Fig. 5. Examples of vertical radar profiling (VRP) data from the Trecate site. Time zero correction and trace normalization were applied to all datasets. Data in (a) and (b) were processed with residual median dewowing, 80-ns filter length, while the corresponding data in (c) and (d) were processed with residual mean dewowing, 10-ns filter length. The latter approach was more effective at preserving reflected events. Note the distinct slope change in the first arrivals in correspondence of the water table depth and the clear up-going reflections at several depths (particularly around 2 and 6 m b.g.l.). See Fig. 7 for the geometry of reflected events.