New scientific discoveries point to the existence of a unique ring-shaped area within the Earth's liquid core, located thousands of kilometers below the surface. This area, discovered by scientists from the Australian National University (ANU), opens up new insights into the dynamics of our planet's magnetic field.
The structure within the liquid core was discovered at low geographic latitudes, and is aligned parallel to the equator. According to seismologists from ANU, this area had not been observed before.
The Earth's core consists of two layers: the inner core, which is solid, and the outer core, which is liquid. Surrounding the core is the mantle. The newly discovered ring-shaped area is located at the top of the outer core, where the liquid core comes into contact with the mantle.
The study co-author, geophysicist from ANU, Professor Hrvoje Tkalčić, explained that seismic waves in the newly discovered area are slower than in the rest of the liquid outer core.
"This structure is aligned parallel to the equatorial plane, is confined to low geographic latitudes, and has the shape of a ring," said Professor Tkalčić.
"We do not know the exact thickness of this ring, but we concluded that it extends several hundred kilometers below the boundary between the core and the mantle."
ANU scientists did not use traditional methods of observing seismic waves but analyzed similarities among waves many hours after the start of the earthquake. This approach allowed them to make a unique discovery.
"By studying the geometry of seismic waves and their paths through the volume of the outer core, we reconstructed their travel times through the Earth. Thus, we determined that this newly discovered area has a low seismic wave speed," explained Professor Tkalčić.
"This particular structure has remained hidden until now because earlier studies collected data with lower coverage of the volume of the outer core, observing waves within one hour after major earthquakes.
"We achieved much better coverage of the volume by studying waves that reflect many hours after major earthquakes."
The study co-author, Dr. Xiaolong Ma, emphasized that this discovery opens new insights into the dynamics of the Earth's magnetic field.
"There are still mysteries about the Earth's outer core that need to be resolved, which requires multidisciplinary efforts from the fields of seismology, mineral physics, geomagnetism, and geodynamics," said Dr. Ma.
The Earth's outer core mainly consists of liquid iron and nickel, and the intense movement of this electrically conductive liquid creates our planet's magnetic field. This field protects the Earth and enables life to be sustained by shielding it from harmful solar winds and radiation.
Scientists believe that understanding the composition of the outer core, including the presence of light chemical elements, is crucial for better understanding the magnetic field and predicting when it might weaken or cease to function.
"Our results are intriguing because this low seismic wave speed within the liquid core implies a high concentration of light chemical elements in these regions, which slows down the waves. These light elements, along with temperature differences, help mix the liquid in the outer core," said Professor Tkalčić.
"The magnetic field is a fundamental element needed to sustain life on the surface of our planet.
"The dynamics of the Earth's magnetic field is an area of great interest to the scientific community, so our results may encourage further research on the magnetic field both on Earth and on other planets."
Source: Australian National University, Canberra
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Erstellungszeitpunkt: 05 September, 2024