Inversion of Rayleigh-wave ellipticity for shallow strong-velocity-contrast structures
Inversion of Rayleigh-wave ellipticity for shallow strong-velocity-contrast structures
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DOI：
10.1190/geo2022-0260.1
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发表时间：
2023
期刊：
影响因子：
3.3
通讯作者：
Jianghai Xia
中科院分区：
文献类型：
--
作者：
Binbin Mi;Jianghai Xia
Rayleigh-wave ellipticity polarization, or horizontal-to-vertical spectral ratio ( H/V), is particularly sensitive to shallow earth model parameters (e.g., shear wave velocity). We propose a novel Rayleigh-wave H/V inversion method to delineate near-surface strong-velocity-contrast structures. In the new inversion method, the shear wave velocity model is perturbed until the synthetic Rayleigh-wave H/V curve is fitted to the observed one based on the cross-correlation misfit function. This criterion neglects the absolute amplitude of the observed and synthetic H/V curves, which can eliminate the amplitude influence caused by inconsistent coupling of the horizontal and vertical geophones. Peaks and/or troughs in the H/V curve are inverted with no need of picking. Numerical simulations show that the proposed H/V inversion succeeds for models consisting of unconsolidated sediments overlying stiff bedrock with large velocity contrasts. We also show that the active Rayleigh-wave ellipticity estimation and inversion can be carried out for reconstructing pseudo-2D laterally varying models. Application to a real-world example suggests that a 2D model above 6 m depth with large velocity contrasts is successfully reconstructed from Rayleigh-wave ellipticity data. The proposed method provides an effective and efficient alternative for near-surface characterization.
