A pressure gradient sensor for seismic and other applications utilizing the principle of diamagnetic drift. The sensor comprises at least one transducer, each transducer made of or containing a medium having at least one species of mobile charged particles such as electrons or holes that exhibit diamagnetic drift under a pressure gradient. A magnet and a pair of electrodes are installed in each transducer. Diamagnetic drift current collected by the electrodes can be measured by an ammeter or similar device, and formulas and methods are disclosed to determine the pressure gradient from the measured current.