The relative wavelengths of fast and slow velocity anomalies in the lower mantle: Contrary to the expectations of dynamics? (original) (raw)

This study analyzes shear velocity anomalies in the Earth's mantle across various tomographic models, focusing on the amplitude spectra of both fast and slow anomalies at different depths. The findings indicate that while mid-mantle heterogeneity is relatively flat, slow anomalies in the deep mantle exhibit consistently higher amplitudes at harmonic degrees 1-12, contradicting existing dynamic models that suggest narrow upwellings and broad downwellings. The results imply potential variations in phase, chemistry, and/or viscosity in the lowermost mantle, providing a new framework for understanding the discrepancies between tomographic and dynamic models.