For processes such as the glacial isostatic adjustment GIA, the viscous behavior of the earth's mantle must be taken into account in addition to the elastic behavior. The viscoelastic behavior caused that during the last glacial maximum, around 20,000 years ago, the ground in the glaciated areas sank by up to one kilometer and the ground is still rising after the ice sheets have melted

See also: Glacial isostatic adjustment

References:

Bagge, M., Klemann, V., Steinberger, B., Latinovic, M., Thomas, M. (2021): Glacial-isostatic adjustment models using geodynamically constrained 3D Earth structures. - Geochemistry Geophysics Geosystems (G3), 22, 11, e2021GC009853. doi.org/10.1029/2021GC009853

Tanaka, Y., Hasegawa, T., Tsuruoka, H., Klemann, V., Martinec, Z. (2015): Spectral-finite element approach to post-seismic relaxation in a spherical compressible Earth: application to gravity changes due to the 2004 Sumatra-Andaman earthquake. - Geophysical Journal International, 200, p. 299-321.  doi.org/10.1093/gji/ggu391

Cambiotti, G., Klemann, V., Sabadini, R. (2013): Compressible viscoelastodynamics of a spherical body at long timescales and its isostatic equilibrium. - Geophysical Journal International, 193, 3, p. 1071-1082. doi.org/10.1093/gji/ggt026

Spada, G., Barletta, V. R., Klemann, V., Riva, R. E. M., Martinec, Z., Gasperini, P., Lund, B., Wolf, D., Vermeersen, L. L. A., King, M. (2011): A benchmark study for glacial isostatic adjustment codes. - Geophysical Journal International, 185, 1, 106-132. doi.org/10.1111/j.1365-246X.2011.04952.x

Klemann, V., Martinec, Z., Ivins, E. R. (2008): Glacial isostasy and plate motion. - Journal of Geodynamics, 46, 3-5, p. 95-103. doi.org/10.1016/j.jog.2008.04.005