http://ontario.indymedia.ca/twiki/bin/view/Archives/ImcOntario7336
The WTC Collapse: What the Videos Show
by Jeff King
1:35am Mon Mar 4 '02 (Modified on 5:11am Fri Aug 29 '03)
[EMAIL PROTECTED]
A collection of seven video clips of the WTC collapse,
with a critical analysis of certain engineering aspects. (article 1)
Download attached MPG file: --_close-up_of_south_tower_collapse.mpg
Why The Immense Dust Clouds?
In trying to come to terms with what actually happened during the
collapse of
the World Trade Towers, the biggest and most obvious problem that I see
is the
source of the enormous amount of very fine dust that we see generated
during the
collapse. Even early on, when the top of the building has barely
started to
fall, we see this characteristic fine dust (mixed with larger chunks of
debris)
being shot out very energetically from the building. During the first
few
seconds of a gravitational fall nothing is moving very fast. Where does
the
energy come from to turn all this reinforced concrete into dust? It is
difficult to know the exact amount of energy it would take to reduce a
four inch
thick by almost one acre slab of concrete to a fine powder, but it is
clearly
very large. The chemical bonds holding the concrete together are very
strong, I
would guess several orders of magnitude greater than the gravitational
energy of
a floor falling through one or several stories. And yet the collapse
occurs in
about 9 seconds, only slightly more than an unresisted free fall from
the same
height, indicating that there was very little resistance.
The floors themselves are quite robust. Each one is 39" thick; the top
4" is a
poured concrete slab, with interlocking vertical steel trusses
underneath. This
steel would absorb a lot of kinetic energy by crumpling as one floor
fell onto
another. And yet we see a very fine dust being blown very energetically
out to
the sides as if the entire mass of concrete (about 400,000 cubic yards
for the
whole building) were being converted to dust.
Puzzling Evidence: the Videos
The video "--=Ground level closeup of WTC South Tower collapse and
escape from
dust cloud.avi" shows the WTC south tower very soon after it starts to
collapse,
and shot from almost underneath the building. (You can see a lot more
if you can
slow it to .25X or go frame-by-frame.) At the very start of the clip
you can see
how perfectly even the collapse is, advancing with what look for all
the world
like rows of explosions progressing in a perfectly straight line around
the two
sides of the building that you can see, and advancing down in an
extremely
uniform way. As the demolition wave advances there is only dust and
smoke where
the top of the building used to be, and a great quantity of dust mixed
with
small pieces of structural steel is ejected out horizontally and quite
rapidly.
To account for this very rapid ejection of debris without the use of
high
explosives, especially in the early stages of the collapse, seems quite
impossible.
If you look closely as the wave travels down it seems to spare the
corners,
perhaps letting them lag behind to help keep the implosion aligned. The
demolition wave is clearly advancing ahead of the actual collapse of
the
structure, and speeds up as it travels down. The delays between
demolition
charges would have to be very precisely controlled to create this
effect,
suggesting to me that each floor was wired to a separate detonator,
with control
of the sequencing most likely done remotely. This would also allow the
collapse
to be triggered from the point of impact of the plane to make it look
more
realistic. Such sequencing could easily be done from a laptop connected
wirelessly to the towers, as long as each floor could be detonated
separately.**
Soon the photographer is running away to escape the dust cloud, holding
the
video camera at his side and pointing back. As he runs you can see an
enormous
cloud of dust chasing people down several blocks of the surrounding
streets. The
cameraman and the people with him are running full tilt to get away
from the
dust flow, which seems to rapidly fill all the streets for a several
block
radius around the site. ("Close-up views of huge dust cloud from 1st
collapse.mpg" also shows an interesting view of the immense pillar of
dust where
the South Tower had been as it pours down and races out along the
surrounding
streets.)
The other striking thing visible at the beginning of the clip is how
much very
fine concrete dust is ejected from the top of the building very early
in the
collapse. Since it should at most be accelerating under gravity at 32
ft. per
second per second, things would actually be moving quite slowly at
first,
reaching about 200 mph at the end of the ~1400' fall if nothing slowed
it
down. It is very hard to imagine a physical mechanism to generate that
much
dust with concrete slabs bumping into each other at 20 or 30 mph. And
the
extreme fineness - I have heard it described as like talc - and
uniformity of
the dust makes its origin quite puzzling.
This huge amount of very fine dust seems to virtually fall in place,
much of it
within the outlines of the former building. This created a pyroclastic
flow, or
perhaps more properly a turbidity current: a slurry of dust and air
much denser
than the air around it, that can accelerate to considerable speeds as
it falls.
This is the dense cloud that chases the cameraman down the street for
several
blocks, and can be seen in several of the videos. From what I
understand the
surrounding area for several blocks radius was covered by several
inches of very
fine concrete dust, which would seem to account for most of the
concrete in the
structure. And there seem to have been very few macroscopic chunks of
concrete
found at the sites, much less the pile of broken but not pulverized
floors that
one might reasonably expect to find after the dust cleared.
The Afterglow
This is perhaps the strangest feature of the collapse: in both
collapses, the
videos show a bright glow that develops as the bulk of the dust cloud
hits the
ground. A good example of this is "Close and medium view north tower-
immense
dust cloud and strange afterglow.mpg". At 45 sec., as the dust cloud
from the
North Tower collapse hits the ground, there is a sudden very bright
glow that
develops. It may seem at first that this is some kind of video
artifact, but a
similar glow is seen in several views, and occurs at the same point in
the
collapses (see "Both collapses - bright afterglow at 1min 07sec.mpg").
At about
16 sec. Into "South tower of WTC collapse from north, then closeup.mpg"
we see
the beginning of this glow after the South Tower collapse, but the clip
abruptly
cuts away before it is well established.
"Bright afterglow of south tower collapse.avi" starts after the South
Tower has
fallen, but a very bright and persistent glow can be seen where it had
been.
The beginning of "Both collapses - bright afterglow at 1min 07sec.mpg"
shows the
South Tower afterglow, and the sudden "ignition" of the North Tower
afterglow at
1 min. 07 sec., which is so bright that it almost burns out the image.
I have no explanation to offer for this effect, and have heard no
accounts of it
being seen by witnesses. Is this something that shows up on video (near
UV?)
but is not visible to the naked eye? All I can say is that it seems to
be real,
and occurs with both collapses.
** Actually the sequence of the south tower collapse is a bit strange.
(See the
video clip "--=Close-up of south tower collapse.mpg") First we see the
top of
the building start to tip to one side as a monolithic block, which we
would
expect to continue to rotate and topple to the side. Instead, almost as
soon as
it starts to tip, the building below it starts to collapse, allowing it
to drop
straight down. There are very visible rings of explosions that start at
the
level where the building has begun to tip and travel rapidly down the
building.
And instead of continuing to topple to the side, the top portion
actually
telescopes into itself at the same time that it sinks effortlessly into
the
building beneath it. Before it disappears into an immense dust cloud,
we see
the distance between the roof and the bottom of the upper section
actually
collapse to less than half its original height. This is especially
remarkable
because it is essentially in free fall at this point, so there should
not be any
internal forces causing it to collapse on itself.
PlaguePuppy?Download
attached AVI file: --_ground_level_closeup_of_wtc_south_tower_collapse_and_escape_from_dust_cloud.avi
Download attached MPG file: both_collapses_-_bright_afterglow_at_1min_07sec.mpg
Download attached AVI file: bright_afterglow_of_south_tower_collapse_.avi
Download attached MPG file: close_and_medium_view_north_tower-_immense_dust_cloud_and_strange_afterglow.mpg
Download attached MPG file: close-up_views_of_huge_dust_cloud_from_1st_collapse.mpg
Download attached MPG file: south_tower_of_wtc_collapse_from_north__then_closeup.mpg
View
comments only
Another view of "spire" collapse - video
by plaguepuppy
11:37am Wed Oct 2 '02
http://images.indymedia.org/imc/ontario/dustspire-view.gif
Search the archives for political-research at http://www.terazen.com/
Subscribe to the RSS feed for political-research at http://rss.groups.yahoo.com/group/political-research/rss
SPONSORED LINKS
YAHOO! GROUPS LINKS
