Primitive geological knowledge tells us that the structure of the Earth consists of four layers. The crust (Crust), the mantle (Mantle), the outer core (Outer Core) and the inner core (Inner Core). Our world still has one layer of the innermost core.
team of geophysicists Dr Phạm Thành Sơn and Prof Hrvoje Tkalčić of the Australian National University (ANU) brought data from the International Seismological Center collected data. for many decades Analyzed with specific techniques until evidence of the existence of solid metal spheres is found. It is about 650 km in diameter at the center of the inner crust. It is considered a newly discovered world structure from what has been known before.
The structure of the world layer 5
Danish seismologist Inge Lehmann The inner core has been discovered since 1936 and it is only 0.69% of the Earth’s volume. Because it is very deep and relatively small. This makes direct measurement very difficult. Scientists interested in this field have turned to seismic waves as the main tool for studying the inner core. Measured by seismometers scattered in countries around the world.
“When there is a big earthquake The resulting seismic waves can bounce back and forth from one side of the earth to the other like a ping pong ball,” explains Dr. Pham Thanh Son. depending on density, temperature and chemical composition
“Twenty years ago, researchers began using seismometer data to suggest the existence of a 5th Earth structure, and since then efforts have been made to provide evidence for the existence of the Innermost Inner Core. IMIC) or the innermost core of the Earth more and more.”
Dr Pham Thanh Son Discuss the latest work of the team that “Advances in this study is that we have found a new way to prove that the IMIC or the inner core exists.”
Primary seismic wave (P-wave) type PKIKP phase generated by the Alaska earthquake. Moves through the Inner Core (IMIC), reflects back and forth 5 times (Drew Whitehouse, Son Phạm and Hrvoje Tkalčic)
The team of Dr. Pham Thanh Son Choose to analyze primary seismic waves (P-wave) phase type PKIKP, which has the important property of being able to travel through all layers of the earth’s structure. The team then selected large earthquake events that caused PKIKP to bounce more than once through the Earth’s center. which chooses to use the PKIKP wave that passes through the center of the earth only once
Using this technique, the team found that seismic waves travel through the innermost core (IMIC) at a different speed than the surrounding inner core (IC). The speed at which this will change depending on the angle of the wave. From a physical property called anisotropy, choosing to use multiple reflected waves makes it possible to observe the speed relative to the direction. It can be done precisely and with little error.
Dr Pham Thanh Son Referring to this discovery, In addition to providing reliable evidence of the existence of the Innermost Core (IMIC), it can be said that the region is likely to have an iron-nickel alloy chemical composition. The same as the inner core (IC) that surrounds it. But the atoms are arranged in a different way. That is, the iron ore in the IMIC region has atoms arranged in a crystalline pattern. causing the inner core to not be completely homogeneous But separated into 2 sub-tiers, namely the 4th floor and the 5th floor
Dr Pham Thanh Son Concluding the discovery that “Building on this study will help us understand more about how Earth’s magnetic field is formed. Can living things survive on other planets too?”
This research was published in the journal https://www.nature.com/articles/s41467-023-36074-2
picture: Space Frontiers / Getty Images
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