By means of a Monte Carlo simulation, we explored the extent to which large earthquakes may induce fluctuations on the secular variation of the Earth's magnetic field. We speculate that the energy released by large earthquakes may perturb the dynamical interaction between the outer core and the lower mantle, and consequently give rise to rapid variations of the main field detectable on the Earth's surface (geomagnetic jerks). In order to test the existence of a possible correlation between the seismic activity and the occurrence of magnetic jerks, we examined both the number of earthquakes and the total moment released in a lapse of time preceding the known geomagnetic jerks of this century. Our results are compatible with the hypothesis of a causal relationship between periods of time characterized by an anomalous global seismic activity and rapid changes of the main magnetic field. Several possible mechanisms accounting for such a correlation are discussed.