While most of us take the earth beneath our feet for granted, Earth's
history is preserved inside its many layers, much like a book's pages.
historical past.
Deep beneath Earth's past, there are little-known chapters in its history,
according to research. In fact, it appears that Earth's inner core has a
second core that is considerably deeper. Geophysicist Joanne Stephenson of
Australian National University
stated in 2021
that the Earth's four major layers are the crust, mantle, outer core, and
inner core.
Much of what volcanoes have shown and what seismic waves have whispered
have been used to deduce what is underneath the Earth's crust.
The scorchingly hot inner core, with temperatures exceeding 5,000 degrees
Celsius (9,000 degrees Fahrenheit), takes up only 1% of the entire volume of
Earth, according to calculations based on these indirect measurements.
Nevertheless, Stephenson and colleagues discovered evidence that suggests
Earth's inner core may possibly contain two separate layers a few years
ago.
It's incredibly fascinating and may need a revision of the textbooks, so
Afterwards,
Stephenson gave an explanation.
The researchers searched through and compared thousands of inner core model
predictions with actual data acquired by the International Seismological
Center over many decades about how long seismic waves took to travel within
the Earth.
What's down there, then? The researchers examined several models of the
inner core's
anisotropy, or how variations in the composition of its material affect seismic wave
characteristics, and discovered that some were more plausible than
others.
While some models predict that the inner core's material channels seismic
waves more quickly parallel to the equator, others predict that the inner
core's material mix permits quicker waves that are more readily parallel to
the Earth's rotating axis. Even then, there are disputes over the precise
amount of variation at particular angles.
The study found that although there was a change in the slow direction of
waves to a 54-degree angle and that the quicker direction of waves ran
parallel to the axis, there was not much variation with depth in the inner
core.
According
to Stephenson, "We discovered data that may point to a shift in the
structure of iron, suggesting maybe two independent cold periods in Earth's
history."
Although some of the specifics of this significant event remain a mystery,
we have now contributed another piece to our understanding of the Earth's
deep core.
These new discoveries could provide an explanation for why
certain experimental data
has been incongruent with our predictions of the structure of the
Earth.
Iron crystals that make up the inner core have various structural
alignments, which is evidence that there may be an innermost layer.
The scientists
explained in their study
that the distribution of earthquakes and receivers throughout the world,
particularly in the polar antipodes, limits them and reduces the accuracy of
their findings.
Yet, their findings concur with those of prior investigations of the
anisotropy of the deepest inner core.
Future study might close some of these informational gaps, enabling
researchers to confirm or refute their results, and, ideally, translate more
of the tales preserved in this early period of Earth history.
This research was published in the
Journal of Geophysical Research.
