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Updated: Jul 18, 2026
06:04
Simulation of the Planetary Interior Differentiation Processes in the Laboratory
Published on: November 15, 2013
Short wavelength topography on the inner-core boundary
Aimin Cao1, Yder Masson, Barbara Romanowicz
1Berkeley Seismological Laboratory, University of California, Berkeley, CA 94720, USA.
Summary
Inner-core boundary topography influences Earth's geodynamo. Seismic data reveal significant temporal changes in the inner core reflected phase PKiKP, suggesting 10 km scale topography possibly sustained by convection and inner core super rotation.
Area of Science:
- Geophysics
- Seismology
- Earth's deep interior
Background:
- Inner-core boundary (ICB) topography is crucial for understanding core-mantle coupling and geodynamo processes.
- Previous studies have lacked definitive evidence for ICB topography and its temporal variability.
Purpose of the Study:
- To present evidence for significant temporal variability in the amplitude of the inner core reflected phase PKiKP.
- To constrain the topography and dynamics of the inner-core boundary.
Main Methods:
- Analysis of high-quality earthquake doublets observed postcritically at the Yellowknife seismic array (YK).
- Utilizing seismic data from the South Sandwich Islands region over a 10-year interval (1993/2003).
- Complementary analysis of data from multiple seismic doublets.
Main Results:
- Observed significant temporal variability in the amplitude of the PKiKP phase.
- Indicated the presence of inner-core boundary topography with a horizontal wavelength of approximately 10 km.
- Results are compatible with inner core super rotation of 0.1-0.15 degrees per year.
Conclusions:
- The findings support the existence of small-scale convection sustaining ICB topography.
- Decadal scale changes in topography provide constraints on the viscosity at the top of the inner core.
- This study advances our understanding of inner core dynamics and geodynamo generation.
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