Gravitational Instability in the Earth's Viscoelastic Crust

This paper studies instability of a heavy inclusion in the Earth's upper layers by the linear theory method for small perturbations. The existence of such inclusions with increased density is associated with chemical inhomogeneity or phase transitions. The viscoelasticity of the geomaterial is described by the Maxwell rheological model. Two layouts of the inclusion with increased density are considered. The heavy inclusion in the cold upper elastic layer of the crust does not change its location under small perturbations, i.e., it is stable according to the linear theory. The heavy inclusion which is located in the hot viscous crustal layer underlying the upper cold layer, is unstable (slowly sinking into the underlying viscous mantle layers).