Changes in the Earth's rotation by tectonic movements

Present‐day true polar wander and the secular non‐tidal acceleration of the earth are usually attributed to post‐glacial rebound. In the models which relate this rebound to changes in rotation, the mantle is assumed to relax passively to the melted ice‐loads. The lithosphere is usually modeled as a highly viscous upper layer in these models, having viscosities which exceed mantle viscosities by several orders of magnitude. We propose that lithospheric processes unrelated to post‐glacial rebound and taking place under non‐isostatic conditions are also able to induce non‐negligible influences on the earth's rotation. Examples of such processes are mountain building and erosion, foundering flexure of oceanic basins and lithospheric snapbacking resulting from detachment of subducting slabs. Lithospheric and crustal rheologies and intraplate‐stresses are the dominant factors in these mechanisms, contrary to the mantle rheologies which are assumed to dominate the process of post‐glacial rebound.