Innermost core seismic waves behave differently from exterior section
seismic waves.
According to a research that was released in Nature Communications this
week1, the reverberations from earthquakes as they bounce back and forth
through the planet's center have disclosed new information about the
structure of the inner core.
There has been growing proof for several decades that the planet's solid
inner core is made up of different layers2, 3, but little is known about the
layers' characteristics.
Researchers used a number of seismometers to study how seismic waves are
bent as they travel through the solid mass of iron nickel at Earth's core in
order to better understand the innercore's structure. Hrvoje Tkali, a
geophysicist at the Australian National University in Canberra, Australia,
and a co-author, claims that the earth oscillates like a bell following a
significant earthquake, and not just for hours but for days.
Researchers captured waves near to the earthquake's initial epicenter and
at the antipode, which is the exact opposite location on Earth's surface, in
order to identify these oscillations. They were able to examine the various
passages through the center of the Earth as a result. According to co-author
Thanh-Son Pham, a postdoctoral associate at the Australian National
University, "it's like a ping-pong ball that's moving back and forth." The
seismometers captured up to five bounces from a single incident. Each
reverberation takes about twenty minutes to travel from one half of the
globe to the other.
Built-in dimensions
Each of the initial tremors had a magnitude higher than six, but as the
waves traveled through the Earth's interior, they became increasingly
weakened. To create a more accurate representation of the distortion coming
from the deepest center, the researchers used a method known as "stacking,"
in which they merged the waveforms from a single occurrence.
They discovered that the waves behaved differently in the innermost inner
core than in the outward portion; this core is thought to be approximately
650 kilometers thick. In the core's deepest region, waves slowed down in one
direction, while waves in the outer stratum slowed down in a different
direction. It simply means that the iron crystals, which are prevalent in
the inner core, are likely arranged differently than they are in the inner
core's exterior shell, according to Tkali.
The research is significant, according to geophysicist Vernon Cormier of
the University of Connecticut in Storrs, because it provides an extremely
challenging assessment of the innermost region of the Earth. To determine
the wave speed in the extremely deep core of the Earth, Cormier explains
that it is necessary to locate seismic waves that have been captured at a
great distance and are relatively weak in amplitude.
Although the method is frequently employed in the discovery of resources,
it is not frequently applied in geophysics.
The most recent discovery will aid in understanding how Earth's solid inner
core developed and what impact it may have had on the magnetic field. This
process is believed to have begun between 600 million and 1.5 billion years
ago.
