Comparing shear-wave velocity profiles inverted from multichannel surface wave with borehole measurements

Xia, Jianghai; Miller, Richard D.; Park, Choon B.; Hunter, James A.; Harris, James B.; Ivanov, Julian

doi:10.1016/s0267-7261(02)00008-8

Cited by 238 publications

(120 citation statements)

References 14 publications

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“…The physical parameters of the top and bottom layers (labeled 1 and 2 in Figure 7) are listed in Table 2. The high Poisson's ratios of the top and bottom layers (about 0.45 and 0.41, respectively) are commonly seen in the near surface (Xia et al, 2002). All the modeling parameters, such as the grid spacing, source and receiver positions, are exactly the same as those in the test for the model shown in Figure 5.…”

Section: An Improved Vacuum Formulation T5mentioning

confidence: 96%

An improved vacuum formulation for 2D finite-difference modeling of Rayleigh waves including surface topography and internal discontinuities

et al. 2012

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Rayleigh waves are generated along the free surface and their propagation can be strongly influenced by surface topography. Modeling of Rayleigh waves in the near surface in the presence of topography is fundamental to the study of surface waves in environmental and engineering geophysics. For simulation of Rayleigh waves, the traction-free boundary condition needs to be satisfied on the free surface. A vacuum formulation naturally incorporates surface topography in finite-difference (FD) modeling by treating the surface grid nodes as the internal grid nodes. However, the conventional vacuum formulation does not completely fulfill the free-surface boundary condition and becomes unstable for modeling using high-order FD operators. We developed a stable vacuum formulation that fully satisfies the free-surface boundary condition by choosing an appropriate combination of the staggered-grid form and a parameter-averaging scheme. The elastic parameters on the topographic free surface are updated with exactly the same treatment as internal grid nodes. The improved vacuum formulation can accurately and stably simulate Rayleigh waves along the topographic surface for homogeneous and heterogeneous elastic models with high Poisson's ratios (>0.4). This method requires fewer grid points per wavelength than the stress-image-based methods. Internal discontinuities in a model can be handled without modification of the algorithm. Only minor changes are required to implement the improved vacuum formulation in existing 2D FD modeling codes.

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Section: An Improved Vacuum Formulation T5mentioning

confidence: 96%

An improved vacuum formulation for 2D finite-difference modeling of Rayleigh waves including surface topography and internal discontinuities

et al. 2012

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“…The agreement between the methods was good, and an overall difference of 15% or less was observed between the shear wave velocities derived from the two methods (Xia et al [38]). The database of the mentioned borehole-derived shear wave velocities can be found in Hunter et al [39].…”

Section: Masw Case Studiesmentioning

confidence: 99%

On the Efficiency of the Multi-Channel Analysis of Surface Wave Method for Shallow and Semi-Deep Loose Soil Layers

Banab

Motazedian²

2010

International Journal of Geophysics

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The multi-channel analysis of surface waves (MASWs) method was used to obtain the shear wave velocity variations through near surface (depth < 30 m) and semideep (30 m < depth < 100 m) soil layers in the city of Ottawa, Canada. Sixteen sites were examined to evaluate the capability of the active and passive MASW methods for cases where the shear wave velocity (V s ) contrast between very loose soil (V s < 200 m/s) and very firm bedrock (V s > 2,300 m/s) is very large. The MASW velocity results compared with those of other geophysical approaches, such as seismic reflection/refraction methods and borehole data, where available, mostly confirming the capability of the MASW method to distinguish the high shear wave velocity contrast in the study area. We have found that, of the inversion procedures of MASW data, the random search inversion technique provides better results than the analytical generalized inversion method.

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“…Many near-surface materials are unlithified and have much higher Poisson's ratios than the sedimentary rocks. For example, Xia et al (2002) showed that the materials of upper 7 m at a mining site in Wyoming, U.S.A., have the Poisson's ratio of about 0.48. They also reported that the unconsolidated sediments of the Fraser River Delta near Vancouver, Canada, have the Poisson's ratio of about 0.49, which is close to the maximum theoretical Poisson's ratio (0.5).…”

Section: Introductionmentioning

confidence: 99%

“…For near-surface seismic modeling, Rayleigh waves dominate the P-SV (the coupling of compressional waves and the vertical components of shear waves) wavefield (e.g., Xia et al, 2002;Saenger and Bohlen, 2004). Compared to conventional seismic modeling that focuses on P-waves, a higher spatial sample density of grid points per wavelength (ppw) is required to avoid the numerical dispersion of Rayleigh waves during the model discretization procedure (Mittet, 2002).…”

Section: Introductionmentioning

confidence: 99%

Application of the multiaxial perfectly matched layer (M-PML) to near-surface seismic modeling with Rayleigh waves

et al. 2011

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Perfectly matched layer (PML) absorbing boundaries are widely used to suppress spurious edge reflections in seismic modeling. When modeling Rayleigh waves with the existence of the free surface, the classical PML algorithm becomes unstable when the Poisson's ratio of the medium is high. Numerical errors can accumulate exponentially and terminate the simulation due to computational overflows. Numerical tests show that the divergence speed of the classical PML has a nonlinear relationship with the Poisson's ratio. Generally, the higher the Poisson's ratio, the faster the classical PML diverges. The multiaxial PML (M-PML) attenuates the waves in PMLs using different damping profiles that are proportional to each other in orthogonal directions. The proportion coefficients of the damping profiles usually vary with the specific model settings. If they are set appropriately, the M-PML algorithm is stable for high Poisson's ratio earth models. Through numerical tests of 40 models with Poisson's ratios that varied from 0.10 to 0.49, we found that a constant proportion coefficient of 1.0 for the x-and z-directional damping profiles is sufficient to stabilize the M-PML for all 2D isotropic elastic cases. Wavefield simulations indicate that the instability of the classical PML is strongly related to the wave phenomena near the free surface. When applying the multiaxial technique only in the corners of the PML near the free surface, the original M-PML technique can be simplified without losing its stability. The simplified M-PML works efficiently for homogeneous and heterogeneous earth models with high Poisson's ratios. The analysis in this paper is based on 2D finite difference modeling in the time domain that can easily be extended into the 3D domain with other numerical methods.

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Comparing shear-wave velocity profiles inverted from multichannel surface wave with borehole measurements

Cited by 238 publications

References 14 publications

An improved vacuum formulation for 2D finite-difference modeling of Rayleigh waves including surface topography and internal discontinuities

An improved vacuum formulation for 2D finite-difference modeling of Rayleigh waves including surface topography and internal discontinuities

On the Efficiency of the Multi-Channel Analysis of Surface Wave Method for Shallow and Semi-Deep Loose Soil Layers

Application of the multiaxial perfectly matched layer (M-PML) to near-surface seismic modeling with Rayleigh waves

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