Nearshore magnetotelluric (MT) survey using inter-station impedance data

We present the implementation of inter-station impedance data for a nearshore Magnetotelluric (MT) survey and apply it to the synthetic Littoral Fault Zone (LFZ) model to analyze its capability to reproduce the fault anomaly and compare it with regular impedance. There are difficulties in deploying a magnetometer onto the seafloor as it is vulnerable to water without proper protection, and the seafloor magnetic field can be highly distributed by seawater current and other electromagnetic (EM) interferences. We chose inter-station acquisition, which only records the electric field data on the seafloor while using the nearby onshore magnetic field data to calculate the inter-station impedance. Sensitivity analysis has been conducted using the elementary effects method on the fault’s resistivity and geometry parameters for inter-station and regular impedance. It quantifies the influence of each parameter. The analysis shows that inter-station impedance produces a similar influence pattern as regular impedance for different parameters. The synthetic fault model inversion also shows that inter-station impedance can invert the conductive fault.