The data is unprocessed other than by multiplication by a spherical divergence correction t .
Air is slower and lighter than water while sea-floor sediment is almost always faster and denser.
This means that successive multiple reflections almost always have alternating polarity. The polarity of a seismic arrival is usually ambiguous, but here the waveform is distinctive and it clearly alternates in polarity from bounce to bounce. The ratio of amplitudes of successive multiple reflections is the reflection coefficient. At the right, the near trace is expanded. Multiply reflected head waves are also apparent, as are alternating polarities on them.