Constraining Mantle Rheology with Long-Period Tides:Modeling Earth Tidal Response with Maxwell, Burgers, Andrade, and Sundberg-Cooper models and comparison with superconducting gravimeters, low-degree time-variable gravity & length-of-day observations

Tidal forcing induces significant deformation of the Earth, investigated as early as the 19th century by Kelvin and later formalized by Love through the Love number formalism. The viscoelastic response of Earth’s mantle is traditionally modelled using the Maxwell rheology, and more rarely using the Burgers rheology. This work presents a comparative analysis of four viscoelastic rheological models: the Maxwell, Burgers, Andrade, and Sundberg–Cooper models. Although rarely used for the Earth, the Andrade and Sundberg–Cooper models have proven to be relevant for other planetary bodies. Theoretical responses have been developed for these models over a broad frequency range, from the seismic band to very long periods. Model predictions are compared with observations from the IGETS (International Geodynamics and Earth Tide Service) worldwide network of superconducting gravimeters, low-degree time-varying space gravity measurements, and length-of-day variations to better constrain Earth’s mantle rheology and viscosity.