Alternate description of the wavefield generated by two vertical vibrators in counterphase

Donald T. Easley

Experimental evidence for the existence of shear waves in the near-vertical direction generated by two vertical vibrators in counterphase was collected by Edelmann, who also made some conjectures as to the cause of these shear waves. Dankbaar put the conjectures of Edelmann on a more theoretical footing, by expressing the wavefield as the far-field radiation of a couple. I propose the possibility of a different dynamic mechanism, namely the radiation from a double-couple system from vibrators with displacements in counterphase.