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Three powerful earthquakes that have hit Mexico in the month of September have killed nearly 400 people.  The death toll is expected to rise as rescuers work around the clock to search for survivors who may be trapped in the rubble.  Homes and structures already damaged by the first earthquake, have collapsed after the 2nd and 3rd quake, leaving more devastation.

The first earth quake, a magnitude 8.1, struck off Mexico’s southern coast on Thursday, September 7th.  It was the most powerful to hit the country in a century and was felt as far as Mexico City and Guatemala City by an estimated 50 million people.  The quake’s epicenter was in the Pacific Ocean, some 600 miles southeast of Mexico’s capital and 74 miles off the coast.  The United States Geological Survey (USGS) reported multiple aftershocks, including at least six with tremors measuring above 5.0 in magnitude.  Ninety people were confirmed dead after the quake and the death toll was expected to rise as searchers dug through rubble for survivors.

Eleven days later, on Tuesday September 19th, a magnitude 7.1 earthquake struck central Mexico.   Dozens of buildings in Mexico City collapsed and over 200 people were reported dead and almost 2,000 injured.  The disaster caused extensive damage across Mexico, leveling at least 44 buildings in the capital alone, including homes, schools and office buildings.  Its epicenter was located 74 miles south-east of Mexico City at a depth of 31 miles and roughly 400 miles from the first quake.  Experts say the second earthquake was not an aftershock but a separate quake entirely.  Exactly 32 years ago, on 19 September 1985, a magnitude 8.0 earthquake devastated Mexico City and killed 10,000 people.

The third quake, on September 23rd, which was one of hundreds of aftershocks from the second quake, had a 6.1 magnitude, according to the US Geological Survey. It was centered about 11 miles south-southeast of Matias Romero in Oaxaca state, a region worst hit by the first earthquake this month.

The quakes were sparked by heightened tension between the Cocos tectonic plate, which borders the western coast of Mexico, and the North American tectonic plate. As the Cocos plate slid underneath the North American plate, it fractured in two different places, known as faults.  The two fractures were several hundred miles apart -both caused by bending and tension in the Cocos plate, but in different ways.

The depth of the subduction zone – where the Cocos plate is thrusting under the North American plate – makes it difficult to assess how the strain is building up but the fear is that it will cause another sequence of aftershocks that will cause additional deaths and damage.  Mexico qualifies as highly active because the country sits at the boundary of three tectonic plates which are pieces of the Earth’s crust that fit together like a jigsaw puzzle.

Unlike most natural disasters, there’s no way to predict earthquakes, making preparations extremely important, whether it’s through building codes or earthquake drills-planning ahead is still the only defense for earthquakes.

 

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