The contribution of seismic processes to the variations in the Earth’s rotation has always been a place of debate. Most recently, Kiani Shahvandi, et al. (2024a) have demonstrated that the role of seismic processes on the polar motion is insignificant. In fact, compared to barystatic, glacial isostatic adjustment and mantle convection, and core dynamics, the influence of seismic processes is smallest.   

Similarly, Kiani Shahvandi, et al. (2024b) have shown that the budget of secular trend observed in the length of day record since 1935 can be closed when we account for barystatic, glacial isostatic adjustment, and core dynamics. This demonstrates that the room for a contribution from seismic processes is very small.

References

Kiani Shahvandi, M., Adhikari, S., Dumberry, M., Modiri, S., Heinkelmann, R., Schuh, H., Mishra, S., Soja, B. (2024a). Contributions of core, mantle and climatological processes to Earth’s polar motion. Nature Geoscience, 17: 705-710, https://doi.org/10.1038/s41561-024-01478-2

Kiani Shahvandi, M., Adhikari, S., Dumberry, M., Mishra, S., Soja, B.  (2024b). The increasingly dominant role of climate change on length of day variations. Proceedings of the National Academy of Sciences, 121: e2406930121, https://doi.org/10.1073/pnas.2406930121