Method for electromagnetic geophysical surveying of subsea rock formations

12121122112121212nr1r2r3rnA method for electromagnetic geophysical surveying of rock formations under a sea-floor comprising the following steps: *-towing first and second alternating field (E, E) emitting sources (s, S) in first and second depths below the sea surface, said first field (E) having a first phase (Φ);-said second alternating field (E) given a second phase (Φ) different from said first phase (Φ), said sources (S, S) constituting a phased array emitter antenna with directivity for transmitting a major proportion of the combined electromagnetic energy downwards;-said first and second fields (E, E) for propagating partly down through the sea-floor and being reflected and/or refracted through said rock formations and partly propagating back through the seafloor;-said first and said second fields (E, E) for merging to a total field and being measured by electromagnetic receivers (r, r, . . . , r) recording corresponding field registrations (E(t), E(t), E(t), . . . , E(t)).