Engineer explores causes of Miami building collapse

Families and friends of the 159 people missing after the collapse of a condo building in a Miami suburb were clinging to hope on Friday, as rescue workers sifted through a mountain of debris for signs of life, having found four dead so far.

Libby Hogan reports.

Matthys Levy is a retired structural engineer.

He is also an author and wrote the book 'Why Buildings Fall Down: How Structures Fail'.

He told Reuters that clues to what caused the collapse could be found in the building's foundation.

"The bottom failed somewhere and the whole building pancaked down.

So one should look at what happened, what the condition was of the material at the bottom of the building.

And that will only be discovered once they start looking at the wreckage."