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Abstract:
A 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. If thermal or petrological conditions exist that favor vigorous high-the 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 models of post-seismic relaxation. Here we reconsider the solid Earth response in light of a temperature-dependent transient viscoelasticity 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 acceleration of ice mass loss for Greenland and Patagonia measured by remote sensing since 1992 and 1945, respectively. The Green's function may be used to examine how anelasticity may express itself in the uplift associated with accelerated surface ice and water loss. We perform an extensive parameter exploration of the constants that define the Extended Burgers Material (EBM) 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 time scales. Especially important are the contrasts among elastic, Maxwell and EBM predictions. Implications for the corrections for solid Earth vertical uplift in space gravimetric solutions for long-term hydrology and cryospheric change are also discussed.
© 2023 California Institute of Technology. Government sponsorship acknowledged.
