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The Pacific Plume as seen by S, ScS, and SKS
Author(s) -
Bréger Ludovic,
Romanowicz Barbara,
Ng Christine
Publication year - 2001
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 - 10.1029/2000gl012526
Subject(s) - geology , plume , subduction , partial melting , geophysics , mantle (geology) , mantle plume , crust , seismology , tectonics , lithosphere , physics , meteorology
The forward modeling of S‐SKS and ScS‐S differential travel time residuals sensitive to structure beneath a localized region of the central Pacific suggests the presence of two anomalous domains: first a broad zone which becomes thinner as it extends into the mid‐mantle, where the S‐velocity is reduced by −2 to −4%, and which is deflected to the South‐East as it “rises” towards the surface; adjacent to it, a smaller domain, where the S‐velocity is about 4% higher. These strong velocity anomalies are likely the results of chemical heterogeneity that may involve subducted material, and partial melting. Strong heterogeneity appears to extend, at least locally, well above D', but the morphology of the anomalous domains is more reminiscent of localized rising or sinking currents rather than of a relatively uniform and thick geochemical reservoir.