Investigation on Directivity of the 2008 Wenchuan 8.0 Earthquake by Huang Ke Thesis Supervisor: Prof. Ka-Veng Yuen Department of Civil and Environmental Engineering Estimation of peak ground acceleration is an increasing concern in civil engineering and seismology. The seismic intensity attenuation relationship is a very important basic material for earthquake disaster assessment, estimation of seismic intensity for early warning and earthquake engineering research. To investigate the directivity characteristics of the acceleration ground motions during the Ms 8.0, 2008 great Wenchuan earthquake, a total of 271 sets of ground motion recorded on soil and rock site conditions are analyzed in this study. Compared with most current seismic attenuation models, the directional dependence of seismic intensity attenuation relationship is advanced distinctively. Model class candidates are then constructed based on partial Fourier series. Bayesian inference provides the quantitative criterion to choose the most suitable/optimal model for curving fitting. Therefore, the contours of peak ground acceleration can be obtained from the proposed model to prove the significance of directional dependence on seismic intensity attenuation relationship.