Experts suggest expanding the instrumentation network to detect earthquakes in CDMX

The Mexico City Seismic Network has more than 200 monitoring teams, most of which are concentrated in the lake area, that is, the soft area of ​​the capital of Mexico City where the large buildings that can suffer damage are located; however, the southern part –Xochimilco, Milpa Alta, Tlalpan; and a little bit the western zone- is less instrumented, explained in an interview the researcher of the Institute of Geophysics (IGEF) of the UNAM, Luis Quintanar Robles.

"It is necessary to continue instrumenting the capital in areas that have a shortage of equipment in order to have, at a given moment, more information on the earthquakes that occur," said the former head of the Department of Seismology of that academic entity.

He stressed that the seismicity in the country's capital has nothing to do with the tectonics that occur on the Pacific coast, where the plates interact by subducting (one under the other). Here the movements are due to the activation of pre-existing faults, as well as the interaction of the soil that was previously part of Lake Texcoco with the surrounding hills and volcanoes.

Earthquakes in Mexico City have occurred since the Valley of Mexico existed, that people did not feel them may be due to more obvious conditions such as less population, he explained.

Quintanar Robles He added that since seismic instrumentation is available in the country, phenomena whose origin is in the country's capital have been monitored. The National Seismological Service (SSN) was inaugurated in 1910 by then President Porfirio Díaz; however, it was not until the 1980s when they began to be recorded systematically, especially in 1981 when the existence of earthquake swarms was detected in the Mixcoac area.

The telluric movements of the highest magnitude registered by the Seismic Network of the Valley of Mexico are those that occur in the border area of ​​Milpa Alta, with the municipality of Juchitepec, in the State of Mexico, and present magnitudes of the order of 3.5; Little is said about these because the area has a lower population density, so they do not usually generate damage since there are no large buildings, unlike the phenomena presented to the west of CDMX.

The also academic from the Faculty of Sciences specified that, according to the records, the most intense telluric movement in the city occurred to the west, in the Tacubaya area, in July 2019, with a magnitude of 3.2. As a result of this earthquake, small movements have occurred from 2019 to 2023, but in an isolated way.

Five or six years ago, most of the epicenters were not in the west, but in the east, in the Texcoco area, on the border between Iztapalapa and Ixtapaluca. Although that area continues to present earthquakes, they are not as frequent as those that have occurred lately to the west.

The seismologist pointed out that until 2019 the monitoring of these events was carried out individually by various institutions and for different reasons. Basically the Institute of Geophysics with the SSN, which has installed the so-called Seismic Network for the Valley of Mexico, with approximately 30 stations; the Institute of Engineering, for monitoring structures, also has accelerometers installed at various sites in the City; The Center for Seismic Information and Recording - the agency that manages the CDMX seismic alert - has a hundred instruments.

The 2019 movement was so important that the capital's government summoned the institutions that had instrumentation within the Valley of Mexico and proposed to join efforts in support of Civil Protection; that is, it was decided to unify the signals that are now concentrated in the SSN.

“It was thanks to this initiative that the CDMX Seismic Network currently has some 250 stations -which are the ones that were unified from all these networks- and now allow to have locations in almost real time, accelerations or intensities of the earthquakes that occur. Obviously not the entire city is monitored, ”he noted.

Quintanar Robles stressed that the origin and depth of these earthquakes is one and up to two kilometers, so they should not be confused with the passage of trucks, the construction of buildings or the excavations of the Metro, which do not reach the same depths and are considered "urban noise".

The energy released by a magnitude 3.1 or 3.2 earthquake is important, because people living in the surrounding area can perceive it. If it is compared to what it felt like on May 10, it will be noted that it practically jumped off the ground and caused objects to fall in homes.

In this context, what people should know is that although large earthquakes come from other entities in the country, especially from the coastal area, the Valley of Mexico is not exempt from their occurrence, he warned.

Fortunately, the registered earthquakes do not have magnitudes beyond 3; that is to say, they are relatively low, so more than worrying we must take care of the state of the buildings we inhabit, be careful to verify the conditions of the buildings, verify that there are no cracks, reinforce the constructions, etc., he concluded.