The amplitude characteristics as the fundamental natures of microtremors are discussed at present paper. The experimental field is Hakodate City in Hokkaido.
The power spectral density functions of microtremors were compared with amplitude functions of Rayleigh wave (M11) computed from underground structure. Furthermore, theoretical ratio of the horizontal component to the vertical component of Rayleigh wave (M11) was compared with that of the observed microtremors. From these comparisons, it was shown that the amplitude characteristics of microtremor was mostly composed of Rayleigh wave (M11).