Multicomponent marine geophysical data gathering system

A method of geophysical exploration comprising:

• deploying a seismic cable in a body of water, said seismic cable having a plurality of particle motion sensor assemblies included within said cable;
• wherein said particle motion sensor assemblies comprise a housing, a gimbal-mounted particle motion sensor mounted in said housing, a fluid within said housing substantially surrounding said particle motion sensor, said fluid having a viscosity selected to restrain noise-generating movement of said particle motion sensor and to allow said particle motion sensor to maintain a selected orientation as said housing is rotate;
• and
• utilizing said seismic cable for detecting seismic data signals.

A method of processing marine seismic data to reduce spectral notches resulting from surface ghost reflections, comprising:

• determining the amplitude and phase variation with frequency of the output of a particle motion sensor assembly of a co-located sensor pair comprising a particle motion sensor assembly and a pressure gradient sensor, independently of any variation in amplitude or phase with frequency of said particle motion sensor assembly resulting from impedance mismatch between said particle motion sensor assembly and a medium from which a seismic wave is coupled to said particle motion sensor assembly;
• modifying the output signal of at least one of said motion sensor assemblies or pressure gradient sensors to compensate for said determined amplitude and phase variation, thereby generating modified output signals;
• and
• summing said modified output signals from said pressure gradient sensor and said motion sensor assembly.