Re: New archaeological evidence casts doubt on mega-tsunami theory of Minoan collapse

From: Philip Deitiker (Donevenask_at_worlnet.att.net)
Date: 01/08/05 

Date: Sat, 08 Jan 2005 15:14:21 GMT

Martyn Harrison <nospam@spammers.of.the.world.unite> says in
news:blhvt011g4vrda7cd0po390k3mgmgg4758@4ax.com:

> Apparently on date 7 Jan 2005 10:39:46 -0800, "grapheus"
> <grapheus@www.com> said:
>
>>Dylan Sung wrote:
>>> "grapheus" <grapheus@www.com> wrote in message
>>
>>Of course, the falling down into the sea of a piece of ice is
>>similar to the falling down of a piece of rock.
>>With a DIFFERENCE that you omitted to mention : As the DENSITY
>>of ice is LESS than 1, contrarily to the density of a rock, the
>>tsunami is generally NEGLIGIBLE. Because of what I said at the
>>beginning (YES, we are going back to square one, to the point
>>you didn't understand !!!) : What COUNTS is the "VOLUME of the
>>WATER which is suddently DISPLACED...
>
> There is a fundamental flaw in your reasoning, which concerns
> basic physics.
>
> Displacement of water is key here, this is true. How much water
> is displaced when you abruptly submerge:
>
> 1) 100 cubic meters of ice with a density of 0.99
>
> 2) 100 cubic meters of rock with a density of 4.00
>
> ?
>
> *Hint*, 100 cubic meters of rock does not displace 400 cubic
> meters of water.

E = 1/2mv^2 E=mgh.

If you take ice and drop it from 100 feet into water, it will hit the
water with E and the ferrous-rock with 4E. The ice will create a
displace wave of depth X where as the ferrous-rock rock will continue
to displace water to a depth of 4X until its speed equilibrates with
water. While ice is slowing the speed of the displacement wave is
slowing , whereas the ferrour-rock continues to displace water at a
faster pace. Once both equilibrate in speed the water will cover them
and they will continue not to displace.

In the example above g is constant, h is 100 feet for both, and mass
varies by 4. The energy of impact is converted to heat which is
quickly dissipated and motion, E = 1/2mv^2. Let us argue that argue
that the rock falls into a sea of 100 feet, at its speed equilibrates
at 90 feet, the ice equilibrates at 45 feet. The average speed of the
rock over the 90 feet is 1/2 the contact velocity at 45 feet and the
speed of ice is negligible. That initial speed is 24 m/s, the surface
wave to 20 feet will be approximately half. The surface wave created
by the ferrous rock will be about 3/4ths the subsurface displacenment
of the ice will be negligable, the subsurface wave created by the
falling ore will be about 1/4th that the surface wave.

  The essential flaw of your argument is that you fail to consider
that E=mgh is the same E as 1/2mv^2. That kinetic energy is imparted
on the adjacent body of water as it penetrates the water compressing
and raising the water as it penetrates. The objects can be flat, and
both with impart their energy at the surface, or fusiform and both
pentrating and departing energy deep. But the ferrous object of the
same shape as the ice will _Always_ depart its energy deeper than the
ice. Because it imparts its energy deeper it carries the ability to
move and copress water deeper. One the surface that displacement in
created in the form of a verticle displacement. But under the surface
a compression wave is created. Since water does not compress well
that wave propogates very rapidly forward.

  What is important here to keep in mind is that when ice falls it
generally creates only a surface displacement wave. Surface
displacement waves travel in verticle displacement of rather slow
speeds and in shallow water they frequently curl away their energy.
A dense object can create a displacement wave, which can travel
globally.

 Having said that I cannot think of a single example where a chunk of
rock falling has created a tsunami. If one thinks about volcanic
ejecta that ejecta falls back onto water at random points. For a
really good tsunami one needs a very sharp line of change along the
ocean floor. [Note I am not considering water impacts of a non-
terrestrial origin]
  In terms of the Santorini event, my thoughts on the matter are
this. It is not the surface displacement that would concern me. The
submarine displacement of both water and solids would create a wave
at the maximum depth of that ejecta. The exploding gas would
immediately displace both water and debris before it redirected its
energy on a path of least resistence. On the NW and WSW walls of the
caldera this event is obvious, although we cannot say how exactly far
in terms of water this occurred we can argue that the displacement
moment was at least as far as the center of the caldera depression to
the outside wall in terms of the distance traveled. Some of this was
in the form of a surface wave, probably 100s of feet in height
(meaningless at the point of generation since the ejecta is also
blowing the wave off), but also on a submarine compression.
  Here is the base argument. If the rate of internal displacement is
greater that the speed of tsunami propogation (500 MPH) then a
tsunami is created. The Santorini caldera exploded from its center at
a final velocity of greater than 500 MPH, and the WSW and NW borders
protecting the ocean were destroyed clearly indicating this ejecta
was thrust into the surrounding sea. The density of the horizontally
moving eject is as important as falling rock. 

-- 
Philip
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