Scattering of Rayleigh waves from topographic irregularities at oblique incidence

Otto, O.W.

doi:10.1063/1.323587

Cited by 14 publications

(5 citation statements)

References 10 publications

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“…Therefore, the scattering should be much reduced in the case of irregularities with gentle curvature when compared with irregularities (mountains) with abrupt discontinuities in curvature (bluff topography) (Gilbert & Knopoff, 1960). An important point is that the incident wave is essentially “blind” to features that are much smaller than a wavelength (Otto, 1977). Scattering always becomes weaker at smaller frequencies if all other parameters are kept constant, but generally, there is no simple frequency scaling valid for the entire wavenumber space.…”

Section: Resultsmentioning

confidence: 99%

Simulations of Gravitoelastic Correlations for the Sardinian Candidate Site of the Einstein Telescope

Andríc

Harms

2020

JGR Solid Earth

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Gravity fluctuations produced by ambient seismic fields are predicted to limit the sensitivity of the next generation, gravitational wave detector Einstein Telescope at frequencies below 20 Hz. The detector will be hosted in an underground infrastructure to reduce seismic disturbances and associated gravity fluctuations. Additional mitigation might be required by monitoring the seismic field and using the data to estimate the associated gravity fluctuations and to subtract the estimate from the detector data, a technique called coherent noise cancelation. In this paper, we present a calculation of correlations between surface displacement of a seismic field and the associated gravitational fluctuations using the spectral element SPECFEM3D Cartesian software. The model takes into account the local topography at a candidate site of the Einstein Telescope at Sardinia. This paper is a first demonstration of SPECFEM3D's capabilities to provide estimates of gravitoelastic correlations, which are required for an optimized deployment of seismometers for gravity noise cancelation.

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Section: Resultsmentioning

confidence: 99%

Simulations of Gravitoelastic Correlations for the Sardinian Candidate Site of the Einstein Telescope

Andríc

Harms

2020

JGR Solid Earth

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“…Nevertheless the closed-form solutions have been obtained only in the linear approximation with respect to height to wavelength ratio h / even for isotropic substrates. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] One of the fundamental characteristics allowing to estimate the influence of the surface state on the SAW propagation is the reflection coefficient from single obstacles, such as steps or grooves. Various theoretical methods have been put forward to derive this coefficient: perturbation techniques, 4-7 variational method, 8 impedance method, 9,10 and integral equation method.…”

Section: Rayleigh Wave Reflection From Single Surface Imperfections Omentioning

confidence: 99%

“…There is an incident angle ͑an analog of the Brewster angle͒ at which the reflection coefficient evaluated in the first approximation with respect to h / vanishes. 9,12 A comprehensive analysis of the angle dependence of the first-order reflection coefficient is given in Ref. 10.…”

Section: Rayleigh Wave Reflection From Single Surface Imperfections Omentioning

confidence: 99%

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Rayleigh wave reflection from single surface imperfections on isotropic substrates

Darinskii

Weihnacht

Schmidt

2009

Journal of Applied Physics

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Rayleigh surface waves propagating in (111) Si substrate decorated with Ni phononic nanostructure AIP Conf.The specific features of the Rayleigh wave reflection from single surface imperfections of an isotropic substrate are studied by the finite element method. Six types of the imperfections are considered, namely, upstep and downstep, projection and groove, and strip of foreign material coating the substrate and buried into it. The dependence is found and analyzed of the absolute value and the phase of the reflection coefficients on the geometrical parameters of defects and the angle of incidence. Numerical results are compared to analytical predictions based on a development of the reflection coefficient in powers of the defect height to wavelength ratio h / and limited to the first-order term. In particular, this comparison reveals that in some cases approximate expressions are able to provide a good precision. At the same time situations are met when the linear approximation fails to describe the behavior of the reflection coefficient even at fairly small h / .

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“…After publishing these results in [2], [3] a lot of following publications both theoretically [4]- [8] and experimentally [9] confirmed the existence of such angles. Moreover, it was shown in [10]- [11] that these angles remain unchanged in the case of SAW scattering by local three-dimensional surface irregularities (in this case is better to use the term "angles of zero scattering").…”

Section: Introductionmentioning

confidence: 97%

SAW analogs of Brewster's angles: the dependence on the strip shape

Biryukov¹,

Weihnacht²

IEEE Ultrasonics Symposium, 2005.

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The analogs of Brewster's angles for surface acoustic waves (SAW) were discovered by one of the authors (S.V.B.) thirty years ago. Considering the reflection of classical Rayleigh wave in the isotropic half-space at oblique incidence by long topographic irregularities of small thickness like projections and grooves it was found by perturbation method that the reflection coefficient is equal to zero for some angle of incidence. With Poisson's ratio changing from 0 to 0.5 the angle changes within a narrow range from 25.91 0 to 28.53 0 independently from the shape of irregularities. The problem was never treated more accurately then by the first order perturbation method on a small parameter as the thickness/wavelength ratio. In this work, the impedance method is used for a correct investigation of the problem in the case of periodic strips. A strong dependence of the angle value on a small parameter, if the last is more than 0.03, is observed. Moreover, a second such angle appears and both angles become closer and disappear for thick projections. The practically important cases of the aluminum strips on piezoelectric STXquartz and of 128 0 YX-LiNbO 3 crystals are also considered.

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Scattering of Rayleigh waves from topographic irregularities at oblique incidence

Cited by 14 publications

References 10 publications

Simulations of Gravitoelastic Correlations for the Sardinian Candidate Site of the Einstein Telescope

Simulations of Gravitoelastic Correlations for the Sardinian Candidate Site of the Einstein Telescope

Rayleigh wave reflection from single surface imperfections on isotropic substrates

SAW analogs of Brewster's angles: the dependence on the strip shape

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