Multicomponent Data Acquisition
When acquiring multicomponent seismic data, careful attention must be given to the vector motions associated with P and S seismic displacements. For example, when acquiring onshore data with a vertical-displacement source, it is not necessary to be concerned about the azimuth orientation of the source at a source station. In contrast, when a horizontal-displacement source is used to generate S-wave data, it is essential to know the azimuth orientation of the source baseplate at each source station and the direction of first motion of that baseplate and to create consistent baseplate azimuth orientations at all source stations across a survey area.
Likewise, it is mandatory to know the positive-polarity ends of the two horizontal sensor elements in a three-component (3C) receiver and to orient the horizontal sensors so that the positive-polarity ends point in consistent azimuths at all receiver stations. Such caution is not required when deploying vertical sensors used to acquire one-component (1C) P-wave data. If it is not possible to orient horizontal sensors in a consistent vector azimuth, as can be the case when four-component (4C) receiver nodes are deployed in deep water, a data-processing procedure must be implemented to determine sensor orientations at every receiver station.
Analysis of the vector motion induced in seafloor sensors by first-arrival wavelets traveling from a large number of surface source-station coordinates is a common method used to determine 4C sensor orientation. This orientation information then can be used to mathematically transform data to a new coordinate system that describes data that would be