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Estimation of azimuthal anisotropy in the NW Pacific from seismic ambient noise in seafloor records

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/57347

Title: Estimation of azimuthal anisotropy in the NW Pacific from seismic ambient noise in seafloor records
Authors: Takeo, Akiko Browse this author
Forsyth, Donald W. Browse this author
Weeraratne, Dayanthie S. Browse this author
Nishida, Kiwamu Browse this author
Keywords: Surface waves and free oscillations
Seismic anisotropy
Dynamics of lithosphere and mantle
Issue Date: Oct-2014
Publisher: Oxford University Press
Journal Title: Geophysical Journal International
Volume: 199
Issue: 1
Start Page: 11
End Page: 22
Publisher DOI: 10.1093/gji/ggu240
Abstract: We analysed background surface waves in seismic ambient noise by cross-correlating continuous records of eight ocean bottom seismometers and nine differential pressure gauges deployed in the northwestern Pacific Ocean by the PLATE project. After estimating the clock delay and instrumental phase responses of differential pressure gauges by using cross-correlation functions, we measured average phase velocities in the area of the array for the fundamental-, first higher- and second higher-mode Rayleigh waves, and the fundamental-mode Love waves at a period range of 3-40 s by waveform fitting. We then measured phase-velocity anomalies of fundamental-mode and first higher-mode Rayleigh waves for each pair of stations at a period range of 5-25 s, and corrected the effect of variation in water-depths. The seismic anomalies imply the presence of strong azimuthal anisotropy beneath the eastern part of array. The direction of maximum velocity is approximately N35A degrees E in the fossil seafloor spreading direction perpendicular to magnetic lineations from the ancient triple junction at this location. The peak-to-peak intensity of shear-wave velocity anisotropy in the mantle is similar to 7 per cent.
Rights: This article has been accepted for publication in "Geophysical Journal International" © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.
Type: article
URI: http://hdl.handle.net/2115/57347
Appears in Collections:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 竹尾 明子

 

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