FLEXIBLE GEOPHONE

A pressure sensitive seismic detector is formed of at least two elongated sheets or layers of flexible, rubberous material having particulated magnetic material embedded therein. The particulated magnetic material is preferably barium ferrite. The layers are connected together at spaced apart locations and magnetized across the width thereof so as to form a plurality of parallel bar magnets along the length thereof with the poles of adjacent magnets reversed. Coils are wound between the bar magnets on at least one of the layers. Preferably, the sense of winding of adjacent coils is reversed, and the magnets formed in adjacent flexible sheets are aligned so that they repel each other. To form a hydrophone, the apparatus is encased in a thin flexible bag or enclosure and positioned in a liquid filled cable housing. In one embodiment, magnetic metal foil is affixed to the nonengaging surfaces of two adjacent layers of rubberous material.