>...has to do with this mornings tidal wave(s) that struck many areas
>of the Indian Ocean.

I should gently point out that tsunami have nothing to do with tides
(unless one might be indirectly caused by a volcanic eruption,
initiated by tidal stresses, emptying a magma chamber, which may
collapse... possible on minor planet Io, but unlikely on Terra), and
calling them "tidal" is grossly incorrect. Like calling a car's
dampers "shock absorbers" or a zeppelin a "blimp" or "dirigible".

They are caused by sudden massive displacement of large amounts of
water, which may be due to fault movement, magma-chamber collapse
(Krakatau 1883), submarine landslide or slump (these latter, collapse
of continental margins, will be the largest, and happen relatively
frequently though not in historic times... the next to occur will
wipe out entire oceanic or worldwide coasts to hundreds (or more) of
kilometers inland).

Bolide-impact-produced waves will be another story, and can (briefly)
lay bare ocean bottoms 5km or more down.

I have never seen an analysis of the stucture or mode of propagation
of tsunami, but it seems to me that rather than a moving
(transforming) cyclic overall motion, tsunami may be pressure-waves.
This could explain their rapid rate of travel (800kmh) in deep water,
the fact that they do not crest but appear in shalow waters as a
rising, often seething, mass... as is graphically shwown by the
videos appearing from the recent occurrence. Also why they are not
observed by ships at sea, quite unlike normal large waves (including
solitons, those so-called "freak" waves which grow by stealing energy
from adjacent normal large waves, developing near-vertical "front"
faces and becoming so large that one may shatter a LARGE ship,
causing sinking within seconds); at most a tsunami may be noticiced
by ships as a mild thump, as if the ship has run over a bump.

Anyway, shallow-water collecting may not be so good in some parts for a while.

You won't catch ME buying a house within true tsunami reach!
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<[log in to unmask]>
Seashell, Macintosh, VW/Toyota van nut

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