ABSTRACT
On the assumption that the seismic source is simplified as a linear fault with finite rupture length and constant rupture velocity along a single direction, this paper quantitatively analysizes the effect of seismic source on space correlation of strong ground motion based on the seismic source theory and expansion of seismic motion Fourier spectrum with the space coordinate variables, and obtains a relation of seismic motion spectra between a and its adjacent b points with interval d at a site, that is Ab (f) = Aa (f) exp(α 1 δγ +α 2 δθ), where α 1 and α 2 are two complex numbers which are related to seismic source parameters, media properties, station space coordinates as well as frequency, δγ 0 and δθ are two coefficients which are mainly related to space relative positions between a and b points. According to the Taylor approximate expansion condition of Fourier spectrum with space coordinate variables, this paper also presents a theoretical formula for estimating correlated radius based on α 1 and α 2 by numerical integration. Furthermore, it is pointed out that analytical expression of α 1 and α 2 can be obtained in far-field condition. After comparing numerical integration results with those of analytical formula, this paper finds that both of them are almost same in far field. At last, this paper also discusses the problem how to design strong ground motion field using space correlation of seismic motion.
