The World Trade Center (WTC) twin towers were destroyed by controlled demolitions.
This is how the collapses may have appeared to non-experts, but demolition experts point out many differences:
• Demolition professionals always blow the bottom floors of a structure first, but the WTC tower collapses began at the upper levels, where the planes hit the buildings.
• Non-experts claim that debris seen blowing out of windows was evidence of explosive charges, but experts identify this as air and light office contents (paper, pulverized concrete, etc.) being forced out of windows as floors collapsed on each other.
• Demolition firms had very sensitive seismographs operating at other sites in Manhattan on September 11. None recorded signs of any explosions prior to the tower collapses. Instead, seismic spikes were noted when debris began hitting the ground.
• Cutting away walls, insulation, plumbing, and electrical conduits to place numerous charges on the towers’ structural columns in advance would not have gone unnoticed.
• Clean-up crews found none of the telltale signs of controlled demolitions that would have existed if explosive charges had been used.
World Trade Center building 7 was destroyed by a controlled demolition.
• This allegation was fueled by a comment by the WTC owner that, after WTC 7 was judged to be unstable, he recommended pulling a group of firefighters out of the building, using the phrase “pull it” in reference to the contingent of firefighters.
• Conspiracy theorists have interpreted the “pull it” remark as slang for demolishing the building with explosives. But demolition experts say “pulling” a building means attaching long cables to a weakened structure and literally pulling it down with bulldozers and other powerful machinery — not using explosives.
• The audio tracks of video recordings of the WTC collapse showed no evidence of the extremely loud sounds that would have indicated the use of explosives. Also, seismographs recorded no telltale spikes or anomalies.
• An exhaustive three-year investigation by the National Institute of Standards and Technology (NIST) concluded that fires caused by the collapse of the nearby WTC north tower caused fires that burned out of control in WTC 7. These fires caused steel beams to expand and buckle, leading to the collapse of the building.