Does any relation between microtremors and ground motion induced by the earthquake exist? And what is the relation like? There are different answers by different researches. The Songpan earthquake in 1976 supplied, the chance to discuss this problem. From the investigation we come to the following conclusions:(1)Both the acceleration and the maximum amplitude of Fourier spectrum of ground surface motion induced dy earthquake increase with the earthquake magnitude increasing; and both the amplitude of microtremors and its Fourier spectra increase with the altitude of observation site and the thickness of alluvial stratum increasing. (2) The amplitude of microtremors and the surface motion induced by different series of earthquake in the same site appears to have certain direction. (3)The characteristics of the Fourier spectra of the same series of earthquake are exactly alike. (4)The old style wooden house of one storey does not affect the spectrum of microtremors, but the site condition obviously affects the Fourier spectrum of the microtremors of the wooden house.
By these analyses it is concluded that there is no obvious relation between spectra of ground microtremors and ground surface motion induced by the earthquake.