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Re: Chicxulub's Antipode (Re: cause of death at KT)
On Sat, 02 Sep 2006 15:32:09 -0700 "James R. Cunningham"
> What is the mechanism by which it [P-waves] is absorbed in a liquid?
It has something to do with the differences between the compressability
of liquid rock vs solid rock.
I'm no physicist (trust me!). But I vaguely remember a Geology 101
instructor bringing into class one of those desktop "dynamic art
displays". You know, that contraption with the 3 steel balls on strings?
The impinging ball whacks the middle ball (which doesn't move), and the
middle ball transfers the energy of the impact to the ball on the
opposite side, which swings outward. That's purportedly how P-waves
work; they need a solid medium in order to propogate. To model how
liquid attenuates the energy of a P-wave, just wrap some polyurethane
foam around the middle ball and run the experiment again.
The MOHO layer (a layer of mushy rock at the base of the crust) was
discovered because P-waves from earthquakes got attenuated within this
zone. Seismic recorders picked up strong S-waves but very weak P-waves.
> Phillip Bigelow wrote:
> > Well, maybe not. P-waves ("compression waves") tend to get
> absorbed by
> > liquid,