After 1995 Hyogo-ken Nanbu (Kobe) earthquake, the Japan Society of Civil Engineers suggested that near-source ground motion should be considered in the evaluation of seismic performance of structures when necessary. In the newest version of the technical standards for Japanese port structures, it is suggested to consider near-source ground motion in the evaluation of seismic performance of important quay walls such as so-called high seismic resistance quay walls. It is, therefore, requested to understand the characteristics of near-source ground motion for the evaluation of seismic performance of such quay walls to be carried out adequately. On the other hand, due to the promotion of engineering seismology in recent decades, methodologies are now available to evaluate near-source ground motions based on elasto-dynamics and dislocation theory. In this research, by using
these methodologies, the effects of source parameters on the predominant direction of near-source ground motion is investigated. The results suggests a robust tendency for the strike-normal component to be predominant in the region which is subject to the most intense ground motion in the near-source region of a large intra-plate earthquake. This tendency is consistent with the results of strong motion observation in the near-source region in Japan and the United States. Based on the results, the authors suggest that important quay walls should be oriented perpendicular to the strike of the fault to further improve their seismic performance. The adequacy of this suggestion is validated by conducting FEM analysis for the deformation of a caisson quay wall subject to near-source ground motions.