Govind Tekale
One of the five elements worshipped by mankind is Mother Earth. While it carries oceans on its crust, there are deeper oceans inside its inner core.
Now it is found that the inner core at the center of the Earth may not be perfectly solid. The inner core is a ball of iron and nickel about 2,400 kms wide. Evidence has been found by a new study that the inner core’s outer boundary has noticeably changed shape over past few decades.
John Vidal, earth sciences professor at the University of Southern California says, “The most likely thing is the outer core is kind of tugging on the inner core and making it a little bit different.”
The findings of Vidal and his colleagues are reported on 10 Feb25 in the journal Nature Geoscience. This finding adds to the mysteries about the planet’s center. It was earlier reported by geophysicists that the inner core does not spin at exactly the same rate as the rest of the Earth. The inner core appears to be spinning slightly faster than outer layers a decade ago. Now it is spinning slightly slower.
The Earth’s inner core is the deepest geological layer. The layer on which we live – the crust – is just a few kms thick. Filling up 84% of the planet below the crust is the 2,880-km thick mantle. That mantle is soft enough in places to flow up and down. It generates the forces that push the continents around.
The liquid outer core is between the mantle and the inner core. Vidal and his colleagues looked at earthquakes in the South Sandwich Islands for this study. The South Sandwich Islands are a volcano in the South Atlantic Ocean.
More than 100 such “earthquake pairs” were identified by the scientists. Readings from 1991 to 2004 at two arrays of seismometers were analyzed. These arrays of seismometers are 12,800 kms away from the islands. One seismometer is near Fairbanks, Alaska. The other seismometer is at Yellowknife, in Canada’s Northwest Territories.
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Identical earthquake vibrations passing through the identical part of the Earth should have produced identical seismic signals at Fairbanks and Yellowknife. That was true at Fairbanks. But at Yellowknife the signals were different. It suggested something had changed near the outer boundary of the inner core.
The inner core could have been deformed by the turbulent flow in the outer core or gravitational pull from denser parts of the mantle. That may account for the change in seismic signals. Vidal said, “So it’s no surprise if it deforms”.
Geophysicists have argued in recent years over whether differences in the seismic signals are caused by a change in the rotation rate or by a change of the inner core. The geophysicist Hrvoje Tkalcic said, “The study thus reconciles the last debate by proposing a combination of both causes”.
The Earth’s inner core isn’t just slowing down, it’s possibly changing shape too. This is revealed in a new study published in the journal Nature Geoscience on February 10, 2025. The study was led by John Vidale, professor of earth sciences at the University of Southern California. This only proves that our Mother Earth has strange ways of behavior.
