U.S.-Japan Cooperative Science: Studies of Mantle Electrical Conductivity Beneath the Pacific Basin

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

9909931 Chave This award supports a two year collaborative research project between Professor Alan Chave of the Woods Hole Oceanographic Institute in Massachusetts and Professor Hisashi Utada of the University of Tokyo in Japan. The researchers will be undertaking a study of mantle electrical conductivity beneath the Pacific basin. Due to the recent turn down of analog submarine telephone cables by their commercial operators, an opportunity has arisen to make planetary scale measurements of the geoelectric field on unpowered cables at many places around the world. Currently, investigators have instrumented a total of six Pacific Ocean and two Atlantic Ocean cables and the Japanese are making similar measurements on four other western Pacific cables. These data will be merged and used for two purposes: 1) a study of the size and spatial variability of the poloidal electric field produced in the core using time series that are at least 4 times longer than any previously available, and 2) a study of mid-mantle electrical conductivity and its lateral variability beneath the Pacific basin using a combined magnetotelluric/geomagnetic depth sounding approach. Substantial progress has been made in using cable data for deep magnetotelluric sounding of Earth's conductivity structure and they hope to extend and improve that type of result. The project brings together the efforts of two laboratories that have complementary expertise and research capabilities. Very long period submarine cable data have application to studies of core processes by detecting leakage currents from the toroidal magnetic component of the geomagnetic dynamo (whose magnetic field vanishes at the earth's surface). This research advances international human resources through the participation of a younger scientist. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understanding and cooperation. The researchers plan to publish results of the research on the web (www.whoi