Curtin University Homepage
  • Library
  • Help
    • Admin

    espace - Curtin’s institutional repository

    JavaScript is disabled for your browser. Some features of this site may not work without it.
    View Item 
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item

    How frequency dependency of Q affects spectral ratio estimates

    Access Status
    Fulltext not available
    Authors
    Gurevich, Boris
    Pevzner, Roman
    Date
    2015
    Type
    Journal Article
    
    Metadata
    Show full item record
    Citation
    Gurevich, B. and Pevzner, R. 2015. How frequency dependency of Q affects spectral ratio estimates. Geophysics. 80 (2): pp. 39-44.
    Source Title
    Geophysics
    DOI
    10.1190/geo2014-0418.1
    ISSN
    0016-8033
    School
    Department of Exploration Geophysics
    URI
    http://hdl.handle.net/20.500.11937/30546
    Collection
    • Curtin Research Publications
    Abstract

    Because seismic amplitudes can be affected by purely geometrical factors, attenuation is often estimated not from amplitudes but from the evolution of the amplitude spectra of the waveform. Such estimation methods (e.g., the spectral ratio method and the centroid frequency shift method) assume that the quality factor Q is constant (independent of frequency) in the frequency band of the signal. If this assumption is violated, then Q estimates become biased. In particular, when the frequency dependency of Q is a power law Q−1 ∝ωn, then Q is systematically under- or overestimated by a factor of n + 1. The errors are larger for larger values of n, particularly when n is negative. In particular, if n = -1, the frequency content of the signal does not change, and Q is estimated to be infinite, regardless of the true value of Q. To avoid these systematic errors, it is necessary to monitor the evolution of frequency content and amplitude with distance. Zero-offset vertical seismic profile data from the North West Shelf of Australia revealed the decay of the signal amplitude with depth that can be explained by a combination of intrinsic constant Q and a frequency-independent factor, which in turn is caused by the geometric spreading plus transmission loss due to variations of acoustic impedance on a scale larger than the dominant wavelength in the signal.

    Related items

    Showing items related by title, author, creator and subject.

    • Passive grid impedance estimation using several short-term low power signal injections
      Alyan Nezhadi, M.; Zare, Firuz; Hassanpour, H. (2017)
      © 2016 IEEE. In this paper, a method is proposed for passive grid impedance estimation using several short-term low power signal injections. Impedance estimation is used in many applications such as designing filters and ...
    • The measurement of underwater acoustic noise radiated by a vessel using the vessel's own towed array
      Duncan, Alexander John (2003)
      The work described in this thesis tested the feasibility of using a towed array of hydrophones to: 1. localise sources of underwater acoustic noise radiated by the towvessel, 2. determine the absolute amplitudes of these ...
    • The Impact of Point-Source Subtraction Residuals on 21 cm Epoch of Reionization Estimation
      Trott, Cathryn; Wayth, Randall; Tingay, Steven (2012)
      Precise subtraction of foreground sources is crucial for detecting and estimating 21 cm H I signals from the Epoch of Reionization (EoR). We quantify how imperfect point-source subtraction due to limitations of the ...
    Advanced search

    Browse

    Communities & CollectionsIssue DateAuthorTitleSubjectDocument TypeThis CollectionIssue DateAuthorTitleSubjectDocument Type

    My Account

    Admin

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Follow Curtin

    • 
    • 
    • 
    • 
    • 

    CRICOS Provider Code: 00301JABN: 99 143 842 569TEQSA: PRV12158

    Copyright | Disclaimer | Privacy statement | Accessibility

    Curtin would like to pay respect to the Aboriginal and Torres Strait Islander members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Whadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.