Submarine cable electrical voltages to probe the Earth's deep interior

Geomagnetic field variations are often used for the study of the deep interior of the Earth. On the other hand, the geoelectric field has seldom been employed for these studies although it has sensitivity to phenomena that the geomagnetic field variations does not have. A reason for this is the smallness of the electric field of deep Earth origin if it is measured at the Earth's surface. Thousand kilometer scale trans-oceanic submarine cables are very attractive tool to measure such small but global scale geoelectric field, and the observation of the electric field from deep Earth is possible only when such long cables are used. In this paper, we show the capability of submarine cable electrical voltages to probe the Earth's deep interior, especially for the phenomena related with the toroidal magnetic field in the core.