Can the Earth's magnetic field be sustained by core oscillations?

Some recent suggestions for generating the earth's magnetic field via short period oscillations of the liquid core are critically examined. Seismic energy seems inadequate for the purpose. Limits on the minimum amplitude of such oscillations are derived and these are shown to be so large that they would be accompanied by observable gravity anomalies. It is concluded that waves with periods much less than years are unimportant for the dynamo problem.