Earth's Inner Core: A Viscous Deformation Unveiled

A new study reveals that Earth's inner core, approximately 5,100 km beneath the surface, undergoes viscous deformation. Anchored by gravity within the molten outer core, scientists previously believed this region to be a solid sphere of iron and nickel. However, analysis of seismic waves from 121 repeating earthquakes between 1991 and 2024 near the South Sandwich Islands, Antarctica, showed changes in wave patterns between 2004 and 2008. These alterations indicate the waves briefly penetrated the inner core, leading to the conclusion that the core's surface deforms, altering the boundary between the inner and outer core. The research, led by John Vidale, professor of Earth sciences at USC [University of Southern California], suggests interaction between the inner and outer core layers causes this deformation.