Plate Motions and Stresses from Global Dynamic Models

• Published in: Science (American Association for the Advancement of Science) Vol. 335; no. 6070; pp. 838 - 843
• Main Authors: Ghosh, Attreyee, Holt, William E.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 17.02.2012; The American Association for the Advancement of Science
• Subjects: Compressive stress; Convection; Deformation; Dynamic modeling; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geomorphology; Geophysics; Internal geophysics; Kinematics; Kinetics; Mathematical models; Modeling; Plate tectonics; Solid-earth geophysics, tectonophysics, gravimetry; Tectonic plate interactions; Tectonics. Structural geology. Plate tectonics; Topography; Viscosity; plate movement; stress; rheology; topography; lithosphere; rigidity; crust; lateral variations; coupling; subduction; viscosity; geodynamics; numerical models; prediction; deformation; mantle; plate boundaries; flow
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1214209

Delineating the driving forces behind plate motions is important for understanding the processes that have shaped Earth throughout its history. However, the accurate prediction of plate motions, boundary-zone deformation, rigidity, and stresses remains a difficult frontier in numerical modeling. We present a global dynamic model that produces a good fit to such parameters by accounting for lateral viscosity variations in the top 200 kilometers of Earth, together with forces associated with topography and lithosphere structure, as well as coupling with mantle flow. The relative importance of shallow structure versus deeper mantle flow varies over Earth's surface. Our model reveals where mantle flow contributes toward driving or resisting plate motions. Furthermore, subducted slabs need not act as strong stress guides to satisfy global observations of plate motions and stress.