Powerful magnitude 7 quake hits near Acapulco, Mexico, killing at least one
Map of areas where last night's quake in Mexico was felt

A powerful magnitude 7.0 earthquake hit Mexico’s west coast near Acapulco city Thursday night Sep 7, 2021 at 8:47 pm local time. According to preliminary news, it caused only relatively moderate damage, fortunately, despite its dangerously large magnitude. However, at least on man was reported killed by a falling post.



Damage in the wider earthquake area consisted mainly of cracks, broken windows, weaker construction parts and loose objects fallen down, parked cars hit by bricks, and similar. Rock falls and small landslides affected roads near slopes.

According to local news, the quake caused power outages in several states including in some areas of the capital Mexico City.

The full extent of damage by the quake is still difficult to asses as it's night and Civil Protection is busy assessing the situation.



Small tsunami triggered: The quake caused a small tsunami, which was observed with maximum wave heights of 0.48 m (1.8 ft) in the coastal areas near Acapulco. A tsunami warning was issued and has been now lifted again.



The quake hit at only 8 km SE from the popular sea side town of Acapulco where shaking was most pronounced, but it was felt through much of the country in up to several hundred miles distance. In Mexico City, 230 miles (375 km) away from the quake, shaking lasting up to one minute had people leave buildings in fear. One user from Mexico City described the quake: “Was on the 3rd floor of a modern hotel. The building was swaying back and forth like a boat for a very long time, it felt like at least 5 minutes. I heard noises of things breaking inside the structure and evacuated… there is no visible damage but they are not letting anyone back in until it gets checked out.”

See how the ground shaking makes it difficult for people to stand:





Initially, the quake had been measured as 7.4, but then downgraded to “only” 7.0. Magnitude 7.4 would have been almost 10 times stronger than the 7.0 magnitude now indicated by most agencies. According to the U.S. Geological Survey (USGS), its shallow depth of only 12 miles (20 km) amplified the shaking effect.



What caused the quake?

Last night’s quake occurred at the plate boundary between the oceanic Cocos and continental North America plates, as a result of shallow thrust faulting, as the Cocos Plate is sliding (subducting) in northeastward motion underneath the other, at a rate of approx. 65 mm per year. Accumulated stress in the contact zone is occasionally relased during many smaller and sometimes very strong quakes.

This earthquake was one of the larger events; early estimates indicate that it affected (ruptured) a fault area of approx. 40 km length and 20 km width.



Earlier quakes

In the past 100 years, 17 earthquakes of M7 or larger have occurred within 250 km of the September 8, 2021 earthquake. An M7.0 earthquake occurred on May 11, 1962 in approximately the same location as the September 8, 2021 earthquake. The 1962 earthquake caused four fatalities, extensive regional infrastructure damage, and a local tsunami with a peak recorded amplitude of 2.8 meters.

An M7.6 earthquake occurred about 75 km away on July 28, 1957. The September 2021 earthquake occurred at the southeastern end of the Guerrero Gap, a segment of the Middle America subduction zone that is thought to be capable of producing M8 or greater earthquakes. (Source: USGS)



Earthquake data:

Date & time: Sep 7, 2021 8:47 pm (GMT -5) local time (8 Sep 2021 01:47 GMT)

Magnitude: 7.1

Depth: 10.0 km

Epicenterlatitude / longitude: 16.78°N / 99.93°W (North Pacific Ocean, Mexico)

Primary data source: SSN
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