f A Hybrid fk Filter for VSP Wavefield Separation

Estimates of anelastic attenuation from vertical seismic profiles (VSP) normally use the downgoing wave arrivals. Unless the geology of the survey area is very simple, any window chosen around the direct arrivals (downgoing wavefield) is likely to contain a significant amount of upgoing energy, leading to distortion of the downgoing wave spectra. As attenuation measurements are based on the spectral properties of the seismic data, they are very sensitive to the methods used for wavefield separation if these distort the remaining downgoing wavefield.