the present invention relates to methods of seismic exploration utilizing vibrationally generated , elliptically polarized shear waves in an earth medium for subsequent detection of one or more dimensions of orthogonal particle motion . the invention relies upon a shear wave source of a type which couples a continually rotating longitudinal force into an earth medium thereby to propagate an elliptically polarized shear wave for refraction , reflection or subsurface detection , various forms of exploration being well within the capabilities .