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PKP(BC‐DF) Travel time residuals and short scale heterogeneity in the deep Earth
Author(s) -
Bréger Ludovic,
Romanowicz Barbara,
Tkalčić Hrvoje
Publication year - 1999
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 - 10.1029/1999gl008374
Subject(s) - inner core , anisotropy , geology , mantle (geology) , scale (ratio) , geophysics , geodesy , polar , earth model , core (optical fiber) , travel time , physics , engineering , quantum mechanics , astronomy , transport engineering , optics
Differential PKP(BC)‐PKP(DF) travel time residuals for quasi‐polar paths in the earth present large excursions from the trends predicted by simple models of inner core anisotropy. We analyze a set of such paths classified according to specific source and station regions, and show that observations are compatible with a constant anisotropy model of at most 1.5% in the outer 400 km of the inner core. To explain local departures of up to 3 sec from the predictions of such a model, strong lateral variations on scale lengths shorter than a few hundred km need to be invoked, either in the core or in the mantle. Independent results of D' modelling argue in favor of an important contribution from the latter.