Scientists discovered that the Earth has a “fifth layer” in the form of an inner core, deeper in the center of the planet.
Geologists from the Australian National University have created algorithms that allow them to search thousands of models from the Earth’s inner core.
For a long time, textbooks taught students that the earth consists of four layers: the crust, the mantle, the outer core (the outer core) and the inner core (the inner core). However, scientists have suspected the existence of a fifth layer for more than a decade, but it has been proven that it is Nearly impossible to spot.
Scientists discovered changes in the structure of iron within the inner core, indicating the presence of a new “boundary line” extending 650 km from the center of the Earth.
“It’s very exciting, and it might mean we have to rewrite the textbooks,” said lead author Joanne Stephenson.
The scientists used travel time data for seismic waves that travel within the Earth, captured by the International Seismological Center, as part of the study.
Then they used their new algorithm to search through the data to discover evidence of changes to the structure of the deepest part of Earth’s inner core.
Finding these small changes in the structure of iron proved “especially difficult”, but they were able to demonstrate two separate cooling events in Earth’s history.
This indicates that an exciting and previously unknown event occurred at some point in the early years of Earth’s evolution, 4.5 billion years ago.
“The details of this major event are still a bit mysterious,” Stephenson explained, “but we have added another piece of the puzzle when it comes to our knowledge of the inner core of the Earth.”
Until recently, our understanding of the deepest depths of our world was through a combination of volcanic eruptions and seismic waves.
They are indirect observations but have allowed geologists to determine that the inner core reaches temperatures in excess of 5,000 degrees Celsius.
The inner core is relatively small, and it constitutes only 1% of the Earth’s volume and exists as a single body, with the outer core surrounding it, the surrounding mantle and the crust surrounding the mantle.
The structure of the Earth’s deep inner core has important implications for core development, as it is believed to be associated with the early stages of core formation.
Previous studies indicated a deeper inner core with a distinct contrast with respect to the rest of the inner core.
Anisotropy is the way in which differences in material composition change the properties of seismic waves.
The idea of another distinct class was proposed two decades ago, said Stevenson, the doctoral researcher, but the data was not entirely clear.
“We bypassed this by using a very clever search algorithm to search thousands of samples from the inner core,” she added.
The changes in the waves revealed slight differences in the structure of the iron as it moved through the inner core, according to Stephenson.
The data are not perfect due to the presence of “a lot of noise” and the gaps, but the scientists say they are confident in the results because they are consistent with other studies into the anisotropy of the inner parts of the inner core.
The scientists wrote in their research paper: “We are limited by the distribution of earthquakes and global receivers, especially at the antipole.”
The full results are published in the Journal of Geophysical Research.
Source: Daily Mail