Lg-wave attenuation in the Australian crust

We estimate the Lg-wave quality factor (Q) across the Australian continent from vertical-component Lg waveforms. A tomographic inversion is performed to construct an Lg attenuation model for 58 frequencies between 0.05 and 10.0Hz. The available spatial resolution is approximately 1.5°×1.5° for the 0...

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Bibliographic Details
Published in:Tectonophysics 2017-10, Vol.717, p.413-424
Main Authors: Wei, Zhi, Kennett, Brian L.N., Zhao, Lian-Feng
Format: Article
Language:English
Subjects:
Attenuation
Australian continent
Boundaries
Cratons
Frequencies
Frequency-dependent Q of Lg waves
Geological features
Ground motion
Lg attenuation model
Orogeny
Power law
Q factors
Regional variations
Sedimentary basins
Spatial resolution
Wave attenuation
Wave power
Waveform analysis
Waveforms
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Summary:We estimate the Lg-wave quality factor (Q) across the Australian continent from vertical-component Lg waveforms. A tomographic inversion is performed to construct an Lg attenuation model for 58 frequencies between 0.05 and 10.0Hz. The available spatial resolution is approximately 1.5°×1.5° for the 0.5–2.0Hz band. At 1.0Hz, the Lg-wave Q over the whole island continent varies from 50 to 1250 with an average value of 850. Significant regional variations in the Lg-wave Q images tie well with many geological features and boundaries in Australia. The cratons in western, northern and southern parts of Australia usually have higher Q values (700–1250), while the volcanic regions, sedimentary basins and orogenic areas in eastern Australia are characterized by increased attenuation (lower Q values, 50–650). We determine the frequency-dependent Q of Lg waves for different blocks across Australia, and find the frequency dependence of Q is much more complex than the traditional single power law representation. When combined with the assumed geometrical spreading relation, the Lg Q maps provide a new way of assessing potential ground motion across the continent for any event location. •An Lg attenuation model is constructed for the Australian crust.•Variations of Lg-wave Q tie well with the Australian geological features.•Frequency dependence of Lg Q varies in different geological areas.•Lg Q maps provide a new way of assessing potential ground motion in Australia.
ISSN:0040-1951
1879-3266
DOI:10.1016/j.tecto.2017.08.022