Probabilistic seismic hazard analysis (PSHA) is nowadays the more complete analysis method to estimate the seismic input for structural analysis. However, it is strongly influenced by seismogenic parameters and attenuation equations. Here PSHA using empirical Green’s functions (EGFs) with 2 + 2 variables is carried out, which, as proposed, are related to each other through the moment magnitude. This combination, already known as “physically based PSHA (pb-PSHA),” is an approach that should be disseminated since it could provide a good alternative in countries where the seismogenic zones and/or attenuation equations are not well established. The proposed model, using differential equations, is based on a linear fault, random/periodic/impulsive/linear source functions, and punctual hypocenter. Results are shown in terms of new seismic parameters, specific return periods, and ground accelerations. The studied country is Portugal since it appears to the authors that no study has been published about pb-PSHA for Portugal. In this sense, the model could be of importance for hazard analyses to incentivize more research on the earthquake source physics.