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Lateral variation of the D″ discontinuity beneath the Cocos Plate
Author(s) -
Lay T.,
Garnero E. J.,
Russell S. A.
Publication year - 2004
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 - 10.1029/2004gl020300
Subject(s) - geology , seismology , discontinuity (linguistics) , shear (geology) , deconvolution , geodesy , physics , optics , petrology , mathematics , mathematical analysis
Broadband shear wave signals from 15 deep South American earthquakes reveal small‐scale variations of the D″ shear velocity discontinuity beneath the Cocos Plate. Deconvolution by average event source wavelets allows multiple event and California station combinations to be double‐array stacked in 4 geographically separate reflection point bins with lateral dimensions of about 200 km. Reflections from the top of D″ are apparent in all 4 bins, with significant variations in timing and strength relative to ScS. The data are compatible with a discontinuous shear velocity increase 264 km above the core‐mantle boundary that varies laterally in strength from 0.9% to 2.6%, with corresponding lateral velocity variations within D″.