Spectral element modelling of three-dimensional wave propagation in a self-gravitating Earth with an arbitrarily stratified outer core

Abstract

This paper deals with the spectral element modeling of seismic wave\npropagation at the global scale. Two aspects relevant to low-frequency studies\nare particularly emphasized. First, the method is generalized beyond the\nCowling approximation in order to fully account for the effects of\nself-gravitation. In particular, the perturbation of the gravity field outside\nthe Earth is handled by a projection of the spectral element solution onto the\nbasis of spherical harmonics. Second, we propose a new formulation inside the\nfluid which allows to account for an arbitrary density stratification. It is\nbased upon a decomposition of the displacement into two scalar potentials, and\nresults in a fully explicit fluid-solid coupling strategy. The implementation\nof the method is carefully detailed and its accuracy is demonstrated through a\nseries of benchmark tests.\n