Figure 8: The effect of an along axis gap in the mid-crustal low resistivity anomaly. The source (S) is at the seafloor oriented perpendicular to the invariant direction and along the axis of the AVR. The transmission frequency is 0.35 Hz. The shallow structure is based on the axial structure of the AVR. At a depth of 2.1 km is a 400 m thick layer of low resistivity, in which there is a gap between Y1 km and Y2 km. Resistivities are given in . (b) shows the electric field along a line parallel to the axis of the source dipole. The upper dotted line is the response of a 1-dimensional model in which the 0.2 layer is continuous. The lower dotted line is the response of a 1-dimensional model without the 0.2 layer included.}