Comparing the timing of seismic signals as they touched the core revealed changes in core rotation over time, confirming the 70-year rotation cycle. But the depth and inaccessibility of the inner core mean that uncertainties remain, she added. The mysterious region where the liquid outer core envelops the solid inner core is especially interesting, Vidale added. “We might have volcanoes on the inner core boundary, for example, where solid and fluid are meeting and moving,” he said. Because the spinning of the inner core affects movement in the outer core, inner core rotation is thought to help power Earth’s magnetic field, though more research is required to unravel its precise role.

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Persons: seismologist Inge Lehmann, —, ”, Lauren Waszek, “, ” Waszek, John Vidale, “ We’ve, ” Vidale, we’ve, what’s, Vidale, Seismologists, Lehmann, Waszek, ” Mindy Weisberger Organizations: CNN, James Cook University, Earth Sciences, University of Southern California’s Dornsife, of Letters, Arts and Sciences, Geological Survey, Scientific Locations: Australia, New Zealand, South Sandwich, South