We studied the influence of the topography on the oceanic response to a traveling atmospheric disturbance and the relevance of its propagation direction on the generation of seiche oscillations. A primitive equation ocean model was used to analyze the response of two harbors located in insular systems to a pressure disturbance. The spectral component at the frequency of fundamental harbor resonance was determined from these data for different propagation directions of the incoming atmospheric disturbance. A conceptual model of interferences of resonantly generated ocean waves was introduced in order to explain energy maxima obtained by the numerical model close to the most affected areas.