Some engineers looking at the failure of a 13-story condo tower in Florida said the collapse appeared to have begun somewhere near the bottom of the building.

By James Glanz, Anjali Singhvi and Mike Baker

The investigation into what may be the deadliest accidental building collapse in American history has just begun, but experts who have examined video footage of the disaster outside Miami are focusing on a spot in the lowest part of the condominium complex — possibly in or below the underground parking garage — where an initial failure could have set off a structural avalanche.

Called “progressive collapse,” the gradual spread of failures could have occurred for a variety of reasons, including design flaws or the less robust construction allowed under the building codes of four decades ago, when the complex was built. But that progression could not have occurred without some critical first failure, and close inspections of a grainy surveillance video that emerged in the initial hours after the disaster have given the first hints of where that might have been.

Sequence of the Collapse

Video captured from south of the building appears to show it collapsing in stages.

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