A 7.3 magnitude earthquake slammed the southern Mexican Pacific coast on Friday morning, shaking everything from Mexico City to El Salvador, triggering a tsunami alert, and sending hospital workers sprinting down stairwells during rush hour. The good news: authorities are reporting no severe damage or casualties. The other news: there were five aftershocks, the biggest clocking in at magnitude 6, and the region has been through this before with much worse results.
What Actually Happened and Where
According to the U.S. Geological Survey, the earthquake's epicenter was about 30 miles southwest of Aquiles Serdan, right along the coast of Chiapas, at a depth of 9 miles. That shallow depth is important. Shallow earthquakes transfer more energy to the surface, which is why a quake that might read as a number on a page turns into a very real, very terrifying experience for people standing in tall buildings.
The quake was preceded by a smaller one with an epicenter a bit farther out in the ocean, which in retrospect was the opening act nobody wanted. Then came the main event, followed by at least five aftershocks ranging from magnitude 5.1 to 6.0, per USGS. At that point it stops being an earthquake and starts being a very bad morning.
On the Ground: Stairwells, Streets, and Rush Hour Chaos
In Tapachula, the main city on Mexico's southern border with Guatemala, the shaking started gently before intensifying. Alejandra Mendoza, an administrative employee at a public hospital there, told The Associated Press: "We were upstairs on the second floor when it started shaking; we thought it would pass, but then it got stronger, so we all went downstairs and evacuated in an orderly manner to the front courtyard." An orderly evacuation from a hospital during a 7.3 earthquake. Genuinely impressive.
In Guatemala City, CBS News reports that the duration of the shaking was what frightened residents most. People poured into the streets right in the middle of rush hour, as the workday was getting started. There are few experiences more universally rattling than the ground moving beneath your feet when you're just trying to get to work.
Mexico City felt it too. Buildings in certain areas creaked and swayed. But here's the strange part: the city's earthquake alert system never activated. The government explained that the energy radiated during the first few seconds of the quake did not exceed the system's activation thresholds. Which is a very technical way of saying the warning system looked at a 7.3 magnitude earthquake and said, "Nah, we're good."
The Tsunami Scare That Wasn't (Mostly)
The U.S. Tsunami Warning System initially put out a warning that hazardous tsunami waves were possible along coasts within 186 miles of the epicenter. That is a lot of coastline and a lot of people being told to get away from the beach. The Meteorological Service of Chiapas went further, alerting that waves up to 3.3 feet could hit the coasts of Mexico and Guatemala.
About an hour later, the tsunami threat was lifted. Mexican President Claudia Sheinbaum said preliminary reports showed no damage, though the navy still recommended staying away from beaches for six hours as a precaution. In the town of Suchiate, right along the river that divides Mexico from Guatemala, the mayor told CBS News that coastal areas were being monitored for tsunami risk. By all accounts, the worst did not arrive.
This Region Does Not Get a Break
The southern Mexican Pacific coast is seismically active in the way that some neighborhoods are known for bad parking: persistently, structurally, with no obvious solution in sight. Earlier this year, CBS News notes, a strong earthquake rattled southern and central Mexico and killed two people. In 2017, a 7.1 magnitude earthquake killed hundreds in Mexico City alone. Friday's quake did not reach that level of catastrophe, but the proximity to that history is not lost on anyone who lives there.
And this comes just weeks after Venezuela was devastated by twin tremors on June 24 that killed over 4,800 people and collapsed hundreds of buildings in the coastal state of La Guaira, according to CBS News. The Western Hemisphere has had a brutal stretch of seismic activity, and the people living along these fault lines are living with that reality every single day.
The Dingo Take
Here's where we land on this one: Friday was a close call dressed up in relatively good news. A 7.3 earthquake with five significant aftershocks, a tsunami warning covering nearly 200 miles of coastline, buildings shaking in multiple countries simultaneously, and the final outcome being "no severe damage or casualties" is not the norm. That is luck, and geography, and the particular physics of where this quake hit. Do not mistake it for resilience of the system.
The Mexico City alert system not activating during a 7.3 earthquake is the detail that should stick with people. The official explanation is technically accurate and also somewhat terrifying. These systems have thresholds, and those thresholds are not always calibrated for every scenario. The people in those swaying buildings did not know the alert had decided everything was fine.
What this story really is, underneath the relief, is a reminder that this region absorbs enormous seismic punishment on a semi-regular basis. The 2017 Mexico City earthquake killed hundreds. The Venezuela tremors killed nearly 5,000 people less than a month ago. Friday ended without a body count, and that matters enormously. But the tectonic plates do not check the calendar, and they are not done.
