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Detectability of temporal changes in fine structures near the inner core boundary beneath the eastern hemisphere
Author(s) -
Yu W.
Publication year - 2016
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 - 10.1002/2016gl069664
Subject(s) - coda , inner core , geology , context (archaeology) , core (optical fiber) , seismology , geophysics , geodesy , physics , optics , paleontology
The inner core boundary (ICB), where melting and solidification of the core occur, plays a crucial role in the dynamics of the Earth's interior. To probe temporal changes near the ICB beneath the eastern hemisphere, I analyze differential times of PKiKP ( dt (PKiKP)), double differential times of PKiKP‐PKPdf, and PKiKP coda waves from repeating earthquakes in the southwest Pacific subduction zones. dt (PKiKP) values are mostly within ±30 ms of one another, without systematic temporal dependence. Some observations of PKiKP coda waves have absolute time shifts of >50 ms relative to their main phases. The combination of temporal changes in PKiKP coda arrivals and negligible changes in PKiKP arrivals favors a smooth ICB with fine‐scale structures in the upper inner core. dt (PKiKP) values are interpreted in the context of melting‐ or growth‐induced ICB topography, based on dynamic models. Uncertainties in dt (PKiKP) prevent verification of ICB melting or growth on decadal time scales.