A numerical model for evaluating the order of magnitude of earthquake-induced piezomagnetic anomalies is proposed. The stress field associated with normal or reverse faulting with a 10-MPa mean stress drop is determined by mean of displacement discontinuity method. The induced piezomagnetic tensor is then used to predict the associated magnetic field variations observed at ground surface. The model shows that for earthquake occurring in homogeneous magnetic masses with piezomagnetic properties of andesite rocks, the associated anomalies are of the order of 0.2 nT for faults with a 5-km dip slip and 2 nT when the dip slip is 20 km long. The variation of magnetic field for the case of a piezomagnetic dyke intruding a nonmagnetic body is found to be much greater: for a 4-km-thick dye parallel to the fault and located 4 km from it, the observed ground surface magnetic field variations is of the order of 10 nT. These results outline that induced piezomagnetic effects strongly depend on the stress drop and stress distribution along and outside the fault, the location of the earthquake source with respect to the piezomagnetic body, and the piezomagnetic properties of the rock.