P and S seismic waves impinging on a liquid-solid interface give rise to energy on both horizontal and vertical geophones. The response of the vertical geophone at an interface is quite similar to that on a free surface. The horizontal geophone has a stronger response to impinging P waves and a smoother response to incident S waves. Presented here is a filtering method operating in the τ-p domain, that separates P and S waves by taking into account the geophone response. The filter requires estimates of the near-interface P and S wave velocities but is robust with respect to errors in these velocities. The P-S separation filter is tested on synthetic elastic-wave data and performs the wave type separation well.
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