Core–mantle boundary deformations and J2 variations resulting from the 2004 Sumatra earthquake |
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Authors: | V Cannelli D Melini P De Michelis A Piersanti F Florindo |
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Institution: | Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605;, I-00143 Rome, Italy |
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Abstract: | The deformation at the core–mantle boundary produced by the 2004 Sumatra earthquake is investigated by means of a semi-analytic theoretical model of global coseismic and postseismic deformation, predicting a millimetric coseismic perturbation over a large portion of the core–mantle boundary. Spectral features of such deformations are analysed and discussed. The time-dependent postseismic evolution of the elliptical part of the gravity field ( J 2) is also computed for different asthenosphere viscosity models. Our results show that, for asthenospheric viscosities smaller than 1018 Pa s, the postseismic J 2 variation in the next years is expected to leave a detectable signal in geodetic observations. |
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Keywords: | core–mantle boundary deformation rheology seismic modelling spectral analysis |
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