The solid Earth extends from its surface to its core and generally does not include the oceans, atmosphere or ice sheets. The mechanical properties of the solid Earth are described using a continuum mechanics approach. This means that the Earth is split into small volume elements for which the corresponding material properties are described. In a good approximation, the material properties such as density or elasticity only change with depth, which leads to a spherically symmetrical structure. General physical principles are used to describe the interaction of the volume elements. Integration over the volume of the earth body then defines its response to an acting force. For the surface and tidal forces considered in this section, the lithosphere and the Earth's mantle are of main interest. Depending on the time scale on which the processes take place, elastic or viscous material behavior can be assumed.

References:

Klemann, V. (2024 online): Gravito-viscoelastodynamics. - In: Sideris, M. G. (Ed.), Encyclopedia of Geodesy, (Encyclopedia of Earth Sciences Series (EESS)), Cham : Springer International Publishing, 1-6; doi.org/10.1007/978-3-319-02370-0_141-1