Earthquake Update: 453 Aftershocks Reported in 21 Days

Published April 3, 2012, in Mexico City's Milenio newspaper:

Following the March 20, 2012, earthquake of 7.4 Richter, Mexico's National Seismological Service (NSS) reports 286 aftershocks, with magnitudes ranging from 3.9 to 6.0 degrees on the Richter scale. 

Yesterday's quake at 12:36 PM (Central Daylight Time) had an intensity of 6.0 degrees on the Richter scale, which makes it the strongest aftershock so far. The epicenter of yesterday's movement was located 45 kilometers west of Pinotepa Nacional, on the Pacific Coast of Oaxaca. 

According to the NSS, 16 additional aftershocks were recorded on Monday, the latest at about 7 PM (CST) showing a magnitude of 4.7 on the Richter scale with its epicenter 105 kilometers southwest of Pinotepa National, in Oacaxa state.

Yesterday's (April 2, 2012) aftershock occurred while we were traveling by bus back to Mexico City from Pátzcuaro, Michoacán, so we didn't feel anything. But our friends in Mexico City tell us the city was on the receiving end of another good shaking.

453 Aftershocks Since March 20, 2012, Earthquake

Update: April 10, 2012: 427 aftershocks measuring 3.0 Richter or greater in a 21-day period means an average of nearly one temblor an hour, 24-hours a day. The frequency is  diminishing, albeit barely perceptibly.

Mexico rests at the southern edge of the North American Plate. To the west is the Pacific Plate. These tectonic plates come together in the Guerrero-Oaxaca region, on Mexico's Pacific Coast. 

Two smaller plates exert pressure against these larger plates: 

• Caribbean Plate pushes northward from the southeast; 
• Cocos Plate presses northward from the southwest, thus acting like a wedge pushing against the North American and Caribbean Plates.  

Pacific Plate is the pinkish plate to the west.

As they shift and settle after the March 20 earthquake, they continue to exert considerable energy. 

What if you doubt the stability of the earth under your feet? 

For those of us raised in the 'modern' world, it's sometimes easy to think that physical uncertainty is a thing of the past. But people who have survived hurricanes, floods, tornadoes, tsunamis, etc., know the raw power of nature. In English, we use the phrase nature's fury to describe extreme weather conditions.

Mexico's original people were also familiar with nature's fury. Myths were developed to explain the workings of natural forces. Rites and rituals developed in an attempt to influence, if not control, those same forces.  

The core of Mesoamerican mythology is the belief that humans have a responsibility to live in harmony with the natural world—a world in which deities and humans co-exist in a relationship of mutual responsibility and mutual obligation.

In the aftermath of the March 20 seismic event, our Mexican friends remain nervous, cautious. They fear an even larger terremoto, earthmover.  Older Mexicans recall the 1985 earthquake that devastated Mexico City. At 7.4 Richter, the March 20 quake is the strongest since 1985.

The uncertainty expressed by our Mexican friends must be a tiny fraction of the fear that gripped Mexico's original people when confronted with nature's fury—which they interpreted as evidence of the gods' displeasure.

Still Curious?

Journalists in the Guerrero-Oaxaca area have written well about what it feels like to cope with acute, potentially life-threatening, physical uncertainty.

Reporter's first-person account of the first night at the epicenter of the 7.4 Richter earthquake; title: Ométepec's Longest Night.

Another journalist's first-person account from a different village; title: Ruins, fears, strong aftershocks...but no help arrives.

Reed and I collaborated on developing Geography: Ground of Mexico Culture and History. 

We've written a lot about volcanoes, such as Mexico's Volcanoes and Mythology. 

And this post, which describes what happened when the volcano Xitle erupted in the Valley of Mexico, Cuicuilco, Volcanoes and the Fragility of Life in Mesoamerica.