College of Geo- exploration Science and Technology��Jilin University��Changchun 130026��China

Based on the Huygens��Fresnel principle and the source array theory��a method of directional seis- mic illumination on the rugged surface is proposed�� This method rotates coordinates in accordance with the topogra- phy of the rugged surface and the required direction of seismic illumination�� According to the new coordinates��bi- directional seismic illumination can be achieved by calculating the excitation delay of the source array and the direc- tional seismic wave field�� The numerical examples on a simple 2D velocity model and the rugged Marmousi model have verified the validity of this method�� The results indicate that calculating the directional seismic illumination by rotating coordinates is practical and flexible in the exploration areas with a rugged surface�� Besides��it can be ap- plied to analyze the influence of underground complicated geological body on the distribution of seismic energy��