Patent ID: 8299794

Claim:
A method for electromagnetic geophysical surveying of rock formations under a sea-floor, the method comprising: towing a phased array emitter antenna including at least two alternating field emitting sources; and during said towing, transmitting alternating fields with a selected phase from each of the alternating field emitting sources, the alternating fields propagating partly down through the sea-floor and being reflected and/or refracted through the rock formations and partly propagating back through the sea-floor, wherein the alternating field emitting sources include a first alternating field emitting source and a second alternating field emitting source, wherein the first alternating field emitting source is towed at a first depth and emits a first alternating field having a first phase, and the second alternating field emitting source is towed at a second depth different from the first depth and emits a second alternating field having a second phase different from the first phase, wherein the phased array emitter antenna provides directivity such that a major proportion of combined electromagnetic energy from transmission of the alternating fields is transmitted downwards and a significantly smaller proportion of the combined electromagnetic energy is transmitted upwards, wherein said alternating fields merge to a total field and are measured by electromagnetic receivers which record corresponding field registrations.