In order to realize microregionation of the site conditions in Lanzhou, the observation of ground microtremors was carried out in 75 points within this city.
It is shown that the characteristics of ground microtremors are obviously regional. The Fourier spectra of different, points in Lanzhou are more or less alike with each other. The pikes of the majority of the Fourier spectra occur at 0.3-0.45 sec. But in different areas of Lanzhou there are some various characteristics in the spectra and according to the appearance of the spectra it is able to divide the whole area of this city into 5 regions. So it can be imagined that the characteristics of ground microtremors are dependent on the total natural conditions over the whole region rather than on the local subsoil conditions.
The maximum amplitude of the ground microtremors at 9-11 in the morning is 0.5-1.5μ. The maximum amplitude of ground microtremors is obviously dependent on the thickness of the soft ground, such, as leoss, loam, silt ect.. The thicker the stratum of the soft ground, the greater the maximum amplitude of microtremors.
The results of microtremors measurement can be used in the micro regionation of site conditions.