Geology in Mexico. The increase in severity of earthquakes

Geology in Mexico.

David Piles Perea

It is normal to have especially severe earthquakes in Mexico, it is a simple reason and it makes not just Mexico city, but all of the country to increase severity of earthquakes. Mexico in itself sits on many tectonic plates, and the ones it is not sitting directly on, it is very near.

According to the U.S. Geological Survey, who tracks earthquake activity worldwide, over the last hundred years, there have been roughly 19 other earthquakes over 6.5 magnitude within just 250 kilometres of the epicenter of the latest quake. This latest quake was centered on a region where the Cocos tectonic plate which is being pressed under the North american plate, causing massive disturbances.

However, Mexico city is more vulnerable to earthquakes; despite this recent one’s epicentre being around 160 kilometres southeast from the city.

Mexico city lies atop a drained lake. With sediments from thousands of years ago built up in the soil. The reason this affects the city to such a scale is that rather than just shake, like normal hard rock, this softer sediment traps the vibrations, reverberating. Similar to that of a tub of liquid, you shake the harder container, where the water creates waves sloshing back and forth.

The waves don't just get carried, but amplify in most cases. This is because of the frequency of the shakes, the shorter the interval, the more noticeable the effect. Like pushing a pendulum or a swing.

Liquefaction is also makes Mexico’s already dangerous situation, more destructive. The soil loses strength, due to the stress caused by the earthquake, to the point it acts like a slime or liquid, swallowing cars and even buildings.

Opinion

Esto realmente ha ampliado mi vista de geología; conecta de otra manera a la física y la geología. Me refiero a que me enseñó que los terremotos pueden tener efectos severos en áreas más lejanas, tsunamis no incluidos. Debido a que la tierra más blanda puede amplificar vibraciones. Y me enseñó la razón de porqué México tiene terremotos más peligrosos que, por ejemplo, Japón, NZ o Indonesia a pesar del hecho de que estos tienen muchas placas tectónicas debajo de ellas o las tienen cerca.

Sobre todo, encontré este artículo interesante y educativo debido a su información sobre la situación geológica de México y su lección sobre física.

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- Original article: How Mexico City’s Unique Geology Makes Deadly Earthquakes Even Worse

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