This is a common perception, reinforced by recent coincidences: September is a month of major earthquakes in Mexico.
Especially for a date 09/19Well, back then, two powerful earthquakes happened: one in 1985 with a magnitude of 8.1 and another in 2017 (7.1) that left hundreds dead and destroyed houses and buildings.
And this year 2022 occurred on the same day with a magnitude of 7.7 according to the Mexican National Seismic Service (7.6 according to the United States Geological Survey). and this was felt in the center, west and north-east of the country.
This has led many Mexicans to wonder if there is some phenomenon that makes September a month of major earthquakes.
For scientists, there is a clear answer: they are just coincidences. Why?
Did it shake the most in September? nope
There have been seismic records in Mexico since 1900 87 earthquakes are considered “large” for a magnitude greater than 7.0, according to statistics from the Mexican National Seismic Service (SSN).
There is a tie in 12 earthquakes between September and December in the last 121 years. but June it’s not far behind, with 10 major seismic events.
This shows that in reality these three months accumulate the greatest seismic activity, however a marginal difference. The rest have different records.
Why do people “feel” they shake more in September?
Scientists concede that the reluctance of the population is understandable against this background a person is used to telling the events that he had to experience.
Every resident of Mexico City over the age of 40 has experienced multiple earthquakes on the same day, September 19, those of 1985, 2017 and 2022.
“It’s a perception. Valid perception, logical perception of people, because we are used to measuring natural phenomena on the human life scale, which is not always the most appropriate point of view,” says Mexican seismologist Luis Quintanar.
“To measure its frequency, its intensity, it must be on a geological scalenot on the scale of human life, which is 60, 70 years, but on a slightly larger scale of 100, 200 or more years,” he added.
Can earthquakes be predicted? nope
That’s what scientists from the SSN and the National Autonomous University of Mexico (UNAM) say emphatically it is not possible to know when it will tremble againincluding whether it will happen again on September 19th.
“Earthquakes are unpredictable. And this needs to be looked at very clearly from both points of view: we cannot say when an earthquake will occur, but neither will we be able to ensure that earthquakes will not occur,” said Jorge Aguirre of the UNAM Institute of Mechanical Engineering.
“We know that there is some seismic activity due to the dynamics of the Earth and that eventually we will continue to have earthquakes in Mexico, but We don’t know when and at what time. And we cannot guarantee that there will be no earthquakes, nor can we guarantee that there will be earthquakes anywhere or at any particular time,” he added.
The populations of central, southern and southeastern Mexico, including the country’s capital, are exposed to earthquakes due to the various geological faults in their vicinity, making it likely that seismic events will continue to occur.
Does the rainy season cause earthquakes? nope
As the belief has spread that September is a month of major earthquakes, word has also spread among people that this may be because it is the rainy season, it may have some impact on the subsoil.
But that is not the case: “From a scientific point of view (…) Neither the rain let alone other things have anything to do with it being more shaking in September. Not only in Mexico, there is no evidence of this anywhere in the world,” said Arturo Iglesias, head of the SSN.
“Perhaps the exception is seismicity, which is sometimes caused by dam backfilling. Yes, sometimes when a dam is recharging in a typical way, for example after a hurricane or similar, there is usually a small local seismicity related to the weight of the water itself changing the state of stress around a prey, ” he explained.
And is there a connection between earthquakes and climate change? nope
In connection with the most intense rains, hurricanes, floods or droughts of recent years with climate change, doubts have also been raised as to whether there could be a connection with earthquakes.
But the experts again point out that there is no evidence for this.
“No context”explained Rosa María Ramírez, director of the UNAM Engineering Institute.
“Climate change causes disasters, just like earthquakes. But there is no connection,” he emphasized.
Scientists say the technology has advanced over the past few decades Improving the detection, measurement and prognosis of affections of an earthquake saving lives through early warning and improved building codes.
But they ask the population prevent the spread of rumours like that September is a month of “great tremors”. (yo)