Scientists have found evidence suggesting that Earth's inner core has changed shape over the past 20 years, possibly deforming at its edges due to interactions with the liquid outer core and gravitational forces. The BBC reports: The inner core is usually thought to be shaped like a ball, but its edges may actually have deformed by 100 million or more in height in places, according to Prof John Vidale who led the research. [...] The new analysis looked at seismic wave patterns from earthquakes that repeated in the same location between 1991 and 2023. That helped to show how the inner core is changing over time. Prof Vidale, an earth scientist at the University of Southern California, found more evidence to back up the theory that during those years the inner core slowed down around 2010. But his team also found the evidence of the inner core's changing shape. It appears to be happening at the boundary of the inner and outer core, where the inner core is close to melting point. The liquid flow of the outer core as well as pull from an uneven gravity field may cause deformation. Prof Hrvoje Tkalcic from Australian National University said the findings could allow scientists "to make more informed estimates of some important material properties, such as the viscosity of the inner core, which is one of the least known quantities in modern science."

The research is published in the scientific journal Nature Geoscience.

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