High‐temperature viscoelastic relaxation in iron and its implications for the shear modulus and attenuation of the Earth's inner core

Jackson, Ian; Gerald, John Fitz; Kokkonen, Harri

doi:10.1029/2000jb900131

Cited by 59 publications

(49 citation statements)

References 91 publications

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“…These results confirm inferences on the basis of shock wave measurements of v P and estimates of v S at core conditions [Brown and McQueen, 1986]. It does not seem necessary to invoke additional mechanisms to explain the high Poissons ratio of the inner core such as viscoelastic dispersion [Jackson et al, 2000] or the presence of partial melt [Singh et al, 2000].…”

Section: High Temperature Elasticitysupporting

confidence: 78%

Physical properties of iron in the inner core

Steinle‐Neumann¹,

Stixrude²,

Cohen³

2003

Earth's Core: Dynamics, Structure, Rotation

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The Earth's inner core plays a vital role in the dynamics of our planet and is itself strongly exposed to dynamic processes as evidenced by a complex pattern of elastic structure. To gain deeper insight into the nature of these processes we rely on a characterization of the physical properties of the inner core which are governed by the material physics of its main constituent, iron. Here we review recent research on structure and dynamics of the inner core, focusing on advances in mineral physics. We will discuss results on core composition, crystalline structure, temperature,and various aspects of elasticity. Based on recent computational results, we will show that aggregate seismic properties of the inner core can be explained by temperature and compression effects on the elasticity of pure iron, and use single crystal anisotropy to develop a speculative textural model of the inner core that can explain major aspects of inner core anisotropy.

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Section: High Temperature Elasticitysupporting

confidence: 78%

Physical properties of iron in the inner core

Steinle‐Neumann¹,

Stixrude²,

Cohen³

2003

Earth's Core: Dynamics, Structure, Rotation

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show abstract

“…Non-linear response is then expected to generate deviations from the KramersKronig relationship which can be observed if the real and imaginary parts of the moduli are measured independently over a very large frequency range. The first work by Jackson et al (2000) confirmed that 'essentially linear' behaviour exists for viscoelastic relaxations in iron. Further work in other systems and for wider frequency ranges would be desirable.…”

Section: Resultsmentioning

confidence: 74%

(An)elastic softening from static grain boundaries and possible effects on seismic wave propagation

Salje

2008

Phys Chem Minerals

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It is argued that low-frequency wave propagation shows, in most cases, very little dependence on the atomistic properties of grain boundaries if the thickness of the grain boundary is atomistically thin while the grain size is in the mm region. Large effects do exist for specific textures (e.g. the brick wall texture). The essential ingredient for the assessment of an-elastic and non-linear elastic features of seismic wave propagation does not primarily depend on the structural properties of immobile, dry grain boundaries but on the way the grain boundary properties can be related to those of macroscopic mineral assemblies. Specific results for coated sphere textures are derived using Hashin-Shtrikman theory. An-elastic seismic features are more likely to be related to the mobility of boundaries and dislocations which can be attached to the grain boundaries, or bulk-related defect structures, rather than the intrinsic materials properties of the grain boundaries.

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“…This is because anharmonic and/or pre-melting effects at high temperature (e.g. Laio et al, 2000;Vočadlo et al, 2009;Sha and Cohen, 2010;Martorell et al, 2013), as well as the possible presence of fluid inclusion in the core (Vočadlo, 2007), or frequency-dependent viscoelastic relaxations (Jackson et al, 2000), are all expected to more strongly influence V S than V P .…”

Section: Density Dependence Of the Compressional Sound Velocity In Hcmentioning

confidence: 99%

Sound velocity of hcp-Fe at high pressure: experimental constraints, extrapolations and comparison with seismic models

Antonangeli

Ohtani

2015

Prog. in Earth and Planet. Sci.

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Determining the sound velocity of iron under extreme thermodynamic conditions is essential for a proper interpretation of seismic observations of the Earth's core but is experimentally challenging. Here, we review techniques and methodologies used to measure sound velocities in metals at megabar pressures, with specific focus on the compressional sound velocity of hexagonal close-packed iron. A critical comparison of literature results, coherently analyzed using consistent metrology (pressure scale, equation of state), allows us to propose reference relations for the pressure and density dependence of the compressional velocity of hexagonal close-packed iron at ambient temperature. This provides a key base line upon which to add complexity, including high-temperature effects, pre-melting effects, effects of nickel and/or light element incorporation, necessary for an accurate comparison with seismic models, and ultimately to constrain Earth's inner core composition.

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High‐temperature viscoelastic relaxation in iron and its implications for the shear modulus and attenuation of the Earth's inner core

Cited by 59 publications

References 91 publications

Physical properties of iron in the inner core

Physical properties of iron in the inner core

(An)elastic softening from static grain boundaries and possible effects on seismic wave propagation

Sound velocity of hcp-Fe at high pressure: experimental constraints, extrapolations and comparison with seismic models

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