Venezuelan towers that collapsed in the quakes appear to have rebar ties bent to 90 degrees, not the required 135

The towers, each more than eight stories with at least 240 apartments, were ordered by Hugo Chávez in 2011 and built in five complexes by OPPPE, a presidential agency in charge of special plans and projects. They went up in about a year, with crews working two or three shifts a day, according to a blog by the office's former director, Francisco Sesto. The government has not released a full death toll. CNN reported that thousands of residents likely died in the twin quakes, of magnitude 7.2 and 7.5.

Venezuela's 2006 code required stirrups in La Guaira high-rises to be bent to 135 degrees, a detail meant to keep ties from breaking open or slipping loose in an earthquake. CNN verified over 40 images and clips that show stirrups, and few of them show a clearly correct bend. A March 2012 inspection photo at the complex called OPPPE 27 appears to show the defect in a tower foundation. All four towers there fell. Engineer Kit Miyamoto, whose team of about 100 engineers is assessing buildings for the Ministry of Public Works, told CNN the problem was widespread in La Guaira rubble, in private buildings as well as public ones.

Footage from at least three collapsed complexes shows deep rust on rebar, and Miyamoto estimates about half the collapsed buildings in the area had corrosion. Two workers on one complex said in a New York Times interview that the crew mixed other products into the concrete to stretch it. The Times found no visible shear walls. Engineers who reviewed the images said a direct cause will be hard to prove.

A government commission is testing material from nearly 100 buildings, its president, Francisco Garcés, told CNN. At OPPPE 25, where five of seven towers survived and were then evacuated, a 2012 photo shows the same 90-degree bends. Sesto did not answer CNN. He told the Times it made little sense to focus on a few government buildings when hundreds of private ones also fell.