An Effective Method to Extract Overtones of Surface Wave From Array Seismic Records of Earthquake Events

To remove surface waves from seismic records while preserving other seismic events of interest, we introduced a transform and a filter based on recent developments in image processing. The transform can be seen as a weighted Radon transform, in particular along linear trajectories. The weights in the transform are data dependent and designed to introduce large amplitude differences between surface waves and other events such that surface waves could be separated by a simple amplitude threshold. This is a key property of the filter and distinguishes this approach from others, such as conventional ones that use information on moveout ranges to apply a mask in the transform domain. Initial experiments with synthetic records and field data have demonstrated that, with the appropriate parameters, the proposed trace transform filter performs better both in terms of surface wave attenuation and reflected signal preservation than the conventional methods. Further experiments on larger data sets are needed to fully assess the method.

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GROUND ROLL COUPLING TO ATMOSPHERIC COMPRESSIONAL WAVES

Geophysics ◽

10.1190/1.1437684 ◽

1951 ◽

Vol 16 (3) ◽

pp. 416-430 ◽

Cited By ~ 19

Author(s):

Frank Press ◽

Maurice Ewing

Keyword(s):

Surface Wave ◽

Speed Of Sound ◽

Body Wave ◽

Wave Pattern ◽

Theoretical Treatment ◽

Compressional Waves ◽

Wave Velocities ◽

Seismic Records ◽

Ground Roll ◽

Theoretical Results

A theoretical treatment of ground roll originating from air shots and hole shots is given. It is shown that coupling of ground roll to compressional waves in the atmosphere exists for both air shots and hole shots. Experimental data obtained in the field are in excellent agreement with the theoretical results; namely, that the effective coupling exists for surface waves whose phase velocity is equal to the speed of sound in air. In regions where Rayleigh wave velocities vary with period due to layering in such a way that they are less than the speed of sound in air for short periods and exceed this value for longer periods, this coupling gives rise to a unique surface wave pattern on seismic records. It is shown that body wave and surface wave character is almost independent of charge elevation in the range from 0 (on the ground) to 30 feet. In a reciprocal manner ground roll from hole shots was recorded with air microphones as predicted by the theory.

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Applications of the Trace Transform in Surface Wave Attenuation on Seismic Records

IEEE Transactions on Geoscience and Remote Sensing ◽

10.1109/tgrs.2011.2156417 ◽

2011 ◽

Vol 49 (12) ◽

pp. 4997-5007 ◽

Cited By ~ 3

Author(s):

Ning Wu ◽

Yue Li ◽

Baojun Yang

Keyword(s):

Surface Wave ◽

Wave Attenuation ◽

Seismic Records ◽

Trace Transform

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Estimation of Deep Shear-Wave Velocity Profiles in Lima, Peru, Using Seismometers Arrays

Journal of Disaster Research ◽

10.20965/jdr.2013.p0252 ◽

2013 ◽

Vol 8 (2) ◽

pp. 252-258 ◽

Cited By ~ 2

Author(s):

Diana Calderon ◽

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Zenon Aguilar ◽

Fernando Lazares ◽

Toru Sekiguchi ◽

...

Keyword(s):

Surface Wave ◽

Dispersion Curve ◽

Shear Wave ◽

Wave Velocity ◽

Shear Wave Velocity ◽

Velocity Profiles ◽

Good Resolution ◽

Period Range ◽

Wave Observation ◽

Seismic Records

The estimation of the shear-wave velocity profile in Lima, Peru, was originally performed through surface wave observation in microtremor arrays. In the observation of these surface waves, a low signal problem for long periods was identified that resulted in a poorly done correlation between signals recorded by sensors and, consequently, in difficulty obtaining deep velocity profiles with good resolution. As an alternative, surface wave observation from seismic records was proposed. To confirm the feasibility of this methodology, seismometers were installed in an approximately circular configuration on the campus of the National University of Engineering in Lima. The procedures used to carry out analysis are similar to those used when analyzing microtremor arrays, with the exception that only the coda of seismic records is used for analysis. Results show that the dispersion curve obtained from seismometer arrays agree well with dispersion curve obtained from microtremor arrays and are predominant in a large period range. Finally, the estimated profile is verified using the observed H/V spectrum.

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Exit-surface wave reconstruction using a focal series

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129577 ◽

1992 ◽

Vol 50 (2) ◽

pp. 988-989

Author(s):

W.J. de Ruijter ◽

M.R. McCartney ◽

David J. Smith ◽

J.K. Weiss

Keyword(s):

Surface Wave ◽

Spherical Aberration ◽

Data Extraction ◽

High Sensitivity ◽

Geometric Distortion ◽

Variation Method ◽

Objective Lens ◽

Immediate Reconstruction ◽

Exit Surface ◽

Electron Microscopes

Further advances in resolution enhancement of transmission electron microscopes can be expected from digital processing of image data recorded with slow-scan CCD cameras. Image recording with these new cameras is essential because of their high sensitivity, extreme linearity and negligible geometric distortion. Furthermore, digital image acquisition allows for on-line processing which yields virtually immediate reconstruction results. At present, the most promising techniques for exit-surface wave reconstruction are electron holography and the recently proposed focal variation method. The latter method is based on image processing applied to a series of images recorded at equally spaced defocus.Exit-surface wave reconstruction using the focal variation method as proposed by Van Dyck and Op de Beeck proceeds in two stages. First, the complex image wave is retrieved by data extraction from a parabola situated in three-dimensional Fourier space. Then the objective lens spherical aberration, astigmatism and defocus are corrected by simply dividing the image wave by the wave aberration function calculated with the appropriate objective lens aberration coefficients which yields the exit-surface wave.

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