A doughnut-shaped structure has been discovered in the core of the Earth. Just like the universe and space, Earth is also full of mysteries that are yet to be uncovered and this doughnut-shaped mystery is one of them. This hidden region challenges our notion and comprehension about how the Earth actually functions and how it is built and attributed.
We learnt at school that the Earth has four main layers: the crust, the mantle, the outer core, and the inner core, but today, we are discovering that the newly found doughnut-shaped area is located where the liquid core and mantle meet at the top of Earth’s outer core. This is quite fascinating and confusing at the same time because it makes us wonder if this developed after the other Earth’s layers were discovered.
We have mostly deduced what is beneath the crust of the Earth from what seismic waves have murmured and what volcanoes have shown. Based on these indirect measurements, scientists have determined that only 1% of Earth’s volume is made up of the blazingly hot inner core, which has temperatures beyond 5,000 degrees Celsius. However, Stephenson and associates discovered evidence a few years ago that suggests the Earth’s inner core might consist of two separate layers.
A secret area miles and miles below the surface of the Earth
According to Professor Hrvoje Tkalčić, a geophysicist at ANU and a study co-author, the seismic waves found in the recently identified area are slower than those found in the rest of the liquid outer core. According to him, the area is confined to the low latitudes, has a doughnut form, and lies parallel to the equatorial plane. Although the doughnut’s precise thickness is unknown, we deduced that it extends several hundred kilometres below the core-mantle barrier.
This structure appears to be located in the ultra-low velocity zone (ULVZ), where seismic waves drastically slow down. Although the exact nature of this area is unknown, it may consist of thick materials, such as compounds richer in iron, or the relics of old oceanic plates that fell into the mantle billions of years ago. Understanding this discovery helps us to perceive how the Earth functions and is influenced.
Professor Hrvoje Tkalčić stressed that although they are unsure of the doughnut’s precise thickness, they have deduced that it extends several hundred km below the core-mantle border. The ANU scientists made the remarkable discovery by comparing waveforms many hours after the earthquake origin timings, as opposed to employing conventional seismic wave observation techniques and monitoring signals produced by earthquakes during the first hour.
Consequences for Earth’s core dynamics and magnetic field
The doughnut-shaped anomaly may play a significant role in the creation of Earth’s magnetic field. Researchers think it might change the flow of molten iron in the outer core, which powers the magnetic field-producing geomagnetic dynamo. The mystery surrounding magnetic field reversals—occurrences in which the North and South Poles alternate positions—is further elucidated by this discovery.
The rare occurrence of these reversals over millions of years may be explained if the doughnut structure has an impact on the stability of the molten iron flow. The structure’s function in material and thermal exchange between the core and mantle may provide fresh perspectives on how heat escapes from the core, impacting plate tectonics and volcanic activity on the surface.
Liquid iron and nickel make up the majority of the outer core. The intense movement of this electrically conductive liquid produces Earth’s magnetic field, which surrounds the planet and supports all life by shielding it from dangerous radiation and solar winds. To comprehend the magnetic field and forecast when it might eventually stop or weaken, scientists think it is essential to learn more about the makeup of the Earth’s outer core, particularly light chemical components.