Seismic waveform inversion for core-mantle boundary topography
Contribuinte(s) |
Institut für Geophysik (ETHZ) ; Swiss Federal Institute of Technology in Zurich (ETH Zurich). Institut des Sciences de la Terre de Paris (iSTeP) ; Université Pierre et Marie Curie - Paris 6 (UPMC) - Centre National de la Recherche Scientifique (CNRS) Institut für Geophysik |
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Data(s) |
2014
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Resumo |
International audience The topography of the core–mantle boundary (CMB) is directly linked to the dynamics of both the mantle and the outer core, although it is poorly constrained and understood. Recent studies have produced topography models with mutual agreement up to degree 2. A broad-band waveform inversion strategy is introduced and applied here, with relatively low computational cost and based on a first-order Born approximation. Its performance is validated using synthetic waveforms calculated in theoretical earth models that include different topography patterns with varying lateral wavelengths, from 600 to 2500 km, and magnitudes (∼10 km peak-to-peak). The source–receiver geometry focuses mainly on the Pdiff, PKP, PcP and ScS phases. The results show that PKP branches, PcP and ScS generally perform well and in a similar fashion, while Pdiff yields unsatisfactory results. We investigate also how 3-D mantle correction influences the output models, and find that despite the disturbance introduced, the models recovered do not appear to be biased, provided that the 3-D model is correct. Using cross-correlated traveltimes, we derive new topography models from both P and S waves. The static corrections used to remove the mantle effect are likely to affect the inversion, compromising the agreement between models derived from P and S data. By modelling traveltime residuals starting from sensitivity kernels, we show how the simultaneous use of volumetric and boundary kernels can reduce the bias coming from mantle structures. The joint inversion approach should be the only reliable method to invert for CMB topography using absolute cross-correlation traveltimes. |
Identificador |
hal-01392382 https://hal.archives-ouvertes.fr/hal-01392382 DOI : 10.1093/gji/ggu112 |
Idioma(s) |
en |
Publicador |
HAL CCSD Oxford University Press (OUP) |
Relação |
info:eu-repo/semantics/altIdentifier/doi/10.1093/gji/ggu112 |
Fonte |
ISSN: 0956-540X EISSN: 1365-246X Geophysical Journal International https://hal.archives-ouvertes.fr/hal-01392382 Geophysical Journal International, Oxford University Press (OUP), 2014, 198 (1), pp.55-71. <10.1093/gji/ggu112> |
Palavras-Chave | #[SDU.STU] Sciences of the Universe [physics]/Earth Sciences |
Tipo |
info:eu-repo/semantics/article Journal articles |