Figure 2
Electrode configuration of the electrical resistivity tomography (ERT) system, observed ERT data, and model responses. (a) Electrode location of the ERT system38. The ERT system uses eight current electrodes, C1–C7 and COM, and two receiver electrodes, P1 and P2. Current was transmitted using electrode pairs: C1–COM, C2–COM, C3–COM, C4–COM, C5–COM, C6–COM, and C7–COM. (b) Observed apparent resistivity data38. (c) Response from the inverted resistivity model shown in Fig. 3b. (d) Response from an initial model comprising a 1.0 Ωm homogeneous subseafloor layer and a 0.35 Ωm seawater layer. (e) Difference between the observed data and the initial model response. (d) and (e) highlight data that the homogeneous sub-seafloor structure of 1 Ωm cannot explain. The vertical axis is based on source electrode pairs. The C7–COM pair reflects deeper resistivity structures than C1–COM because of longer source–receiver septation. Data are shown with southwest on the left (start point of towing) and northeast on the right (end point of towing). The observed apparent resistivity at a horizontal distance of 900–1200 m is low because of the high tow height of the system.
