Anisotropic Earth's Inner Core within a Dynamic Core Scenario
Abstract
Recent global expansion of seismic data motivated a number of seismological studies of the Earth's inner core (EIC). An increasingly complex structure and anisotropy in EIC have been proposed to explain seismic data. In the meantime, new hypotheses of dynamic mechanisms have been put forward to interpret seismological results. In this study, the nature of anisotropy in EIC has been re-investigated by using PKP(BC-DF) core-sensitive differential travel-times and Fe-bcc/-hcp elastic constants calculated from first-principles. A Modified Transversely Isotropic Model (MTIM) has been introduced to account for a dynamic picture of EIC (e.g., eastward drift of material and heat flux variations at the CMB), where different chemical compositions could be stabilized at the polar/equatorial regions. Hemispherical patterns and anisotropic behaviour of EIC have been ascribed to the presence of denser polar regions (Si-poor Fe alloys) and lighter equatorial zones (Si-rich Fe alloys). A conglomerate-like EIC structure containing different material domains is then needed to address the complex anisotropy behaviour of the solid part of the Earth's core. Results have been discussed using both the seismic data from South Sandwich Islands (SSI) recorded in Alaska and the more recently collected travel-time residuals from the northern hemisphere to Antarctica.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMDI51B2135M
- Keywords:
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- 3909 MINERAL PHYSICS / Elasticity and anelasticity;
- 7207 SEISMOLOGY / Core