Core-mantle boundary deformations and J2 variations resulting from the 2004 Sumatra earthquake

摘要

The deformation at the core-mantle boundary produced by the 2004 Sumatraearthquake is investigated by means of a semi-analytic theoretical model ofglobal coseismic and postseismic deformation, predicting a millimetriccoseismic perturbation over a large portion of the core-mantle boundary.Spectral features of such deformations are analysed and discussed. Thetime-dependent postseismic evolution of the elliptical part of the gravityfield (J2) is also computed for different asthenosphere viscosity models. Ourresults show that, for asthenospheric viscosities smaller than 10^18 Pa s, thepostseismic J2 variation in the next years is expected to leave a detectablesignal in geodetic observations.