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Estimation of inelastic seismic material properties of a surficial sea‐bed from multi‐component marine seismic data
Author(s) -
Eggenberger Kurt,
Muijs Remco,
Robertsson Johan,
van Manen DirkJan,
Holliger Klaus
Publication year - 2010
Publication title -
near surface geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.639
H-Index - 39
eISSN - 1873-0604
pISSN - 1569-4445
DOI - 10.3997/1873-0604.2010032
Subject(s) - geology , attenuation , viscoelasticity , seabed , seismology , seafloor spreading , anelastic attenuation factor , elastic modulus , seismic wave , geophysics , oceanography , physics , optics , thermodynamics , materials science , composite material
To date, state‐of‐the‐art seismic material parameter estimates from multi‐component sea‐bed seismic data are based on the assumption that the sea‐bed consists of a fully elastic half‐space. In reality, however, the shallow sea‐bed generally consists of soft, unconsolidated sediments that are characterized by strong to very strong seismic attenuation. To explore the potential implications, we apply a state‐of‐the‐art elastic decomposition algorithm to synthetic data for a range of canonical sea‐bed models consisting of a viscoelastic half‐space of varying attenuation. We find that in the presence of strong seismic attenuation, as quantified by Q ‐values of 10 or less, significant errors arise in the conventional elastic estimation of seismic properties. Tests on synthetic data indicate that these errors can be largely avoided by accounting for the inherent attenuation of the seafloor when estimating the seismic parameters. This can be achieved by replacing the real‐valued expressions for the elastic moduli in the governing equations in the parameter estimation by their complex‐valued viscoelastic equivalents. The practical application of our parameter procedure yields realistic estimates of the elastic seismic material properties of the shallow sea‐bed, while the corresponding Q ‐estimates seem to be biased towards too low values, particularly for S‐waves. Given that the estimation of inelastic material parameters is notoriously difficult, particularly in the immediate vicinity of the sea‐bed, this is expected to be of interest and importance for civil and ocean engineering purposes.