Why are there so many earthquakes in Mexico? 2:16 (CNNSpanish) — Earthquakes are a common phenomenon in Mexico, since the country is located in an area of ”high seismicity”, according to the National Seismological Service (SSN). Five tectonic plates interact there: the North American, Cocos, Pacific, Rivera and Caribbean plates. LOOK: Strong earthquake of magnitude 7.6 shakes southwestern Mexico on the anniversary of devastating earthquakes (Credit: SSN) “Mexico is a highly seismically active country. Last year the National Seismic Service registered 15,400 earthquakes,” said Xyoli Pérez Campos, head of the National Seismological Service of Mexico at a press conference in 2017. Each tectonic plate moves through the earth in a “capricious” way, as explained to CNN in Spanish Víctor Espíndola, chief analyst at the SSN, and when two of these plates meet, they release a large amount of stress that deforms the earth’s crust, something that can only be seen with appropriate measuring instruments. “When that material can no longer hold up accumulating so much energy, it breaks,” says Espíndola. “Just like a plastic ruler when it bends: it breaks.” And what happened in the deadly earthquake of September 2017, which left hundreds dead, was that the Cocos plate passed under the North American plate and “when the material of that plate breaks, movement is generated,” Pérez Campos explained. At the press conference. A greater movement in the south All the earth’s crust is fragmented and each plate has its own movement, says Espíndola. In the northern part of Mexico these plates move at about 3 centimeters per year, while in the south the speed can reach 7 centimeters per year, explained the expert. “The relative movement between these plates, in the part of the Gulf of Tehuantepec (in the south of the country), is greater, which is why one of the states and their coasts where the most seismic activity is recorded is in Chiapas and Oaxaca,” he said. spying on her The head of the SSN warned that there may be aftershocks that can reach magnitudes of up to 7 points. “However, we don’t know when or how big they are going to be,” Pérez Campos said. “The recommendation to the population is to be vigilant.” Increase in the number of earthquakes Between January 1, 1990 and September 8, 2017, more than 86,000 earthquakes of different magnitudes were recorded in Mexico. Every 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 registered in 1990 —most of them with a 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 that there is reason to be alarmed, since it is an improvement in the measurement systems. “In the past, very few instruments were available and the sensitivity of the instruments has become more refined,” he says. “It doesn’t mean that seismicity increases over the years,” he adds. “It’s just that there’s more instrumentation.” Editor’s note: This text was updated in September 2022.
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