Dangerous 7.4 magnitude earthquake struck Guerrero and Oaxaca, Mexico

Dangerous 7.4 magnitude earthquake struck Guerrero and Oaxaca, Mexico

Magnitude 7.4 earthquake struck highly populated area of Guerrero and Oaxaca, Mexico at 18:02:48 UTC on March 20, 2012 according to USGS. The epicenter was located 322 km (200 miles) SSE of Mexico City (16.662°N, 98.188°W). The depth of epicenter was at 20 km (12.4 miles).

Nearest populated places are: Coyul (16km), Putla de Guerrero (18km), Cuitlapa (15km), Laguna (3km). The closest civilian airport is Pinotepa Nacional (77km). There or no Nuclear Plants in the vicinity of the epicenter

This earthquake is a subduction earthquake, which means that the Oceanic plate is gliding below the North American plate and often hangs for a while. When the accumulated energy is suddenly freed a massive earthquake is generated.

The area has currently a lot of aftershocks as could be expected. These aftershocks will go on for many hours and even days and people in the epicenter area will have to spend the night on the streets out of fear for aftershocks.


GDACS, another agency who calculates tsunami heights has calculated that a max. tsunami wave of 0.1 meter may have occurred, nothing to be scared of.

Preliminary data from different seismological agencies referred to magnitudes from 7.9 (USGS), to 7.6 (GEOFON) and only 6.4 (EMSC). Both Geofon and USGS are referring to an extremely dangerous shallow depth of 10 km. EMSC mentions a 60 km much weaker impact. The Mexican Seismological service is maintaining a magnitude of 7.8.


Early reports say 500 houses have been destroyed or highly damaged in Guerrero. Most of these are expected to be old adobe houses. Omotopec is expected to have major damage. Damage will likely be in the tens of millions of US dollars.

2.5 million users have had outages in their electricity following the earthquake. After 90 minutes, 1.5 million users were restored to the grid. In the Eastern control area partial outages  in the cities of Poza Rica and Coatzacoalcos and parts of the states of Puebla, Tlaxcala and Morelos. CFE crews will continue working to restore power as quickly as possible in the affected areas. Follow in depth updates and live reports here.

The number of houses damaged in the epicenter region continues to grow. Up to 800 houses are reported uninhabitable in the epicentral region.

Thursday, March 22;

 Mexican seismological agency has said that more than 80 aftershocks have been recorded since the mainshock on Tuesday.

In Guerrero, 30000 houses have been reported to have been damaged (it is expected many with cracks in the adobe or fallen cardboard) to some extent. Given that Guerrero is an extremely poor part of Mexico with the second lowest HDI in Mexico, the economic loss will not be significant. However, the impact to locals will be quite high. 800 houses are reported to have collapsed in Guerrero or be so severely damaged that they are uninhabitable. This is the report of the local governor. 2 people were injured in Cuajinicuilapa and Ometepec. Shelter has been provided.

20 schools and hospitals were damaged in four municipalities, including the Ometepec, where the epicenter of the quake was, and one remains without electricity at Tlacoachistlahuaca.

In Oaxaca, 2000 homes and public buildings have been damaged to varying extents.

In Mexico City, 250,000 people were without water service due to a pipe burst by the quake, said City Mayor Marcelo Ebrard.

A local official reported that two people were killed. During a meeting with state and federal government officials, Mayor Salvador Cruz Castro of Cuajinicuilapa, said a collapsed wall crushed one of the victims to death while the other succumbed to complications from a heart attack. The mayor added that the tremor also badly damaged 500 homes and partially damaged about 1,000 others. It was the first report of casualties from the powerful earthquake, with its epicenter in Ometepec of Guerrero state. The tremor was the strongest in Mexico since 1985 when an 8.1-magnitude quake left more than 10,000 people dead.

  • Tuesday, March 20, 2012 at 18:02:48 UTC
  • Tuesday, March 20, 2012 at 12:02:48 PM at epicenter
Location16.662°N, 98.188°W
Depth20 km (12.4 miles)
Distances136 km (84 miles) SSW of Huajuapan de Leon, Oaxaca, Mexico
162 km (100 miles) WSW of Oaxaca, Oaxaca, Mexico
170 km (105 miles) SE of Chilpancingo, Guerrero, Mexico
322 km (200 miles) SSE of MEXICO CITY, D.F., Mexico
Location Uncertaintyhorizontal +/- 15.8 km (9.8 miles); depth +/- 6.5 km (4.0 miles)
ParametersNST=438, Nph=440, Dmin=312.8 km, Rmss=0.88 sec, Gp= 79°,
M-type=teleseismic moment magnitude (Mw), Version=9
  • Magnitude: USGS NEIC (WDCS-D)
    Location: USGS NEIC (WDCS-D)
Event IDusc0008m6h


By Thursday, March 22, more than 90 aftershocks have been recorded. Some of them include:

March 20, 2012 (all times UTC)

Magnitude 5.3 at 18:22:35 with depth 18.0 km  OAXACA, MEXICO
Magnitude 5.1 at 18:35:40 with depth 10.1 km OAXACA, MEXICO
Magnitude 5.1 at 19:02:45 with depth  25.9 km OAXACA, MEXICO
Magnitude 5.1 at 20:14:40 with depth 10.5 km OAXACA, MEXICO
Magnitude 5.0 at 22:25:43 with depth 21.3 km GUERRERO, MEXICO

March 21, 2012 (all times UTC)

Magnitude 5.0 at 02:54:10 with depth 20.9 km GUERRERO, MEXICO
Magnitude 5.0 at 11:36:16 with depth 20.0 km GUERRERO, MEXICO

March 22, 2012 (all times UTC)

Magnitude 5.2 at 16:46:47 with depth 12.2 km OAXACA, MEXICO

Featured image: Google Earth + USG



Toadmac 8 years ago

Very strange that this did not make the headline news in Australia? In fact out of ten or so people I spoke to today only one new about it? Why is this not headline news?

Alicia 8 years ago

Thank god my family is ok. I was so worried. Lets pray for the people who lost homes.

grant 8 years ago

Um, I would think the important thing would be, is everyone okay?

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