OKC Bombing: Expert Analysis

For most of us, the first images of the enormous damage done to
Oklahoma City's Alfred P. Murrah Federal Building in the April
19th bombing were overwhelming.  Besides the terrible toll of
death and suffering, the news photos and live video recordings of
the physical destruction of the blast to the building itself
showed a devastation completely beyond the ken of Americans
unaccustomed to the ravages of war and terrorism.  Lacking mental
reference points to frame the enormity of this destruction, and
recoiling from the barbarity of the deed, our primary reactions
were visceral, emotional.


Beyond Emotion

However, for many men accustomed by profession to dealing with
explosives, the aftermath of the explosion brought troubling
cerebral reactions as well.  When the smoke cleared to reveal the
now-familiar gaping cavity, they were faced with severe cognitive
dissonance: The reported "facts" did not match observable
reality. For Brigadier General Benton K. Partin (USAF, Ret.), the
"facts" contradicted not only the laws of physics but a lifetime
of experience as well.

As one of the world's foremost experts in both the theoretical
and practical applications of explosives technology, General
Partin possesses virtually unparalleled qualifications to
authoritatively evaluate the public-source information available
on the bombing.  When we contacted General Partin shortly after
the explosion, he expressed very strong misgivings about the
official story_that the horrendous damage to the federal building
had been caused solely by the reported truck bomb.  Too many
facts, he said, "simply just don't add up" to support that
convenient explanation.  However, unlike other "experts" who were
offering instant analyses and publicly speculating about various
bombing scenarios, he had a great deal of investigating to do
before presenting a definite opinion.  After three weeks of
intensive examination of the evidence, he was ready.  However, a
major problem loomed: Authorities were planning to demolish the
still-standing remains of the building.

In a letter to Oklahoma Senator Don Nickles, which he personally
delivered to the senators Washington office on May 1 8th.
General Partin appealed for action to delay destruction of the
Murrah building until a full, independent forensic examination of
the site could be conducted.  In that letter, which was also
personally delivered to the offices of 23 other senators and some
30 members of the House, the general wrote:

I am concerned that vital evidence will soon be destroyed with
the pending demolition of the Federal Building in Oklahoma City.
From all the evidence I have seen in the published material, I
can say with a high level of confidence that the damage pattern
on the reinforced concrete superstructure could not possibly have
been attained from the single truck bomb without supplementing
demolition charges at some of the reinforced column bases.  The
total incompatibility with a single truck bomb lies in the fact
that either some of the columns collapsed that should not have
collapsed or some of the columns are still standing that should
have collapsed and did not.

General Partin offered what he called an "oversimplified analogy"
to illustrate his point.  The pattern of damage to the reinforced
concrete columns was so totally at odds with the laws of physics
and explosives experience, he said, that it "would be as
irrational or as impossible" as a situation in which a 150 pound
man sits in a flimsy chair causing the chair to collapse, while a
man weighing 1,500 pounds sits in an identical flimsy chair and
it does not collapse.

"To produce the resulting damage pattern on the building," wrote
Partin. "there would have to have been an effort with demolition
charges at column bases to complement or supplement the truck
bomb damage.  A careful examination of the collapsed column bases
would readily reveal a failure mode produced by a demolition
charge.  This evidence would be so critical, [that] a separate
and independent assessment should be made before a building
demolition team destroys the evidence forever."


Sterling Credentials

Another "wacko conspiracy theory"?  Absolutely not.  What makes
General Partin's position so noteworthy and compelling is his
methodical, scientific analysis combined with his sterling career
and credentials.  Twenty-five of his 31 years of active service
in the Air Force were involved in intensive research, design,
testing, and management of weapons development at all levels.
This included extensive hands-on work at the Ballistic Research
Laboratories and field testing of all types of explosive devices
on a broad spectrum of structures and targets.  He served as
commander of the Air Force Armament Technology Laboratory and was
the first chairman of the joint service Air Munitions
Requirements and Development Committee in the Office of the
Secretary of Defense.  This committee was responsible for the
harmonization of air munitions requirements and development for
the Army, Navy, Air Force, and Marine Corps.

General Partin is recognized as a long-time guiding force behind
our modern precision-guided weapons and related target
acquisition, target designation, and guidance systems.  He
initiated, fought for, and helped get into service many weapons
now in our nation's munitions inventory.  As the Air Force System
Command's Special Assistant for Advanced Weapons, he started the
earliest focused energy weapons program in 1957, wrote the first
contract for a coherent optical frequency generator (i.e. Laser)
in 1958, and pushed for development of a functional "Star Wars"
missile system decades before it became the hotly debated issue
in the 1980s.  General Partin was a Command Pilot and Command
Missileman, a Distinguished Graduate of the Air War College, a
recipient of the Distinguished Service Medal and thrice a
recipient of the Legion of Merit.  He received a B.S. degree in
chemical engineering, an M.S. in aeronautical (armament)
engineering, and completed academics for a Ph.D. in operations
research and statistics.

In short, General Ben Partin is not just your average "expert,"
and his reasoned analysis deserves a careful examination, instead
of snide dismissal as "just another Elvis sighting"_a response
typical of the media elite's and "sophisticated" political
savants.


Single Bomb Problem

"When I first saw the pictures of the truck bomb's asymmetrical
damage to the Federal Building in Oklahoma City," Partin wrote in
his letter, "my immediate reaction was that the pattern of damage
would have been technically impossible without supplementing
demolition charges at some of the reinforced concrete column
bases (a standard demolition technique)."

Partin then explained some of the basic physics problems
associated with the single-truck-bomb scenario: "First, blast
through air is a very inefficient energy coupling mechanism
against heavy reinforced concrete beams and columns.  Second,
blast damage potential initially falls off more rapidly than an
inverse function of the distance cubed.  That is why in
conventional weapons development, one seeks accuracy over yield
for hard targets.  Columns in large buildings are hard targets
for blast."

This principle was very well illustrated, he noted, in the
bombing of the World Trade Center.  In that case, General Partin
told THE NEW AMERICAN, a similar truck bomb blew a large cavity
through several floors above and below the bomb but caused very
limited lateral damage.  "The floor areas directly above and
below the bomb were accelerated by the blast force and completely
stripped away, but you can see in the published photos [as, for
instance, in Time magazine of March 8, 1993] that the column is
still standing there in the middle of the cavity."

"The entire building in Oklahoma City could have been collapsed
with relatively small demolition charges against the base of the
columns and with even less explosives if linear cavity cutting
charges had been used," General Partin wrote in his letter to
Senator Nickles.  "I know of no way possible to reproduce the
apparent building damage without well-placed demolition charges
complementing the truck bomb damage."  As the final demolition of
the Murrah building on May 23rd demonstrated, a very small amount
of explosives is required to bring down a building_if the
demolition charges are strategically placed within, or in direct
contact with, the key structural points of the building.


Detailed Account

Partin provides a careful look at the Murrah building' s
structure in the following description and accompanying diagram:

From published photographs, the basic building structure is three
rows of eleven columns each.  The four corner columns have
external clamshell like structure for air ducts, etc., as
revealed in magazine photographs of the damage.  If we label the
column rows A, B, & C, from front to back, and number the columns
1 through ll from left to right, then published pictures show
columns A2, A3, A4, A5, A6, A7, A8, and B3 collapsed, essentially
vertically.  The 5-1-95 U.S. News and World Report and other
damage photos show a very large reinforced concrete header at the
second floor level of column row A.  Much larger columns extend
from the header down for the odd numbered columns i.e. A3, A5,
A7, A9.  The even numbered columns extended down to the header
with apparently reinforced concrete joints.  The heavy, odd-
numbered columns were all accessible from the sidewalk, but
collapsed Column B3 is well inside the building.  If the truck
bomb was not nearest to column A3 then a single truck bomb theory
would be even more questionable.

A rough sketch of the Federal Building and its columns shown [on
page 16] has superimposed circles of roughly equal levels of
damage potential which drop rapidly (exponentially) as they get
further and further away from the truck bomb (Assuming the damage
potential falls off as an inverse function of the distance cubed
then the damage potential at circle two would be one-eighth that
at circle one, the damage potential at circle three would be one-
twenty-seventh that at circle one. etc. _Editor.).  If we
consider the damage potential at column A3, the closest column to
the truck on the sketch, to be damage potential level one at
distance one, then moving out further multiples of that distance,
the destructive potential drops off as an exponential function of
one over the number of multiples.  Therefore at circle "1" you
have a decisively destructive force that brought down column A3.
At circle "2" the destructive potential is marginal for row A;
column A5 came down but the heavier column A1 did not.  Inside
circle "3" level, column B3 came down; but columns B2 and B4 did
not come down.  Therefore circle 3 is marginal for the columns in
row B which are much smaller than the odd numbered columns in row
A.  Moreover, the higher numbered columns in row A are seeing
more of a lower side-on pressure than column row B.

For any odd-numbered column failure in row A, the adjacent even
numbered columns would also necessarily fail.  The still
standing, extended, cantilevered header, from A 11 to almost back
where A8 was, is probably due to the seesaw effect, over A7 as an
instant pivot point, as the A row collapsed sequentially to the
right by either the truck bomb or supplemental demolition
charges.  If the header at column A8 had survived explosives,
cascading floors could have caused it to fail.  However, one
would not expect such a long remaining cantilever.


Beyond Credulity

From what has been stated thus far, and considering only the
potential damage from the truck bomb, Partin notes, there are a
number of irreconcilable problems:

If column A7 was brought down by the truck bomb, then most of the
much smaller columns B1, B2, B4, B5, and B6 should not be
standing, but they are.

A truck bomb that could not bring down columns B1, B2, B4, and B5
could certainly not be expected to collapse the lower two floors
of a much heavier column A7.  Columns A7 and A8 should still be
standing, but they are not.

For a truck bomb of the size and composition reported, to be able
to reach out on the order of 60 feet and collapse a reinforced
column base the size of column A7 is beyond credulity.  Even
bringing down B3 at its range is highly suspect.  Glass and
plaster can be broken a long way off with explosives, but not
heavy, reinforced, concrete columns.

However, he observes, if demolition charges were used to
complement the truck bomb, the above problems disappear. But is
such an explanation practicable?  Yes, he answers, for the
following reasons:

Columns A3, A5, A7, and A9 were readily accessible from the
sidewalk or the curb.

Adequate demolition charges could easily and quickly have been
put into position.

A simple primacord interconnect (fuse) would not look too
different from a piece of coaxial cord.

If the bomb attack was intended to do more than deface the
building, then inside help or loose security may have permitted
placement of a charge at column B3


Corroborating Opinions

Seven other explosives experts we interviewed endorsed General
Partin's analysis as the most coherent and logical explanation of
an otherwise unexplainable dilemma.  These included professional
civilian demolitionists. scientists, and bomb specialists who
currently serve, or previously served, in military and police
units.

Sam Gronning, a licensed, professional blaster in Casper, Wyoming
with 30 years experience in explosives, told us the Partin letter
"states in very precise technical terms what everyone in this
business knows: No truck bomb of ANFO [ammonium nitrate fuel oil]
out in the open is going to cause the kind of damage we had
there" in Oklahoma City. "  In 30 years of blasting, using
everything from 100 percent nitrogel to ANFO, I've not seen
anything to support that story."

Gronning notes that he recently detonated an ANFO charge more
than three times the size of the one reportedly responsible for
the Oklahoma destruction.  "I set off 16,000 pounds of ANFO and
was standing upright just 1,000 feet away from the blast," and
even a bomb that size would not have caused the extent of, or
pattern of, destruction experienced in the April l9th explosion,
he said.

Dr. Rodger Raubach, who took his Ph.D. in physical chemistry and
served on the research faculty at Stanford University, says,
"General Partin's assessment is absolutely correct.  I don't care
if they pulled up a semi-trailer truck with 20 tons of ammonium
nitrate; it wouldn't do the damage we saw there."

Raubach, who is the technical director of a chemical company,
explained to THE NEW AMERICAN that the detonation velocity of the
shock wave from an ANFO explosion is on the order of 3,500 meters
per second.  In comparison, military explosives generally have
detonation velocities that hit 7,000 to 8,000plus meters per
second.  Things like TNT have a detonation velocity of about
7,100 meters per second.  The most energetic single-component
explosive of this type, C-4_which is also known as Cyclonite or
RDX_is about 8,000 meters per second and above.  You don't start
doing big-time damage to heavy structures until you get into
those ranges, which is why the military uses those explosives."


Dramatic Drop-Off

Several very qualified experts we interviewed, however, took
issue with the general's assessment. Jim Redyke of Dykon Inc., a
demolition outfit in Tulsa, Oklahoma, has imploded hundreds of
buildings and was a consultant at the Oklahoma City bomb site.
Redyke told THE NEW AMERICAN that ' this was consistent with the
kind of damage (one would expect) from this size of bomb.  This
was a huge bomb!"

An Army Special Forces officer with explosives experience
seconded this opinion, mentioning that nearly identical damage
was done in the two 1983 Lebanon incidents, in which truck bombs
were used to collapse the U.S. Marine barracks and the U.S.
embassy.

Responding to these critiques, General Partin observed that it is
not surprising that even many people with a professional
knowledge of explosives might be unduly impressed with the size
and explosive wallop of the bomb and fail to reckon with the
fundamental laws of physics.  "Yes, this was a big bomb with a
big blast," agreed General Partin.  "But most people fail to
appreciate how inefficient a blast is in air and how dramatically
its destructive potential drops off just a few feet from the
explosion.  In the Lebanon barracks bombing, the truck was driven
directly under the building so that the explosion had maximum
effectiveness against a much lower building with much smaller
columns."

Demolitionists, Partin pointed out, rarely deal with the size of
explosive charge used in the Oklahoma City truck bomb.  "They use
a couple hundred pounds of explosive that may be distributed
among dozens_or hundreds_ of small charges detonating
microseconds or milliseconds apart."  Those charges placed
directly on, or in, a structure, "propagate a wave of deformation
nearly a million pounds per square inch that pulverizes concrete,
which has a yield strength of only about 50,000 pounds per square
inch."  But if you put just a few feet of air between the
explosive and the target, the blast wave quickly drops from
millions of pounds per square inch to thousands of pounds per
square inch.  It still makes an impressive boom, but has very
little effect on heavy reinforced concrete.

It was this fact of physics which occupied much of Partin's
attention in weapons development for the U.S. Armed Forces and
made him an untiring crusader for the development and deployment
of precision-guided munitions.  General Partin cites accounts of
the many laboratory and field tests he ran using large-yield
bombs on numerous structures and targets.  That experience, he
says, together with all the known history of modern warfare shows
that bombs can detonate close to a hard structure without causing
severe destruction.


Advice to Congress

In his letter Partin strongly urged "that the U.S. Congress take
steps to assure that evidence in Oklahoma City be independently
evaluated by a collection of demolition experts from the private
sector before the building is demolished.  It is easy to
determine whether a column was failed by contact demolition
charges or by blast loading."  The counsel for the defense did
obtain a temporary delay of the demolition in order to have a
team of experts examine the sight, but they have, as yet,
revealed none of their findings.  According to news coverage of
the inspection by the defense team, it was a very brief
examination and much of the most important evidence had already
been removed or was still covered by rubble.

The most critical evidence that has to be assessed, said Partin,
would be the collapsed column bases, especially those of columns
A9 and B3.  "If a satchel charge or linear cavity cutting charge
or other explosive were used on the columns," he explained to THE
NEW AMERICAN, you would find a very distinctive signature."  Is
it likely that the defense team would have been able to make that
kind of visual examination during its inspection?
"Unfortunately, it doesn't look like the investigators had the
time or opportunity.  It is doubtful that they had access to the
critical points."

Because of the care taken by the demolition team to cover the
remaining debris, and the use of minimal demolition charges,
verification of General Partin's analysis should still be
possible _ if the evidence has not been deliberately destroyed.
In addition, there are still many other related pieces of
evidence to consider.  As reported in the June 12th issue of THE
NEW AMERICAN (' Were There Two Explosions"), the seismograms
recorded independently by two seismometers in the Oklahoma City
area on the morning of April 19th provide strong evidence of more
than one blast.

There is also the matter of conflicting accounts concerning the
discovery of other explosive devices at the Murrah building.
Those who were present at the blast site during the early hours
of the rescue, as well as the millions of viewers watching on
television, remember the fear and horror they experienced when
police and fire authorities announced that an additional bomb (or
bombs) had been discovered in the still smouldering building.
Rescuers were forced to leave trapped victims and run for safety.
Official accounts vary as to what object (or objects) actually
were found to cause this alarm.  Some say nothing was found.
Others claim that it was a case of false alarm caused by a
"dummy" bomb used as a teaching aid by the ATF.  Still other
reports assert that a military bomb squad removed an unexploded,
but live, device (or devices).  THE NEW AMERICAN is continuing to
investigate these and many other still-unresolved and conflicting
"facts" in this "worst terrorist attack on American soil." _

_ William F Jasper
THE NEW AMERICAN / JUNE 26, 1995

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