The Subduction Zone Flow Field from Seismic Anisotropy: A Global View
Maureen D. Long* and
Paul G. Silver
Although the morphologies of subducting slabs have been relatively well characterized, the character of the mantle flow field that accompanies subduction remains poorly understood. To analyze this pattern of flow, we compiled observations of seismic anisotropy, as manifested by shear wave splitting. Data from 13 subduction zones reveal systematic variations in both mantle-wedge and subslab anisotropy with the magnitude of trench migration velocity |Vt|. These variations can be explained by flow along the strike of the trench induced by trench motion. This flow dominates beneath the slab, where its magnitude scales with |Vt|. In the mantle wedge, this flow interacts with classical corner flow produced by the convergence velocity Vc; their relative influence is governed by the relative magnitude of |Vt| and Vc.
Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015, USA.
* To whom correspondence should be addressed. E-mail: long{at}dtm.ciw.edu
