A woman on a bicycle drives pass a house destroyed by the earthquake that struck the southern coast of Mexico late on Thursday, in Ixtaltepec, Mexico.
A woman on a bicycle drives pass a house destroyed by the earthquake that struck the southern coast of Mexico late on Thursday, in Ixtaltepec, Mexico. Carlos Jasso/Reuters

When the earth is about to move, seconds are precious.

The alert came. It worked as it should. People in Mexico City took note when countless sirens and alarms went off at 11:49 p.m on September 7, warning of an imminent earthquake.

How strong was it going to be? Nobody knew. How long would it last? Unknown. The sirens only meant that the earth was going to move any minute.

The earthquake originated in the Pacific Ocean, almost 100 kilometers off the coast of Chiapas. It reached 8.3 on the Richter scale, according to the National Seismological Service (SSN)—the second-most powerful earthquake recorded in the history of Mexico.

When the sirens sounded in Mexico City, residents of the capital had about 92 seconds to take some kind of precaution: They could seek shelter under a desk or a table, or take the nearest exit to an open space and minimize the risk of injuries from falling objects.

But almost 700 miles southeast of Mexico City, in the state of Chiapas, the scenario was different. This region, the poorest state in the whole country, isn’t part of the alert system. So while Mexico City could duck, the residents of Chiapas, where 16 people died in the quake, had no warning at all.

A system born of tragedy

A 1985 earthquake continues to be a collective trauma for Mexicans, especially for those living in the capital. After that earthquake, whose epicenter was recorded only 220 miles from Mexico City, human and economic losses were devastating. It claimed the lives of more than 5,000 people—although the SSN put the death toll at 40,000—left almost $4 billion in losses, and destroyed vulnerable neighborhoods on the periphery of the city.

Four years later, in 1989, Mexico City’s local government assigned the installation and management of a seismic alert system to a non-profit company called Center for Instrumentation and Seismic Recording (or CIRES, in Spanish). This company has been managing the whole system ever since.

Mexico City inaugurated the Seismic Alert System (or SAS) in 1991, becoming a pioneer in the region. The system, launched by Manuel Camacho Solis, then Mexico City’s head of government, had 12 seismic sensors along the coast of Guerrero, in the middle of the seismic zone. The system expanded to Oaxaca in 1999, and then expanded again in 2005 under the name Mexican Seismic Alert System (SASMEX). Acapulco, Chilpancingo, Puebla, and others have since joined. However, seismic alerts in Mexico remain highly dependent on the capital’s local government, which focuses its work on warning Mexico City.

“The system has spread to other cities, but its purpose is towards Mexico City. I think it requires something with more flow, that can be applied not only to a city, but to other parts. We need more coverage,” says Dr. Allen Husker, a seismologist and researcher at the Department of Seismology at the National Autonomous University of Mexico.

How does it work?

The system has 97 sensors in several places with high seismic activity along the Mexican Pacific. Those devices measure the movement of the earth and are connected to a station through a mini processor, which searches for a seismic pattern. If the devices detect seismic waves, the signal is sent through a government-run radio channel that has a unique frequency and activates the alarms and the sirens, whose waves travel faster than the seismic ones.

There are two types of alerts: early and public. The early one is only emitted to certain devices, distributed by the city government to schools and public buildings if the earthquake is lower than 6 on the Richter scale. If it is above that threshold, the alert is public: the sirens begin to sound from video surveillance cameras, along with broadcasts on radio and television.

The challenge of modernization

From Husker’s perspective, the system needs quick reform. “The problem is that the only information that gets delivered is an alert, nothing more,” he says. “They could deliver, along with the alert, an estimated time of arrival of the earthquake and its magnitude, among other things. The government, for its part, could promote a more informative system,” Husker adds.

The equipment is old, and there are practically no new players that can modernize the system. That means there are still areas without coverage—such as Chiapas and Baja, California—and others that are affected by the slow processes and the old technology of alerts.

Andrés Meira might have a better way to do things. Meira, a British architect, has tried to improve the seismic alert system in Mexico—first through unsuccessful talks with Mexico City’s local government, and then through a $150,000 grant from the U.S. Department of State via the Agency for International Development (USAID). This was how he founded Grillo and began installing earthquake sensors along Mexico’s Pacific Coast, running independently from the government. So now Mexico has two sets of sensors: the ones managed by CIRES, and the ones privately administrated by Grillo, Meira’s startup.

“The current system is not reliable,” Meira says. “We are all grateful that this system exists, but the experts agree that it is not very good and needs to be modernized. I welcome [the government’s] investment each year, but they could do something a thousand times better.”

Meira hopes that Grillo will avoid some of the most serious problems with the current system, such as false positives—public alerts sent about earthquakes that never existed, or whose intensity was so low that they didn’t warrant an alert. The sensors are in place, and Grillo is currently testing the system. Meira says the service will be free for those who download an app on their smartphones, and will include georeferenced information about earthquakes, including position, estimated arrival, and magnitude.

While Mexico City rebuilt its homes and buildings with anti-seismic technologies after the 1985 mega-earthquake, things were different in Chiapas and Oaxaca, where communities are poorer and more rural. They may also be in more danger. According to a study carried out in 2015 by the Academic Corps of Natural Disaster Prevention of the Autonomous University of Chiapas and the Institute of Geophysics of the University of Granada, the seismic vulnerability of the buildings in Tapachula—the second-most populated city in Chiapas—is worrying. Of all houses and buildings located within 22 blocks of the city center, 83 percent were classified as “highly vulnerable” or “extremely vulnerable” to destruction after an earthquake.

Following this recent earthquake, 42 schools in Chiapas need rebuilding; 40,000 homes are reported to be damaged. An alert system won’t prevent destruction, but it will at least give residents precious time to prepare.

This post originally appeared in Spanish on our sister site, CityLab Latino.

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