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Re: Tsunami propagation

Subject: Re: Tsunami propagation
From: Bret <>
Date: Wed, 5 Jan 2005 12:20:45 -0800 (PST)
--- Walter Knapp <> wrote:

> 
> From: Marty Michener <>
> 
> > This case is a happy instance for the victims, because (and I
> thought 
> > EVERYBODY ALREADY KNEW) the water level begins oscillating BEFORE
> the main 
> > wave hits, and so if you ever see the water leave the bay - RUN for
> 
> > it!  Evidently a lot of children went out into the tide pools to
> catch the 
> > flopping fish, instead of seeking higher ground.  This is the most 
> > appalling fact I have yet heard about the current tragedy - so
> preventable, 
> > yet again I also wonder how many American school kids living on a
> coast 
> > know this simple rule?  BTW does everyone know why a tsunami is
> physically 
> > impossible on the Atlantic coast?  The news guy yesterday didn't! 
> It is 
> > protected by the relatively shallow banks, upon which 99% of the
> energy 
> > would be spent.
> 
> I've not been following the news reporting much since some of the
> early 
> stuff. Video there showed no initial backwash, the folks nearest to
> the 
> water were laying around sunbathing. I suppose what you refer to is
> some 
> later reporting.
> 
> The tidal wave I went through on the Oregon coast also had no
> backwash 
> to warn. It would start each wave with forward current. There was
> then a 
> following outwash of near equal proportions. Because we were in a
> bay, 
> the current from the forward part hit the marina, the outwash current
> 
> was on the other side of the bay at our part due to a curve in the
> bay. 
> We could hear it rushing out from our side.
> 
> I did also talk to some who were in a campground at one of the Oregon
> 
> beaches. They too reported no initial outwash. The Coast Guard boat 
> which was in the entrance channel was hit with inbound first, not 
> initial outwash there either.
> 
> I did know the rule about the initial outwash. If it occurs, you are 
> right, get to high ground fast. Just don't count on it occurring. And
> 
> hardly anybody knows this. We live in a society that thinks all of 
> nature is just our playground. Nothing to worry about. Things like
> this 
> remind us we are trivia against nature.
> 
> Walt
> 
I had heard about this initial outwash, negative wave or drawdown
before.  It is discussed here:

http://answers.google.com/answers/threadview?id=447382 



                
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