Geologists have discovered the secret of the mysterious earthquakes in Portugal
Lisbon is the capital of Portugal, is located quite far from the active tectonic faults, so in its territory the occurrence of earthquakes is extremely unlikely. Despite this, the tremors in the area still have occurred, and one of them even claimed hundreds of thousands of lives. Local geologist João Duarte several years studying the seismic history of his native city, and seems to have found the cause of earthquakes.
One of the worst earthquakes in Lisbon was in 1755 - it caused a tsunami that almost destroyed the city and killed 100,000 people. A few centuries later, in 1969, it was recorded another quake, which was much weaker and did not leave behind victims. Geologists still could not explain their reasons, but João Duarte version sounds plausible.
He believes that the cause of the earthquake lies in a geological process called serpentinization. It occurs in the absorption of water rock structures, which leads to the fact that the oceanic lithosphere at the coast of Portugal crumbles two. It is believed that the anomaly occurs in the region under the Atlantic Ocean, along the Iberian Peninsula, at a depth of about 250 kilometers. This theory has been verified by computer simulation, but the results have not yet been reviewed. If the researchers are right, it can be considered a first detection of stratification of the oceanic lithosphere in history. Perhaps this activity in the future has arisen a new subduction zone, where one layer of the earth's crust sink beneath another. As a result, this layering can be the basis of formation of a new supercontinent.
Recently, scientists managed to uncover the secret of another previously unexplained phenomena - the formation of a mysterious hole in the Antarctic. Read about it can be in our material.
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