MEXICO CITY (CN) — A magnitude 7.7 earthquake shook southern Mexico on Monday — the same day as major quakes in 2017 and 1985.
Mexico’s National Seismological Service reported the epicenter was in the Pacific Coast state of Michoacán, about 260 miles west of Mexico City. The original magnitude reported was 6.8, but this was later updated to 7.4 and finally 7.7 within a matter of hours. The U.S. National Geological Survey maintains the quake was a magnitude 7.6.
At least 168 aftershocks were reported in the hours following the initial quake, the largest of which registered a magnitude of 5.3.
Mexico held its annual seismological drill just an hour before the real earthquake struck.
Sept. 19 has come to be a traumatic day for citizens of Mexico City, many of whom have lived through several major seismological events on the date throughout their lifetimes.
“We had the drill at 12:19, and less than an hour later, we heard the siren again,” said Clemente Ruiz López, who has lived in Mexico City’s Roma neighborhood for over 21 years. “When I saw the ceiling lights swaying, I said, ‘Oh, I don't like this.’”
Most of Mexico City is built on the sediment of an ancient lakebed. Areas like Roma are on some of the loosest subsoil in the capital, making them especially dangerous during seismic events.
Although earthquakes have become a fact of life for residents like Ruiz, Sept. 19 has become a rather worrisome day of the year.
“You have to take precautions and be calm when it happens,” he said. “People don’t want to be scared, but what can you do?”
Despite residents’ learned fear of the month, there is still no scientific evidence to prove that September is more seismically active than other months, according to Raúl Valenzuela Wong, a seismologist at Mexico’s National Autonomous University.
“There’s nothing special about the month of September, but by now no one is going to believe me,” said Valenzuela. “It’s a wicked, tragic coincidence, but it’s still a coincidence.”
Still, that is a hard argument to make to those who have lived through so many seismic Septembers.
Grant Cogswell has seen several earthquakes during his 11 years owning and operating Under the Volcano Books, an English-language used bookstore in the neighborhood of Condesa. Like Roma, Condesa is built on loose subsoil and often sees the worst of the quakes that affect the city.
When it comes to earthquakes on Sept. 19, he no longer believes in happenstance.
“There are 365 days in a year. Twice is a coincidence, three times is something else,” he said only half-jokingly.
The 7.1 magnitude quake that brought the capital to a standstill on Sep. 19, 2017, toppled his bookshelves and left a mountain of literature on the floor. After that, he secured the shelves to the walls with braces in preparation for future tremors.
That earthquake was actually the second of September 2017. An 8.2 magnitude quake rocked the southern state of Oaxaca on Sep. 7. While it was larger than the Sept. 19 quake, it was further away and did not cause as much damage as the second of that month.
Those 2017 quakes also greatly damaged Terminal 2 of the Mexico City International Airport. In July, President Andrés Manuel López Obrador announced that the facilities are at risk of collapse.
The tremor on Sept. 19, 2017, left nearly 400 people dead and over 180,000 residences damaged. That event, however, paled in comparison to the devastation on the same day in 1985. The official death count from that 8.1 magnitude quake was 3,692, though some estimates were as high as 20,000.
No major damage was reported in Mexico City as a result of Monday’s earthquake.
Michoacán’s Civil Protection agency said on Twitter that it was checking for damage in the state, but had not reported any major issues as of press time.
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