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

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. 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

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)

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.