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Lower Mantle Substructure Embedded in the Farallon Plate: The Hess Conjugate
Author(s) -
Ko Justin YenTing,
Helmberger Don V.,
Wang Huilin,
Zhan Zhongwen
Publication year - 2017
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 - 10.1002/2017gl075032
Subject(s) - geology , slab , seismology , subduction , slab window , mantle (geology) , amplitude , substructure , geophysics , physics , tectonics , optics , oceanic crust , structural engineering , engineering
The morphologies of subducted remnants in the lower mantle are essential to our understanding of the history of plate tectonism. Here we image a high‐velocity slab‐like (HVSL) anomaly beneath the southeastern U.S. using waveforms from five deep earthquakes beneath South America recorded by the USArray. In addition to travel time anomalies, the multipathing of S and ScS phases at different distances are used to constrain the HVSL model. We jointly invert S and ScS traveltimes, amplitudes, and waveform complexities to produce a best fitting block model characterized by a rectangular shape with a 2.5% S wave velocity increase and tapered edges. While the Farallon slab is expected to dip primarily eastward, the HVSL structure apparently dips 40° to 50° to the SE and appears to be related to the eclogitized Hess conjugate.