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Complexity of D″ in the presence of slab‐debris and phase changes
Author(s) -
Sun Daoyuan,
Song TehRu Alex,
Helmberger Don
Publication year - 2006
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 - 10.1029/2005gl025384
Subject(s) - slab , geology , jump , seismology , mantle (geology) , debris , tomography , phase boundary , waveform , phase (matter) , geophysics , physics , optics , oceanography , quantum mechanics , voltage
A lower mantle S‐wave triplication with a S cd branch is easily observed beneath Central American and its lateral variations has been studied extensively. Attempts to model S cd depth variations with a phase boundary based on tomography predict smooth variations [e.g., Sidorin et al., 1999a]. Recently, Hutko et al. [2005] presents evidence of a sharper feature with a vertical step‐like jump of over 50 km, for paths sampling the western edge of a fast lower mantle structure beneath the Cocos Plate. We present a similar type of very anomalous S cd waveforms sampling the edge further to the east. We are able to model these waveforms by adopting the phase‐boundary model but enhancing the existing tomographic anomaly just above the velocity jump, which appears to be a folded‐slab.