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New constraints on the structure of the inner core from P’P’
Author(s) -
Bréger Ludovic,
Romanowicz Barbara,
Rousset Sébastien
Publication year - 2000
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 - 10.1029/1999gl008467
Subject(s) - inner core , core (optical fiber) , differential (mechanical device) , geology , anisotropy , geodesy , physics , geometry , mathematics , seismology , optics , thermodynamics
We measured absolute P’P’df as well as differential P’P’bc‐P’P’df and P’P’ab‐P’P’df travel time residuals for earthquakes in Alaska and the Aleutians recorded at NORSAR array (Norway). For such paths, P’P’df samples two regions of the inner core which have been identified as strongly anisotropic (∼3.5%), respectively beneath the Central Pacific and Africa, and should arrive some ∼6s earlier than predicted by a standard model. Absolute and differential travel times do not appear to be anomalous. A very complex texture and/or heterogeneity of the top ∼400 km of the inner core, or a significant contribution from the strongly heterogeneous D”, is required to explain this discrepancy.