| | AbstractThe spectral ratio
between horizontal and vertical components (H/V ratio) of microtremors
measured at the ground surface has been used to estimate fundamental
periods and amplification factors of a site, although this technique
lacks theoretical background. The aim of this article is to formulate
the H/V technique in terms of the characteristics of Rayleigh and Love
waves, and to contribute to improve the technique. The improvement
includes use of not only peaks but also troughs in the H/V ratio for
reliable estimation of the period and use of a newly proposed smoothing
function for better estimation of the amplification factor. The
formulation leads to a simple formula for the amplification factor
expressed with the H/V ratio. With microtremor data measured at 546
junior high schools in 23 wards of Tokyo, the improved technique is
applied to mapping site periods and amplification factors in the
area.Return to Table of
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