Electromagnetic study of the Atlantic Continental Margin using a section of a transatlantic cable.

The induction of currents in an approximately 1200 km length of the TAT-7 transatlantic telecommunications cable by geomagnetic field fluctuations is studied. Analysis of the induced voltage drop across the essentially geomagnetically east-west oriented cable and of magnetic field data obtained at field sites at the cable head (Tuckerton, N.J.) and in New Hampshire suggest that there are telluric currents flowing in an approximately north-south direction off the East Coast of the U.S. The region of the induced current flow may be related to the East Coast Magnetic Anomaly (ECMA). If so, these results indicate that in addition to being a static magnetic anomaly, the ECMA is a structure with significant electrical characteristics such as higher conductivity.