The Pentagon Attack
At around 9:39 AM,
after both towers had been
but before either had
a 757 thought to be
approached the Pentagon.
Having flown over the capital from the north,
it ultimately approached the west block of the Pentagon
from the southwest, after making a 270-degree turn
while descending 7000 feet.
The jetliner was less than 100 feet overhead as it
swooped over stalled traffic on the highway
adjacent to the large lawn and heliport on the west
side of the sprawling building. Some
said that the plane banked left and its left wing
hit the heliport.
Witnesses variously describe the plane
crashing into the facade,
hitting the ground in front of the facade it and exploding,
disappearing into the building,
and being swallowed by rings of smoke.
They agree that there was a huge explosion and fireball,
and torrents of smoke in the wake of the strike.
Some describe small fragments of aircraft raining down.
Some onlookers were surprised at the lack of apparent aircraft debris
in front of the Pentagon, and some remarked that the impact hole
seemed small given the size of the jetliner.
Similar observations based on photographs of the crash zone
shortly after the attack have fueled controversy over the attack, and
that something other than a 757 hit the Pentagon that day.
A section of the building
above the heavily damaged first and second floors
collapsed about 20 minutes after the initial attack.
No Impact Photos
In the minutes following the attack,
the FBI confiscated from nearby businesses video recordings
that might have captured the attack.
In contrast to the well-documented tower crashes and collapses in Manhattan,
the story of Flight 77 crashing into the Pentagon
had no corroborating pictures,
only eyewitness accounts and photos of the building's damaged facade.
And those post-collapse photos convinced many researchers that
no Boeing 757 crashed into the building.
In early 2002, the Pentagon released a series of five images
from a security camera, supposedly showing the moments of impact.
However, the images show
evidence of manipulation.
s u m m a r y
This highly original article breaks with the orthodoxy in the
skeptics' community about the Pentagon attack,
by suggesting that the popular drone and/or missile attack theories
were cultivated by the perpetrators to create a "false dialectic".
Stanley and Russell suggest that the damage to the building
was accomplished with internal demolitions rather than an aerial assault,
and provide support for Eastman's theory that Flight 77 overflew
Faint Seismic Signal
Both of the tower impacts were recorded by seismic observatories,
and so was the crash of Flight 93.
In contrast, scientists had difficulty finding the seismic signal
for the Pentagon crash.
e x c e r p t
Since the time of plane impact at the Pentagon had often been reported
with large scatter, the United States Army contacted us to inquire
whether we could obtain an accurate time of the Pentagon attack
on September 11, 2001 based upon our seismic network. We analyzed
seismic records from five stations in the northeastern United States,
ranging from 63 to 350 km from the Pentagon. Despite detailed analysis
of the data, we could not find a clear seismic signal. Even the closest
station (Delta = 62.8 km) at Soldier's Delight, Baltimore County,
Maryland (SDMD) did not record the impact. We concluded that
the plane impact to the Pentagon generated relatively weak seismic signals.
However, we positively identified seismic signals associated
with United Airlines Flight 93 that crashed near Shanksville,
Somerset County, Pennsylvania. The time of the plane crash was
10:06:05 +/- 5 (EDT).
A page once on the geo.arizona.edu website contained a brief report
with a seismogram showing a clear signal labeled
"Arrival of the seismic energy from the collision [of Flight 77]".
(See seismogram image in right margin.)
Curiously, later versions of this report contained a retraction and
referred to Dr. Kim's report:
... preliminary analysis indicated that the impact might have produced
a seismic signal that was recorded at the USGS station CBN, but later
work showed this not to be the case. The best work on the forensic
seismology of the impact is by Dr. Kim ...
Some researchers have seized on Kim's report as evidence that
no 757 crashed at the Pentagon.
However this is not the conclusion of the scientists who wrote the report,
and such an inference is not justified for a number of reasons.
- The interpretation of seismic data is a complex subject,
depending on details of geology between the event and the station,
among other things.
The fact that obvious signals were generated by
767s ramming into steel towers in Manhattan anchored to granite bedrock
should not lead us to expect that a 757 crashing into a heavy
masonry wall of a sprawling building on an alluvial plain
of the Potomac River.
- The seismic stations whose data was analyzed in the report
were all at least 35 miles from the Pentagon,
much further than the stations that
recorded events at the World Trade Center were from Lower Manhattan.
- Of the various types of seismic disturbances that are recorded
by seismic recording stations, plane crashes apparently generate
only strong S-waves -- vibrations in which the displacement is
perpendicular to the ground.
The strength of an S-wave produced by a plane crash would presumably
be highly dependent on the inclination of the plane's trajectory
from the horizontal plane of the ground.
Since by all accounts, the Pentagon attack plane approached at
a very shallow inclination, perhaps at an angle of less than 10 degrees,
we would expect any S-waves generated by the impact to be very weak.
Forensic seismology analysis of the terrorist attacks on the pentagon, geo.Arizona.edu,
page last modified: 2010-12-18