In order to simulate the horizontal-to-vertical (H/V) spectral ratios of microtremors, analytical formulas are presented for computing the H/V ratios of Rayleigh and surface waves propagating on a layered half-space. Assuming that Rayleigh to Love wave amplitude ratio in horizontal motions is 0.7, the H/V spectra of Rayleigh and surface waves are computed at four sites, where the PS log data are available. The comparison among the H/V spectra of microtremors and Rayleigh and surface waves at the sites leads to the following conclusions: (1) The higher modes of Rayleigh waves have significant effects on the H/V spectra of microtremors in the frequency range where response functions of higher modes are predominant; (2) The H/V ratios of Rayleigh waves considering higher modes are in good agreement with those of microtremors, although the H/V values of Rayleigh waves are less than those of microtremors; (3) The H/V ratios of surface waves are in fairly good agreement with those of microtremors; and (4) V_s profiles of subsurface soils may be estimated from the H/V ratios of microtremors using the proposed formulas.
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