Core–mantle boundary deformations and J 2 variations resulting from the 2004 Sumatra earthquake

摘要

The deformation at the core–mantle boundary produced by the 2004 Sumatra earthquake isinvestigated by means of a semi-analytic theoretical model of global coseismic and postseismicdeformation, predicting a millimetric coseismic perturbation over a large portion of thecore–mantle boundary. Spectral features of such deformations are analysed and discussed. Thetime-dependent postseismic evolution of the elliptical part of the gravity field (J 2) is also computedfor different asthenosphere viscosity models. Our results show that, for asthenosphericviscosities smaller than 1018 Pa s, the postseismic J 2 variation in the next years is expected toleave a detectable signal in geodetic observations.