Why did the second World Trade Tower to be hit collapse before the first one hit?

Answer 1

Because it lost more critical support systems - the plane hit the building at a different angle, crippling the tower more severely than the other.

They discovered later major flaws in the materials and construction of the towers. Some shortcuts too...sad.

PBS just ran a special on this...

Answer 2

The collapse of the World Trade Center

Main article: Collapse of the World Trade Center

An illustration of the World Trade Center 9-11 attacks with a vertical view of the impact locations. Many architects and structural engineers have analyzed the collapse of the Twin Towers.
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An illustration of the World Trade Center 9-11 attacks with a vertical view of the impact locations. Many architects and structural engineers have analyzed the collapse of the Twin Towers.

Three buildings in the World Trade Center Complex collapsed due to structural failure on the day of the attack. The south tower (2 WTC) fell at approximately 10:05 a.m., after burning for 58 minutes in a fire caused by the impact of United Airlines Flight 175 at 9:03 a.m.. The north tower (1 WTC) fell at 10:28 a.m., after burning approximately 103 minutes in a fire caused by the impact of American Airlines Flight 11 at 8:45 a.m.. A third building, 7 World Trade Center (7 WTC) also collapsed at 5:30 p.m., after burning for at least 70 minutes and being heavily damaged by debris from the Twin Towers a short distance away. [13]

A federal technical building and fire safety investigation of the collapses of the Twin Towers and 7 WTC has been conducted by the United States Department of Commerce's National Institute of Standards and Technology (NIST). The goals of this investigation, completed on April 6, 2005, were to investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the WTC disaster. The investigation was to serve as the basis for:

* Improvements in the way buildings are designed, constructed, maintained, and used
* Improved tools and guidance for industry and safety officials
* Revisions to building and fire codes, standards, and practices
* Improved public safety

September 13, 2001: A New York City firefighter looks up at what remains of the South Tower.
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September 13, 2001: A New York City firefighter looks up at what remains of the South Tower.

The report concludes that the fireproofing on the Twin Towers' steel infrastructures was blown off by the initial impact of the planes and that, if this had not occurred, the towers would likely have remained standing. The fires weakened the trusses supporting the floors, making the floors sag. The sagging floors pulled on the exterior steel columns to the point where exterior columns bowed inward. With the damage to the core columns, the buckling exterior columns could no longer support the buildings, causing them to collapse. In addition, the report asserts that the towers' stairwells were not adequately reinforced to provide emergency escape for people above the impact zones. NIST stated that the final report on the collapse of 7 WTC will appear in a separate report.[52]

Answer 3

The first tower was struck at the 90th floor and the second was struck at about the 68th floor. So there was a lot more weight pushing down on the South tower, the second hit.
When the trusses, used to hold up each floor started to buckle from the intense heat of the fires, the weight pressing down caused the second tower to collapse first.

Answer 4

It had to do with the way the plane hit each tower, where each burning plane was positioned and how hot each one's fire was. What caused the buildings to collapse was the heat of the fuel burning melted the main support of one floor and when one floor collapsed the weight kept the whole thing going down. so I guess the second plane was either positioned better or burning hotter to make the building collapse first...

Answer 5

It had to do with where the plane hit and the amount of fuel in that plane. It hit lower than the first plane causing more to burn upward. This increased the heat. The heat from the first crash was traveling into the second as well.

Answer 6

Becuase one trade center was made earlier than the other that was made less sturdy.So the vibrations in the ground would cause it to collapse.

Answer 7

Depends which exact part of the structure it hit, it probably hit a very important part which weakened structural integrity.

Answer 8

from the top of my memory it's becouse the plane damaged the core, while of the other tower the plane stoped at the office ares. (I'm an architect)

Answer 9

Obviously the first impact didnt do as much damage as the second impact.

Answer 10

i cant remember exactly but i guess the plane hit at a lower level