Therefore, they appear later than P-waves on a seismogram. This is a more efficient way to read a seismogram. The next set of seismic waves on the seismogram will be the S-waves. This series is convolved with a seismic wavelet to produce the synthetic seismogram. A seismogram is a graph output by a seismograph. A recording of earth motion as a function of time is called a seismogram.