Disclosed is a seismic surface cable detector system where the detector comprises axially aligned, tubular, piezoelectric elements having outer metallic coatings and the elements are radially polarized in opposite senses. Electrically nonconductive end walls on the elements define enclosed chambers and at the ends of the chambers are stainless steel electrodes. Mercury is placed in the chambers in an amount less than one-half of the volume of a chamber and provides a reaction mass and an electrical path between the piezoelectric material and the electrode plate. Take out leads are attached to the electrode plates. An open celled foam in the chambers prevents or inhibits splash. The mercury is injected into the chamber by a hypodermic needle which passes through a self-sealing silastic closure.
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