Figure 7: The bathymetry along a line perpendicular to the AVR axis passing through Quail. (b) A bathymetric profile across the AVR passing through its centre. Both (a) and (b) are derived from swath bathymetry data collected during the RAMESSES experiment and plotted with no vertical exaggeration. The vertical axes show the depth below sea level. (c) shows the model with central AVR seafloor topography included which fits the data to RMS 2.3. The source positions are marked (S1 and S2 for the first and second tows respectively). Limitations in the number of model parameters which could be included before the problem became intractable meant that only the main features of the across axis topography were included. Resistivities are maked in . (d) The solid line shows the response of the final model shown in (c). Parameterisation limitations meant that the 11 Hz response could not be calculated with the seafloor topography included, and therefore the result with a flat seafloor is shown. The solid dots show the on axis 0.35 Hz response of the model when the topography around instrument Quail shown in (a) is used instead of the central AVR topography. Also shown (dashed line) is the off-axis response when the 1 lens and surrounding 2.5 region are removed from the model. In this case the difference between the 0.35 Hz and 0.75~Hz response between 8 and 15 km range is small demonstrating that the the frequency difference cannot explain the difference in amplitude.}