  Experimental data suggest that the Earth short time dynamics is related to
stochastic fluctuation of its shape. As a first approach to this problem, we
derive a toy-model for the motion of a rotating ellipsoid in the framework of
stochastic differential equations. Precisely, we assume that the fluctuations
of the geometric flattening can be modeled by an admissible class of diffusion
processes respecting some invariance properties. This model allows us to
determine an explicit drift component in the dynamical flattening and the
second zonal harmonic whose origin comes from the stochastic term and is
responsible for short term effects. Using appropriate numerical scheme, we
perform numerical simulations showing the role of the stochastic perturbation
on the short term dynamics. Our toy-model exhibits behaviors which look like
the experimental one. This suggests to extend our strategy with a more
elaborated model for the deterministic part.
