Quake damage in Mexico City. Quake damage in Mexico City.

Quake danger zones: maps show risky areas

Information can help citizens make decisions about where to live

A digital tool designed to detect risks posed by natural disasters has been updated to show which areas of Mexico City and the rest of the country are most vulnerable to earthquakes.

Twelve different zones of the capital, located in the boroughs of Iztacalco, Venustiano Carranza, Cuauhtémoc, Xochimilco, Benito Juárez, Tláhuac and Iztapalapa, present signs of critical deformation, according to the National Risk Atlas.

They are more likely to suffer damage from seismic activity because they are on or near identified fracture zones.

Experts from the National Disaster Prevention Center (Cenapred) and the National Autonomous University of México (UNAM) contributed to the project to update the federal government tool, which includes a series of interactive, digital maps.

UNAM geological engineering specialist Dora Carreón Freyre, who headed the project, said her team had three main objectives.

They were to identify high-risk areas, evaluate the extent of vulnerability faced by socio-economically marginalized areas and come up with solutions to the risks of living in a city that was built over land that was once covered by a series of lakes.

Freyre explained that fractures in the earth’s crust occur for a variety of reasons including contact between lake bed sediments and volcanic rock, as in the cases of Iztapalapa, Tláhuac and Xochimilco.

Xochimilco was one of the worst affected areas in the destructive September 19 earthquake.

However, the more central boroughs of Cuauhtémoc and Benito Juárez, where significant damage also occurred, are situated “between two very large structural faults,” she said.

Mexico is located on the Pacific rim within an area called the Ring of Fire, making it one of the world’s most earthquake-prone countries. But some parts of the country are far more susceptible than others.

Cenapred divides Mexico into four different zones, depending on how frequently they are affected by seismic activity.

Zone A consists of states where no major seismic activity has been reported in decades, including Zacatecas, Chihuahua, San Luis Potosí, Tamaulipas, Baja California, Coahuila, Nuevo León and Hidalgo.

Zones B and C include states where seismic activity occurs but at infrequent intervals, including Guanajuato, Sonora, Querétaro, Durango, Morelos, México state and Puebla.

Mexico City is in Zone B although its geography makes it more susceptible to damage than other states in the same category.

In Zone D, where historically significant earthquakes have been recorded, are the states of Chiapas, Jalisco, Oaxaca, Colima, Michoacán and Guerrero.

The extent to which seismic activity can vary between regions of the country is emphasized by the number of aftershocks that have occurred after last month’s two major earthquakes.

According to data from the National Seismological Service, more than 9,000 aftershocks have been recorded since the September 7 earthquake compared to just 39 after the September 19 quake.

The National Risk Atlas can not only help governments better prepare for inevitable disasters such as earthquakes but even assist ordinary citizens to make decisions about where to live, Carreón said.

The online tool (Spanish only) can be accessed by clicking here.

Source: Sin Embargo (sp), El Financiero (sp)

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