Before and after: the building at left was 60 years old. A lot covered in rubble at right is all that remains. Before and after: the building at left was 60 years old. At right, a lot covered in rubble is all that remains.

Most quake fatalities in older buildings

Building regulations cited for protecting newer construction

The vast majority of deaths in Mexico City from last week’s 7.1-magnitude earthquake occurred in older buildings that predated stricter building codes introduced after the 1985 quake, the newspaper Reforma reported today.

Of 187 deaths in the capital, at least 165 occurred in buildings that were on average 43 years old, the newspaper found, with most of the collapsed buildings between 30 and 60 years old.

The oldest was a 70-year-old building in the Del Valle neighborhood that was completely destroyed although no deaths occurred there. A building that collapsed in La Roma neighborhood killing 14 people was 50 years old while a textile factory that collapsed in the Obrera neighborhood, killing 21, was 40 years old.

The Enrique Rébsamen school in southern Mexico City where 26 people lost their lives was 34 years old. Structural defects had already been detected in both its original construction and additions prior to last Tuesday’s devastation.

The vice-president of the Mexican Society of Civil Engineers said the fact that so many fallen buildings were of older construction is testament to the success of modern building codes.

“This reveals that construction regulations do work. The lifespan of a building is 50 years and modern buildings didn’t suffer damage,” Sergio Alcoser Martínez said.

One exception was a one-year-old apartment block in the Portales neighborhood where two people died.

But a report by the New York Times said that while tighter building codes, better construction materials and greater public awareness about the danger of earthquakes undoubtedly played a role in limiting damage from last week’s quake, luck was also a factor.

The shock waves, despite emanating from a closer epicenter than in 1985, were different and less powerful than that quake meaning that shorter buildings were affected more than high-rises, a seismic engineering researcher said.

An estimated 10,000 people were killed in the capital in the 1985 disaster that occurred 32 years to the day before last Tuesday’s quake.

Tougher building standards that take Mexico City’s unique topography into account have been introduced since then but the Times reported that while the city’s building codes are among the best in the world, their enforcement is often outsourced to engineers hired by developers.

That conflict of interest has the potential to undermine the standards, the report said, and a 2016 study of 150 buildings found that many failed to meet the stricter standards.

Still, more modern buildings proved more resistant to last week’s quake than older ones, a fact also highlighted by Mexico City Mayor Miguel Ángel Mancera.        

“. . . Of the buildings that collapsed, a high percentage of that construction was old or at least [built] before the ´85 earthquake,” he told Foro TV.

Apart from collapses, thousands more buildings suffered structural damage and the number is likely to rise as inspections continue. Mancera said buildings are given a traffic light style rating of green, amber or red depending on the severity of the damage sustained.

“There will be some that require minor or major repairs but won’t be left in uninhabitable conditions and others that will be demolished,” he said.

Source: Reforma (sp), Milenio (sp), The New York Times (en)

Reader forum