Can the 1D viscosity profiles inferred from postglacial rebound data be affected by lateral viscosity variations in the tectosphere?

We have tested the impact of lateral viscosity variations (LVV) in the top 200 km of the mantle (tectosphere) on the interpretation of Fennoscandian p ostglacial uplift data in terms of 1D viscosity models. Our test consists o f two steps. In the first step, we simulate the postglacial uplift for a gi ven 2D viscosity structure involving a cratonic lithospheric root below the ice sheet and an asthenosphere below oceanic areas. In the second step, we interpret the result of this simulation in terms of a 1D viscosity model. The resultant ID viscosity model shows a lower viscosity in the lower mantl e, a higher viscosity in the shallow sublithospheric mantle and a smaller t hickness of the lithosphere than the synthetic model of viscosity.