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Frequency dependent Lg attenuation in south‐central Alaska
Author(s) -
McNamara D. E.
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl011732
Subject(s) - coda , attenuation , amplitude , seismology , geology , anelastic attenuation factor , inversion (geology) , quality (philosophy) , frequency dependence , seismic wave , physics , geodesy , tectonics , optics , nuclear magnetic resonance , quantum mechanics
The characteristics of seismic energy attenuation are determined using high frequency Lg waves from 27 crustal earthquakes, in south‐central Alaska. Lg time‐domain amplitudes are measured in five pass‐bands and inverted to determine a frequency‐dependent quality factor, Q(f) , model for south‐central Alaska. The inversion in this study yields the frequency‐dependent quality factor, in the form of a power law: Q(f) = Q 0 f η = 220(±30) f 0.66(±0.09) (0.75≤ f ≤12Hz). The results from this study are remarkably consistent with frequency dependent quality factor estimates, using local S ‐wave coda, in south‐central Alaska. The consistency between S ‐coda Q(f) and Lg Q(f) enables constraints to be placed on the mechanism of crustal attenuation in south‐central Alaska. For the range of frequencies considered in this study both scattering and intrinsic attenuation mechanisms likely play an equal role.