Hey, 10 years ago today.
The Bombing of the World Trade Center in New York City
On 26th February 1993, at approximately 12.18 p.m., an improvised explosive device exploded on the second level of the World Trade Center parking basement.
The resulting blast produced a crater, approximately 150 feet in diameter and five floors deep, in the parking basement. The structure consisted mainly of steel-reinforced concrete, twelve to fourteen inches thick. The epicenter of the blast was approximately eight feet from the south wall of Trade Tower Number One, near the support column K31/8. The device had been placed in the rear cargo portion of a one-ton Ford F350 Econoline van, owned by the Ryder Rental Agency, Jersey City, New Jersey. Approximately 6,800 tons of material were displaced by the blast.
The main explosive charge consisted primarily of approximately 1,200 to 1,500 pounds of a home-made fertilizer-based explosive, urea nitrate. The fusing system consisted of two 20-minute lengths of a non-electric burning type fuse such as green hobby fuse. The hobby fuse terminated in the lead azide, as the initiator.
Also incorporated in the device and placed under the main explosive charge were three large metal cylinders (tare weight 126 pounds) of compressed hydrogen gas.
The crime scene and prosecution
On 26th February 1993, at approximately 12.18 p.m., an explosion occurred under the World Trade Center complex in New York City. Early media reports and some telephone com-munications from law enforcement personnel in New York suggested that a generator had exploded. Bomb technician Special Agents from the New York FBI had responded as a first analysis team and their conclusion was that an improvised explosive device had exploded. Subsequent requests to the FBI Laboratory for field support were met with two Special Agent Examiners from the FBI Laboratory Explosives Unit who arrived in New York on 27th February. Initial analyses of the crime scene confirmed that the damage had been caused by an improvised explosive device. Within one week following the explosion, more than 300 law enforcement officers from around the country had sifted through more than 2,500 cubic yards of debris weighing in excess of 6,800 tons, and had pieced together evidence in the most significant international terrorist act ever committed on U.S. soil.
The resulting explosion killed six people and injured more than a thousand. More than 50,000 people were evacuated from the Trade Center complex during the hours immediately following the blast.
The initial inspection on 27th February was described as "a scene of massive devastation, almost surreal". It was like walking into a cave, with no lights other than flashlights flickering across the crater. There were small pockets of fire, electrical arcing from damaged wiring, and automobile alarms whistling, howling and honking. The explosion ruptured two of the main sewage lines from both Trade towers and the Vista Hotel and several water mains from the air conditioning system. In all, more than 2 million gallons of water and sewage were pumped out of the crime scene.
After an initial inspection of the underground parking area, FBI explosive unit personnel were able to determine that a crater had been formed, measuring approximately 150 feet in diameter at its widest point and over five stories deep. The damage done to automobiles, concrete and structural steel, for example, suggested that the explosive had a velocity of detonation of around 14,000 to 15,500 feet per second. It is known that there are several commercial explosives that fall within that range of detonation, including some dynamites, water gels, slurries and fertilizer-based explosives. The explosive damage was more of a pushing and heaving type rather than the damage one would expect from a more brisant shattering and splitting explosive such as TNT or C-4. Also, by an initial assessment of the type of damage and the size of the crater, it was determined that the explosive main charge must have been between 1,200 and 1,500 pounds. When making this type of extrapolation, the explosive expert must consider external factors such as confinement by the target itself, witness materials and structural integrity of the building.
Once the type and amount of explosive had been estimated, it was possible to surmise that the bomb had been too large to transport in a sedan-type automobile, while the ceiling clearance limited the height of the vehicle. By this method of reasonable deduction, the initial opinion was that the explosive device had to have been transported into the Trade Center parking area in either a pickup truck or a van.
During the initial assessment of explosive damage to the complex, it became very clear that the structural integrity of Trade Tower Number One was at risk, and that the Vista Hotel would probably collapse within days if structural steel support was not in place as soon as possible. It was also apparent that structural problems were not the only safety hazard. The raw sewage present could present a biological hazard, as could the asbestos and mineral wool (a level 2 carcinogen), acid and fuel from the automobiles, and small fires caused by short circuits. Another concern was the possibility of pieces of concrete 14 inches thick and as large as a kitchen table falling from 70 feet above. And as one would expect at a bombing crime scene, there were a great many sharp metal fragments from both the building and the vehicles present during the blast.
Before establishing a plan of attack to begin the collection of evidence, other concerns were important. The Port Authority Transportation system, PATH, which operates a train system from New Jersey into New York, a major commuter umbilicus, was damaged by the blast. If the system could not operate on the Monday morning, commuting would be a nightmare. Late on Saturday night, it was decided to evacuate the complex, place seismographic equipment around the damaged area and run a train through the system. Results of this test showed that with minimal structural support, the train could be allowed to run on Monday: one problem solved. Within hours of the blast, OSHA, the Occupational Safety and Health Administration, advised that certain personal safety and breathing equipment must be used by crime scene personnel. OSHA personnel volunteered to conduct personal sessions with every individual and fit dust proof masks. They also provided numerous air quality monitors to determine if the crime scene effort disturbed any hazardous materials.
See remainder of article, with photos, here:www.interpol.int/Public/Publications/ICPR/ICPR469_3.asp |
