EM induction in the new Zealand Southern Alps region

The geomagnetic coast effect is known to comprise a major component in magnetic field observations at coastal sites. As the New Zealand South Island is relatively narrow, significant induction effects of the surrounding oceans are expected at most on-land sites. Interpretations of the observations as the responses of anomalous conductors would be simplified if these coast effects were not present. In this work, the removal of the coast effects at sites on the South Island is accomplished by subtracting analogue model coast effect induction arrows from the field site induction arrows. With the coast effects removed, the resulting difference induction arrows at some of the 26 sites would appear to be attributable to the induction responses of some of the sedimentary basins and faults, structures that were not included in the analogue model simulations.