Figure 2. Example of the BSR on the mid-Norwegian margin. The BSR is mainly identified as the termination of enhanced reflections. The P-wave velocity profile of OBS JM516 shows a clear velocity inversion at the depth of the BSR. Higher velocity above the BSR indicates the presence of gas hydrates; lower velocity underneath the BSR provides evidence for the presence of free gas within the sediments. S-wave velocities are unaffected by either the presence of hydrates, or the presence of gas underneath the BSR. Therefore, we conclude that gas hydrates do not cement the sediments, but are rather disseminated in the sediment pore space.