The sudden collapse of a building is a shocking and frightening occurrence, a nightmare of falling debris and tumbling bodies. Buildings collapse for various reasons and in different ways. The scale of the disaster can range from the collapse of a single small building to the simultaneous collapse of multiple structures over an extended area, as from an earthquake. The actual experience of those inside a collapsing building, however, may be most affected by whether the building is a skyscraper like the two World Trade Center (WTC) towers, a smaller multistory office building, or a one or two-story home.

An Unthinkable Impact

The two commercial-jet terrorist attacks on the WTC skyscrapers on September 11, 2001, resulted in by far the single worst collapse of buildings in history. Never before had such immense buildings, crowded with thousands of people, fallen so quickly and...