assert that at no depth whatsoever would the sound
be audible to someone under the surface.

   Now of course, soil is a pretty good accoustical insulator; it
scatters sound energy rapidly with depth. At a depth of just a few
feet it's possible that ordinary sounds of people going about their
business could be indiscernible to a human ear. But on the other hand,
it's just a matter of degree. Surely, were I a few feet underground
while powerful artillery shells airburst above the surface, I would
expect to hear the bombardment.

Greetings,
As you can see from Qed's comment, in the abstract, there is no
question that there is a transfer.  IF you could be more specific
about the actual incident, there is a much greater likelihood that an
authoritative text can be found.
Regards, Myoarin

Yes, this is point in contention before the jury.   What books or
articles can I use.    Jeff

Well, without knowing the details of the controversy in your
particular case, I'd advise you to recruite the services of a college
physics professor as an expert witness. Said expert will be able to
explain why sound is known to carry energy, and why some portion that
energy certainly does penetrate into soil. (Not all. Some of the
energy will be reflected back into the air.) Or, you could procure a
seismologist for the same expertise. Seismology is essentially
studying the geology deep beneath our feet by way of sound waves,
which are known to travel through rocks & soils. The destructive
energy of an earthquake is really just very powerful soundwaves
propagating through the ground.

   In addition, a simple experiment can be performed, which would be
to emplace two identical sound recording devices: one above ground,
and one below, in the soil. Set off a loud sound-generating event,
such as a firecracker, etc., with both devices simultaneously
recording the event. If the event is loud enough, and the depth of the
soil shallow enough, the sound will be recorded even by the buried
microphone.

Sometimes we get sidetracked from the basic question.
Of course major air explosions create shock waves in the ground, as
any observer of such has experienced.  Even very loud noises, such as
a starting jet, can be felt as vibrations under one's feet.  Of
course, as the force of the blast is reduced, the ground shock
decreases very greatly.

Here are some sites that may be of help.

http://iac.dtic.mil/iac_dir/SAVIAC.html

http://www.blastgardintl.com/td_explosion_terminology.asp
scroll down to "collateral damage"

http://www.fema.gov/pdf/fima/427/fema427_ch3.pdf
see end of second paragraph

http://cmmfa.mmu.ac.uk/project/blastwave.html
see end of second paragraph

http://www.jpyro.com/journal/issue_12/
see third abtract

http://www.pci.org/pdf/DN/DN_blast1.pdf
See "blast basics".  The graphics  (car bomb) and government sources
referenced may be of additional help to your argument.

http://www.emergency.com/carbomb.htm
scroll down to "post-bomb cordon"

http://library.witpress.com/pdfs/abstracts/SU04/SU04006AU.pdf
See last lines of this unfortunately truncated site.

http://www.saviac.org/Newsletters/Jan_2005/January%202005.pdf
SAVIAC is the DoD center for Shock and Vibration studies.  I expect
that it could direct you to specific texts directly appropriate to
your case.

http://www.asial.com.au/files/EndUser_BowesDec04.pdf
See page two, first column.

http://www.earthquakes.bgs.ac.uk/latest/hemel_hempstead_11122005.htm

I hope this is of use.