VISCOELASTIC VERSUS VISCOUS DEFORMATION AND THE ADVECTION OF PRE-STRESS

The Heaviside response of an incompressible viscous half-space is compared to that of a viscoelastic half-space that may or may not be compressible elastically. It will be shown that the difference between viscous and viscoelastic response is detectable from uplift data provided that the age of the data goes back far enough. It is also possible to resolve, using the post-glacial rebound data, whether the viscous model or the viscoelastic model is preferred provided that the ice model is better constrained. Moreover, the rate of solid-fluid transition is wavenumber (k) dependent and the transition is not as rapid nor as small as was previously predicted. Finally, the advection of pre-stress is shown to be required in viscoelastic deformation problems of the earth and that it is responsible for viscoelastic gravitational relaxation.