The coaxial telephone cable crossing the Sea of Japan was laid by ROSTELECO
M (Russia), KDD (Japan), and the Northern Telegraph Company (Denmark) in 19
69. In 1995, a new optical-fiber cable was put into operation, and the old
cable was given to Russian and Japanese geophysics for studying the natural
electric field variations in the Sea of Japan. This made it possible to an
alyze regional behavior of electrical variations in one of the marginal Rus
sian seas using a measuring line longer than 700 km. This paper discusses p
reliminary results of the experiment that started on March 27, 1996 and aim
ed at solving two geophysical problems: (1) estimation of the electrical re
sistivity of the Sea of Japan lithosphere and (2) monitoring of the water m
ass transport.