An Incredibly Powerful 7.1M Earthquake Just Struck Mexico City


Robin Andrews

Science & Policy Writer


Poeple try and remove wreckage of a collapsed building in Mexico City after a 7.1M quake on September 19, 2017. Omar Torres/Getty Images

An incredibly powerful earthquake, registering as a 7.1M, has rocked Mexico City, a densely-packed metropolis containing nearly 20 million people, and its many suburbs and nearby towns. According to the United States Geological Survey (USGS), it was a deep-seated earthquake (51 kilometers/32 miles depth) that struck at 1:14 pm local time. The epicenter was 122 kilometers (76 miles) southeast of the city center.

Although deep and not centered on Mexico City, the tremor was powerful enough to cause multiple buildings in the capital to collapse; the damage in villages and towns outside of the city and nearer to the epicenter are likely to be harder hit, but that’s not possible to confirm at this stage.


Fatalities are expected. The USGS, based on the earthquake’s seismic energy and location, is estimating that there’s a 39 percent chance that 100-1,000 people have died; there’s a 30 percent chance that 1,000 to as many as 10,000 people have died.

It’s likely to be a costly quake too. There’s a 36 percent chance it will cost between $100 million and $1 billion in damages; there’s a slightly less chance it will cost as much as $10 billion.

The shake map, showing the epicenter. Mexico experienced a 6/10, others a 7/10. USGS

“Overall, the population in this region resides in structures that are a mix of vulnerable and earthquake resistant construction,” the USGS ominously notes.


Apart from the capital, other major cities affected by the quake include Ayutla (7,000 people), Izucar de Matamoros (43,000 people), and Puebla (1.6 million people), which is nearest to the epicenter. All experienced “very strong” shaking, a 7 on a 1-10 scale of earthquake shaking intensity.


The extent of the damage won’t be known until tomorrow morning at the earliest.


Horrifying details are emerging on Twitter. One user posted a video that appears to show a building exploding in the aftermath of the earthquake – although it cannot be independently verified at this stage. Other images coming through show entire buildings collapsed, with people scrambling through the wreckage, perhaps to find people trapped beneath it.


This follows on from another powerful tremor that struck the country days earlier on September 7. Registering as an 8.1M quake, it struck off the southern Pacific coast, and briefly, tsunami warnings were given. Although none ultimately emerged, nearby infrastructural collapses killed at least 61 people, and the tremor proved to be the most energetic in more than a decade.

Coincidentally, the earthquake struck on the 32nd anniversary of the powerful 1985 Mexico City quake, which almost certainly involved the same fault network. Back then, between 5,000 and 10,000 people perished across the region.


As this new earthquake struck, plenty across the region were taking part in a pre-arranged earthquake drill. This may have inadvertently saved several people's lives.


Mexico City is on a weakly consolidated, depressed lake bed, which is itself atop a junction of three battling tectonic plates. All in all, the capital is one of the most earthquake-vulnerable cities in the world.


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