Mexico City: Ready for the Next Earthquake?

By: Alex Meyer

A little over a month since a massive earthquake rocked the region, Mexico City is still reeling from the damage. The epicenter of the September 19 quake was located just 76 miles southwest of the city, and measured 7.1 on the Richter scale. With dozens of buildings destroyed and over 360 confirmed dead nationwide—219 in Mexico City alone— the damage was devastating. But experts agree it could have been much worse.

Mexico City, after all, sits in one of the most seismically active regions in the world. The boundary between the Coco and North American plates is just south of the city, running parallel to Mexico’s southern coast. Another earthquake shocked the region just two weeks prior. That 8.1-magnitude earthquake struck just off the coast of Oaxaca and left over 70 dead in the state.

Mexico City’s unique topography is also problematic. The city sits on an ancient lakebed, meaning that structures are built on soft sediment and especially susceptible to damage during tremors. In a sprawling metropolis that is home to over 20 million people, a stronger quake could be catastrophic.

Residents of Mexico City don’t need seismologists to tell them this, though. When the earthquake struck on September 19, many had just finished participating in earthquake drills marking the 32-year anniversary of a 1985 earthquake that hit the city. That 8.0-magnitude earthquake destroyed 100,000 homes and left over 10,000 dead. In the aftermath of the devastating quake, grassroots movements challenged the government over everything from disaster preparedness to a lack of adequate housing for the poor.

Many have credited these efforts for limiting the damage this time around—specifically citing the city’s updated building codes. The municipal building codes were expanded extensively in 1993 and again in 2004. The most recent regulations were based on innovations in shock-wave propagation and foundation technology. City officials also eased administrative burdens while strengthening the regulatory standards. The updated regulations were widely-praised and were cited as a model for cities in other seismically active regions throughout the world.

However, some argue that the limited damage in the most recent quake may have been due to pure luck. Seismologist have pointed out that the type of waves that hit the city in the 1985 and 2017 earthquakes were very different. The smaller 2017 quake hit closer to the city, creating short waves most damaging to smaller structures like single-family homes. The 1985 quake, which was centered farther away, shocked the city with longer waves. These waves were more destructive to high-rise buildings, leading to a significant number of deaths.

But even if a bigger earthquake hit the city, scholars, city officials, and buildings inspectors all report that compliance with the updated building codes is problematic.  A 2016 study sampling 150 buildings constructed after 2004—when the most stringent standards were put in place—found that 71 percent failed to meet a high threshold of compliance. Building inspections have been largely privatized, and developers have started hiring preferred inspectors with lucrative deals—often creating massive conflicts of interest. All of this has led to haphazard application of the building regulations.

Things may be changing, though, after the most recent earthquake. The Mexico City prosecutor’s office has announced it opened almost 150 investigations relating to the 2017 quake. The office is particularly focused on the 38 buildings that collapsed in the city, and said that builders who failed to keep up with building codes could face charges of homicide, fraud, and negligence. City officials hope the swift punishment will show that noncompliance with the building codes is no longer an option.

For the residents of Mexico City, that could mean the difference between life and death for thousands. It’s not if the next earthquake will strike, but when.


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