This award provides funding to design and build a set of instruments to measure the electric and magnetic fields while deployed in the submarine environment of continental shelves. The design will permit simultaneous recording of variations in the horizontal electric field, the 3-component magnetic field, tilt of the instrument, and ambient temperature. The instruments will be developed and built by collaborating groups at the Woods Hole Oceanographic Institution in Massachusetts and the Scripps Institution of Oceanography in California. They will subsequently be used as an essential part of a planned magnetotelluric geophysical transect reaching from the continental southeastern Appalachians to the deep Atlantic ocean. Electrical conductivity in rocks, which depends on ionic fluid content, metal or carbon content, and temperature can provide information about large scale geological structures that is complementary to other geophysical measurements such as seismic or gravity. Recent experiments have demonstrated that large-scaled structures can be imaged with this approach but that a combination of land and seafloor measurements are essential to proper interpretations of continental structures extending seaward. Instrumentation for measuring electrical conductivity on land and in the deep (calm) ocean environments already exist. This project will result in instrumentation to fill in the gap for measurements in the shallower waters of the continental shelf areas.
