Collapse of the Regis Hotel Collapse of the Regis Hotel, Mexico City, 1985

It’s been 29 years since the big quake

So far this year there have been 5,026 earth tremors, but only 13 were over 5.5

Earthquakes have been in the news for the past week, last Friday having been the 29th anniversary of the devastating Mexico City quake that killed 10,000 people or more, injured 30,000 and left thousands more homeless.

ADVERTISEMENT

But earth movements are in fact quite a normal event in Mexico, it’s just that they don’t come in the magnitude of the one in 1985, nor do they last as long: it measured 8.1 on the Richter scale, and lasted nearly three minutes.

To mark the anniversary, El Universal did some research on earth tremors, and found that in the first eight months of this year there have been 5,026, but only 13 measured more than 5.5, according to figures from the National Seismological Service.

The strongest tremors during that period were felt in Petatlán, in Guerrero, and Tapachula, in Chiapas, which were recorded at 7.2 and 6.9, respectively. Other states with high seismic activity were Oaxaca, Baja California, Jalisco and Veracruz, with tremors between 5.5 and 6.4.

Anything over 5.5 is considered a strong tremor. In the last 24 years there have been 752 such events, the strongest being a 7.6 in Costa Colima in 2003 and a 7.4 in Ometepec, Guerrero, in 2012.

The year 2012 was a particularly bad one, with a total of 21 strong quakes, while 2009 was in second place with 15.

The reason for all this seismic activity is found in the techtonic plates that form the earth’s crust. Most of Mexico sits atop part of the North American plate, but four others have an influence on tremors, through their own movements in relation with each other.

ADVERTISEMENT

A tremor of more than 8 can be expected once every 20 years, says Raúl Valenzuela Wong of the Institute of Geophysics at the National Autonomous University, which isn’t to say that you can simply mark the next one off on the calendar.

Preparation is the best precaution, he says, and that starts with well constructed homes and other buildings. “In Mexico there have always been earthquakes, and there always will be.”

Following is a list of the the major tremors in Mexico since the late 1800s. M indicates the magnitude on the Moment scale.

  • 1887 05 03 – Northern Sonora, Mexico – M 7.4 Fatalities 51
  • 1907 04 15 – Guerrero, Mexico – M 7.7
  • 1911 06 07 – Off Guerrero, Mexico – M 7.7 Fatalities 45
  • 1931 01 15 – Oaxaca, Mexico – M 7.8 Fatalities 114
  • 1932 06 03 – Jalisco, Mexico – M 8.1 Fatalities 45
  • 1932 06 18 – Colima, Mexico – M 7.8
  • 1957 07 28 – Guerrero, Mexico – M 7.9 Fatalities 68
  • 1959 08 26 – Vera Cruz, Mexico – M 6.8 Fatalities 20
  • 1962 05 11 – Guerrero, Mexico – M 7.0 Fatalities 4
  • 1962 05 19 – Guerrero, Mexico – M 7.1 Fatalities 3
  • 1964 07 06 – Guerrero, Mexico – M 6.9 Fatalities 30
  • 1965 08 23 – Oaxaca, Mexico – M 7.3 Fatalities 6
  • 1968 08 02 – Oaxaca, Mexico – M 7.1 Fatalities 18
  • 1979 10 15 – Imperial Valley, Mexico – California Border – M 6.4
  • 1985 09 19 – Michoacan, Mexico – M 8.0 Fatalities 9,500
  • 1999 06 15 – Central Mexico – M 7.0
  • 1999 09 30 – Oaxaca, Mexico – M 7.5
  • 2002 02 22 – near Mexicali, Mexico – M 5.7
  • 2002 12 10 – Mexicali, Baja California, Mexico – M 4.8
  • 2003 01 22 – Offshore Colima, Mexico – M 7.6 Fatalities 29
  • 2003 09 11 – near Mexicali, Baja California, Mexico – M 3.7
  • 2004 06 15 – Offshore Baja California, Mexico – M 5.1
  • 2006 01 04 – Gulf of California – M 6.6
  • 2006 08 11 – Michoacan, Mexico – M 5.9
  • 2008 02 12 – Oaxaca, Mexico – M 6.5
  • 2009 08 03 – Gulf of California – M 6.9
  • 2009 12 30 – Baja California, Mexico – M 5.9
  • 2010 04 04 – Baja California, Mexico – M 7.2 Fatalities 2
  • 2012 03 20 – Oaxaca, Mexico – M 7.4
  • 2012 04 11 – Michoacan, Mexico – M 6.5

 Source: El Universal (sp), U.S. Geological Survey (en)

Stories from our archives that you might enjoy

FreeCurrencyRates.com
ADVERTISEMENT