Earth’s ‘solid’ inner core may not be so strong after all, study finds

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Earth’s “solid” inner core may not be so strong after all! Ball-shaped mass 3,200 miles below the surface contains both pasty and hard iron, study finds

  • Earth’s inner core is not solid but actually contains pasty and hard iron – study
  • Researchers claim the nucleus is made up of a range of liquid, soft and hard structures
  • Because the inner core is so inaccessible, they used seismic waves for the study
  • How Seismic Waves Travel Can Identify Minerals, Heat, and Density in Earth’s Layer

By Sam Tonkin for Mailonline

Posted: | Update:










No human or machine has ever been 3,200 miles below the Earth’s surface because depth, pressure and temperature make it inaccessible.

But scientists have long believed that the inner core of our planet is solid, unlike the region of liquid metal that surrounds it.

Now, that has been called into question by a new study which claims that the ball-shaped mass, which is responsible for the Earth’s magnetic field, contains both pasty and hard iron.

Scientists have long believed that the inner core of our planet is strong. This has been called into question by a new study which claims that the ball-shaped mass contains both pasty and hard iron. Seismic waves (photo) were used as a basis for research

Scientists have long believed that the inner core of our planet is strong. Now that has been called into question by a new study which claims that the ball-shaped mass contains both pasty and hard iron. Seismic waves (photo) were used as a basis for research

FOUR LAYERS OF PLANET EARTH

Crust: Up to a depth of 70 km, it is the outermost layer of the Earth, covering both oceans and land.

Coat: Descending to 2,890 km with the lower mantle, it is the thickest layer on the planet and made up of silicate rocks richer in iron and magnesium than the above-ground crust.

External core: Extending from a depth of 2,890 to 5,150 km, this region is made up of liquid iron and nickel with lighter trace elements.

Inner core: Descending to a depth of 6,370 km in the very center of planet Earth, this region would have been made of massive iron and nickel. But this new study suggests that it contains both pasty and hard iron.

The research was led by Rhett Butler, a geophysicist at the University of Hawaii, who suggests that the “solid” inner core of the Earth is in fact made up of a range of liquid, soft and hard structures that vary within 150 first miles from the mass.

The interior of the Earth is layered like an onion. The iron-nickel inner core has a radius of 745 miles, or about three-quarters the size of the moon, and is surrounded by a fluid outer core of molten iron and nickel about 1,500 miles thick.

The outer core is surrounded by a mantle of hot rock 1,800 miles thick and covered with a thin crust of cold rock on the surface.

Because the inner core is so inaccessible, researchers had to rely on the only means available to probe the Earth’s interior: seismic waves.

“Illuminated by earthquakes in the crust and upper mantle, and observed by seismic observatories on the Earth’s surface, seismology offers the only direct way to study the inner core and its processes,” said Butler.

As seismic waves travel through different layers of the Earth, their speed changes and they can reflect or refract depending on the minerals, temperature and density of that layer.

To better understand the characteristics of the Earth’s inner core, Butler and his co-author Seiji Tsuboi, a researcher at the Japan Agency for Marine and Terrestrial Science and Technology, used data from seismometers directly in front of where an earthquake was generated.

They used Japan’s Earth Simulator supercomputer to evaluate five pairings to largely cover the central interior region: Tonga and Algeria, Indonesia and Brazil, and three between Chile and China.

A section of the interior of the Earth shows the inner core (red) and the outer core of liquid iron (orange). Seismic waves pass through the Earth's inner core faster between the north and south poles (blue arrows) than across the equator (green arrow)

A section of the interior of the Earth shows the inner core (red) and the outer core of liquid iron (orange). Seismic waves pass through the Earth’s inner core faster between the north and south poles (blue arrows) than across the equator (green arrow)

Because the Earth's inner core is so inaccessible, researchers had to rely on the only means available to probe the Earth's interior - seismic waves (stock image)

Because the Earth’s inner core is so inaccessible, researchers had to rely on the only means available to probe the innermost Earth – seismic waves (stock image)

“In stark contrast to the soft, homogeneous iron alloys considered in all earthly models of the inner core since the 1970s, our models suggest that there are adjacent regions of hard, soft and liquid or pasty iron alloys in them. 150 miles above the inner core. core, ”Butler said.

“This places new constraints on the composition, thermal history and evolution of the Earth.”

The researchers said this discovery of the diverse structure of the inner core could offer important new information about the dynamics at the boundary between the inner and outer core, which has an impact on the Earth’s magnetic field.

“Knowledge of this boundary condition from seismology may allow better predictive models of the geomagnetic field that protects and protects life on our planet,” said Butler.

Researchers now plan to model the structure of the inner core in more detail using the Earth Simulator supercomputer so that it can be compared with various features of the Earth’s geomagnetic field.

The research was published in the journal Science Direct.

THE EARTH’S LIQUID IRON CORE CREATES THE MAGNETIC FIELD

Our planet’s magnetic field is believed to be generated deep within the Earth’s core.

No one has ever traveled to the center of the Earth, but by studying shock waves from earthquakes, physicists were able to determine its likely structure.

At the heart of the Earth is what was believed to be its strong inner core, two-thirds the size of the moon, and composed mostly of iron. However, this new study disputes it.

At 5,700 ° C, this iron is as hot as the surface of the Sun, but the crushing pressure caused by gravity prevents it from becoming liquid.

Surrounding this is the Outer Core, which is a 1,242 mile (2,000 km) thick layer of iron, nickel, and small amounts of other metals.

The metal here is fluid, due to the pressure lower than that of the inner core.

Differences in temperature, pressure, and composition in the outer core cause convection currents in the molten metal as cold, dense matter descends and hot matter rises.

The force of “Coriolis”, caused by the rotation of the Earth, also causes swirling vortices.

This flow of liquid iron generates electric currents, which in turn create magnetic fields.

The charged metals that pass through these fields create their own electric currents, and so the cycle continues.

This autonomous loop is known as geodynamo.

The spiral caused by the Coriolis force means that the separate magnetic fields are roughly aligned in the same direction, their combined effect adding up to produce a vast magnetic field engulfing the planet.

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