Seismic peak ground acceleration is an important parameter of earthquake intensity.It is also one of the main results of seismic safety evaluation of engineering sites.To get reasonable seismic peak ground acceleration is of positive significance.While working on seismic safety evaluation of engineering sites in the past decade

the author found that some more serious scatter characters are showed in the seismic peak ground analysis.To evaluate the influence

this paper calculates the seismic peak ground acceleration of 662 real bore sections from 307 project sites in Guangdong province

using 20 groups of mutual independent bedrock acceleration histories as the input seismic waves for different sites.The relative root-mean-square errors are used to evaluate the scatter characters of seismic peak ground acceleration.The maximum relative root-mean-square errors of seismic peak ground acceleration are 19%

while the mean relative root-mean-square errors are 7.53%.The larger relative root-mean-square errors are in regions with higher magnitude than those with lower and the larger relative root-mean-square errors are in the worse site sort than in the better site sort region.In order to get the reasonable seismic peak ground acceleration using 1 or 3 acceleration histories as the input seismic waves is obviously not enough.The number of the input seismic waves shall be increased especially in regions of magnitude and with worse site sorts.