Abstract: Sets of at least three geophones are oriented in different directions perpendicular to the longitudinal axis of a seismic cable in which they are assembled, so that at least one geophone in each set will detect substantially vertically-propagating reflected seismic signals when the cable is rotated in any orientation about its longitudinal axis. Arrangements may be provided to selectively enable the one geophone of each set that has its axis most nearly oriented to the vertical.