Earthquakes 300 km from Earth’s surface: Scientists are solving the mystery of the deepest earthquakes on Earth

The Because Earthquakes Earth’s deepest was a mystery to science For more than a century, but a team of scientists from UD Carnegie (EE.UU) You may have solved the case.

New investigation Published in the journal Predecessor AGU Provides proof of that Fluids play a major role in deep-focused earthquakes, Which occurs between 300 and 700 km below the planet’s surface.

Most earthquakes occur close to the Earth’s surface for a distance of about 70 kilometers. It occurs when pressure builds up in a fracture between two blocks of rock, This is known as a fault, causing them to suddenly slide side to side.

But in the depths of the earth, The extreme stresses create too much friction to allow this type of slip to occur The higher temperatures enhance the rock’s ability to deform to adapt to changing stresses. Although not expected in theory, scientists have been able to identify earthquakes that have arisen more than 300 kilometers below the surface since the 1920s.

“The big problem that seismologists have faced is how can we have these deep-focused earthquakes?”And the Lara Wagner, one of the authors of the investigation, said in a statement. “Once you go down a few dozen kilometers, it becomes very difficult to explain how we slip into the fault when the friction is incredibly high.”

Lara Wagner, one of the authors of the investigation. Photo: Yu Carnegie

Continuous work over the past decades has shown us that water plays a role in earthquakes of medium depth. Those that occur between 70 and 300 km below the surface of the Earth.

In these cases, The water is freed from the minerals, weakening the rocks around the rift and allowing the rock masses to slide away. However, scientists did not believe that this phenomenon could explain deep-focused earthquakes, due in large part to the belief that water and other fluid-forming compounds could not reach deep enough into Earth’s interior to cause a similar effect.

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This thought He changed for the first time at Sherry and Wagner Depth comparison Diamonds are rare from the depths of the earth With mysterious earthquakes of deep focus. “Diamonds are formed in liquids, if there are diamonds, then there are liquids,” Sherry said.

Diamonds themselves indicate the presence of liquids, however, They also brought samples from Deep earth To the surface for scientists to study. When diamonds form inside the ground, they sometimes pick up bits of minerals from the surrounding rock. These are called minerals Inclusions and can make your jewelry less expensive, But it is invaluable to scientists on the ground. It is one of the only ways that scientists can study live samples from deep within our planet.

This ultra close-up of the ultra-deep diamond highlights its blemishes that look like black dots. Inclusions like these provide geochemical evidence that a submerged oceanic plate can carry water and other fluids in the mantle. .

Diamond inclusions have the distinct chemical signature of similar substances found in the oceanic crust. This means that water and other materials did not somehow form deep underground. Instead, they were swept away as part of a submerged oceanic plate.

Wagner said:The seismology community has moved away from the idea that there is water at this depth. But diamond amputators like Steve used to show us samples and say, “No, no, no. There is definitely water here. So we got together to find out how I got there.”

To test the idea, Wagner and Van Keiken built advanced mathematical models to simulate the temperatures of sunken plates at depths much greater than they had previously attempted.. In addition to modeling, Walter examined the stability of water-containing minerals to show that under intense heat and pressures deep within the Earth, they would in fact be able to hold water under certain conditions. The team showed that although the warmer plates do not retain water, Minerals in cold oceanic plates could, in theory, carry water to depths that we associate with deep-focused earthquakes.

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To give rigidity to the study, The team compared the simulations with realistic earthquake data. They were able to show that the panels that could theoretically carry water to these depths were also those that had experienced deep earthquakes that had not been previously explained.

This study is unusual in applying four different specializations (Geochemistry, Seismology, Geodynamics, and Rocks) To the same question, and they all point to the same conclusion: water and other fluids are an essential component of deep-focused earthquakes.

Aileen Morales

"Beer nerd. Food fanatic. Alcohol scholar. Tv practitioner. Writer. Troublemaker. Falls down a lot."

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