Origin of the inner core's seismic anisotropy

The earth inner core is axisymmetric seismic anisotropy, and there is an an gle of about 11 degrees between the symmetric axis of the inner core's seis mic anisotropy and the earth axis. In this article, we discussed the origin of 'this anisotropy, basing on the observation of differential rotation be tween the solid inner core and the molten outer core. According to the theo ry on crystal growth from molten status, the crystal growth speed is propor tional to the relative linear speed between the solid and the molten crysta ls. As a result, the inner core grows faster at the equator than at polar a rea. Under the action of gravitational force, the inner core remains quasi- orbicular. Consequenlly the material will flow from the equator to the pola r area, resulting in an axial symmetric viscous flow. This flow is accompan ied by an axial symmetric stress field, which align c-axes of hcp iron alon g the inner core's rotation axis, resulting in observed seismic anisotropy. As a deduction, there may be a notation as well as a precession of the inn er core relative to the outer earth.