First results of the MOSES experiment: Sea sediment conductivity and thickness determination, Bute Inlet, British Columbia, by magnetometric offshore electrical sounding

A static electrical method has been developed to determine the electrical resistivity of crustal rock beneath the sea. The transmitter is a vertical, long‐wire bipole, extending from the sea surface to the sea floor. A commutated current, generated on the ship, is fed to two large electrodes: one near the sea surface, the other at the end of a long insulated wire. The return path for the current is through the sea and the subjacent crust. The receiver is a self‐contained, remote, microprocessor‐controlled magnetometer which is deployed from the ship to the sea floor and subsequently recovered. The data are measurements of the azimuthal component of the magnetic field as a function of transmitter‐receiver horizontal separation. The acronym MOSES has been coined for the method. The choice of the name MOSES is appropriate because the system geometry is carefully arranged to remove many of the adverse effects of the relatively conductive sea water. In particular, accurate estimates of sea floor resistivity ar...