The inner core began to slow down around 2010, moving slower than the Earth’s surface. – USC GRAPHIC
MADRID, June 13. (EUROPA PRESS) –
A new study published in the Nature magazine shows that the inner core of the Earth has been registering a slowdown in relation to the surface of the planet for some years.
The motion of the inner core has been debated by the scientific community for two decades, and some research indicates that the inner core rotates faster than the planet’s surface. The new study provides “unequivocal evidence that the inner core began to slow down around 2010, moving more slowly than the Earth’s surface.”
“When I first saw the seismograms hinting at this change, I was perplexed,” he said. it’s a statement John Vidale, senior professor of Earth Sciences at USC, lead author of the study. “But when we found two dozen more observations indicating the same pattern, the result was inescapable. The inner core had slowed down for the first time in many decades. Other scientists have recently advocated similar and different models, but our latest study provides the most compelling resolution“.
The relativity of recoil and slowdown The inner core is considered to be reversing and receding relative to the planet’s surface because it is moving slightly slower rather than faster than Earth’s mantle for the first time in about 40 years. . Relative to its speed in previous decades, the inner core is slowing down.
A SOLID SPHERE OF IRON AND NICKEL
The inner core is a solid sphere of iron and nickel surrounded by the outer core of liquid iron and nickel. About the size of the moon, the inner core lies more than 4,600 kilometers beneath our feet and presents a challenge to researchers: cannot be visited or seen. Scientists must use seismic waves from earthquakes to create representations of the movement of the inner core.
Vidale and Wei Wang of the Chinese Academy of Sciences used waveforms and repeated earthquakes in contrast to other research. Repeat earthquakes are seismic events that occur at the same location to produce identical seismograms.
In this study, the researchers collected and analyzed seismic data recorded around the South Sandwich Islands from 121 repeat earthquakes that occurred between 1991 and 2023. They also used data from twin Soviet nuclear tests between 1971 and 1974, as well as repeated French and American nuclear tests of other inner core studies.
Vidale said the slowing speed of the inner core was caused by the churning of the surrounding liquid iron outer core, which generates Earth’s magnetic field, as well as the gravitational pulls of dense regions of the overlying mantle rock.
THE IMPACT ON THE EARTH’S SURFACE
The implications of this change in inner core motion for the Earth’s surface can only be speculated. Vidale said the inner core recoil can alter the length of a day in fractions of a second: “It’s very difficult to notice, on the order of a thousandth of a second, almost lost in the noise of the churning oceans and atmosphere.”
Future research by USC scientists aims to chart the trajectory of the inner core in greater detail to reveal exactly why it is changing.
