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Seismic anisotropy reveals focused mantle flow around the Calabrian slab (Southern Italy)
Author(s) -
Baccheschi P.,
Margheriti L.,
Steckler M. S.
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl028899
Subject(s) - geology , slab , subduction , seismology , anisotropy , trench , mantle (geology) , perpendicular , mantle wedge , geophysics , slab window , tectonics , geometry , oceanic crust , physics , chemistry , mathematics , organic chemistry , layer (electronics) , quantum mechanics
SKS splitting at the Calabrian subduction zone, with delay times ( δ t) up to 3s, reveals the presence of a strong anisotropic fabric. Fast directions (ϕ) are oriented NNE‐SSW in the Calabrian Arc (C.A.) and rotate NNW‐SSE to the north following the arcuate shape of the subducting plate. We interpret the trench‐parallel ϕ as local‐scale mantle flow driven by the retrograde motion of the slab; the absence of trench perpendicular ϕ below the Southern Apennines (S.A.) excludes the presence of a seismically detectable return flow at its NE edge. This may be due to the relative youth and limited width of the S.A. slab tear. A possible return flow is identified farther north at the boundary of the S.A. and Central Apennines. Different and weaker anisotropy is present below the Apulian Platform (A.P.). This implies that the influence of the slab rollback in the sub‐slab mantle is limited to less then 100 km from the slab.