Evidence for inner core super-rotation from time-dependent differential PKP traveltimes observed at Beijing seismic network

Xiaoxia Xu, Xiaodong Song

Research output: Contribution to journalArticlepeer-review

Abstract

In an effort to confirm and constrain inner core rotation, we examine earthquakes from the South Sandwich Islands recorded at the Beijing Seismic Network. We obtained a total of 109 high-quality measurements of PKP(BC)-PKP(DF) differential traveltimes by waveform cross-correlations from earthquakes spanning over 30 years. The results show robust temporal changes in PKP(BC)-PKP(DF) residuals along this pathway, providing new support for the differential inner core hypothesis. We also observed evidence for a lateral velocity gradient in this part of the inner core. Assuming that the temporal changes result from a shift of a lateral structure due to an inner core rotation, we estimate the inner core rotation rate to be about 0.41 ± 0.12° yr-1 faster than the mantle.

Original languageEnglish (US)
Pages (from-to)509-514
Number of pages6
JournalGeophysical Journal International
Volume152
Issue number3
DOIs
StatePublished - Mar 2003

Keywords

  • Beijing Seismic Network
  • Inner core rotation
  • PKP

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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