Seismic Anisotropy: Tracing Plate Dynamics in the Mantle

摘要

Elastic anisotropy is present where the speed of a seismic wave depends on its direction. In Earth's mantle, elastic anisotropy is induced by minerals that are preferentially oriented in a directional flow or deformation. Earthquakes generate two seismic wave type: compressional (P) and shear (S) waves, whose coupling in anisotropic rocks leads to scattering, birefringence, and wave with hybrid polariza- tions. This varied behavior is helping geophysicists explore rock textures within Earth's mantle and crust, map present-day upper-mantle convection, and study the formation of lithospheric plates and the accretion of continents in Earth history.