On the attenuation of seismic waves in the Earth's core

Stiller, H.; Franck, S.; Schmit, U.

doi:10.1016/0031-9201(80)90036-9

Cited by 17 publications

(2 citation statements)

References 12 publications

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“…Widmer et al (1991) have argued that the high Q -values obtained with modes are due to a misidentification of neighboring modes, and come to Q $ 110 for PKIKP-equivalent modes. 1.19.7.3.2 The attenuation mechanisms in the inner core Several mechanisms may contribute to attenuation: viscoelasticity (e.g., Doornbos, 1974;Stiller et al, 1980;Cormier, 1981;Li and Cormier, 2002), diffusion (Loper and Fearn, 1983), and scattering . 1.19.7.3.2 The attenuation mechanisms in the inner core Several mechanisms may contribute to attenuation: viscoelasticity (e.g., Doornbos, 1974;Stiller et al, 1980;Cormier, 1981;Li and Cormier, 2002), diffusion (Loper and Fearn, 1983), and scattering .…”

Section: The Apparent Incompatibility Of Body Wave and Normal Mode Rementioning

confidence: 99%

Deep Earth Structure – The Earth’s Cores

Souriau¹

2007

Treatise on Geophysics

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Section: The Apparent Incompatibility Of Body Wave and Normal Mode Rementioning

confidence: 99%

Deep Earth Structure – The Earth’s Cores

Souriau¹

2007

Treatise on Geophysics

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“…The presence of liquid inclusions in a solid matrix close to its melting point is presently the preferred inner core model for explaining the low quality factor (Qa -300) obtained for P waves in the inner core (Doornbos 1974;Stiller, Franck & Schmit 1980;Cormier 1981;Loper & Fearn 1983). According to Loper & Fearn (1983), the physical processes at the origin of the absorption in such a medium are mainly thermal diffusion between solid and liquid, and material diffusion due to the different compositions between liquid and frozen materials.…”

Section: Introductionmentioning

confidence: 99%

Attenuation in the uppermost inner core from broad-band GEOSCOPEPKPdata

Souriau

Roudil

1995

Geophysical Journal International

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S U M M A R YThe attenuation in the uppermost 500 km of the inner core is investigated at the global scale from the comparison of PKP(DF) and PKP(BC) phases recorded at broad-band GEOSCOPE stations. From the amplitude ratio DFIBC, we show that for most paths the attenuation is not frequency-dependent in the range 0.2-2 Hz. This result follows from the linearity of ln(DF/BC) with frequency. A notable exception occurs for paths from the south-west Pacific to Europe, as analysed in previous studies which infer a frequency dependence of inner core attenuation.The DF/BC amplitude ratios are determined at 3 s periods for the different paths. The data include the diffracted branch of BC at long distances, providing a deeper sampling of the inner core by the DF phase. The variations of the DF/BC amplitude ratio with epicentral distance exhibit a rather large scatter around a mean curve. This mean curve is compared to the theoretical ratios obtained for several earth models using synthetic seismograms. A trade-off exists between the velocity at the base of the liquid core and the attenuation in the uppermost inner core. Robust features include a velocity decrease in the lowermost liquid core, inferred from previous studies of the PKP(BC) propagation times, and a Q decrease at the top of the inner core, required by the DF/BC amplitude ratios. The preferred model exhibits a constant velocity gradient in the lowermost 150 km of the liquid core, and Q=200 in the uppermost 100 km of the inner core, Q = 440 below. With the adopted velocity model, an increase of Q with depth is required by the data.The amplitude ratio DF/BC exhibits regional variations, which cannot be attributed with certainty to regional variations of Q inside the inner core, due to the large Fresnel zone at the inner core and the possibility of wave focusing and defocusing in the mantle. On the other hand, with the available data, we failed to detect an anisotropy in attenuation inside the inner core.

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A generalization of the Vashchenko-Zubarev formula for the Grüneisen parameter

Stiller¹,

Franck²

1980

Physics of the Earth and Planetary Interiors

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On the attenuation of seismic waves in the Earth's core

Cited by 17 publications

References 12 publications

Deep Earth Structure – The Earth’s Cores

Deep Earth Structure – The Earth’s Cores

Attenuation in the uppermost inner core from broad-band GEOSCOPEPKPdata

A generalization of the Vashchenko-Zubarev formula for the Grüneisen parameter

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