f Detection of Polarity Reversals in Multicomponent Data

It has now become comparatively common in shear-wave 'exploration to analyse qS 1 and qS2 to determine the orientation and degree of subsurface anisotropy. Such measurements are best made using multicomponent VSP, as an increase in resolution can be obtained with the overlap of information. Unfortunately, such data are also more sensitive to inaccurate knowledge of the source and receiver conditions, and can result in large errors in these estimates (Zeng and MacBeth, 1993a). Here we address one important aspect that often occurs in real data: the effect of polarity changes in the source and receiver components.