The Empirical Green Function (EGF) technique, using the small earthquakes, recorded by a temporary seismological network, was applied to estimate the effect of the strong seismic motions, due to probable future great earthquakes in Tehran. The reconstruction of two earthquakes strongly felt in Tehran in the recent years, namely that of Changureh-Avaj (22/06/2002) and Kojour (28/05/2004) provide us the occasion to study the sensitivity of our simulations and to calibrate the considered parameters. Four reasonable scenarios, were considered, including the occurrence of a strong earthquake on the Mosha, North-Alborz and Garmsar faults. For these three faults, an earthquake of magnitude MW = 7.1 was simulated. For the last one, an event with magnitude MW = 7.6, corresponding to the historical earthquake reported for this fault was also considered.