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    Ice shelf structure derived from dispersion curve analysis of ambient seismic noise, Ross Ice Shelf, Antarctica

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    Geophys. J. Int.-2016-Diez-785-95.pdf (4.435Mb)
    Date
    2016-02-16
    Author
    Diez, Anja  Concept link
    Bromirski, Peter D.  Concept link
    Gerstoft, Peter  Concept link
    Stephen, Ralph A.  Concept link
    Anthony, Robert E.  Concept link
    Aster, Richard C.  Concept link
    Cai, Chen  Concept link
    Nyblade, Andrew A.  Concept link
    Wiens, Douglas A.  Concept link
    Metadata
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    Citable URI
    https://hdl.handle.net/1912/7902
    As published
    https://doi.org/10.1093/gji/ggw036
    DOI
    10.1093/gji/ggw036
    Keyword
     Glaciology; Surface waves and free oscillations; Seismic anisotropy; Antarctica 
    Abstract
    An L-configured, three-component short period seismic array was deployed on the Ross Ice Shelf, Antarctica during November 2014. Polarization analysis of ambient noise data from these stations shows linearly polarized waves for frequency bands between 0.2 and 2 Hz. A spectral peak at about 1.6 Hz is interpreted as the resonance frequency of the water column and is used to estimate the water layer thickness below the ice shelf. The frequency band from 4 to 18 Hz is dominated by Rayleigh and Love waves propagating from the north that, based on daily temporal variations, we conclude were generated by field camp activity. Frequency–slowness plots were calculated using beamforming. Resulting Love and Rayleigh wave dispersion curves were inverted for the shear wave velocity profile within the firn and ice to ∼150 m depth. The derived density profile allows estimation of the pore close-off depth and the firn–air content thickness. Separate inversions of Rayleigh and Love wave dispersion curves give different shear wave velocity profiles within the firn. We attribute this difference to an effective anisotropy due to fine layering. The layered structure of firn, ice, water and the seafloor results in a characteristic dispersion curve below 7 Hz. Forward modelling the observed Rayleigh wave dispersion curves using representative firn, ice, water and sediment structures indicates that Rayleigh waves are observed when wavelengths are long enough to span the distance from the ice shelf surface to the seafloor. The forward modelling shows that analysis of seismic data from an ice shelf provides the possibility of resolving ice shelf thickness, water column thickness and the physical properties of the ice shelf and underlying seafloor using passive-source seismic data.
    Description
    Author Posting. © The Author(s), 2016. This article is posted here by permission of The Royal Astronomical Society for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 205 (2016): 785-795, doi:10.1093/gji/ggw036.
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    • Geology and Geophysics (G&G)
    Suggested Citation
    Geophysical Journal International 205 (2016): 785-795
     

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