In its different historical stages, the inhabitants of the Mexican territory have had to deal with the seismic activitya natural phenomenon that usually occurs constantly. During the Viceroyalty, in Oaxaca the shaking of the largest magnitude ever recorded in Mexican territorywhich caused the largest tsunami ever seen in the country, raising waves of up to 18 meters and which penetrated eight kilometers into solid ground.
According to the National Seismological Service (SSN), Mexico is a country with high seismic activitysince the movement of five tectonic plates generates constant earthquakes in the country. In addition, in Oaxaca there is the North American plate that interacts with the oceanic plate called the Cocos Plate.
Why is the San Sixto earthquake considered the strongest in Mexico?
On March 28, 1787, the inhabitants of the intendancy of Antequeratoday Oaxaca experienced the strongest earthquake ever recorded in Mexican territory (at that time the New Spain). He was named as the San Sixto earthquake because that day was the celebration of the Catholic saint.
The earthquake began at 11:30 in the morning and It recorded a magnitude of 8.4 to 8.6 with a duration of approximately seven minutes.which caused multiple landslides such as:
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Temple of the Third Order of Saint Francis
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More than a hundred houses destroyed
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The Royal Houses of the Council and the Corregidor
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Parade ground
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Convents
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Aqueducts
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Pipes
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A prison
Chaos broke out in Antequera in seconds. The prisoners had to evacuate to the central square under the threat that anyone who tried to escape would be executed. In addition, after the earthquake, there were massive cases of looting and the inhabitants of the Oaxacan capital had to take refuge in the streets for a week due to the aftershocks that lasted until April 3, 1787.
According to the National Seismological Service (SSN), Seismic activity continued intermittently after the San Sixto earthquake, causing aftershocks that reached magnitude 7.
This great earthquake had its greatest repercussions in Oaxaca and Guerrero (Intendencia de Puebla), however, other places in New Spain were also affected, such as:
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Valladolid (now Morelia)
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Teotitlan del Valle
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Ometepec
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Tulancingo
Even in the Mexico City There was severe structural damage, because buildings built between the 16th and 17th centuries had to be demolished.
The epicenter of the earthquake is unknown. as well as the number of deaths, although it is estimated that it was high because multiple Oaxacan buildings collapsed.
Tsunami of 1787, the largest in the history of Mexico
When it seemed that the mass destruction was over, they did not count on the appearance of the largest tsunami ever witnessed in Mexican territorywith waves that reached up to the 20 meters high and 8 km inland invasions of ocean water
Thomas Molinedomayor of Tehuantepec, informed the Royal Court through a letter that the earthquake unleashed “a strange commotion of the waters and a frightful roar of the sea.” For his part, the mayor of Igualapa in Guerrero, Francisco Gutierrez de Teransaid the earthquake showed a violence that had never been experienced before.
The letter even relates that the fishermen saw the sea move away up to four kilometers in a matter of minutes and return with the same speed with which it had departed.
How did it become known that the San Sixto earthquake was the strongest ever recorded in Mexico?
The event happened 237 years ago. At that time there was no instrumentation to record and analyze the figures of the accident. What worked as a direct source were the accounts of the time and the evidence in tsunami deposits, which indicate the magnitude of the fault that gave rise to the San Sisto earthquake.
The fault is estimated to have stretched for up to 400 or 450 km, covering the entire state of Oaxaca and a portion of Guerrero.
According to EarthquakelistMexico was the second country in the world with the highest seismic activity during 2023, only below Chile. Mexico is located between the interaction of five tectonic plates: the Caribbean, Pacific, North American, Riviera and Cocos.
It is therefore important to be aware of the constant seismic activity in Mexico, as the danger of another major earthquake is always present. For this reason, it is important to take prevention practices such as drills, among other protective measures, seriously.