Rayleigh-wave ellipticity polarization, or horizontal-to-vertical (⁠H/V⁠) spectral ratio, is particularly sensitive to shallow earth model parameters (e.g., S-wave velocity). We develop a novel Rayleigh-wave H/V inversion method to delineate near-surface strong-velocity-contrast structures. In the new inversion method, the S-wave velocity model is perturbed until the synthetic Rayleigh-wave H/V curve is fitted to the observed one based on the crosscorrelation 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 indicate that the proposed H/V inversion succeeds for models consisting of unconsolidated sediments overlying stiff bedrock with large velocity contrasts. We also find 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 in depth with large velocity contrasts is successfully reconstructed from Rayleigh-wave ellipticity data. This method provides an effective and efficient alternative for near-surface characterization.

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