Apparatus and methods for multicomponent marine geophysical data gathering

A seismic sensor streamer having an internal diameter no greater than about 66 millimeters, comprising:

• a plurality of pressure gradient sensors disposed at spaced apart locations along a streamer cable;
• the streamer cable adapted to be towed behind a vessel through a body of water at a selected depth below the water surface, and
• a plurality of particle motion sensor assemblies, each particle motion sensor assembly substantially collocated with one of the pressure gradient sensors, each particle motion sensor assembly comprising a housing, a particle motion sensor gimbal-mounted in said housing, a fluid within said housing substantially surrounding said particle motion sensor, said fluid having a viscosity providing sufficient damping of sensor movement to reduce noise while enabling sufficient movement of said particle motion sensor to maintain said particle motion sensor in a desired orientation as said streamer and housing are rotated, and wherein said particle motion sensor assembly has an acoustic impedance within the range of about 750,000 Newton seconds per cubic meter to about 3,000,000 Newton seconds per cubic meter, and wherein the dimensions of said particle motion sensor assembly are adapted for mounting within an internal diameter of said seismic streamer cable having an internal diameter no greater than about 66 millimeters.