S waves detection in a Zero offset VSP. S waves Velocity estimation, Poisson modulus and seismic quality factor (Q) for Quintuco-Vaca Muerta Fms.S waves presumably generated in the near surface have been detected on a Z-VSP and can be followed along the whole profile. The intensity of this Down S-wave train allowed the estimation of shear velocities (Vs) in several intervals along the well, including the Quintuco and VacaMuertaFms. These velocities were used together with compresional velocities (Vp) in the determination of elastic parameters such as Poisson Modulus (s). Seismic quality factors Q(p) and Q(s) were also estimated from the analysis of the Down P and S wave trains.