Figure 2
From: Distributed acoustic sensing for active offshore shear wave profiling

DAS data from site 1 showing (a) 2Â h 45Â min waterfall FBE data with passive and active data recording. (b) 2.5Â min passive data showing ocean pressure waves, with apparent group wave velocities highlighted (red dashed lines). (c) 25Â s active data showing airgun shot with pressure wave interference. (d) 5Â s shot record on 900 channels.