Enhanced inner core fine-scale heterogeneity towards Earth's centre

Area of Science:

• Geophysics
• Seismology
• Earth Science

Background:

• Earth's inner core solidifies within the outer core, developing texture from iron grains.
• This texture records inner core growth and may change due to geodynamical forces.
• Seismic waves can image inner core fabric to understand Earth's core evolution.

Purpose of the Study:

• To model the fine-scale heterogeneity and texture of Earth's inner core.
• To investigate the spatial distribution and strength of seismic scattering within the inner core.

Main Methods:

• Utilized a novel dataset from a global array of small-aperture seismic arrays.
• Analyzed seismic energy backscattered from fine-scale heterogeneities in the inner core.
• Developed a three-dimensional model of inner core fine-scale heterogeneity.

Main Results:

• Observed ubiquitous seismic scattering across all sampled longitudes and latitudes of the inner core.
• Found a substantial increase in scattering strength 500-800 km beneath the inner core boundary.
• The fine-scale heterogeneity constitutes the larger-scale inner core fabric.

Conclusions:

• The enhanced scattering in the deeper inner core supports a model of rapid growth following delayed nucleation.
• Inner core texture provides insights into its formation and evolution over geologic time.