Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 On the History of Inner Core Discovery
- 2 Seismological Tools to Study the Inner Core
- 3 Inner Core Surface and Its Interior
- 4 Inner Core Anisotropy
- 5 Inner Core Rotational Dynamics
- 6 The Limitations, the Obstacles, and theWay Forward
- Appendix A Transmission/Reflection Coefficients for the Flat Inner Core Boundary
- Appendix B The Angle Between PKIKP Waves and the Rotation Axis of the Earth
- Appendix C P-Wave Velocity in a Transversely Isotropic Inner Core
- Appendix D Transdimensional Bayesian Inversion
- References
- Index
- Plate section
5 - Inner Core Rotational Dynamics
Published online by Cambridge University Press: 26 January 2017
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 On the History of Inner Core Discovery
- 2 Seismological Tools to Study the Inner Core
- 3 Inner Core Surface and Its Interior
- 4 Inner Core Anisotropy
- 5 Inner Core Rotational Dynamics
- 6 The Limitations, the Obstacles, and theWay Forward
- Appendix A Transmission/Reflection Coefficients for the Flat Inner Core Boundary
- Appendix B The Angle Between PKIKP Waves and the Rotation Axis of the Earth
- Appendix C P-Wave Velocity in a Transversely Isotropic Inner Core
- Appendix D Transdimensional Bayesian Inversion
- References
- Index
- Plate section
Summary
“This is not just a grand curiosity; it has implications for the dynamics of the whole planet and for the generation of the Earth's magnetic field.”
Comment on “Seismological evidence for differential rotation of the Earth's inner core” published in the same issues by Song and Richards (1996).
Kathy Whaler and Richard Holme, Nature (Whaler and Holme, 1996)“Right now, the differential rotation of the inner core is not yet firmly established.”
Annie Souriau, ‘Is the rotation real?’, Science (Souriau, 1998b)“Observations from our laboratory and the independent confirmations of travel time changes using our original method, which document a pattern of change that implies differential rotation of the inner core, should not be obscured by different or negative results from methods that are less capable.” In response to Souriau (1998b).
Paul G. Richards et al., Science (Richards et al., 1998)“Thus, there is no undeniable demonstration of the existence of inner core rotation. But there is also no undeniable demonstration of the absence of rotation.”
Annie Souriau, Science (Souriau, 1998a) In response to Richards et al. (1998).Introduction to IC Rotation
The above remarks clearly illustrate the controversy associated with the detection of differential rotation of the IC. It is a fascinating topic that, one could say, gradually overtook, or at least rivalled in its intensity, the seismological research on IC anisotropy.
It is easy to understand the captivation of the seismologists who strove to detect this phenomenon. The changing geomagnetic field observed at the Earth's surface mostly reflects the processes at the top of the liquid OC. However, due to the geomagnetic field's relationship with IC dynamics, seismological observations of IC rotation could invaluably constrain the dynamics of the geomagnetic field at the deeper, inward-facing surface of the OC. Seismologists not only posed the question, “How do we measure IC rotation?”, but also, “Can we even detect it?”. Doubt was rooted in the pioneering seismological papers on IC rotation. Perhaps the most relevant question was, “What is the magnitude and direction of differential rotation?”. This was important because it could indirectly provide relevant information about the IC, such as its viscosity, gravitational relationship with the lowermost mantle, and even its age.
- Type
- Chapter
- Information
- The Earth's Inner CoreRevealed by Observational Seismology, pp. 131 - 168Publisher: Cambridge University PressPrint publication year: 2017