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D″ beneath the Arctic from inversion of shear waveforms
Author(s) -
Kawai Kenji,
Geller Robert J.,
Fuji Nobuaki
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 - 10.1029/2007gl031517
Subject(s) - geology , inversion (geology) , seismometer , arctic , the arctic , geodesy , seismology , waveform , physics , oceanography , quantum mechanics , voltage , tectonics
The structure of the D″ region beneath the Arctic has not previously been studied in detail. Using waveform inversion, we find that the average S‐wave velocity in D″ beneath the Arctic is about 0.04 km/s higher than PREM, which is consistent with the existence of post‐perovskite (ppv) in D″. It is difficult to strongly constrain the fine structure of S‐velocity within D″ due to the small number of stations at epicentral distances Δ < 90°, but by weighting those stations heavily in the inversion, we show that the data suggest the existence of high S‐velocity in the upper half of D″ and low S‐velocity in the lower half, consistent with the possibility of a double crossing (ppv → pv reverse phase transition) within D″. We conduct a computational experiment to show that resolution of the velocity structure within D″ could be significantly improved by temporary installation of a portable array of seismographs in northern Canada, which would greatly increase the number of stations in the range 70° < Δ < 90°.