Surface wave dispersion curve calculation in TIV medium

Ke, Ganpan; Dong, Hefeng; Cao, Zhen; Liu, Lanbo

doi:10.1190/1.3513219

Cited by 1 publication

(2 citation statements)

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“…Motivated by the development of the multichannel analysis of surface waves technique Xia et al, 1999), surface-wave methods have become widely accepted for applications in near-surface velocity characterizations (see the review by Socco et al, 2010). In particular, recent studies have shown the potential of applying such methods to the Arctic regions (Strobbia et al, 2009;Ke et al, 2010).…”

Section: Introductionmentioning

confidence: 98%

“…For instance, in areas with thin permafrost, the near-surface material resembles a velocity model with a fast top layer (Ke et al, 2010); in areas with thick permafrost, layers or zones of unfrozen ground could occur as low-velocity layers or pockets that are enclosed in a high-velocity background (Strobbia et al, 2009;Trupp et al, 2009). The irregular velocity variations in permafrost, combined with the marked velocity contrasts between frozen and unfrozen materials, could render conventional surface-wave inversion methods inapplicable.…”

Section: Introductionmentioning

confidence: 99%

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Full-wavefield inversion of surface waves for mapping embedded low-velocity zones in permafrost

Dou

Ajo‐Franklin

2014

GEOPHYSICS

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Surface waves are advantageous for mapping seismic structures of permafrost, in which irregular velocity gradients are common and thus the effectiveness of refraction methods are limited. Nevertheless, the complex velocity structures that are common in permafrost environments often yield unusual dispersion spectra, in which higher-order and leaky modes are dominant. Such unusual dispersion spectra were prevalent in the multichannel surface-wave data acquired from our permafrost study site at Barrow, Alaska. Owing to the difficulties in picking and identifying dispersion curves from these dispersion spectra, conventional surface-wave inversion methods become problematic to apply. To overcome these difficulties, we adopted a full-wavefield method to invert for velocity models that can best fit the dispersion spectra instead of the dispersion curves. The inferred velocity models were consistent with collocated electric resistivity results and with subsequent confirmation cores, which indicated the reliability of the recovered seismic structures. The results revealed embedded low-velocity zones underlying the ice-rich permafrost at our study site -an unexpected feature considering the low ground temperatures of −10°C to −8°C. The low velocities in these zones (∼70%-80% lower than the overlying ice-rich permafrost) were most likely caused by saline pore-waters that prevent the ground from freezing, and the resultant velocity structures are vivid examples of complex subsurface properties in permafrost terrain. We determined that full-wavefield inversion of surface waves, although carrying higher computational costs than conventional methods, can be an effective tool for delineating the seismic structures of permafrost.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%