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Approximation to cutoffs of higher modes of Rayleigh waves for a layered earth model

Pure and Applied Geophysics

By:
, ,
DOI: 10.1007/s00024-008-0443-4

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Abstract

A cutoff defines the long-period termination of a Rayleigh-wave higher mode and, therefore is a key characteristic of higher mode energy relationship to several material properties of the subsurface. Cutoffs have been used to estimate the shear-wave velocity of an underlying half space of a layered earth model. In this study, we describe a method that replaces the multilayer earth model with a single surface layer overlying the half-space model, accomplished by harmonic averaging of velocities and arithmetic averaging of densities. Using numerical comparisons with theoretical models validates the single-layer approximation. Accuracy of this single-layer approximation is best defined by values of the calculated error in the frequency and phase velocity estimate at a cutoff. Our proposed method is intuitively explained using ray theory. Numerical results indicate that a cutoffs frequency is controlled by the averaged elastic properties within the passing depth of Rayleigh waves and the shear-wave velocity of the underlying half space. ?? Birkh??user Verlag, Basel 2009.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Approximation to cutoffs of higher modes of Rayleigh waves for a layered earth model
Series title:
Pure and Applied Geophysics
DOI:
10.1007/s00024-008-0443-4
Volume
166
Issue:
3
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Pure and Applied Geophysics
First page:
339
Last page:
351
Number of Pages:
13