A combination of weak building codes and poor construction are the main reasons for the widespread destruction caused by the magnitude 7.0 earthquake in Haiti, according to a recent damage assessment by a team of earthquake experts and engineers.

The perhaps unsurprising conclusion was outlined in a joint U.S. Geological Survey and Earthquake Engineering Research Institute Reconnaissance Team Report released February 18.

The five-member team studied buildings in Port-au-Prince and communities to the west of the city between January 26 and February 3. Of the 107 buildings in downtown Port-au-Prince surveyed, 28 percent had collapsed and another 33 percent were damaged enough to require repairs, according to the report. A similar survey of 52 buildings in Léogâne found 62 percent had collapsed and 31 percent required repairs.

“Usually when I go to earthquakes I find that the amount of damage is less than what appears on the television,” stated team member Marc Eberhard, a University of Washington civil and environmental engineering professor, in a press release. “In this case it was much more.”

The poverty of the people combined with the density of population and lack of building codes resulted in the widespread devastation, he said.

Reinforced concrete frames with concrete block masonry infill performed especially poorly, according to the report. Buildings with roofs made of lighter materials, such as tin or wood, performed better than those with concrete roofs and slabs.

“These observations suggest that structures designed and constructed with adequate stiffness and reinforcing details would have resisted the earthquake without being damaged severely,” the report stated.

In another assessment of damage from the Haiti quake, a team of more than 500 scientists from around the world examined high-resolution aerial imagery of the earthquake region to learn how many buildings collapsed or were heavily damaged. This new initiative, called GEO-CAN—the Global Earth Observation Catastrophe Assessment Network—was coordinated by ImageCat.

According to an ImageCat description of the process, “an area of some 300 square kilometers has been divided up into squares, and numbers of squares allocated for damage assessment to each GEO-CAN expert. The aerial imagery they are studying shows high-resolution images of houses, public buildings, cars and vegetation with detail that even shows the folds in tents in the temporary encampments. This is compared to imagery taken before the earthquake and buildings that have collapsed, or are heavily damaged are mapped.”

The results will be used to inform the reconstruction program in Haiti.