10. Permittivity Structure Derived from Group Velocities of Guided GPR Pulses

Haney, Matthew M.; Decker, Kathryn; Bradford, John H.

doi:10.1190/1.9781560802259.ch10

Cited by 3 publications

(3 citation statements)

References 40 publications

(63 reference statements)

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“…Haney (2009) uses the finite-element method to model guided waves in a fluid by considering sound waves in the atmosphere. In fact, fluid finite elements have a similar form to finite elements in electromagnetics, which were used by Haney et al (2010) to model guided waves in ground-penetrating radar data. Here, we combine fluid finite elements with solid finite elements to model a water layer on the top of an elastic medium.…”

Section: Appendix C Forward Modeling With a Water Layermentioning

confidence: 99%

Perturbational and nonperturbational inversion of Rayleigh-wave velocities

Haney

Tsai

2017

GEOPHYSICS

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The inversion of Rayleigh-wave dispersion curves is a classic geophysical inverse problem. We have developed a set of MATLAB codes that performs forward modeling and inversion of Rayleigh-wave phase or group velocity measurements. We describe two different methods of inversion: a perturbational method based on finite elements and a nonperturbational method based on the recently developed Dix-type relation for Rayleigh waves. In practice, the nonperturbational method can be used to provide a good starting model that can be iteratively improved with the perturbational method. Although the perturbational method is well-known, we solve the forward problem using an eigenvalue/eigenvector solver instead of the conventional approach of root finding. Features of the codes include the ability to handle any mix of phase or group velocity measurements, combinations of modes of any order, the presence of a surface water layer, computation of partial derivatives due to changes in material properties and layer boundaries, and the implementation of an automatic grid of layers that is optimally suited for the depth sensitivity of Rayleigh waves.

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Section: Appendix C Forward Modeling With a Water Layermentioning

confidence: 99%

Perturbational and nonperturbational inversion of Rayleigh-wave velocities

Haney

Tsai

2017

GEOPHYSICS

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“…Such an approach, when applied to the modeling of surface-wave dispersion, is known as the thin-layer method (Lysmer, 1970;Kausel, 2005;Haney et al, 2010). When applied to inversion, this is an overparameterized method in which a choice of regularization leads to a preferentially smooth model.…”

Section: Inversion With An Overparameterized Modelmentioning

confidence: 99%

“…We keep Poisson's ratio constant throughout the model at 0.25 and use the Gardner relation (Gardner et al, 1974) to compute density from the shear wave velocity. We model the phase velocities from 3 to 13 Hz, in steps of 0.2 Hz, with the thin-layer method (Lysmer, 1970;Kausel, 2005;Haney et al, 2010), which is a finite-element variational method for solving the surface-wave dispersion problem with arbitrary accuracy. After modeling, we corrupt the synthetic phasevelocity data with 1% noise.…”

Section: Inversion With An Overparameterized Modelmentioning

confidence: 99%

Nonperturbational surface-wave inversion: A Dix-type relation for surface waves

Haney

Tsai

2015

GEOPHYSICS

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We extend the approach underlying the well-known Dix equation in reflection seismology to surface waves. Within the context of surface wave inversion, the Dix-type relation we derive for surface waves allows accurate depth profiles of shear-wave velocity to be constructed directly from phase velocity data, in contrast to perturbational methods. The depth profiles can subsequently be used as an initial model for nonlinear inversion. We provide examples of the Dix-type relation for under-parameterized and over-parameterized cases. In the under-parameterized case, we use the theory to estimate crustal thickness, crustal shear-wave velocity, and mantle shear-wave velocity across the Western U.S. from phase velocity maps measured at 8-, 20-, and 40-s periods. By adopting a thin-layer formalism and an over-parameterized model, we show how a regularized inversion based on the Dix-type relation yields smooth depth profiles of shearwave velocity. In the process, we quantitatively demonstrate the depth sensitivity of surface-wave phase velocity as a function of frequency and the accuracy of the Dix-type relation. We apply the over-parameterized approach to a nearsurface data set within the frequency band from 5 to 40 Hz and find overall agreement between the inverted model and the result of full nonlinear inversion.

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Application of Surface-Wave Methods for Seismic Site Characterization

et al. 2011

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Surface-wave dispersion analysis is widely used in geophysics to infer a shear wave velocity model of the subsoil for a wide variety of applications. A shear-wave velocity model is obtained from the solution of an inverse problem based on the surface wave dispersive propagation in vertically heterogeneous media. The analysis can be based either on active source measurements or on seismic noise recordings. This paper discusses the most typical choices for collection and interpretation of experimental data, providing a state of the art on the different steps involved in surface wave surveys. In particular, the different strategies for processing experimental data and to solve the inverse problem are presented, along with their advantages and disadvantages. Also, some issues related to the characteristics of passive surface wave data and their use in H/V spectral ratio technique are discussed as additional information to be used independently or in conjunction with dispersion analysis. Finally, some recommendations for the use of surface wave methods are presented, while also outlining future trends in the research of this topic

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10. Permittivity Structure Derived from Group Velocities of Guided GPR Pulses

Cited by 3 publications

References 40 publications

Perturbational and nonperturbational inversion of Rayleigh-wave velocities

Perturbational and nonperturbational inversion of Rayleigh-wave velocities

Nonperturbational surface-wave inversion: A Dix-type relation for surface waves

Application of Surface-Wave Methods for Seismic Site Characterization

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