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Journal Article
Journal: Geophysics
Published: 29 June 2023
Geophysics (2023) 88 (5): T237–T258.
..., interpolation, and classical nine-point method (CM). The results indicate that the number of grid points per qS wavelength of the interpolation scheme is closest to that of the point-by-point optimization scheme and much lower than that of the overall optimization scheme and CM. In addition, the surface...
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Journal Article
Journal: Geophysics
Published: 12 April 2023
Geophysics (2023) 88 (3): V215–V231.
...Ali M. Alfaraj; D. J. (Eric) Verschuur; Felix J. Herrmann ABSTRACT Surface consistency forms the basis for short-wavelength statics estimation. When raypaths in the near surface diverge from a normal incidence or when the normal moveout (NMO) velocity is inaccurate, surface-consistent methods may...
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Journal Article
Journal: Geophysics
Published: 31 August 2021
Geophysics (2021) 86 (5): T387–T399.
... sizes are kept fixed at 10 m. The velocity c 1 is kept fixed at 2000 m/s. The sources and receivers will be in the c 1 -part of the model. If c 1 = 2000  m/s, we have that a temporal frequency component at 100 Hz has a wavelength λ of 20 m. The corresponding...
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Journal Article
Journal: Geophysics
Published: 31 August 2021
Geophysics (2021) 86 (5): T401–T410.
..., which are much larger than the average pore size and much smaller than the average fast P-wave wavelength. When analyzing this mechanism in hydrocarbon reservoirs with the pore space saturated by multiphase fluids, it is important to include capillary pressure effects and flow interaction between fluids...
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Journal Article
Journal: Geophysics
Published: 18 August 2021
Geophysics (2021) 86 (5): T349–T359.
.... The performance of existing Helmholtz preconditioners usually deteriorates when the minimum spatial sampling density is small (approximately four points per wavelength [PPW]). To improve the efficiency of the Helmholtz preconditioner at a small minimum spatial sampling density, we have adopted a new...
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Journal Article
Journal: The Leading Edge
Published: 01 August 2021
The Leading Edge (2021) 40 (8): 567–575.
... apply a dedicated time-windowing algorithm to isolate and pick the different modes. A multimodal tomographic inversion is applied to estimate a V S model. The V S model is then converted to a V P model with the Poisson's ratio estimated through the wavelength-depth method. We apply the method to a 2D...
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Journal Article
Published: 05 January 2021
Bulletin of the Seismological Society of America (2021) 111 (2): 791–800.
...Jagdish Chandra Vyas; Martin Galis; Paul Martin Mai ABSTRACT We derive a theoretical parameter for three seismic scattering regimes where seismic wavelengths are either much shorter, similar, or much longer than the correlation length of small‐scale Earth heterogeneities. We focus our analysis...
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Journal Article
Journal: Elements
Published: 01 April 2020
Elements (2020) 16 (2): 117–122.
...., fluorescence, luminescence, or phosphorescence) (see Gaft et al. 2015 for further details). Many natural samples exhibit an inherent background, which often overwhelms the Raman signal. This may be due to rough surfaces or small grain sizes on the same order of magnitude as the laser wavelength...
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Journal Article
Published: 22 October 2019
Bulletin of the Seismological Society of America (2019) 109 (6): 2658–2673.
... , STN trends. Subsequently, the site term is replaced with (a) linear 1D shear‐wave (horizontal) transfer function (1D‐SHTF) amplification, (b) horizontal‐to‐vertical ratios, and (c) quarter wavelength amplification to calculate Δ M L , STN ( M ) in the absence of S/B. We find that Δ M L , STN ( M...
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Journal Article
Journal: Geophysics
Published: 06 September 2019
Geophysics (2019) 84 (5): S449–S458.
... velocity errors by tuning interfaces or tolerating the errors by tuning extrapolated wavefields. It is reported that some methods may encounter problems in revealing high-contrast and short-wavelength velocity anomalies ( Etgen et al., 2014a ; Esser et al., 2016 ). Specifically, MVA based...
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Journal Article
Journal: Geophysics
Published: 12 August 2019
Geophysics (2019) 84 (5): S389–S399.
... structural boundaries, isolated scatterers, reflector edges, fault, fracture zones, and erosional. Reflections and diffractions result from seismic waves interacting with subsurface geologic structures. Reflections are generated by continuous interfaces whose spatial wavelength is larger than the dominant...
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Journal Article
Journal: Geophysics
Published: 28 May 2019
Geophysics (2019) 84 (4): B269–B284.
.... Significantly, differences were observed between the results when inverting the single T z z component and when inverting the 5C combination. We also found that the T z z model failed to reproduce the long-wavelength signals from other components, whereas the model recovered from five components accommodated...
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Journal Article
Published: 19 March 2019
Bulletin of the Seismological Society of America (2019) 109 (3): 1005–1024.
... is clearly a function of more than one variable. In general, it appears that both regional topography (i.e., long‐wavelength topography) and deeper subsurface seismic structures (basins and sediments) have a large impact on site amplification. Whether or not the HVSR method measures the amplification...
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Journal Article
Journal: Geosphere
Published: 21 December 2018
Geosphere (2019) 15 (1): 146–170.
.... We define this modification as “structural geometric anisotropy” (SGA). The seismic anisotropy signals produced by this structure are influenced by the length scale of seismic waves: shorter wavelengths respond to each larger part of the structure (path integration) whereas longer wavelengths respond...
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Journal Article
Journal: Geophysics
Published: 04 December 2018
Geophysics (2019) 84 (1): C1–C14.
... wavelengths are well-recovered. On the other hand, the η parameter impact is weak on the inversion results and can be fixed. However, a good background η , with accurate long wavelengths, is needed to correctly invert for v h . Furthermore, we invert a real data set acquired by CGG from offshore Australia. We...
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Journal Article
Journal: Geophysics
Published: 26 November 2018
Geophysics (2019) 84 (1): IM1–IM9.
... both evoke diffracted waves. Thus, diffracted waves are a direct seismic response from subsurface heterogeneities, which have a size comparable with the prevailing wavelength or a curvature growing locally to infinity. We investigate a dedicated processing of diffracted waves, which allows direct...
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Journal Article
Published: 26 September 2018
Seismological Research Letters (2018) 89 (6): 2274–2283.
... dispersion measurement at period required an interstation distance at least three times the wavelength, but alternative techniques also be tested in recent studies, for example, two‐wavelength criteria ( Lin et al. , 2009 ; Porritt et al. , 2011 ; Mordret et al. , 2013 ) or one‐wavelength criteria ( Luo...
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Journal Article
Published: 22 August 2018
Seismological Research Letters (2018) 89 (6): 2025–2033.
... observed from the 2004 M w  8.1 Macquarie ridge earthquake as acoustic signals with relatively large wavelengths coupled from shallow underwater features ( Evers et al. , 2014 ). Previous studies of infrasound from earthquakes have shown that most of the coupled seismo‐acoustic signals...
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Journal Article
Published: 24 July 2018
Bulletin of the Seismological Society of America (2018) 108 (6): 3160–3168.
... (2013) in choosing β = 3 ( H = 1 ), which is the case for a self‐similar fractal. The inverse Fourier transform of this set of numbers gives one realization of a rough fault profile. We then apply a low‐pass filter to remove short‐wavelength components, such that there are 30 grid points...
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Journal Article
Published: 29 May 2018
Bulletin of the Seismological Society of America (2018) 108 (4): 2022–2031.
... by at least λ / 4 (in which λ is the laser wavelength) to allow for accurate phase tracking (see Zumberge et al. , 2004 ). The microseismic background provides this modulation for the vertical component as its free period is near the microseismic peak, which excites the mass to always...
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