Variational formulation of the earth's elastic-gravitational deformations under low regularity conditions

We present a construction of the action, in the framework of the calculus of variations and Sobolev spaces, describing deformations and the oscillations of a uniformly rotating, elastic and self-gravitating earth. We establish the Fr\'{e}chet differentiability of the action under minimal regularity assumptions, which constrain the possible composition of an earth model. Thus we obtain well-defined Euler-Lagrange equations, weakly and strongly, that is, the system of elastic-gravitational equations.