scholarly journals Inversion of massive surface wave data sets: Model construction and resolution assessment

2004 ◽  
Vol 109 (B2) ◽  
Author(s):  
Eric Debayle ◽  
Malcolm Sambridge
Keyword(s):  
Surface Wave ◽  
Model Construction ◽  
Data Sets ◽  
Wave Data ◽  
Surface Wave Data

Retrieving 2D structures from surface-wave data by means of space-varying spatial windowing

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. EN39-EN51 ◽  
Author(s):  
Paolo Bergamo ◽  
Daniele Boiero ◽  
Laura Valentina Socco
Keyword(s):  
Surface Wave ◽  
Real Data ◽  
Processing Technique ◽  
Dispersion Curves ◽  
Data Sets ◽  
Local Dispersion ◽  
Wave Data ◽  
Survey Line ◽  
Wave Path ◽  
Surface Wave Data

Surface-wave techniques are mainly used to retrieve 1D subsurface models. However, in 2D environments, the 1D approach usually neglects the presence of lateral variations and because the surface-wave path crosses different materials, the resulting model is a simplified or misleading description of the site. We tested a processing technique to retrieve 2D structures from surface-wave data acquired with a limited number of receivers. Our technique was based on a two-step process. First, we extracted several local dispersion curves along the survey line using a spatial windowing based on a set of Gaussian windows with different shapes; the window maxima span the survey line so that we were able to extract a dispersion curve from the seismic record for every window. This provided a set of local dispersion curves each of them referring to a different subsurface portion. This space varying spatial windowing provided a good compromise between wavenumber resolution and the lateral resolution of the obtained local dispersion curves. In the second step, we inverted the retrieved set of dispersion curves using a laterally constrained inversion scheme. We applied this procedure to the processing of synthetic and real data sets and the method proved to be successful in reconstructing even complex 2D structures in the subsurface.

scholarly journals Time-lapse monitoring of climate effects on earthworks using surface waves

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. EN1-EN15 ◽  
Author(s):  
Paolo Bergamo ◽  
Ben Dashwood ◽  
Sebastian Uhlemann ◽  
Russell Swift ◽  
Jonathan E. Chambers ◽  
...  
Keyword(s):  
Surface Wave ◽  
Transportation Network ◽  
Wave Dispersion ◽  
Time Lapse ◽  
Spatial And Temporal Variability ◽  
Data Sets ◽  
Initial Model ◽  
Surface Wave Dispersion ◽  
Wave Data ◽  
Surface Wave Data

The UK’s transportation network is supported by critical geotechnical assets (cuttings/embankments/dams) that require sustainable, cost-effective management, while maintaining an appropriate service level to meet social, economic, and environmental needs. Recent effects of extreme weather on these geotechnical assets have highlighted their vulnerability to climate variations. We have assessed the potential of surface wave data to portray the climate-related variations in mechanical properties of a clay-filled railway embankment. Seismic data were acquired bimonthly from July 2013 to November 2014 along the crest of a heritage railway embankment in southwest England. For each acquisition, the collected data were first processed to obtain a set of Rayleigh-wave dispersion and attenuation curves, referenced to the same spatial locations. These data were then analyzed to identify a coherent trend in their spatial and temporal variability. The relevance of the observed temporal variations was also verified with respect to the experimental data uncertainties. Finally, the surface wave dispersion data sets were inverted to reconstruct a time-lapse model of S-wave velocity for the embankment structure, using a least-squares laterally constrained inversion scheme. A key point of the inversion process was constituted by the estimation of a suitable initial model and the selection of adequate levels of spatial regularization. The initial model and the strength of spatial smoothing were then kept constant throughout the processing of all available data sets to ensure homogeneity of the procedure and comparability among the obtained [Formula: see text] sections. A continuous and coherent temporal pattern of surface wave data, and consequently of the reconstructed [Formula: see text] models, was identified. This pattern is related to the seasonal distribution of precipitation and soil water content measured on site.

scholarly journals A Reduced Order Approach for Probabilistic Inversions of 3DMagnetotelluric Data II: Joint inversion of MT and Surface-Wave Data

2021 ◽  
Author(s):  
María Constanza Manassero ◽  
Juan Carlos Afonso ◽  
Fabio Iván Zyserman ◽  
Sergio Zlotnik ◽  
Ilya Fomin
Keyword(s):  
Surface Wave ◽  
Joint Inversion ◽  
Reduced Order ◽  
Wave Data ◽  
Surface Wave Data

Focal mechanism and source depth of earthquakes from body- and surface-wave data

1971 ◽  
Vol 61 (5) ◽  
pp. 1369-1379 ◽  
Author(s):  
Nezihi Canitez ◽  
M. Nafi Toksöz
Keyword(s):  
Surface Wave ◽  
Body Wave ◽  
Source Parameters ◽  
Focal Depth ◽  
Spectral Ratio ◽  
The Body ◽  
Spectral Ratios ◽  
Motion Data ◽  
Wave Data ◽  
Surface Wave Data

abstract The determination of focal depth and other source parameters by the use of first-motion data and surface-wave spectra is investigated. It is shown that the spectral ratio of Love to Rayleigh waves (L/R) is sensitive to all source parameters. The azimuthal variation of the L/R spectral ratios can be used to check the fault-plane solution as well as for focal depth determinations. Medium response, attenuation, and source finiteness seriously affect the absolute spectra and introduce uncertainty into the focal depth determinations. These effects are nearly canceled out when L/R amplitude ratios are used. Thus, the preferred procedure for source mechanism studies of shallow earthquakes is to use jointly the body-wave data, absolute spectra of surface waves, and the Love/Rayleigh spectral ratios. With this procedure, focal depths can be determined to an accuracy of a few kilometers.

Effects of thin soft layers on body waves

1969 ◽  
Vol 59 (5) ◽  
pp. 2071-2078
Author(s):  
Tom Landers ◽  
Jon F. Claerbout
Keyword(s):  
Surface Wave ◽  
Upper Mantle ◽  
Body Wave ◽  
Wave Dispersion ◽  
Soft Material ◽  
Body Waves ◽  
Surface Wave Dispersion ◽  
Wave Data ◽  
Use Of Time ◽  
Surface Wave Data

abstract The inability of simple layered models to fit both Rayleigh wave and Love wave data has led to the proposal of an upper mantle interleaved with thin soft horizontal layers. Since surface-wave dispersion is not sensitive to the distribution of soft material but only to the fraction of soft material a variety of models is possible. The solution to this indeterminancy is found through body-wave analysis. It is shown that body waves are dispersed according to the thinness and softness of the layers. Three models, each of which satisfy all surface-wave data, are examined. Transmission seismograms calculated for these models show one to be impossible, one improbable and the other possible. Synthesis of the seismograms is accomplished through the use of time domain theory as the complicated frequency response of the models makes a frequency oriented Haskell-Thompson approach impractical.

Stacking of multilayout and multichannel surface-wave data on the f-k domain

2018 ◽  
Vol 159 ◽  
pp. 93-107 ◽  
Author(s):  
Maria João Coelho ◽  
Jaime Santos ◽  
Marília Pereira
Keyword(s):  
Surface Wave ◽  
Wave Data ◽  
Surface Wave Data
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