Polarization filter for multi-component seismic data

D. T. Nguyen, R. James Brown, Donald C. Lawton

The application of three-component seismic data has gained a growing interest in exploration geophysics. The common use of three-component recordings in seismic survey gives access to the real movements of the free surface of the Earth, hence we can deduce the trajectory of this particle displacement which is the response from a complex incoming wavefield. This wavefield is the superposition of body waves and surface waves as well as other disturbances. Conventional filtering processes, such as bandpass filtering, and frequency-wavenumber filtering, are often not very efficient in separating them.

The polarization is characterized by parameters that determine the trajectories of the particle motion of a medium. The trajectories of particle motion are in most cases represented by complex three-dimensional curves. The tracking components of each wave are found by combining the discrimination of waves, based on the direction of propagation, with that according to their type of polarization. The optimum component will correspond to the vector of oscillations.

Polarization filtering of waves based on the combination of characteristics of particle motion at a point, with their direction of propagation in space, makes it possible to separate regular waves with different polarizations propagating in different directions and with different velocities.