Geophysical data acquisition system

A marine geophysical acquisition system comprising:

• one or more seismic signal sources to be arranged in a sea or at a seafloor for emitting seismic signals;
• a plurality of seismic sensors for sensing propagated seismic signals emitted from said one or more seismic signal sources, said seismic sensors being arranged on a receiver cable to be extended in the sea;
• one or more electromagnetic (EM) signal sources arranged in the sea, or on the sea floor, for emitting EM-signals, said one or more EM signal sources being provided with electrical power through an insulated electric cable connected to an electric signal generator aboard a marine vessel;
• a plurality of electromagnetic sensor electrodes for sensing EM-signals propagated from said one or more EM-signal sources, said EM sensor electrodes being arranged along and on said receiver cable, wherein said receiver cable includes a plurality of electronic units, each electronic unit including a voltage amplifier having a first voltage input line to be connected to a first one of said EM sensor electrodes and a second voltage input line to be connected to a second one of said EM sensor electrodes, said EM sensor electrodes being arranged at a generally fixed distance relative to said seismic sensors along said receiver cable.