The core of a VHTR is a stacked structure of graphite blocks. For the development of a seismic analysis methodology, a preliminary evaluation of one single block and single column stacked block structure under a harmonic excitation was performed. In a real design, the blocks are connected by pin and socket component. So, the evaluations were conducted for a stacked structure with and without pin and socket component, respectively. And the evaluation results were compared to each other. For these evaluations, the commercial finite element analysis software ABAQUS/Explicit was utilized.