Response of the mantle to flat slab evolution: Insights from local S splitting beneath Peru

Caroline M. Eakin, Maureen D. Long, Susan L. Beck, Lara S. Wagner, Hernando Tavera, Cristõbal Condori

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

The dynamics of flat subduction, particularly the interaction between a flat slab and the overriding plate, are poorly understood. Here we study the (seismically) anisotropic properties and deformational regime of the mantle directly above the Peruvian flat slab. We analyze shear wave splitting from 370 local S events at 49 stations across southern Peru. We find that the mantle above the flat slab appears to be anisotropic, with modest average delay times (∼0.28s) that are consistent with ∼4% anisotropy in a ∼30km thick mantle layer. The most likely mechanism is the lattice-preferred orientation of olivine, which suggests that the observed splitting pattern preserves information about the mantle deformation. We observe a pronounced change in anisotropy along strike, with predominately trench-parallel fast directions in the north and more variable orientations in the south, which we attribute to the ongoing migration of the Nazca Ridge through the flat slab system.

Original languageEnglish (US)
Pages (from-to)3438-3446
Number of pages9
JournalGeophysical Research Letters
Volume41
Issue number10
DOIs
StatePublished - May 28 2014

Keywords

  • Flat Subduction
  • Mantle Deformation
  • Nazca Ridge
  • Peru
  • Seismic Anisotropy
  • Shear Wave Splitting

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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