Asthenosphere flow and plate motions

Influence of continental roots and asthenosphere on plate-mantle coupling

[1] The shear tractions that mantle flow exerts on the base of Earth’s lithosphere contribute to plate-driving forces and lithospheric stresses. We investigate the sensitivity of these tractions to sub-lithospheric viscosity variations by comparing shear tractions computed from a mantle flow model featuring laterally-varying lithosphere and asthenosphere viscosity with those from a model with l...

Horizontal versus vertical plate motions

We review both present and past motions at major plate boundaries, which have the horizontal component in average 10 to 100 times faster (10–100 mm/yr) than the vertical component (0.01–1 mm/yr) in all geodynamic settings. The steady faster horizontal velocity of the lithosphere with respect to the upward or downward velocities at plate 5 boundaries supports dominating tangential forces acting ...

Absolute plate motions constrained by shear wave splitting orientations with implications for hot spot motions and mantle flow

[1] Here, I present a new absolute plate motion model of the Earth’s surface, determined from the alignment of present-day surface motions with 474 published shear wave (i.e., SKS) splitting orientations. When limited to oceanic islands and cratons, splitting orientations are assumed to reflect anisotropy in the asthenosphere caused by the differential motion between lithosphere and mesosphere....

Lithosphere, Asthenosphere, and Perisphere

"Lithosphere" is a mechanical concept implying strength and relative permanence. Unfortunately, the term has also been applied to the surface thermal boundary layer (TBL) and a shallow enriched geochemical reservoir, features having nothing to do with strength. The "strong" lithosphere is about one half the thickness of the TBL. The bottom of the elastic plate, the maximum depths of midplate an...

Gps Constraints on Africa (nubia) and Arabia Plate Motions