Conclusions on World Trade Center 7?
- Shyam Sunder, here in 2002
- What caused World Trade Center 7 to collapse
- First time a fire caused the total failure of a skyscraper
- 7 went down about seven hours after the twin towers crumpled
- The NIST investigators ruled out the possibility that an explosion inside WTC 7 brought down the building
The 47-story trapezoid-shaped building sat north of the World Trade Center towers, across Vesey Street in lower Manhattan. On Sept. 11, it was set on fire by falling debris from the burning towers, but skeptics have long argued that fire and debris alone should not have brought down such a big steel-and-concrete structure.
Federal investigators said Thursday they have resolved a lingering question from the Sept. 11, 2001, terrorist attacks: What caused World Trade Center 7 to collapse? They determined the building, which sat north of the World Trade Center towers, was brought down by fire started by debris from the twin towers.
Federal investigators said Thursday they have resolved a lingering question from the Sept. 11, 2001, terrorist attacks: What caused World Trade Center 7 to collapse? They determined the building, which sat north of the World Trade Center towers, was brought down by fire started by debris from the twin towers.
“The reason for the collapse of World Trade Center 7 is no longer a mystery,” said Dr. Shyam Sunder, the lead investigator on the NIST team.
Investigators also concluded that the collapse of the nearby towers broke the city water main, leaving the sprinkler system in the bottom half of the building without water.
The building has been the subject of a wide range of conspiracy theories for the last seven years, partly because the collapse occurred about seven hours after the twin towers came down. That fueled suspicion that someone intentionally blew up the building in a controlled demolition.
Critics like Mike Berger of the group 9/11 Truth said he wasn’t buying the government’s explanation.
“Their explanation simply isn’t sufficient. We’re being lied to,” he said, arguing that there is other evidence suggesting explosives were used on the building.
Sunder said his team investigated the possibility that an explosion inside the building brought it down, but found there was no large boom or other noise that would have occurred with such a detonation. Investigators also created a giant computer model of the collapse, based partly on news footage from CBS News, that they say shows internal column failure brought down the building.
Investigators also ruled out the possibility that the collapse was caused by fires from a substantial amount of diesel fuel that was stored in the building, most of it for generators for the city’s emergency operations command center.
The 77-page report concluded that the fatal blow to the building came when the 13th floor collapsed, weakening a critical steel support column that led to catastrophic failure.




