Why does it tremble so much in Mexico?

In Mexico, five tectonic plates converge, making it a highly seismic country. Experts warn that it is possible that there are replicas or new earthquakes that can reach the magnitude of 7 degrees ...


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(CNNEspañol) - Earthquakes are a common phenomenon in Mexico because the country is located in an area of ​​"high seismicity," according to the National Seismological Service (SSN). There, five tectonic plates interact: the North American, the Cocos, the Pacific, the Rivera and the Caribbean plate.

(Credit: SSN)

"Mexico is a very seismically active country. Last year the National Seismic Service recorded 15,400 earthquakes, "said Xyoli Pérez Campos, head of the National Seismological Service of Mexico at a press conference.

Each tectonic plate moves through the earth in a "capricious" way, explained to CNN en Español Víctor Espíndola, head of the SSN's analysts, and when two of these plates meet, they release a great amount of effort that deforms the earth's crust, something that can only be seen with appropriate measuring instruments.

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"When that material can no longer hold so much energy, it breaks," says Espíndola. "Just like a plastic ruler when it is folded: it breaks."

And what happened in the deadly earthquake of September 2017, which left hundreds dead, was that the Cocos plate went under the North American one and "when the material of that plate is broken, the movement is generated", explained Pérez Campos At the press conference.

Greater movement in the south

The entire earth's crust is fragmented and each plate has its own movement, says Espíndola. In the northern part of Mexico, these plates move about 3 centimeters per year, while in the south the speed can reach 7 centimeters per year, the expert explained.

"The relative movement between these plates, in the Gulf of Tehuantepec (in the south of the country), is greater, that's why one of the states and their coasts where seismic activity is most recorded is in Chiapas and Oaxaca," he said. Spy it

The head of the SSN warned that it is possible that there are replicas that can reach magnitudes of up to 7 points.

"However, we do not know when or how much they will be," said Pérez Campos. "The recommendation to the population is to be vigilant."

Increase in the record of earthquakes

Between January 1, 1990 and September 8, 2017, more than 86,000 earthquakes of different magnitudes were recorded in Mexico. Each day there are about 15 earthquakes below 2 degrees, according to statistics from the National Seismological Service.

For two decades there has been a gradual increase in the number of earthquakes in Mexican territory.

But although it went from 796 earthquakes recorded in 1990 - most of them with magnitude between 4 and 4.9 - to 15,281 earthquakes in 2016 - most of them with an average magnitude of between 3 and 3.9 - Espíndola says no there is reason to be alarmed, because it is an improvement in measurement systems.

"A long time ago there were very few instruments that were available and the sensitivity of the instruments has become more refined," he says.

"It does not mean that the seismicity increases over the years," he adds. "It's just that there's more instrumentation."

Editor's note: This text was updated in January 2019.

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ref: cnnespanol