Tomography reveals buoyant asthenosphere accumulating beneath the Juan de Fuca plate

• Autores: William B. Hawley, Richard M. Allen, Mark A. Richards
• Localización: Science, ISSN 0036-8075, Vol. 353, Nº 6306, 2016, págs. 1406-1408
• Idioma: inglés
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• Resumen

  • The boundary between Earth’s strong lithospheric plates and the underlying mantle asthenosphere corresponds to an abrupt seismic velocity decrease and electrical conductivity increase with depth, perhaps indicating a thin, weak layer that may strongly influence plate motion dynamics. The behavior of such a layer at subduction zones remains unexplored. We present a tomographic model, derived from on- and offshore seismic experiments, that reveals a strong low-velocity feature beneath the subducting Juan de Fuca slab along the entire Cascadia subduction zone. Through simple geodynamic arguments, we propose that this low-velocity feature is the accumulation of material from a thin, weak, buoyant layer present beneath the entire oceanic lithosphere. The presence of this feature could have major implications for our understanding of the asthenosphere and subduction zone dynamics.