Abstract: A string of seismic detectors is towed at a certain depth underwater by a survey boat over an area to be explored. A seismic disturbance is produced at a distance below the surface of the water such that the propagation time of seismic waves traveling from the disturbance and reflected from the water surface to the detectors is substantially the same as the propagation time of seismic waves traveling from the disturbance and reflected from the water floor to the detectors. Since the seismic waves reflected from the water surface are out of phase with those reflected from the water floor, the reflected waves tend to cancel or attenuate, thereby eliminating or minimizing these unwanted seismic signals.

Abstract: A number of seismic detectors are located in a two-dimensional array on the surface of the earth, either on land or at sea. One or more seismic disturbances are produced in the vicinity of the seismic detectors at points located to produce sampling of various subsurface reflection points to form one or more two-dimensional areas of coverage. For each seismic disturbance, the subsurface reflections thereof received by the various seismic detectors are recorded. In some embodiments, the seismic disturbances are produced at points located to produce multi-directional or multi-azimuth sampling of each of various subsurface reflection points and recordings for different ones of the seismic disturbances are combined to produce stacked recordings wherein multi-directional reflections from common subsurface points are added.