The purpose of this study is to know how to analyze the seismic signals volcanic to determine subsurface characteristics. The method used to analyze seismic signals volcanic is Fast Fourier Transform. Sample signal seismic wave of this study come from Semeru Volcano and Ijen Volcano signal seismic based on seismogram. The first data are given by swarm and wvw software. Analyze seismic wave in this study proves the existence of a relationship between seismic attributes (frequency, amplitude, time (origin, primer dan secondary) and attenuation) of the characteristics of the earth's surface. This study proved there is the correlation between subsurface characteristics and energy, it shows by attenuation factor value (Q value). The value of factor Q indicates how many waves are absorbed by the medium.