A strong earthquake that killed nearly 100 people in Mexico last year should not have happened, according to current understanding, the triggers of quakes, say scientists.
The magnitude 8.2 is in September 2017 just off the coast of the state of Chiapas, near Guatemala. Mexican President Enrique Peña Nieto called it "the largest that the country has seen in a century".
It has been shown that the earthquake was so strong that it split the 60 km thick tectonic plate into two parts within seconds.
"We still have no idea how this is possible," said Diego Melgar of the University of Oregon, who led a study on the quake
"We can only say that it contradicts and indicates our previous models, that we have to do more work to understand it. "
The epicenter of the quake was 46 kilometers deep in the Cocos ocean plate that dives beneath the North American plate. It is well known that earthquakes happen in sinking plates when they bend on their journey into the underworld.
"When you bend an eraser, you can see the top half stretched and stretched while the bottom part is squeezed and compressed." Dr. Melgar said National Geographic .
It is understood that stretching at the tip can cause a quake as the plate splits ̵
Coco's plate is also geologically very young, only about 25 million years old and warm. Scientists believe that these types of quake only occur when plates are old and have cooled and become harder and prone to cracking.
One theory states that seawater penetrated the plate and its cooling quenched accelerated. If that's true, Dr. Melgar endangers the entire west coast of the US and Canada.
"Our knowledge of these places where major earthquakes are taking place is still imperfect," Dr. Melgar.
"We can still do more We need to think more carefully when creating hazard and warning cards, but we still have a lot of work to do to give people very accurate information on what to expect in terms of shocks and tsunami Danger. "
The study was published in the journal Nature Geoscience