During our school years, we learned about the Earth’s five layers, including the crust, mantle, outer core, and inner core.
With advancing technology, recent studies have revealed that the Earth’s inner core also consists of its own distinct layers, confirming the existence of a solid spherical metallic mass with a diameter of approximately 650 kilometers at the center of the Earth.
Direct exploration of the Earth’s core is not possible, so the field of geology is closely linked with seismology. Seismic waves generated by events such as earthquakes travel through the Earth’s layers, providing valuable insights into the planet’s interior.
Illustration of the Earth’s layers
For decades, geologists have debated the possibility of a solid metallic sphere within the inner core, primarily composed of iron and nickel. Data from approximately 200 earthquakes has provided further evidence for this hypothesis. As seismic waves travel through the Earth, they encounter and bounce off the enormous metallic sphere at the core.
A newly published scientific report also suggests that the inner core consists of two layers, which likely formed at different stages during the Earth’s development. “The inner core can be regarded as a time capsule containing the geological history of Earth – it is a fossil record that reveals information about events that occurred on the planet hundreds of millions to billions of years ago,” emphasized Professor Hrvoje Tkalčić.
Scientists utilized a new technique to enhance signals captured by seismic monitoring devices, confirming that seismic waves bounce multiple times upon encountering the solid metallic core. By measuring the speed of these waves as they travel through the Earth’s layers, seismologists can gain insights into the properties of the materials that compose the layers.
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Illustration of seismic waves encountering the spherical mass at the center of the Earth
“This is a very interesting discovery because it provides us with a new approach to investigate the inner core and its central region,” stated researcher Thanh-Son Pham from the Australian National University.
This recent research has generated new questions regarding the formation of the two layers within the inner core. The initial hypothesis suggests that a significant event altered the planetary development process, resulting in a change in the structure of the Earth’s core.
“There are still many unanswered questions about the Earth’s inner core, an enigmatic region that holds secrets about the planet’s formation,” added researcher Hrvoje Tkalčić.