Spain prone to deep earthquakes due to Earth's crust lying upside down under Mediterranean: Study

In a new study, it has been found that Spain has remained prone to rare and deep earthquakes because of a capsized tectonic plate beneath the Earth's surface.

As per the seismographic reports, when Africa and Eurasia slowly collided, a piece of the surface of the planet went upside down deep beneath the Mediterranean.

"Since 1954, there have been five closely located large deep‐focus earthquakes with depths greater than 600 kilometres beneath [the Spanish city of] Granada," said geologists Daoyuan Sun from the University of Science and Technology of China as well as Meghan Miller from Australian National University, in a statement.

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Here's what experts found after examining Spain's 2010 earthquake

Generally, earthquakes which occur at such deep depths arefollowed by major aftershocks. However, when seismic data collected from Spain's 2010 earthquake was examined by Sun and Miller, there were no aftershocks found.

When the tectonic plates underneath the surface of the Earth get pushed into each other, they are generally displaced so that one slides beneath the other in a process which is called subduction.

These collisions sometimes destroy the plate's sinking part and raise the crust which creates mountains and interlocks the two plates.

At other times, the wrestling crusts remain separate but stacked as one slab slowly sinks further towards the mantle of Earth.

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This is what took place at the border between the African and Eurasian plates where the Mediterranean floor is slowly sinking beneath Europe.

During the 2010 Granada earthquake, the seismic waves lasted unusually long and had an extra phase of activity. This happened because the seismic waves were moving slower and that too at the bottom of the Alboran slab and not the top.

"A significant amount of water has been carried down to the mantle transition zone, indicating a relatively cold slab," said geologists Daoyuan Sun.

"Considering a relatively young seafloor age in the western Mediterranean, for the slab to remain cool, the subduction speed must be quite fast, such as a moderate speed of about 70 millimetres per year," he explained.

(With inputs from agencies)