Anthropocene isostatic adjustment on an anelastic mantle

Abstract

AbstractA general assumption in geodesy is that solid Earth deformation in the presence of recent hydrological and ice loading is well approximated by a purely elastic response. In cases where there is clear evidence that thermal and petrological conditions exist that favor vigorous high-temperature creep behavior, such as in the mantle beneath Iceland, Patagonia, Alaska, Japan, and Svalbard, many response models have been approximated by using a Maxwell viscoelasticity. However, non-Maxwellian transient viscoelastic rheology is required for many post-seismic relaxation studies. Here, we reconsider the solid Earth response in light of highly temperature-dependent transient viscoelastic responses currently favored in the mineral physics and seismological communities. We develop a mantle response Green’s function that accounts for the vertical isostatic motion of the mantle caused by the acceleration of ice mass loss for Greenland and Patagonia measured by spaceborne and airborne remote sensing since 1992 and 1945, respectively. The Green’s function may be used to examine how anelasticity influences the uplift associated with accelerated surface mass loss. We perform a parameter exploration of the constants that define the Extended Burgers Material model, a rheology having firm experimental and theoretical underpinnings, in order to isolate those material model parameters that have the greatest impact on anelastic-isostatic uplift over interannual and interdecadal timescales. Anelasticity corrections may be required for solid Earth vertical uplift in space gravimetric solutions for long-term hydrology and cryospheric change.