Study of Earth’s inner core reveals a ‘planet within a planet’

SALT LAKE CITY — Scientists are trying to go where no man has gone before, into the inner core of Earth! A team of scientists at the University of Utah has made significant progress in understanding the formation and structure of the planet’s enigmatic inner core. They believe seismic waves from natural earthquakes will help unravel the secrets of this hidden area.

The inner core, a solid metal ball within our planet, not only influences its magnetic field but also plays a crucial role in supporting life on Earth. The study reveals that the inner core is far from being a uniform mass, contrary to previous assumptions. Instead, it is more akin to a tapestry, composed of various “fabrics.”

“For the first time we confirmed that this kind of inhomogeneity is everywhere inside the inner core,” explains lead author Guanning Pang in a university release.

By examining seismic data from a global network of detectors initially established to detect nuclear blasts, the researchers gained insights into Earth’s deepest reaches.

Earth's structure, layers
(© gritsalak –

Keith Koper, a seismologist involved in the study, likens the exploration of the inner core to a frontier area. He emphasizes that imaging the interior of Earth’s core is challenging due to its depth and unknown characteristics. The seismic waves generated by earthquakes provided valuable information, as they propagate through the planet’s crust, mantle, and core.

“The planet formed from asteroids that were sort of accreting [in space]. They’re running into each other and you generate a lot of energy. So the whole planet, when it’s forming up, is melting,” Koper explains. “It’s simply that the iron is heavier and you get what we call core formation. The metals sink to the middle, and the liquid rock is outside, and then it essentially freezes over time. The reason all the metals are down there is because they’re heavier than the rocks.”

The team’s analysis of seismic data, collected from 2,455 earthquakes, unveiled the structure and behavior of Earth’s inner core. They discovered that the inner core’s inhomogeneity strengthens as one goes deeper toward the center of the Earth. This observation provides insights into the growth process of the inner core over time. The inner core grew rapidly in the past, reaching an equilibrium, and then continued to grow at a slower rate. This growth process resulted in the presence of trapped liquid iron within the solid core.

The significance of this research extends beyond expanding our understanding of Earth’s core. It demonstrates the power of utilizing seismic data to unlock hidden information about our planet. The findings contribute to ongoing efforts to predict seismic activity, improve weather forecasting, and advance our knowledge of Earth’s atmosphere. The research team’s work opens the door to further exploration of Earth’s deep interior, paving the way for future discoveries.

The study is published in the journal Nature.

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